BiasPro Customer Testimonials & Feedback

Testimonials & Feedback

First off I want say this is a well made, American product. The plate voltage switch makes it easier and safer, and the duel probes allow you to bias to the highest value of all the tubes. It is essentially the best in it's class, and at a decent price too!


I got my Bias Pro a few days ago now ( speedy postage BTW ) & I have just used it for the first time and i must say the quality & ease of use is second to none . Such a well built bit of kit . I have been putting buying this off for a while now but i'm so glad i got it . Now i can Bias all my amps with ease . cheers . Dave from Australia


Got my BiasPro!!! I have no experience biasing an amp but this made it very easy! Everything was just as I ordered and just as you said it would be. Thanks for a great way for me to save money by not having to use an amp tech for such a simple task. Thanks, Kevin


Hello Ken. The bias tool arrived safely Yesterday, and no customs fees  Thank you for lowering the value for me. I must say I am very impressed with the quality of your work and your great attention to detail. The label over the battery was very nice to see. My TAD Bias master looks like a toy compared to yours. Thank you again for a fantastic product and great service! Have a nice day     

Regards, Tony Packer  Music Repair Services Wales


Hi Ken I’ve just finished refurbishing my Marshall JMP800 50W Master Volume amp, and the BiasPro tool has been a godsend in helping me do this. Firstly, it highlighted that my bias and plate voltage were WAY off what they should have been, and probably why the EL34’s were glowing brightly all the time  Replacing the bias capacitors (and the filter caps for good measure) got me to bias currents and a plate voltage on the BiasPro that now made sense. I then had an oscillation problem at high gain/low volume that took me a while to sort out but that’s done now as well. The BiasPro allowed me to check the bias currents and plate voltage extremely easily and SAFELY, and meant I could use one meter for all readings by selecting what one I wanted rather than having multiple meters. All in all this is a great product, and I wouldn’t be without it now that I’ve got it!

Many thanks! Steve


The BiasPro is really a easy to use tool for the bias adjustment without touching the circuit inside my amp, especially I like the plate voltage and bias current switch that help me a lot when tuning the bias with carefully monitoring the plate voltage. This is the first time I do the bias check, lucky I was able to discover my amp has some problem on the bias current and I need to take the amp to a amp-tech before damaging my new NOS power tube. I will surely recommend my friend to get one of these for the amp maintenance. Best regards,



Hi Ken, Just wanted to drop you a line to express how happy I am with my new BiasPro. Opening the package, I was greeted with what looked like really great craftsmanship. The probe looks like it was assembled with care and attention to detail. The heat resistant sleeves near the sockets are a nice touch. The sockets inserted nice and firmly, but not too firmly, and felt solid. The probes worked perfectly and were very accurate when compared to a manual bias with 1ohm resistors. The Plate Voltage/Current switch worked flawlessly and really makes getting an amp biased-up a breeze. All in all, I couldn’t be happier! Thanks for a great product! Will shop with you again!  Jerry McDougal Satyrnine Amplification


Just wanted to let you know received unit and am very pleased. I have already biased two amps with it. Got my blackface Bassman sounding incredible with power tubes matched within .5ma and biased at 50%. Volume is more than adequate, tone exquisite. Found my old 71 Champ ( all original ) was biased at 110%. Biased it down to 70% with some other mods cleaned up the tone nice. Great products easy to use.

Thanks a bunch


Hi Ken, My BiasPro came in and have used it to bias my Marshall 1987x. Once I understood the math behind the process and got my amp tuned properly, it hit me how clever your BiasPro is. This thing is fantastic and my amp is useable again! I’m more empowered as a musician to get the most out of my amps now, and I’m really really glad to give my business to a guy like you instead of some giant corporation. Also I really appreciate that you bothered to email with me on a holiday. That is uncommonly great service, brother. Cheers!


Ken,  I received my QuadStage BiasPro MQ13 w/VI MODULE and was very pleased with it. It was straight forward and easy to use. I was able to bias my 6a20 (Deluxe Reverb Clone). Your tool allowed me sort through a lot of vintage 6v6gt tubes and find ones that really did having matching Cathode current. Since that amp doesn’t have individual bias adjustment for each tube this is very important. Found a set of old Magnavox tubes .. they sound great. It’s nice knowing that my bias is set right and not just assuming it is. I also like having the VI/Module so I can read the Plate Voltage and the Cathode current. Another feature that I didn’t appreciated at first is having the Plate voltage switch on the probe separate from the meter (just in case you ever need to use the probes separate from supplied meter). For amps that have external bias adjustments it’s so cool not even having to open up the chassis to set your bias. It’s a great tool Thanks Ken! Brad Mathis Tucson, AZ


Hi Ken, Your Bias Pro was perfect for adjusting the individual power tube bias pots on my Rocknroll Amps 50 watt clone of Robben Ford's Dumble #102 amp. Talk about singing! It is so much easier to use, the nuisance of removing the chassis front the cab in many cases is avoided by using this product. Thanks, Gary "Wheaties" Allen


Hi Ken, I recently received my BiasPro and companion plate voltage probe via post and just wanted to let you know how well the device worked.  Out of the packaging I read through the instructions and proceeded to re-valve and re-bias an Orange Rockerverb 50 MkII with JJ tubes.  The Bias Pro worked a treat to initially determine the plate voltage and bias values, which I could easily adjust to my preferred settings.  Excellent product.  I am an experienced guitar technician with a few years experience doing basic work on amplifiers.  This product has reduced my work time significantly and improved my safety factor ten fold, well done.  I am very happy. Regards, Nathan Sydney, Australia.


Ken, I finally got a chance to use my Biaspro to rebias a new set of EL34's in my Bogner Shiva head this weekend and wanted to drop you a line.  I worked like a charm!  Everything was very well-built and the instructions were VERY easy to follow.  I'd recommend this bias meter to absolutely anyone!  I've got the Quadstage BiasPro Q10 with two (2) BiasPro 8C bias probes and one (1) BiasPro PV8C plate voltage probe.  If I ever get an amp with four (4) octal tubes or an EL84 amp I'll DEFINITELY be ordering more probes!

Also, if I ever get around to it, I've still got a couple of guitars that could use nut adjustments and/or replacements and some possible fretwork.  Just tough to find the time to get ANYTHING done lately! 

Thanks a ton, Matt Thompson


Hi Ken, I ordered the Q10 with 4 current reading probes and 1 voltage probe for el 84 type tubes. The product is really outstanding in quality and so very accurate.

When I received the kit, I measured the tubes in my guitar amp as a reference and then I installed a matched quad of JJ el 84's and began to take measurements. Plate voltage came in at 530 V and current readings of 13 ma, 16 ma, 16 ma and 19 ma (without biasing the circuit (original tube quartet read 13 ma for each tube) so you guessed it, the discrepancy was way too large so I had to order another matched quad to at least get in the ballpark figures.

I got the new set yesterday and this afternoon I proceeded to install and bias the amp. I had 8 tubes to play with as my thinking was that what dealers sell as matched sets may well be in a tube tester but in an amplifier, they may not be so well matched.

I spent 3 hours inserting tubes and trying different permutations before I finally got a quad of tubes to read close enough to call it a successful mission. The amp is a Seymour Duncan 84-40, the diagram is readily available on the internet.

All I can say is that your product was a charm to work with, trust me the probes came in and out of the sockets too many times to count because of the tube permutations that I tried out. The pins on your probes are dead straight after that torture test, I had to straighten the pins on the tubes too many times lol. You offer an outstanding product that is so easy to use and the probes can withstand some abuse, mind you I handle tubes and probes gently but still the probes got in and out of the sockets so many times that I am amazed that they are of such a high quality.

So if this can help any of your customers, even though the differences are beyond 10% (ideally it should be within 5%), try switching your tubes to different sockets, bias below nominal value (60%) and bring it up gently toward the current draw you are aiming at. Large discrepancies at higher current draw may be closely matched at lower (but usable like 60% of max current) current readings.

Still as a buyer, don't believe the matched set that you just bought is actually matched, you may need more tubes to find the closest match.

Thanks again Ken for a fantastic product, I love its accuracy. Regards, Yvon Loiseau


Hey Ken, Well, where do I start?  I tried out the MQ13 with the voltage probe and then the two bias probes on my 7591-driven Ampeg GS-12 Rocket-2 this evening.  

First off, let me say that both your instructions/write up on how to use the MQ13 with the bias probes and the supplement for the voltage probe are written really well and everything was explained clearly.  I had no problem understanding the process and, after reading it through very carefully, the process was quite intuitive.  That was this afternoon.  Then this evening I tried it out on the little Ampeg (cathode-biased push-pull 7591s) just to check it out.  The whole process took maybe 25-30 minutes tops, but that included removing/replacing the back and I was really taking my time and lettng things cool down a bit between probe swaps.  It also included running some calculations at the end to determine at what percentage of max plate dissipation this little cathode-biased amp was running at.  

