Tube Tester

Ron Resnick

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As I wade in the vintage tube waters it seems to me that a lot of uncertainty could be resolved if one has one's own tube tester.

What tube tester do you use to test your vintage audio tubes, and why is that the best tube tester for you?

What tube testers are produced today? I see the Amplitrex AT-1000. Is this tube tester easy to use? Does it produce intelligible, definitive test results?

How about the Vacuum Tube Valley tester?

What tube tester do you recommend?
 

DaveyF

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Interesting idea, and one that has been banded around among a'philes for years. Problem is that in some instances, tubes that test well still do not sound good! So while on the face of it, having such a device is valuable, the expected result may in fact be a disappointment. Better, IMHO, and far cheaper, to simply source tubes from a well known entity with a good return policy and just go from there.
 

microstrip

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The first question you may ask is what tubes do you want to test?

Modern testers, although having much better performance, have a limited number of options. As my equipment only uses KT120, 6H30, 6DJ8 or compatible tubes I have a custom bench where I check gain, bias, distortion and noise of these tubes. Just for general evaluation (trans-conductance) I use a Hicock 600A Dynamic Mutual Conductance universal tube tester.
 

Ron Resnick

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Francisco, I would like to be able to test:

6DJ8/6922
6SN7/5692
12AX7
12AT7

Maybe power tubes 6550 and KT120 and KT150
 

Hi-FiGuy

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Totally off topic and my apologies but this brings back memories of my dad handing me a bag of tubes and sending me down to Sav-on drug store and testing tubes.
Back to your regularly scheduled programming!
 

Kcin

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There are a few modern options listed below with varying cost and complexity.

The Amplitrex might be the most costly - it does not necessarily match tubes though. There were early reports of software problems and other issues I don't know if these have been addressed. I use a combination of vintage and the VTV tester which I found is very good for small signal tubes designed by Eric Barbour. The George Kaye tester was first at this but is extremely rare and neither of these is in production anymore.

Vintage testers may not do what you want either as most do not test for noise and suffer from years of neglect. None of the vintage American testers will place the tube in its proper operating conditions for a real test.

Buying tubes from a reputable knowledgeable seller might be easier. If I were to do it today. I would get the Amplitrex or a combination of the maxi matcher and a well reconditioned Hickok . I have a Hickok 800 that I have rebuilt. There are far more sophisticated models as well.

https://orangeamps.com/products/accessories/amplifier-management/valve-tester/

http://www.maximatcher.com/maxipreamp.html

http://amplitrex.com/

http://www.thebestamp.com/Testing_Equipment/Easy-Tube-Tester3.php

Be prepared to geek out a bit and if your not especially hands on you may get frustrated. There is a feel and a learning curve in doing this where experience can't be over emphasized. Oh and the best tube tester is the circuit that tube is meant to perform in! Good Luck.
 
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Ron Resnick

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Thank you for this very comprehensive and very helpful answer!

Have you used the Maximatcher yourself? Have you used the Easy Tube Tester (4th link) yourself?
 

Kcin

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Hi Ron,

I have used a version of the Maximatcher years ago .. easy to use. The Space Tech labs... never. He builds a bunch of various audio items and seems to have a good rep on his amp builds. Can't vouch for that one though.

Thanks.
 

jazdoc

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IME, the best tube tester is the equipment that the tube goes in....
 

Barry

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The Amplitrex might be the most costly - it does not necessarily match tubes though.

This is not true. If you run the Amplitrex in standalone mode, yes; but in computer mode, you can run pairs of tube curve traces of plate current versus plate voltages. In order to do this, you need to load supplied software onto a laptop and connect the Amplitrex to it. You can set the limits of testing to anything within the range capability of the tube under test. It does take some work to set it up in computer mode and more to learn how to use it if you're not familiar with how tubes work.

Would agree the unit is expensive. Since it's modern technology calibration issues are not a problem. Software works ok once you figure out how to use it. It does work with Windows 10 even though it was introduced with an earlier version of OS. It really does almost anything you could need for most tubes, you can add tubes that are not in the database, and most important, it test tubes at real life working voltages. The one limitation is frequency of software updates. I've never been notified of any, but then again, I don't need any for what I'm testing.
 
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Ron Resnick

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Thank you, Barry. But I do not want to use any tube tester I have to hook up to a computer -- especially to a PC.

What is your recommendation for a standalone tube tester?
 

Barry

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Thank you, Barry. But I do not want to use any tube tester I have to hook up to a computer -- especially to a PC.

What is your recommendation for a standalone tube tester?

Well Ron, you could go with the MaxiMatcher, but you'd have to buy 2 units; one for small signal preamp tubes, and a second for the power tubes. Total cost ~$1,700 for both. There are also a few tube testing kits, but my guess is you wouldn't want to build one. You don't NEED to hook the Amplitrex up to a computer but it may be more than you really need. It is easy to use in 'stand alone" mode.
 

Blue58

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IME, the best tube tester is the equipment that the tube goes in....

Absolutely correct. From experience I've had tightly matched tubes that sound different and so had to match tubes to give the best performance by ear. Don't ask me why this should be. Perhaps someone out there knows why.

