Vintage tube testers...Reliablity???

[Madmaestro]

I often check my customers tubes with my calibrated Eico 667 and Stark 9-55 (with a 9-pin socket added) just to see what condition they are in. One day, just for giggles, I throw a bunch of new J.J. ECC83's and my tube tester fails near half of my stock!!! I panic and take them to test on my friends Hickok 123A which also shows failure! He shows me a "good" testing new NOS RCA just to compare. I was truly baffled and after talking to Jay at Eurotubes I sent them back to be tested again. Here are the results:

We received your eight ECC83S’s and ran them thru the “Professor”. This is our new Amplitrex tester where they all passed with flying colors.

The issues with testing ECC83S’s on old tube testers is that they rarely have separate settings for ECC83 tubes so you’re testing to 12AX7 spec’s. ECC83 tubes and especially the JJ’s have a hotter current output and even my top of the line TV2 will fall down on these tubes. Your tubes were originally tested on one of out VTV Characterizers and we have found them to be more accurate than my TV2.

We are finding the Amplitrex to be an amazing machine. It’s the only tester I’ve found so far that will actually test preamp tubes in full cathode bias under high voltage and this unlike static testing with a fixed grid voltage makes a huge difference.

Anyway, as I said they all test just fine so we will pay the post back. I’ll write “warranty” on them so they don’t get held in customs.

Thanks

Bob

I'm a long time customer of Eurotubes and I don't in any way doubt their knowledge of vacuum tubes. I'm just wondering if anyone else has realized the limitations of these vintage machines? I know my Eico can be set up to test unknown tubes, so maybe if I knew what parameters to change it might still be a valuable machine...Are there any thoughts or suggestions?

[6942]

Most of the tube testers we own are 40-50+ years old.
The odds of all the components being up to spec are just about nil.
I got lucky.....the guy I bought my Sencore from.....was our test equipment calibrator from work.
Even then.....I take what I read with a grain of salt?

Steve

[JimiBryant]

tube testers are OK only to a certain point, I take 'em as an indicator of
a tube's potential strength and leave it at that.

pros such as Eurotubes or KCA test tubes at actual operating voltages,
so let's say out of a batch of 1000 tubes they may weed out a few dozen
that aren't up to snuff due to the tubes literally failing during the testing
process - one isn't going to get this result with a home/hobbyist-type tester.

I'll pay their prices because I know they stand behind what they sell,
but I fully realize that I'm also paying for their time that it takes to test
and match all those tubes, not to mention covering some of the loss
due to the sub-par tubes that get pitched. these people are in business,
they provide good service and I don't mind paying for it.

on the other hand, I'll take a chance on old tubes depending how cheap
they are.. I've got plenty of great tubes I've scored out of thrift-store
purchases of old radios, stereos, and TVs - although all that kinda stuff
has dried up in the thrifts since the advent of eBay, I'll admit it.

yard sales can still be a good source, oddly enough.

one older fellow said it best: "ain't nobody was matching no tubes back
in the fifties!"

my favorite way of testing 12AX7-type tubes is to put 'em in V1 of one
of my Blues Juniors and then crank it up with a good guitar!

12AX7s, ECC83s, 5751s, 12AT7s, ECC82s, 7025s, 12AY7s, and 12AU7s
are all pretty much interchangeable, although some may not be all
that great in the V1 slot, ya know? differing gain levels and all that.

[Madmaestro]

The odds of all the components being up to spec are just about nil.

All the components are up to spec, I calibrated my tube tester myself. I even replaced the only parts inside that can go bad, two electrolytic caps and two diodes. These tube testers are mostly mechanical inside, so therefore there's not much to go wrong. It just baffles me that thousands of these tube testers have been around for years and their accuracy, even if calibrated, is questionable. The new Amplitrex that Eurotubes uses sells for $2550...definitely out of my budget. Anyways, I'll still be buying from Eurotubes, they've got a great reputation and have always treated me well.

[jjmantele]

There was a post here recently on how some newer preamp tubes will test bad since the tester wants them to pass much more current than an amp would ever ask them to.

I’ll have to test some of my new JJ 12ax7s on my 1947 Precision brand tester to see if I get the same problem.