And I'm so glad I did!  I've had this amp since a few months after it was manufactured in 1965 and all the tubes are still original!  I had recently tested all the tubes on my Hickok TV-3 and they all tested string to various degrees.  The two push-pull 7591As were fairly closely matched for transconductance coming in at 9200 and 8750 micromhos, where 4250 is minimum good on the TV-3 -- incredible after 49 years even though it hasn't been used much in the last few decades.  

Anyhow, after testing with the MQ13 it became clear the tube bias was quite mismatched (see below), and that probably suggests some components in this old calthode-biased amp have drifted substantially out of spec, not surprisingly.  

Results were as follows:  #1-7591A showed 351 plate volts and #2-7591 showed 350v (I checked both just for the heck of it).  Bias current on #1-7591 was 43.3mA and on #2-7591 was 52.1mA!   Doing the calculation to see what percentage of the 7591's 19-watt maximum plate dissipation it was running at showed 80% on #1-7591 and 96% on #2-7591 -- seems very high even for a cathode-biased amp?  And that may explain why #2-7591's transconductance has aged more rapidly than #1's.  So, I will likely send this amp to my tech for a thorough going-over wen I can afford it -- it is a little noisy (randomly) so might well need a cap job and probably some out-of-spec resistors replaced as well.

In summary, I'm glad I tried your products!  They worked flawlessly and demonstrably confirmed what I has suspected -- that this little Ampeg needs some professional TLC -- I suspected such but I just didn't realize how far out of spec it really had gotten since it was still working acceptable well overall for occasional practice.

I also have a 1963 Ampeg Super Echo Twin (ET-2A) which I love and am in the process of refurbing and it will likely need a cap job too but now I'm anxious to see how it tets too!.   And the Fender Super 60 210 I want to try using the probes on to adjust the bias once I have time to retrieve it from storage at my friend's house and finish refurbing it -- probably by spring.

Ken, feel free to use whatever pieces of above you would like as a testimonial on your website.  I am very pleased with it all!!  All I'd ask is that you don't use my last name -- maybe just say "Dan from Saugerties, NY" or something like that.

Thanks again for such a nice set of products -- so nicely designed and that work so well -- and for all your help with the weirdness we encountered with ebay not working right -- glad I bought them!

Best regards, Dan 


Ken, Thanks for sending through the meter and probes. They took only about a week to get to me here in Australia and were packed very carefully. Testing has been easy and straightforward. Firstly, I was able to establish the plate voltage of my amp using the plate voltage probe. Having the shunt resistor close to the socket meant I could trust the reading - and conduct the test safely. Testing the cathode current was also very easy with the twin 8-pin probes. In the end, within about an hour I had fully biased my amp for two new EL34s. I saved money on the tech - but best of all had the satisfaction of doing the job myself. Thanks again for an excellent product I’ll use each time I change output tubes. Matt - Australia


I used the BiasPro Q10 to find 2 matching vintage Mullard el34's from my random stock. Then I used it to set the bias on my 1985 50w Marshall JCM 800 with those 2 tubes installed. I followed the very easy to read and understand instructions that were included with the BiasPro and was very suprised at how simple the procedure was. The optional Plate Voltage Probe made things even easier by allowing me to read the amps plate voltage without having to poke around in the chasis. The BiasPro Q10 and its bias probes are build very well and should last a long time. Im very happy with my purchase and my Marshall has never sounded better. Thank you!

Anthony M.


Hi Ken, So I just got done biasing 3 different amps and the BiasPro worked like a charm. Hooked it up to my multimeter and tested it on EL34's/KT77's and 6L6GC's -- super easy to operate, very accurate readings, and way safer than poking around in the chassis. The youtube link you have in your ebay listing was really helpful too (for showing how to do biasing calculations, etc.). All in all, I couldn't be happier with the BiasPro. For anyone who's serious about maintaining their tube amps, this is going to save them a lot of money in the long run. Thanks again for building such a quality product. Robert Brown


The Tube Bias Probe Tester Tool Socket is at home. Extraordinary build quality and superb precision! I am very satisfied with the purchase, and it has been a pleasure to do business with you. Of course, I leave positive feedback in ebay.
Best regards.


Ken, I've really enjoyed using the BiasPro Q10 that I purchased from your company via eBay.  It works great and is well worth the $$ for a professionally made product,  I have a vintage amp restoration business and was getting really tired of installing cathode resistors in the amps for biasing.  This product is simple to use and makes the job fast and accurate! Tom Schupbach


I used your tester it worked great, simple and easy to use, your instructions on biasing were very helpful

thanks rex


Ken,  Thank you so much for a very pleasing and transaction. I am very satisfied with the items. I got my bias probe right real fast and was really surprised when it includes  biasing informations to which I did not expect. It's nice doing business with you Ken and fully satisfied with the outcome. Your #1 on my lists! sam


I received my Bias Pro unit this morning, and have already used it to bias three of my prize amps - it works exactly as advertised, and makes the job so much easier and accurate! I now have total confidence that my power tubes are running right in the center of the 'sweet tone' zone... Thanks, Hadley Hockensmith (Neil Diamond Band/LA Studio Musician) 


Hi Ken, Finally had the opportunity to try out the Bias Pro and it didn’t disappoint. Easy to use, clear instructions made the job simple. For your information I had purchased an AXL AKITA AT30 amplifier, made in China with stock Shuguang 6L6GC tubes. I was lucky in that I had purchased matched sets of RFT ECC83 pre-amp tubes and a matched pair of Tung Sol 6L6GC STR tubes which I planned to put in the amp. I tested the stock Shuguang tubes (remember the amp was brand new with less than 3 hours playing) prior to doing any changes. Results below

Tube 1 Shuguang 6L6GC = 41.6mA

Tube 2 Shuguang 6L6GC = 46.3mA

Not exactly matched were they? Before tweaking any bias I decided to test the brand new Tung Sol 6L6GC STR’s, results below

Tube 1 Tung Sol 6L6GC STR = 34.2mA

Tube 2 Tung Sol 6L6GC STR = 34.3mA

I’m happy I did this before messing around with the bias on the amp. No biasing was necessary, if anything I could hot them up a bit but for my preferences and playing they are spot on.

Again, I can’t recommend the Bias Pro highly enough.


Richard Fearon

Saharri Park T'breds WA


Hello Ken, I bought the Quadstage Bias Probe Q10 from you back in February and now that I've had some time to use it with a few different tube changes and amp bias's, I wanted to let you know that product thing is amazing!!!! Actuate and flawless. I love it!!! Thank you, -Carl


I wanted to thank you for the bias probe - I do a lot of amp repair & tube amp setup - this is the 3rd Bias probe I have owned - The first one was a Groove Tubes Bias Tool which lasted over 9 years - the second probe was purchased from SRS webstore off of ebay - this lasted maybe 5-6 months & was only used around 15 times before the wires snapped right off from being thin & having no strain relief. I also broke a couple of EL34 Guide pins in the SRS Probe because the socket was low quality - you get what you pay for!! Your Bias Pro is top notch - Down to the wires, strain relief & socket - I could tell right away that this was well built & will last many years as well as providing accurate readings. I had an orange Thunderverb 50 that had an electronic problem & the SRS Probe broke in the middle of biasing the amp - I had to shut the amp off until it was Biased so I appreciate your instant shipping - I rarely leave feedback & never feel the need to email an ebay seller - Thanx Again 


Helped me find a bias issue I have with a Mojotone JMP 45 amp kit my dad made for me. The adjustable bias pot ranged between 54-87 mV! Way above optimal 45mV to spec it to 70% max. Troubleshooting issue now. thanks for potentially preventing some damage. FB.


It was the first time i ever biased tube amps, i have 2 for stereo, yea i know im spoiled, but im happy so thats good! Anyway  what a difference, both heads were off and too hot, they're el34 quads, albion tct100's  i followed your instructions, plus some advice from albion and in about 45minutes, warm up time and cool down time included, i was done! the sound was improved 10 fold and im sure my tubes will last alot longer.   P.S.  the guy who used to bias my heads is permanently fired, he was purposely burning up my powertubes for job security, he lost alot of other customers too.  knowledge is a powerful tool, i now know how to change new parameters, VERY important ones, and have the ability to play mad scientist, Thats my favorite job right there, Oh yea, don't be stupid with high current, thats the true killer!  there now noone can sue me for the mad scientist bit!  If you guitarist out there do not get this product and learn to use it, you are pissing away money and multiple available tones in your amp, seriously......try it! S Thom


yes sir, the bias pro worked very good. I am a pro. musician and have been for over 35 years. all I use are fender tube amps and this worked very well easy to use, and will keep your amp performing gig after gig. thanks, scott walker


I have already saved so much money and have been able to bias most of my amps....a side benefit has been calling out tube suppliers that have sent me "matched sets" that have varied significantly more than what is acceptable. Your tool will help keep them honest. Thank you. - felirick


Mr. Koga takes his products and customer service seriously. My QuadStage BiasPro Q10 just arrived yesterday. Shipping was extremely fast. Customer service was above and beyond. As for the product. It seems well made. It comes with two bias probes of your choice plus extra RCA bias jacks to add more probes. I haven’t had too use it much since it arrived yesterday. But it seems to work just fine. Very easy too use. Comes with nstructions and cathode current range chart. Keep up the good work Ken!  Thanks, Andy