A tube tester is really only good to weed out faulty or end of life tubes if old stock or to check new tubes for possible poor manufacture.
 

microstrip

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Francisco, I would like to be able to test:

6DJ8/6922
6SN7/5692
12AX7
12AT7

Maybe power tubes 6550 and KT120 and KT150

This page has a lot of information concerning tube testers. http://jacmusic.com/Tube-testers/Digital-Testers-Compare/compare-Index.htm. One big issue about modern tube testers is reliability and service. One should have an old classical tester from the 50's or 60's just to check if there are no faults in the tube, a short can damage some of the modern testers. Serviceability can be a nuisance with modern testers using DACs, ADCs and software.

In order to match tubes precisely you should be able to carry measurements at anode voltage and current similar to the operating points of the tube in the circuit - it is why most of the time factory matching of KT120's is not enough, or a set of tubes matched for the VTL750 is not matched for an ARC REF250. And some tubes should be burn-in before matching, the parameters change during the first 50 hours.

For small signal tubes we can easily get a cheap board at eBay to build a very simple one tube preamplifier that can be used to listen to the tube sound, like the old George Kaye small tube tester. It can be used for subjective evaluation of tube noise and microphony - it is nice to have two circuits so we can directly compare in A/B mode the tube being tested with a reference tube. Remember tubes should be tapped with a rubber mallet for microphony tests, not with a pencil or the screwdriver handle!
 

Barry

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This is an older comparison I think, but useful. Francisco, you know a lot more about tubes than I do but I find jacmusic overly harsh in his evaluation of the Amplitrex even though he apparently owns 4 of them for his business. I don't test DHT tubes so I'm not sure about those criticisms. So he doesn't like Excel looking type graphs, US convention use of commas instead of periods, and technical use of the term emissions - so what? I do seem to recall you can't vary screen voltage when testing pentodes which would be nice. Some of the other equipment in the comparison is no longer available or you have to build them (uTracer looks nice but is Diy for example).

Your comment about older equipment servicing is important. That's why it somewhat bothers me that the software hasn't been updated since 2009, but the average user won't care if using it in stand alone mode. Infrequently, the program hangs up in computer mode, but it works and most people are not using it that way from what I gather. Albert Porter confirmed to me that the software works in latest Windows 10 in computer mode otherwise I would strongly avoid buying it if you're looking for those features. All in all I think it's a good piece of equipment, though it's expensive and probably much more than most people need.
 
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Kcin

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This page has a lot of information concerning tube testers. http://jacmusic.com/Tube-testers/Digital-Testers-Compare/compare-Index.htm. One big issue about modern tube testers is reliability and service. One should have an old classical tester from the 50's or 60's just to check if there are no faults in the tube, a short can damage some of the modern testers. Serviceability can be a nuisance with modern testers using DACs, ADCs and software.

In order to match tubes precisely you should be able to carry measurements at anode voltage and current similar to the operating points of the tube in the circuit - it is why most of the time factory matching of KT120's is not enough, or a set of tubes matched for the VTL750 is not matched for an ARC REF250. And some tubes should be burn-in before matching, the parameters change during the first 50 hours.

For small signal tubes we can easily get a cheap board at eBay to build a very simple one tube preamplifier that can be used to listen to the tube sound, like the old George Kaye small tube tester. It can be used for subjective evaluation of tube noise and microphony - it is nice to have two circuits so we can directly compare in A/B mode the tube being tested with a reference tube. Remember tubes should be tapped with a rubber mallet for microphony tests, not with a pencil or the screwdriver handle!

This is an older comparison I think, but useful. Francisco, you know a lot more about tubes than I do but I find jacmusic overly harsh in his evaluation of the Amplitrex even though he apparently owns 4 of them for his business. I don't test DHT tubes so I'm not sure about those criticisms. So he doesn't like Excel looking type graphs, US convention use of commas instead of periods, and technical use of the term emissions - so what? I do seem to recall you can't vary screen voltage when testing pentodeswhich would be nice. Some of the other equipment in the comparison is no longer available or you have to build it (uTracer looks nice but is a bit Diy for example).

Your comment about older equipment servicing is important. That's why it somewhat bothers me that the software hasn't been updated since 2009, but the average user won't care if using it in stand alone mode. Infrequently, the program hangs up in computer mode, but it works and most people are not using it that way from what I gather. Albert Porter confirmed to me that the software works in latest Windows 10 in computer mode otherwise I would strongly avoid buying it if you're looking for those features. All in all I think it's a good piece of equipment though it's probably more than most people need.

The amplitrex is likely more than most enthusiasts will need. I stand by my original comment that you must be prepared to be frustrated and become accustomed to the individual character of how a tester responds. I also alluded that you would need more than one tester if you were looking for small tube and power tube testing outside of the amplitrex. I am assuming that Ron is not looking for a kit or to build a single stage amp to test for noise. If your requirements are out of the box solutions then a restored commercial vintage unit for transconductance and shorts/leakage and a unit like the maximatcher for small signal tubes that includes a microphony/noise test. I like the VTV characterizer for noise and balance.. but it is not in production anymore.

Real world voltages on the plates and grids for power tubes only come with the amplitrex but as audiophiles we've been living with machines that don't provide that for decades- allow a good vendor to do that and have the machines to test for the parameters that are best suited to occasional user at home.
 

Illinimax

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Orange unit works great, easy to use. Best $500 I've spent on gear as I have a lot of guitar amps in addition to my hifi rig.
 

Believe High Fidelity

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IME, the best tube tester is the equipment that the tube goes in....

This is truth. Even if you can procure a tube tester is it not going to tell you anything of value unless the tester is based on the circuit it is going in. Easier (and a lot less expensive) to use a multimeter to check if they are good.
 

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