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BiasPro Feedback 1
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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
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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
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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
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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
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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 thomann.de
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
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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
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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
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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.
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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
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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
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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
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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 xxxx@xgmail.com  Thanks, Jeff
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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
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“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… Thanks!
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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
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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
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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
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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
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Hi This is the third one-These are great, I now need the 7591 version. Thanks Tim
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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
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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.  Cameron
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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
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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.
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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.