Hi Ken, just wanted to say that I am more than satisfied with the MQ10. Shipping was faster than I (and USPS) expected, arriving two days earlier than what they told me. Out of the box, it was super simple to set up and the instructions make it virtually impossible to mess anything up. I play out of a modded 6505+ running on two EL34's, and found out that the bias setting on my amp was only allowing the EL34's to run at 14-15 mA. After using your product, I biased the amp so the tubes are running at 35 mA and it made a world of difference. I'll never have to waste my time and money giving my amp to a technician to replace the tubes ever again! Great product and customer service. Keep up the good work! - Joel T


So I finally got to use this yesterday and man am I happy I bought it. Super great tool. Helped greatly. Also, because I bought the 4 probes I found that one of my "matched" pairs was about 10 ma apart. Thanks for such an awesome product. - contentsunknown


Ken, One was a Q 10 and the last one is a MQ 10. I purchased both since I have 3 benches and sometimes need a meter that can be moved around, hence the MQ 10. As far as your products go, I think you are selling as good of a product as any of the other guys and probably better than most, Allesandro, Weber. I have had their stuff and am constantly repairing it. You seem like a good guy and know what you are doing, so why not give yours a try. BTW, I did order a Compu-Bias for 259.00 and have never received the meter or got my money back. I much rather deal with an individual than some company that just takes your money. - rodgersamps


Ken, I think it's a great product. Hooked it up to my multimeter and biased Hot Rod and my Deluxe Reverb. Thanks much. - Rich


Hi Ken , well here's my review and yes i can give your bias meter the thumbs up .. all went well apart from finding out my new "matched" quad of Winged C are actually 13ma apart , though this is really another benefit of doing it yourself in a way as if i took it to a tech unless i was lucky enough for them to have a match for my dud tube i would probably have to pay anyway and take it back to get redone once another tube in range could be sourced , i can match one closer with my old spares to use till a replacement arrives now ..i have also had to wait 2 weeks just to get my amp baised at times so am happy to be doing it myself , was all straight forward and very easy to use and another reason i went with yours even though a cheaper one is available was because im picky about the amp (1995 VHT/ Fryette classic 2x12 combo ) and tone and wanted a precise plate voltage reading so the the optional probe was a no brainer ... i recommened this to anyone with basic electrical knowledge , specifically caps discharge and how amps hold a lethal charge even when unplugged ..if you understand this and are careful where you poke around then biasing / matching your own tubes with this unit is very easy and you'll get your money back in no time ... not to mention no longer having the hassle of drop off / pick up / no amp to use periods .. good stuff , all looks well made and i get the impression you stand behind your product should any probs arise . All good , cheers , Cam .


Hi,I,m very pleased with your Bias Pro it works a treat,I wish to purchase 2 BiasPro 9C leads as my new laney amp runs EL84's, would you send an ivoice. cheers Graham


Hi there, In 1994, I bought one of the first Fender '65 Deluxe Reverb reissues. While it's always sounded very good, it's never been "great". With the recent introduction of better quality 6V6GT tubes, I've been itching to see what I could do with this underappreciated workhorse.

Biasing with the sturdy MQ10 and accessory probes couldn't have been easier. Armed with a cotton cloth to handle the tubes and a small screwdriver to tweak the Fender bias pot, I biased the TungSols in 15 minutes flat. Five minutes of that time was spent reading the included clear instructions on how to successfully bias your output tubes. It's like having a new amp!

If you know how to pull a tube out of your amp, you're halfway there. Even better, it also let me compare the TungSol 6V6GTs to some JJ 6V6S tubes I had laying around. The MQ10 let me tweak my amp in a few minutes. More time playing, less time chasing tone!

Thanks for this great tool. bc


Hi Ken, I received the the bias pro for my fender dual showman red knob head which runs 6l6GC power tubes.

It also has a port to check the bias in the back but its just a single port which checks the overall bias of all four tubes not individuals. So using the bias pro with the 8c plugs I followed the directions that you provide with the unit and found that one of my so called matched tubes isn't so matched.  Thanks for the help and a Great product. Lee Faria


I recently purchased the quadstage bias pro and I love it. As a novice and a long time tube amp collector the bias pro lets me know exactly what my current is going across my power tubes relating to the overall health of my amps.I currently have 13 point to point fender,vox and marshall amps which translates into a lot of power tubes. I find the tool safe and accurate and wish I would have gotten one sooner. I would recomend this tool to every tube amp owner.  Paul Christman  Green Bay WI


Hi Ken, I recently purchased your BiasPro 9C-S and I love it! Its built very well and makes biasing an amp so much easier. Before I purchased it I was poking around the amp's circuitry with my multimeter leads to bias the amp. It can get quite difficult only having two hands trying to hold and adjust everything. The BiasPro is really convenient and also much more safe. The instructions that come with it are great, very detailed. It definitely shows the time and quality you put in to making such great products. Thank you, Thomas Maxwell


Ken, I love this thing. It works great. It can be a money maker matching tubes & doing the bias adjustment. It made a big difference in sound but i followed your instructions specifically. I love the PV8C for checking the actual plate voltage, takes the guess work out of it & don't have to read schematics. i'd recommend this tool to anyone who works with tube amps. Thank you very much for such a good easy to use product. Respectfully, Steve


Ken, I received your bias meter today and just finished bias my amp ! It was just too good to be true ! It was so easy to do and seems so accurate,the reason why I'm saying this is I already have similar biasing meter which was way off compare to your meter ! And another reason why I ordered yours was ,my cayin amp. Anybody who owns this amp knows how ridiculously difficult and dangerously designed for biasing ,especially who doesn't have much experience to begin with ,but it was so easy and fearlessly done I don't feel stupid anymore! I don't know how to thank you for your wonderful product and your first rate service ,I wish everyone who owns Cayin A88t integrated amp finds out about your meter . Once again thank you for your truly great product!
Sincerely, Jae


I recently ordered a Quadstate BiasPro Q10 with two BiasPro 8C bias cables and one BiasPro PV8C plate voltage cable from Ken Koga and A-Sharp Fretworks. First off I must say that Ken was very helpful and informative helping me with my order and the shipment was very prompt. When the package came and I opened it the first thing I noticed was the great craftsmanship of the products. Handmade in the USA by Ken the quality of these biasing tools stand out. I had never tubed my own amp before and with the easy to understand instructions it couldn't have been easier. Overall I cannot stress enough the quality and ease of use of these products. I would recommend them to everyone from the novice to the professional. Thanks Aaron

To Ken Koga @ asharpfretworks, Your Quadstage BiasPro Q10 is a terrific, simple and easy to use bias tool. Both the parts quality and build are excellent. Quality probe sockets that are smooth and easy to insert even in tight sockets. The ability to check four tubes at the same time is a wonderful time and effort saver. Great for checking quads for matching, without the need to power off the amp and move probes. I have been using the Q10 for nearly a year now and it is excellent, and is as accurate as any other method that I have tried.

I liked the Q10 so much, I also bought the MQ10 metered version, and it is also a quality piece of equipment. The MQ10 is even better and easier to use. Great equipment, and a must have for amp techs, or anyone that wants to do their own amp biasing. I really appreciate what you have done at Asharpfretworks, and your awesome customer service. Thank you very much, Shimmilou


Hi Ken, I purchased one of your 8-pin BiasPro products a couple of weeks ago and finally got around to using it. Just wanted to let you know that the instructions were nice and clear, and it took me no time at all to bias a pair of Sovtek 5881 output tubes in my Engl amp head. Great product, easy to use! Cheers from Australia!



Hi Ken, The Bias Pro saved my Marshall Handwired Plexi. I put new Mullard EL34s in her and played it for about a month, and it was sounding a bit edgy on the top end. When I tested the plate voltage and the bias with the MQ10, it turned out I was running those tubes at 95%of its maximum cathode current. Yikes!!! Using the Bias Pro I turned it down to about 70%, and probably saved my tubes, and my tranny. Now it sounds more rounded on the top and the bottom ends, with just the right amount of power tube distortion! Best regards


Mr. Ken, 

the silverface AB763 amps had a 1000k resistor installed on the bias board

the blackface AB763 amps had a 470k resistor installed on the bias board

I removed the 1000k and installed the 470k and the bias adjusts as it should

your tool is great, allows me to easily swap out tubes and read on my FLUKE meter

I am new to the Fender amp electronics including bias adjust

I had the reissue amp and thought to purchase a vintage amp

With a recap and bias adjust this vintage amp is really a joy

great tone and plenty of power

all the best to you Anson Alexander


Hello Ken, I received my BiasPro Meter Yesterday and put it straight to work. Using the instructions included with the meter I determined that the plate voltage of my amp was 400 volts...Wow that was quick and easy! so on to setting the bias. The bias setting on my amp was more than double than recommended { I am suprised that nothing had melted all this time! } So, I set the correct bias for my amp using the BiasPro Meter and it has never sounded better! Just want to say thank you! The BiasPro Meter is easy to use and works as advertised...Money well spent!!! Cheers! Mark Estes


Hi Ken, I received the quadstage biaspro a couple weeks back and tried it out today. Having no previous experience at biasing amplifiers everything went smoothly, and I am very satisfied with how my amp responded. The included instructions were clear and summarized the process in a way that was easy to understand. It's good to see someone who takes pride in their work, and I would recommend this product to anyone looking for a high quality biasing tool. Thanks for the good product support. Take care, Justin


Hi Ken, Just wanted to let you know I received the Quadstage BiasPro MQ10 and was able to bias up my amp for the first time by myself without having to send it off to the amp tech. Very nice tool and so easy to use. The instructions are easy to follow and the info you provide is very helpful. Thanks for making a great bias tool at an affordable price!