[Scott S]

No doubt you've been here already, but it looks like your Eico 667 ought to do the job as well as any. I like being able to check gm as opposed to simple emissions. Shame it can't put more than 180V on the plates though. For me, as long as there aren't any shorts, transconductance is in the ballpark, and the current draw (measured in the amp) is good, I'm content.

Here's another thread on 667 debugging. Good luck!

- Scott

[6x47]

The EICO charts are notoriously messed up.

http://www.tone-lizard.com/Tube_Testers.html

The settings I use for testing 12ax7/ECC83 are:

Fil 12.6
Grid 7
Plate 93
Levers 45112 66661 2 4 test 123 1
66612 45161 test 678 6

[Madmaestro]

The EICO charts are notoriously messed up.

http://www.tone-lizard.com/Tube_Testers.html

The settings I use for testing 12ax7/ECC83 are:

Fil 12.6
Grid 7
Plate 93
Levers 45112 66661 2 4 test 123 1
66612 45161 test 678 6

I have some settings from the Coletronics revised chart that I've been following but the grid is set at 40 and the plate at 76...I think your right about the Eico charts being messed up, but I can't seem to find any standardized charts that people are using. Thanks for all the responses.

Edit: I looked up the specs of the JJ ECC83S and the plate should be 300v max. and the grid voltage is 50v max.

[6x47]

Read the article on Tone Lizard. He (as did I ) found mistakes on the Coletronics chart as well, however he is much more qualified to explain.

I have been asking for "reliable charts" to no avail.

If you read the EICO material on how to handle a tube for which no specs are available you will be even more unenlightened.

Basically they say take a bunch of tubes and develop a set of test parameters based on the average.

Try my recommendation. I have found it reliable and it even agrees with one of the published charts (although I don't recall which one).

[Madmaestro]

Read the article on Tone Lizard. He (as did I ) found mistakes on the Coletronics chart as well, however he is much more qualified to explain.

I have been asking for "reliable charts" to no avail.

If you read the EICO material on how to handle a tube for which no specs are available you will be even more unenlightened.

Basically they say take a bunch of tubes and develop a set of test parameters based on the average.

Try my recommendation. I have found it reliable and it even agrees with one of the published charts (although I don't recall which one).

I see your settings agree with the Tone Lizards. I've just got my tubes back from Eurotubes and I tested a couple...they were not great readings using these new settings. Have you tried testing JJ's? BTW,Thanks for all your help.

[6x47]

"Have you tried testing JJ's?"

I have a modest collection of most recent and current production 12ax7 types (including JJ) as well as a lot of older US tubes I've accumulated from old amps I've bought.

Also stumbled across some Mullards in decommissioned organs I was allowed to scavenge from.

I'm happy with the settings I passed on to you or I would have kept quiet.

[Madmaestro]

I'm happy with the settings I passed on to you or I would have kept quiet.

Sorry, I wasn't meaning to question your Eico settings, I think their fine. I just meant that the tubes that were returned to me didn't test any better (with your settings) than the first time. I still have some NOS tubes that are testing better than the few JJ's that I've been having problems with...

[6x47]

Testing the tubes really is just a guide, a tool you can use to show the tube works or has a high or low reading, just a bit better than flying blind.

What do the test results prove?

I had a JJ ECC83 that tested well and sounded good.

I put it in the V2 slot of my Fender Pro Reverb and after about 2 1/2 hours it started arcing, snapping, popping and making all manner of strange sounds.

It was toast, even though I had bought it from one of the 'good guys' and tested it to my own satisfaction.

In the end it was still a crap shoot.

[Madmaestro]

In the end it was still a crap shoot.

I guess it's like I've heard before, the only true test is in a working amplifier. I just wish that there was less of a "grey" area in acceptability but I also realize that even tubes from the same manufacturing batch can all test differently. Anyways, thanks for your input and the new Eico settings.

[bradduerr]

Back in the old days before PCBs, ICs, and transistors I worked in a tv repair shop that did not own a tube tester. The owner believed that the only good way to test tubes was to substitute a new tube for the tube in question.