Ken, I recently received a Quadstage BiasPro MQ10 with the full quad setup (4) 8C probes and a PV8C probe. The integrated design of the MQ10 is easy to use and a great value. The quick response to my order email was great and the PayPal invoice made payment a breeze. I had my order in 3 days, thanks for getting that right out to me.

The included documentation is easy to follow and informative. I had no trouble setting the bias on my Peavey JSX head. It was set fairly cold, sounded good but after biasing the tubes a bit hotter it really kicks butt now. Getting the full quad configuration made the process quicker and easier.

I then checked my Peavey 6505+ combo and after some searching on the internet found that i will have to get a mod done on that amp to be able to adjust the bias. The tubes are running rather cold on that one as well. While Peavey might set the tubes on the cold side they do ship their amps with decent tubes (not cheap ones that need to be replaced immediately).

Thanks Ken for making a great product! The modular design is fantastic. If I need a couple of 9C probes down the line it will be an easy addition. Sincerely, Joe Roth


hi ken, just to let you know that your bias pro arrived on fri 24th feb, i am new to valve amps so have never biased vales before, within about 1/2 an hour of opening the box i had read the instructions and biased 2 shanling el34 power amps, this would have been quicker if i hadnt needed to leave the valves to cool between amps,

this looks a great piece of equipment that you provide and has given me confidence that my amps are running correctly and efficiently. many thanks keith


Ken,Your meter probably saved me from frying out a couple of amps. Those Crates, were way to hot, I adjusted them with your meter and they run great. The Venus, never did Bias out for me no mateer what we tried and I sent it back to factory. It needed repair, it was a sick amp. Even thouhg it played it was way out of wack. Bias Pro is one great tool. Thank You Mike


Hi Ken, Tyson Fiddler here. Just wanted to let you know I recieved my bias probe last week and finally got around biasing my amp. Couldn't be happier with your product. This was my first biasing job so I was a little hesitant but after much research online, I finally decided to give it a try. Everything worked out fine. The amp was actually running quite hot so I backed it off a bit and got a much better sound out of it. I'll be sure to recommend your BiasPro to anyone I come across looking to bias thier amps as well. Positive feedback will be left for you. Thanks. Tyson


Hi Ken, I finally got around to biasing my SuperReverb Reissue with the Bias Pro MQ10. Following your clear and precise instructions the job was easy and fast. I was very impressed with the quality of the product. The amp has come alive now. Thanks for making such a great product. Steve


Works great. Easy to use. Just plugged it in to my digital multi-meter, hooked up the amp and the tubes. Piece of cake. After the amp warmed up, the actual biasing took less than 30 seconds. Nice workmanship. I had years of experience repairing tube based electronics in a former career. David


The tester came yesterday, but no one was home, so I had to pick it up from the P.O. today. Just removed the chassis plugged the tubes into the tester probes and then plugged those into the amp. They each read around 41.7. I have a Germino Club 40 50 watt head. If you've never heard of this brand, Greg Germino builds "Plexi" style amps that are as close to the originals as can possibly be built with todays components. He even sources items that are still manufactured from vendors from that time period. At any rate, the Club 40 is his take on the original JTM-50 and JMP-50. An absolutely wonderful amp.

I'm not sure what his ideal is for biasing tubes for this amp, but I have a call into him. I biased each tube (for now) at 35 ma. I'm going to try this for awhile and make minor adjustments and see what sounds best to my ear.

Your tester is so easy to use. I love the fact that I now don't have to pay to bias tubes. Before, I had to wait 2 to 3 weeks to get it back. - joeelliso3


Hi Ken, The MQ10 is great, I checked my JVM I just received,a factory restock and it wasn't even close. The tubes do not come close to matching. I did some tube switching to put the range as close as I could. It sounds so much better. Remember this amp is a new restock amp. I have ordered a new tube set for it. The on line store I got it from wants me to send it back so they can check it out. My MQ10 helped me make my amp usable while waiting for the tubes to make it great. thanks ps please send me 4-BIASPRO 9Cs and 1-BIASPRO PV9C. I want to check a peavey 50-50 thanks again


Hi Ken, Just wanted to let you know that your meter worked flawlessly! I recently purchased an integrated stereo tube amplifier. This is my first foray into tube amplification and based upon my limited knowledge (of electricity) and research (your site and others) it became apparent that proper bias setting of the tubes is critical to performance. The amp is equipped with what the manufacturer calls Easy Bias, which is an LED light for each tube, but that really only gets you close (+/- 5mV) to the recommended bias level. The BiasPro MQ10 allowed me to tweak all 4 KT-88's at the same time with ease and has really sweetened up the sound of this beast! With your meter I was able to dial them in so they are now all running within less than 1mV of each other. I think that's fantastic and I am really happy that I found you and your gear!  Joe


Ken: Recieved my MQ10 Tube Bias Tester with two eight pin probes and the optional plate voltage probe. Upon inspecting the the contents of the shipped items I was immediately impressed by the overall quality. I was even more impressed by the usage instructions and supporting documentation!

I followed the easy and clear instructions and took the plate voltage measurement on my Fender Hot Rod Deluxe lll amp in a matter of minutes. I plugged this number into the included formula and found the appropriate bias range for my amp and power tubes. I inserted the power tubes into the included probe sockets, measured the bias, and made the simple bias adjustment - which set it to the desired range. I could not believe how far off the bias was from the factory!! The amp sounds great now! The whole process of reading the instructions, getting the actual (instead of the schematic) plate voltage, and reading and adjusting the power tube bias took less than an hour! To say I am a happy purchaser is an understatement. Especially for the price you charge. I was looking at comparable products that cost 3 times as much! Thanks for the Great Communication and answer to my questions and for Setting me free of the terrible repair shop cost and experience every time I need to change power tubes! I will highly recommend your products to everyone I know!  Mike Morrison


The bias probe is a very nice tool to have and I am pleased with the ultra high quality build of this device. Biasing a 4 tube amp, such as my Fender Twin and Music Man amps is a quick and painless job now. You can be proud of this tool and know that being "Made in the USA" can be a good thing. Randy


I recently ordered the Biaspro tool and even though I haven't received it yet I am already impressed with the customer service I have received. My special request for shipping was accommodated and he was willing to work with me to help me get my tool in the mail quickly to help me get my amp running again for a rapidly approaching gig date. Also, he was quick to respond to any questions or requests via email. Great communication, a great product concept at a great price. I'll let you know if it does not work, but I don't see why it wouldn't; its a brilliantly simple design. Worth every penny for any tube amp owner. Justin Riege


Hello, Ken! I've recently purchased your tube amp biasing tool from ebay and here is my feedback regarding re-biasing my power amp, which is the VHT 2/50/2 with EL34 power tubes.

First of all i would like to express my regrets (no worries, not about the tool!).It was foolish from my side to choose to buy only 2 probes instead of having 4 probes, which makes re-biasing job WAY more easy to accomplish. I've spent numerous dozens of minutes for inserting and pulling out the probes back and forth before having the job done.

My first task was to check whether the old tubes were still good or not, so first i measured them (in 2 attempts because i had only 2 probes). The probe inserting procedure required to partly dismantle the tube support bracket, because the tubes are placed horizontally and there's just not enough space in the chassis for a tube together with the probe. But that was just a technical issue of the amp itself. 

Then i read the biasing tool manual and measured each power tube pair bias currents for each of the channels of my stereo amp. What i came across was that the tube bias currents were a bit different for each tube, and this difference was out of the 2-3 mA range stated in the tool manual. My readings were showing about 6 mA difference between the tubes in channel A and about 10 in channel B.

Besides that i was unable to re-bias the tubes of channel B to keep the currents within the range stated in the manual for the EL34 tubes (as per manual should be 30-40 mA), bacause the biasing potentiometer of the amp was already set to the maximum current. So the tubes were supposed to be replaced anyway.

The next step was to measure the new tubes i got from the web superstore

These were 2 matched pairs of SOVTEK tubes, but when i installed them and measured, it appeared that the bias current difference between the tubes was even greater than with the old tubes. However the re-biasing was possible with the potentiometer of the amp.

I marked the tubes and then tried to swap them with ones from the other channel, but the difference became even greater.

Well, here are my final re-biasing results:

for channel A one tube was reading 38.6 mA, the other one 25.9 mA I choose to leave it this way, because if i tried to increase the lower value, the higher value would go out of the upper permissible value (beyong 40 mA) which is kinda more dangerous than just if it was lower than the lower value.

for channel B one tube was reading 36.2 mA, the other one 30.5 mA That's basically how it is set now with the new tubes in.

My conclusion is that even the matched tubes in sets are sometimes not that well matched as they are meant to be. I really don't know if it can be rectified somehow, maybe you can suggest some method?

Regarding the tool itself i have to admit, that it is easy to use, the manual is full of all the important info regarding the use of the tool and the recommended settings for different tube types. Very important aspect is that there are safety measures in it. Fit for dummies and newbies like me. :D

The only thing i really regret (it is mentioned above) that i haven't ordered immediately another 2 probes, and maybe also a couple of 9 hole probes, just in case if some of my friends ask me to help them to re-bias their amps too. Unfortunately the shipping fee is quite high and those bastards in the customs add the shipping fee to the total taxed value of the unit and now it is more expensive to order them compared if it was done with my first order.

Yeah, the selfish people always pay twice! Well, that's it. If you have some questions don't hesitate to contact me. Best regards and have a nice day! Nikita Oravs


Just a quick note to say that the bias probe kit arrived last Saturday, within the time you suggested. I got back from a business trip yesterday and have been rebiasing a couple of 6L6-based amps with the probes today. The experience has been revelatory:

1. One amp has been biassed very hot (probably too hot for the valves they used) and the pair of 6L6 valves recently installed were not matched - over 10mA difference. This was done by a "professional" amp tech.

2. The other amp was biassed too cool (only 20mA) , which I suspected, and rebiassing has really opened the tone of the amp up.

I now have the freedom to bias these amps the way I want for my playing, rather than relying on a tech's choice. In short, an excellent piece of kit. Thank you. I should have bought one of these from you a long time ago. Paul


Ken..... I have been using the nine pin Bias Probe for tube matching for my Vox amps. When you buy a matched set they are some times a little off or can drift with use. With the Bias Probe it makes it possible to check and keep an eye on the performance of the amp. I can then swap out tubes and make my own matched set as they change or if they were unmatched in the beginning......

Thanks!!!!! Carl


Ken, I had read good reviews about your BiasPro tube biasing tool on ebay and Google so when I got a new amp and wanted to put in some NOS power tubes I thought I would try your product instead of taking my amp down to the local tech and having it disappear for weeks and be out 80.00 dollars. With your excellent detailed instructions, my Fluke multi-meter, and your sturdy well built unit I was able to set my tubes up in 20-30 minutes. The BiasPro worked exactly as you said it would, was not some flimsy piece of foreign made junk, and paid for itself 3 times over the first time I used it. With out a doubt this is one of the best ebay or any other kind of purchases I have made in years. Thanks for the great designed product, the super fast ship, and the easy to follow step by step instructions. Chris in Denver.


Hello Ken! Your gadget arrived today. I purchased a voltmeter from Autozone and in less than an hour I biased 2 amps with no problems. One was a 65 Fender Deluxe Reverb Reissue with 6V6s and the other was an original 66 Vibrolux Reverb with 6L6s. The local big-name tech here in town, while well-respected, was charging almost $55 for biasing service. Well, upon hearing that I decided to teach myself to fish. I'm glad I did. Not only did I bias my power tubes in both amps in less than an hour, but also found out how closely they were matched, as well as finding out that the tubes in my original 65 Vibrolux were biased to 50mA! I imagine that with a bias that hot, it could have damaged something in my prized amp. Luckily I had your gadget around to get it back down to where it should be. I don't know anything about electronics and I'm definitely not a technical person, but this made the project dummy-proof.

Your product also allows me to experiment a bit. I've read on the popular online message boards that a lot of folks like to try running 6L6s in their Deluxe Reverb Reissues. This requires adjusting the bias. Well, now that I have your product I can put the 6L6s from my Vibrolux into the Deluxe Reverb Reissue, bias them accordingly, and see if I like the change. If I don't, no sweat. I can just put them right back in the Vibrolux and re-bias within minutes. All of these things I learned tonight would have taken weeks of going back and forth to the local amp tech and could have cost me a lot of $$$ on top of that! I'm not patting you on the back. I'm patting myself on the back for making such a smart decision to purchase your product.

Now let me qualify this positive feedback by saying that the operation was very quick and easy because I've spent a lot of time over the past few weeks reading the online message boards and trying to familiarize myself with the jargon. I learned a lot from folks much more experienced with this kind of thing than me. Therefore, I did not have to spend time doing calculations with plate voltages and dissipation when I received your product. Every expert out there has a different opinion as to what is too "hot" and what is too "cold" for whatever tubes in whatever amp. I took the time to absorb as much information in as I could and decided for myself. Once I did that, using your product was the easiest part of the operation. Doing the reasearch, putting in the time required to learn about what it actually means to bias an amp, gives confidence to the layperson that what they're doing is for a correct, logical purpose.

Best Regards, Ben Johnson


Hey, Thanks so much for the BiasPro. I've been playing guitar professionally for several years, and just needed something so I could get my amps dialed in when working from home. The BiasPro works great. Biasing products can get pricey, but this was a great deal and will be used often. Got it super fast and couldn't be happier with it. Had it up and running within minutes of opening it. Thanks again!

Clint Milburn


great tool....29.00 bucks...tuned up 4 amps....found out what was wrong with a 65 super reverb i got cheap..a guy put "new" tubes in and it sounded bad....tubes were not in range...retubed, played it 3 showess so far with no issues. thanks, will be getting more from you. send me that page again and i will post my findings if you would like....BIGGIN


Hi, Ken..

I purchased a MQ10 from you last week on ebay..I absolutely love it..I would like to order the companion plate voltage cable(EL34,6L6,etc)please send me an invoice and I will pay as soon as I receive it...My email is

Thanks Jeff


Hi Ken, It's Jarrad from Australia here how are you? I have just received the bias probe and got stuck into a couple of my amps with it, what a fantastic little tool you have made! It made biasing my amps very safe and easy and has instantly won a spot in my tool kit. The instructions included were very concise, and though I have been a professional electrician for 14 years and playing with music gear for longer, I feel that even a complete newbie to amps and multi meters etc. would have absolutely no problem biasing an amp with your probe, a decent meter, and your detailed instruction sheet. Thankyou for providing me with this excellent little helper, I wish you much success and I will definately spread the word around my local scene too, Kind regards and thanks again,

Jarrad Daniel, Adelaide, South Australia


“BiasPro made it a breeze to match-up a quad of 6L6s for my B15 fliptop since I didn’t have to dismount the chassis to take readings.” And even though the B15 is nominally a non-adjustable fixed-bias amp, the (easily obtained) readings have me thinking about testing some other types of tubes or tweaking its bias circuit components for a bit more headroom. Next up is my buddy’s Marshall…



Ken I found problem. Some one modified bias circuits and had V7 and V10 with no bias voltage. I corrected wiring and used bias box and was able to balance out ok. I should of started with more basic trouble shooting and I would of found sooner. But guy I purchased from was not truthful and he did not tell me that amp had been modified so I was going off deep end of things.Thanks for your time and bias box tool makes great troubleshooting tool. GOD BLESS ! jerry Rodriguez


Ken.  Last time I had my hands on tubes it was Raytheon Hawk equipment. (slightly newer than clay tablets).  I am awash in Triple xxx Heads.  A good problem.

So, To bias.  Head one: Checked the Plate V and then the bias's.  The OEM Sovtek 6l6's Ranged 43ma to 24 at 489pv.  Amp sounded hollow on the cleans, top was piercing and bottom was good.  I took out the 24 ma tube and put in one that ran at 35.  Bias adjust put the 43 to 38, paired with the 35 that went to 36.5 as part of the  pair.  The other two, were running at 37.5 and 36, and moved down to 32 and 34.  This resulted in a better more musical clean, the top was still real dingy..for lack of a better descriptive.  OverDrives Had the same issues out of control upper range, hollow in the mids.  I played with EQ, between steps, all night long, so scale wise the description stands.  Changes:  JJ12ax7 in V1 and a new balanced JJax7 in V4..I let the Soviet EH's stay in v2 and v3..This amp turned into a very manageable critter.  I get Super cleans now, the jangly top is now just searing...PRS;  low rent, G&LStrat; hi rent, and Ibenez Artcore with a mini bucker are the inputs I have.  The amp loves the buckers now, but sounded bad with the G&L.  The V1 and V4 change made the G&L responsive and As I discovered the more widely adjustable of my guitars.  Channeling Jimi and Buckethead at will now.

Amp 2 - 484 Plate volts.  Soviet tubes out for full JJ Change to 6Ca7's.  All four new tubes bias ranged at 32.3 to 33.1.  I did notice the Amps really did not settle down for at least a half hour. (they had not been in service for a long time) With the bias wobbling 1-2.5 ma around the settle point.

This amp is now a crusher.  Bottom big and articulate, mids... you can now waltz to a shred fest.  The treble has never sounded better...The Vol knob is your friend with this rig.  A bit of tired old midiverb in the back and the sustain is forever.. could stadium...this...yes I could...

The changes in the sound quality with just a balanced bias are startling. A couple of less harmonic preamp tubes make a difference - together a huge difference.

Oh yes... your Bias tools...People, they are worth the price of admission!  Have fun, be safe, (remember plate volts).  Yes, It is ok to be biased.

Thanks . John
Hey Kenny,  Firstly let me say that the item arrived perfectly. Its a long long trip to North Queensland Australia. Secondly, I am very impressed at the standard, quality of the item. Congratulations on manufacturing, supplying a top notch product that fills a void in what is a growing industry - Valve amps.
I will now train my son how to use this time saving valuable tool.
I will do a video of our experience with your Biaspro and send you the link (it will be on youtube) Hopefully this will help with more sales for you, even if only to Australia.

Oh yeah Kenny, have you sold any of these to Aus before ? Anyway mate, take care, smile, and one day if your really really lucky you can come visit and I'll take ya fishing - REAL fishing mate !

Regards, Greg Ashby 



Ken-  Received the order today (that must be a record for USPS). I have already measured the plate voltage for my Metropoulos GPM45 and am in the process of measuring the cathode current. Having the MQ10 makes this an exceptionally easy procedure. Being a replica of a Marshall JTM45, the most time consuming portion of the measurement procedure has been removing the chassis from the head cabinet!

The amp is decidedly running cool which explains it's present sonic character (the plate voltage is a bit lower than the spec). I confirmed what my ears were telling me about the amps sound. Can't wait to play through it now that it's biased in the correct operating range. Ran the cathode current up to just below 70% plate dissipation for the KT66. The tone test will begin after a cool down and buttoning the amp back up.

Thanks for a terrific package. The BiasPro could not have been simpler to use, the directions were concise and effective, and your customer service has been excellent (I know I asked a lot of questions before I purchased but you always replied in short order). On top of that I placed the order late Friday and it arrived Monday!

A lot of people avoid biasing their own amps and I can't blame them because of the nature of the operating voltages used in tube amps. However, I would guess that those people are potentially leaving a lot of tone on the table. Your MQ10 system is so easy and accurate that anyone thinking about biasing their own amp should consider it an essential tool in optimizing the tone of their tube rig.

Best regards- Matt Kozink
Hi This is the third one-These are great, I now need the 7591 version. Thanks Tim
Excellent service and prompt delivery. The device worked perfectly and easy to understand biasing instructions were provided. Makes biasing simple and safe. I highly recommend this device.
- hellmwc
Just received your BiasPro and went at it with my new DRRI. FINALLY, I am able to evaluate how well my tube vendor does (or does'nt) match my 6V6's.  Additionally, I now know which hardness of tubes I should purchase (given the DRRI's bias limitations).  Setting the bias was the EASY part. Gaining knowledge from the BiasPro's use was the FUN part.
Hello Ken, thank you for the fine product and most especially for the detailed instructions. I had purchased the bias rite as the do it yourself kit from Tube Depot. The instructions for assembly were incomplete and there was nothing on how to properly use it. It was a bit of a pain for newbie to put together but I ended up crushing it by accident pulling out of the amp( a little too strong for my own good at times). Yours looks a lot better! At least I get how and why it works now.

Thanks again.  - joeyp_2718
I don't think I justified your product in my feedback. I can not express enough how neato it is to have my new tube meter. Now a days it is hard to find something that is more than a gimick to make me sound better. Thanks and I am a bi rube roller and this is the mast accurate and most inexpensive tool for a guy like me. A guy named James Hysong turned me on to this too. Best regards Joe Z.
Hi, The BiasPro is great! Physically the unit is much better than any bias tool i've used before. One big improvement with your model is the probe tube sockets. I wrestled with probe testers previously with the tube sockets being too tight and extremely difficult to use.. the BiasPro model is designed just right. Made checking my various amps much more easy and I wasn't afraid of snapping off guide pins. Very happy with the product. One question .. has any of your other customers identified a nice small hard case for the BiasPro QuadStage ? thanks, DAn.

CONTINUED to the 2nd page (BiasPro Feedback - cont.)

  • Hi Ken - Your Bias Pro products arrived very quickly      and were easy to use. Instructions were clear, and I was able to bias my      amps very quickly and interactively so as to get the sound I wanted out of      them within the recommended safe bias ranges. With three amps to keep      tuned up the Bias Pro should pay for itself very quickly.  No more      trips to the tech with a few weeks wait when its time for new power tubes.      I am completely satisfied.

         Best wishes, josh
         With the limited space for feedback, I can't begin to express the value      and pleasure of using the Bias Probe. I had recently acquired a 60 watt      Crate Blue Voodoo. I knew from past experience that there are a lot of      people writing bad reviews about equipment when they have no idea what      they are talking about. Anyone criticizing a Blue VooDoo certainly is      among those folks. In the condition this amp was in, it was easy to      understand why someone would criticize it, but it was not the amps fault.      With a little research and the acquisition of your tester I was able to      easily and quickly determine that some Marty Friedman wanna-be had cranked      the tubes up WAY to hot and the amp sounded like poop. With the voltage      down to an acceptable range (as it was intended to be) this amp is second      to none I've ever played (I'm 56 years old and have been playing about 45      years). It was a BLAST tweeking the amp myself and saved me a fortune.      THANKS for a GREAT, affordable tool.

         - dan62jb
         Hi Ken. Ordered the BiasPro recently for delivery to Australia. I must say      the quality of your product is outstanding, a very robust looking meter. I      had the opportunity to use it today on a re-tube of a Fender Hot Rod      Deville. Works as advertised, easy to setup and use. I have mentioned the      meter in a music forum here in Australia, so hopefully you gain more      business from here in Australia.

         Best of luck, Ray.
         Hi Ken, I am very happy with the purchase of your BiasPro product. It came      with very detailed instruction and useful information. The information is      very easy to understand for 1st time user like myself. Keep up the good      work!  

         "I have been playing guitar seriously for a long time and have always      used tube amps.
         Being one of those guys that likes to experiment with different tubes, I      was
         attracted to products that would allow me to Bias my amps safely and      quickly on my own.
         I tried several similar products from other manufacturers but
         was not pleased until The BiasPro. It is not only a well build unit in      comparison, but
         it was simple to use and provided the consistent accuracy I was trying to      obtain.
         If your searching the net for a Bias  Measuring Tool, look no      further...This is the one!"

         Tony Profera - Guitarist
         Hi Ken,  I received the BiasPro Tester Tool today - an excellent      piece of kit, and it's been a pleasure dealing with you.  Within 5      minutes I found the probable cause for my 3 month old DRRI blowing power      tubes after return from a manufacturer warranty repair (6V6s biased at      49ma) -10 minutes later I had the replacement tubes correctly biased and      DRRI sounding as sweet as it should.  Many thanks for producing a      quality tool and for being a straight-dealing guy (instantly refunding my      over-paid shipping).  

         All the best,  Mark
         Got your package today,6/8.Thanks for the fast shipping.The tester is      great!I had my Deluxe Reverb biased and ready within 10 minutes.I left      positive feedback,thanks for doing the same.Thanks again for a great      transaction.  

         Judy - judy8663
         Hi Ken,  The new quad stage bias pro is just great!  It’s such a      good feeling to have a bit more control over what’s going on with my      amps.  First thing I did was to find out the plate voltage on my old      Fender Deluxe Reverb (AB763 circuit) and then figure out a bias range for      a pair of NOS 6V6 tubes I’ve been wanting to try out.  I also found      out the “matched” pair of Electro Harmonix that were in there were actually      pretty far apart and were also running really hot...guess the bias must      have drifted since I got it back from the tech almost two years ago.       Best of all is how simple and easy it was.  The whole process took      only 10 minutes (and that included reading the instructions for the first      time).  Wish I had done this a long ago, many thanks!  
         Ken  Just wanted to let you know the Quad Bias worked great. I have a      new Line6 DT 50 amp head that had cheap chinese tubes in it. I replaced      with TungSol Russian EL34's.For reference the amp is spec"d for a      35mv bias. But you also need to have the head in Class A/B mode when      biasing. Thanks again

         Bart Puglise
         Howdy, Just letting you know I am AKA The Blues Bondsman on the Fender      community page and I just promoted your item to my friends there      also.  I posted your e-mail so they could find you.  Check out      the forum and see modern amps section, my post about my twin reverb      matched tubes

         Later, Chris
         Received my Biaspro test probe today.  Excellent product !!!, super      easy instructions and made my amp all it was suppose to be.  Thanks      for a great, safe time saving hassle free way to check and adjust the bias      of a tube amp.

         Ken,  I’ve had a chance to use your products and I couldn’t be      happier. Quality at a great price, heads above what else is out there in      this market. If I didn’t already own a Fluke 83-III, I would have bought      your metered version. With the additional probes I’ve purchased I’m good      to go. The Tube Dr. is ready for house calls! Thanks again and I hope to      do business with you again. As I said, Top Notch gear and Top-Notch      service right here in the good ole’ U.S.of A.!!! A breath of fresh air.      I’ll pass the word along. Warm Harmonics,

         David Kelly Duncan   *** A happy customer!  
         Ken, I received your product approximately 2 days after ordering it,      LIGHTING fast shipping, packed securely with care.

         I purchased the Quadstage MQ10 with octals. I have some previous biasing      experience using a single adapter and a digital multimeter and decided it      was time to purchase a tool that would make the job quicker and easier. I      am not a professional repairman. I am a gigging musician who services his      own amps and several of my friends.'

         I wanted to find a unit that was quality made and I wanted it soon. I      searched online and debated which product to buy from a certain auction      site. There were several units made overseas and the delivery time was up      to a month. I did some more searching and found your site.

         I can honestly say your product and service is unparalled. I am was very      glad to find a product that would do exactly what I needed for a      reasonable price and is made in the USA. I am very glad to support the      independent businessman.

         The MQ10 is extremely easy to use and does the basic function it was      designed - simply put it gives accurate readings between individual tubes      or pairs or quads with the turn of a knob and an easy to read display.

         For beginners, all the confusion has been eliminated and for experienced      repairmen this tool will save you time and money in the long run.

         Thank you again Ken. Glad a few minutes of internet searching led me to      your product. I am EXTREMELY pleased.
         Ken, PV8CS adapter arrived on Saturday.  Worked like a charm!  I      used it on my on my hand-wired Marshall 100 watt amp, Fender '57 Twin and      '69 Deluxe Reverb.  Thanks again for all the correspondence, detailed      instructions and super fast shipment.

         Hi Ken,  I purchased a QuadStage Q10 a few weeks ago and finally got      around to use it to check the bias of the new tubes installed on my son      Marshall JCM 800.  The unit itself is nicely built and serves its      purpose well.  I'm neither a musician nor Amplifier tech, but like to      tinker with stuff.  Your instructions were clear enough to be      followed by an amateur like myself.  Thanks.
         BiasPro Amp Tester is an extremely finely constructed and accurate bias      adjustment tool that should be in every tube enthusiast collection. It      makes setting the tube bias extremely simple, even for the novice. Ken is      without question the finest craftsman and seller here on Ebay. Buy with      confidence from Ken
         Hi there, I have now received the Bias Probe. It is a great item and      working really well.

         I had a general tube question I was hoping you could help me with. I had      suspected my amp was biased too high (being secondhand). I measure the      "matched" pair of 6L6 I've had in the amp for 2 years - one      measured 44 the other 36! These tubes are clearly not matched - could they      have done any damage to my amp?

         Also is it possible for a tube to "lose" current reading (from      44 to 36) over that period? Or does it mean I've just had the equivalent      matched pair of 40ma all this time as I do love the sound I'm getting from      them.  Many thanks for your help,

         Hi Ken:  Received the BiasPro today, Thanks. It looks great and I      will put it through its paces. I have used a friends before and was      pleased with its performance, thus my purchase. I do a lot of amp repairs      and this just makes things a little easier. I have thought many times      about making one but you know it goes, I just never seem to be able to      work on my projects. Thanks for doing it for me!

         Greg B, The Radio Guy
         Hey Ken, This is one Awesome product.Very user friendly with a great set      of Instructions.Very cool design,very durable.With the MQ10 I was able to      Bias my own Tube amps.The Best thing about the MQ10 is that I was also      able to Match my own tube with the turn of a knob.The MQ10 will save me      Money and Time.So no more Tech visits for simple issues such as Biasing      and Tubes.Which in the long run will save me 3 times what I paid for the      MQ10.Your responce to my questions and order were Fast and Professional.I      received the MQ10 in a very secure and well protected package.I would have      No Problem ordering from you in the Future.Thanx Ken and I wish you the      Best.
                                                                                 Ron Smith
         Hey Ken, Thanks again for shipping the Biaspro to me so fast. It is very      refreshing to do business with someone who communicates with their      customer so well. I will definately look forward in doing more business      with you as well as refering other!

         Thanks again, Sean
         Hi Ken, Just a quick note to let you know that I used the 9 pin bias probe      and it worked perfectly!  Very nice job assembling the probe.
         Hi Ken thank you so much for the bias probe it sure made my experience so      much easier. I never thought that the bias probe would make much of a      difference ,but it did. I was biasing a b- 52 amp and tried b- 52s tech      support method which is a very dangerous one for the amp and the person      doing the work and set the bias to their specs and after hooking up the      bias probe I got a reading that was about 10ma off. I do know one thing      for a fact after biasing this amp which was 34ma it has never sounded so      good ever.Thanks for such a great product and I will use it every time the      need arises. Thanks again

         Hi!I used the bius tool first time today. Having not done this type of      thing before,I read/followed the directions carfully.I had no problems      whatever!The proceedure went fast and smooth,with excellent results.

         Thank you. Ken Peterson
         Hey Ken,  I just got a chance to use my BiasPro today.  It works      great.  I was able to use it to help debug why my recently-acquired      amplifier's tubes were red-plating (The previous owner nicked a wire on      the bias pot and didn't repair it- the last few strands must have broken      when I was transporting it.).  After that I re-set the bias using the      easy-to-understand instructions you provided.  I'm very happy with      the quality of the build on the BiasPro and I'm sure I'll end up using it      for a long time to come.

         Thanks, Jeff
         Hi Ken, Many thanks for the fantastic service and after sales service. I      understand valves but not electronics and I wanted to set the bias on my      amps to get the very best sound out of them. I cannot believe how easy      this process is with the Bias probe tool that Ken produces.The difference      in sound when the bias is set correctly is amazing. A fantastic product      that every valve enthusiast should own.

         Best, John Fuller
         Hey Ken,  Just wanted to let you know that i recieved your Bias Meter      QuadStage BiasPro!  This is a very nice Bias Meter!  I have been      looking for a Bias Meter for sometime now, but the prices just were out of      my spending limit, untill i accidently stumbled across your meter on Ebay.      I have been biasing my amps using the shunt method, and if anyone knows      using this method takes a great bit of time & patience. Not to mention      its a a bit dangerous unless you know what you are doing.

         I took the meter out of the box, great packing by the way and super fast      shipping. Right out of the box i connected the probes to the amp then the      tubes to the probes, powered my Super Reverb Reissue up and sure enough      the Bias was a little too hot as i expected. So i set the Bias from 40ma      down to 33ma. Everyone that owns a tube amp needs one of these little      babies as it saves time, and money, and most of all its Safe & very      easy!!  Now i will check the bias in my 71 Deluxe Reverb, my 66 Twin      Reverb as well.

         The directions that came with this meter is very helpful, especailly for      those who want to do this their self. Also a great little tube bias chart      you added in your directions!  This looks to last a very long time,      as it is very sturdy for a bias meter at this great price!  I would      recommend Your meter to anyone who needs a great meter to bias their own      amp with & save a lot of money in the long run. This is a great      product period!!!  Easy as 1 2 3!  

         Thanks so much, ~ James
         Hello Ken, I am so glad I purchased the QuadStage BiasPro MQ10 from you,      it is a perfect biasing unit for those with little to no experience      biasing an amp. As soon as I recieved the QuadStage BiasPro I was already      biasing my 63 Fender Deluxe Amp, I find that my two nos Tung Sol 6v6gta      power tubes are about 4.0 ma off from each other so I put in a pair of nos      RCA 6v6gta and find they are less than 1.0ma apart. I am also able to set      the bias a bit higher at 27.0ma, the previous setting seemed a bit low at      22.0, what a great biasing unit you have here, it has already paid for      itself, later I will be biasing my Soldano Hot Rod 50 amp and my friends      two Fender amps, I highly recommend that anyone interested in biasing      their tube amp, definitely check out the QuadStage BiasPro MQ10, thanks      again,

         Ken, Hey there, I just wanted to share my experience with your BiasPro      tool.

         I've never biased a tube amp before today.  Before taking on this      little job I did a lot of research and reading, as well as taking all      necessary precautions, so I felt confident to go ahead with it on my      own.  I looked at all the test probes I could find, and your BiasPro      tool seemed to be the best combination of functionality, workmanship, and      price.

         The BiasPro lived up to all my expectations – using it made my bias job a      piece of cake!  The BiasPro is very well made and I'm sure it will      serve me for many years to come.  I would absolutely recommend the      BiasPro to any pro or hobbyist.  It is a must-have for anyone      servicing tube amplifiers.   Thanks again, and best of luck to      you!

         Hi Ken, I have left feedback and will send a more detailed report as and      when I gain a bit more use. I repair amps as a hobby for a local Music      shop so it will not be long.  Up until now I have been using my DVM      but your Bias Tool will be a lot quicker.!  I might need another set      of leads in the future to speed up the 'set up' on four valve output amps!

         Best regards  Bob Smith.
         I recently received 2 BiasPro tube amp bias probe tester tools, one 8 pin      and one 9 pin. After using these tools to measure the bias on several amps      (EL84 and 6V6) that I own, I can say that I am completely satisfied with      my purchase. The bias probe tools are hands down the easiest and safest      way to measure the bias setting on power tubes. The BiasPro tools are well      made and with a little care they should be good for many years of use. If      you know where to shop, you can save a few dollars by buying the parts and      make your own bias probe tool, but the price charged for the BiasPro tools      is fair, considering the cost of parts, assembly time, and convenience. I      give the BiasPro tools 2 thumbs up, and would not hesitate to recommend      them to a friend.

         - sleeveless
         Got my bias pro the other day and biased up a marshall and fender amp to      test it.Worked like a charm.Very well constructed.Will obviously last for      years and priced reasonably as well.Thanks a lot for making my life easier      and my amps sound better..

         Brett,Port Charlotte,Fl...
         Hi Ken, The tester works great. I think I need a second set of octal      leads. I'm such a cheapskate only getting 2..I just end up having to      switch sockets back and forth! If you could please send me an invoice for      a pair of the octal leads I'd appreciate it. I'll certainly leave some      positive feedback for your website though I don't know what more to say      besides simple and works great...which I guess is pretty good! Thanks      again.

         Best Regards, Bill
         Greetings Ken, Just wanted to let you know how pleased I am with the      BiasPro Q10 Quad I recently purchased from you.  The unit is very      compact and lightweight, and works flawlessly when connected to my Fluke      87 DMM.  The slim profile of the tube sockets actually allowed me to      measure the bias current without having to remove my Soldano SLO chasis      from its headshell.  This saves me a tremendous amount of time, as      I've always had to pull the SLO chasis when using a Weber Bias-Rite in the      past.  I've actually decided to sell my Bias-Rite after purchasing      the BiasPro Q10 Quad!  Thanks for making such a great product, and      for the extremely fast delivery.

         Matt Gentry  Katy, TX
         Hi Ken, I used the tester with my Fluke for the 7591's last week and it      was excellent, very nice! I was able to test all my USA 7591's to achieve      a quad that were all between 33 and 35 milli-volts in my vintage Fisher 500c.      Now the receiver works beautifully.

         After my restoration and tube matching, it really sounds better than ever.      I listened to my music all weekend!  Thank you so much for your      assistance and help; a great tester. I'm very happy and impressed. Thanks a      million,

         Hi Ken,   Just letting you know that I finally got a chance to      try out your Meter-ed Dual Config Quadstage Amp Tube Bias Probe Tool      today. I love it! What an awesome product! Very User friendly, especially      for someone like me who is not an electrician and who is very timid around      hi voltage electrical equipment such as my amp. The Bias Probe  tool      also helped me to find two tubes that tested excellent in my tube checker      but Your Bias Probe tool found problems with bad current      fluxuations.  Id like to thankyou as well for taking your time to      answer all of my questions. Very sorry about the ordering mixup iam very      new to EBay and PayPal.

         Thanks again,   Chris
         Hi, I bought the Very Awsome QuadStage Bias Probe tool for Biasing Tube      Amps. It is a great piece of gear Its constructed very well and seems to      be a great tool.  I almost bought a bias tool that cost $145.00 and      I'm happy to say I didnt.

         I must say this is my first Ebay So I was very scared that I would not get      the meter or it would not work or it would be junk, but the meter is just      great. It has already saved me from the super high bias I had on my amp      that would have blew the new tubes I had just put in.

         Hands down this is a great tool and Ken does great work on these meters.      You really cannot go wrong with this tool and I would tell anyone simply      buy this Probe. Its a great piece of gear with a great price.  Thanks      Ken, I will be buying more later.

         Best Regards, LG
         Hi Ken,  I'm back home and have just used your tester to check and      adjust the bias on my old Scott amp. I've got two pairs of closely matched      tubes and the meter is confirming this which is nice as it allows you to      confirm that they remain closely matched over time without needing to use      a tube tester.   It seems to be working great and is a much      better to check bias then using resistors and hoping you won't electrocute      yourself! I'll be back in touch with you shortly to buy two more 9 pin      cables.

         Regards, Greg
         Hi Ken, The bias tester arrived today. Plugged it into the stereo amp as      per the directions, warmed the amp up for 10 minutes and had the bias on      the 4 tubes set in a minute flat. It was great! Nice stable reading      instead of it jumping all over the place as you get your fingers singed      trying to keep the multimeter probes in those crappy little contact holes      behind the power tubes. I found that the bias on two tubes weren't       the same, which explained the hum I had on one channel and the bias on one      channel was quite a bit different to the other channel?!? The unit worked      perfectly and feels nice and solid. Thanks for a simple to use and very      useful product.

         Cheers, Vic (Melbourne, Australia)
         Just wanted you to know how grateful I am to you for making these up for      me.  Using the (2) Bias Pros, I went through my collection of 6973s      and successfully assembled two matched quads.  I then installed each      quad and set the bias current to 18-20 Milli-amps as you suggested.       The results were great.  My (2) Knight KA-55 stereo amps never      sounded better; much more power and much better fidelity.  I needed      to increase the bias voltage to -27vdc;  -2 volts lower than the      nominal -25 volts called for in the schematic.  I installed      regulated, adjustable DC power supplies to replace the inadequate      unregulated fixed bias supplies, which were only putting out -23      volts.  I suspect the tubes were biased much too high and were      saturating at higher power levels.  Now I have far more CLEAN power      out of these amps than I ever imagined was possible.  6973s sound      great if they are biased correctly.

         Sincerely, Mike Stamper Windsor, CT
         Hi Ken,   GREAT looking unit you have here, performs      wonderfully!!  I have been using it daily!!   I have many      amps, but the one I like to test tubes on is this little Bogen PH10 that      is now converted to play a guitar thru...I need to run the guitar into a small      transistor amp to up the line voltage but I get some great tones in this      6V6 amp.  I also play 5881's thru it, and watch the mA      readings...having fun with all of this stuff.   I have been      collecting tubes for the past three years just for my own amps, and for      the ones that I want to build, and sell in the future.   The thing I      like about this is that not only being accurate, I can leave it on and      watch the voltage/milliamps swings during play, and that I have found that      amps are not static, that a tube will show one thing, then after a while      another, then lose a milliamp, gain a small percentage back, and since all      of the components work in tandem, we need to realize that tube amps      will fluctuate, and that is the same with tubes.    I will be      using this for a long time.  Should I have any problems I will let      you know but trust this is a very durable unit, as which are      the leads.  Thanks for your prompt shipment.  good luck      with your business..   

         Hi Ken,   The Bias Pro arrived last week - sorry it took me until      today to find time to test it. (I am a teacher, so it is an extremely busy      time of year.)   Works great.  I left you very positive      feedback, and 5 star answers to the questions.  Thanks for the      positive feedback you left me.   Thank you for a very smooth, easy      and pleasant transaction.  I appreciate those who make good-quality      products, sell them at reasonable prices, and do so in a nice, considerate      way.  It has been a pleasure doing business with you and I will be      glad to recommend you and your bias probe to others.   

         All the best,   Don Denaburg
         Ken: I have to thank you for your products. They seem to be well thought      out, nicely made and at a reasonable price. I have gone thru two      different sets of your competitors bias probes. None of them last very long      and one set even damaged several of my amplifiers before I figured out      that it was shorted out internally. I wished I new about your products      earlier, I certainly would have been a long time customer by now.       Next payday I will order two additional 8 pin probes.

         Thanks again   Bill Page
         Greetings,   I wanted to let you know that I received the BiasPro      today and I am VERY impressed. Positive feedback is on the way. Do you      have a web site that would allow me to buy additional adapters for the 8      and 9 mini setups. Again thanks for the quick ship and the nice product.      Now to chase down some info on the Twin Reverb RI  and the 6L6GE      tubes.  

         Thanks again,   John    fendercats
         You got it! Thanks again - I used the Bias Pro today on 3 om my amps.      Works great. Really revealing on just how "matched" some tubes      sets are...

         Hi   Ken,   Just thought I'd let you know that the MQ10      Quad  worked wonderfully.   I read a few articles, and      watched  -  and re-watched  -  a few 'YouTube'      presentations of the Biasing procedures . .         Anyway,  your Metering System was simple to use ( once understood      ! ), and, as I'd guessed'  a Twin Reverb that I'd purchased was,      indeed,  all over the place in terms of the mA reading of the Power      Tubes.  the MQ10 helped tremendously in making sure that the      new replacements were operating within Fender specs

         Again,  Thanks !  - Michael H.        /   Boulder CO
          Just to let you know, I am a repeat customer. I bought the 8-Pin one      from you earlier this year and it works great. - ceng
         I wanted to let you know how pleased I am with the BiasPro I just      received.  I have a single octal tube amp (Fuchs Lucky 7) that I      wanted to check the bias on but did not want to pay a tech to do the job.       This was my first time biasing and your instructions along with the      BiasPro made it a breeze.  The BiasPro and my multimeter showed my      amp was running hot at 62 mv instead of the factory recommended 50.  A      few fine turns of the bias adjustment got it right in line.  The tool      is solid and looks like it's going to hold up for many, many years of      usage.   Thanks from a satisfied customer!

         Steve Daily.