ecc83 nos test in TV7 tube tester

[Andrei_T]

Hi, I need to know how much should a nos ecc83 test in a TV7 tube tester?

I know that 32 is the minimum reading for a good tube, what reading should I get for a new unused tube?

Thanks in advance,

Andrei

[Enzo]

Who knows? If your tester says 32 on its meter is the bottom of the "good" range, then anything over that is "good." testers each are different, there is no standard as to the voltages and currents they use for testing, so there is not goung to be a universal "good" number. There is natural variation in gains tube to tube, and two tubes can be substantially different in meter reading and still both be perfectly good tubes.

In my view, tube testers are fine at pointing out failed tubes, and even some use at trying to match tubes, but in general they won't tell you when a tube has lost its tone, gotten noisy, gotten microphonic, and some other things.

[Andrei_T]

I see, thanks enzo.

[TD_Madden]

Yes, that's pretty much how I use my B&K 707.......according to their guide, anything over 22 is "good". I only have a couple where both sides of a 12AX7 are the same....but even the crappiest I've got (except for some SovTeks) test "good".

I did pull a JJ ECC-3S out of a troublesome amp today and it gave ZERO on both sides....obviously bad, although the filament lit up just fine.

[JC@]

In my experience nos ECC83 tubes can't be the standard any longer, as almost any of the new production tubes have almost two times the amplification factor than nos ones.
As far as power consumption they are about the same though.
Also I use to consider all the data provided with tube testers as nominal. Look at it this way: take a good tube, take note of it's readings and use it as your reference standard for tubes of the same type.
Unless you use a perfectly calibrated fully adjustable tester it is very difficult to take the manufacturer's official tube data as a reference for you good - no good or weak - strong - very strong parameters. To me, comparing with a known good one (tube) it's a lot more useful.

[TD_Madden]

Pretty much agree...of course, my unit (purchased recently) was calibrated when i got it.

[TD_Madden]

oh, by the way, here's where I got mine:

http://www.vacuumtubes.com/tubetesters.html

[Andrei_T]

Thanks for your answers guys

[Enzo]

And one added thought: In a commercial shop like mine, if I think a tube is bad, I just stick another one in the socket. That is so much faster than getting out the testeer, setting it up, warming the tube up and making all the tests. If the new tube makes a difference, the old tube was bad. if the new tube makes no difference, I stick the old tube back in and move on.

I don't sell used tubes, but if I wanted to characterize a batch of old tubes for my own use, even then, I'd just slap them in an amp and see how they worked.

[Bruce / Mission Amps]

oh, by the way, here's where I got mine:

http://www.vacuumtubes.com/tubetesters.html

I have about 75 tube testers in my collection, of which at least 16-17 of them are high dollar, vintage Hickok testers.... (including that 752A you see and a 539C).
Yet, I still just simply use my "Golden Tubes" set and my good old, well worn 533A on the bench for comparing.

[JC@]

I have about 75 tube testers in my collection, of which at least 16-17 of them are high dollar, vintage Hickok testers.... (including that 752A you see and a 539C).
Yet, I still just simply use my "Golden Tubes" set and my good old, well worn 533A on the bench for comparing.

I understand Enzo's point of view, but honestly, I couldn't live without my tube tester. And I learned a lot myself about tubes using it. I always wanted a 539C too, but I managed to refrain myself. One good tester properly kept and mantained is enough for me. Mine has it's own place in my workshop.

[Andrei_T]

Speaking of tube testers, can you recommend a good model that can test tubes found in guitar amps and is not too expensive?

I was thinking of an eico 667 but I have no experience with any tube testers so your opinions are wellcome.

Thanks

[JC@]

Speaking of tube testers, can you recommend a good model that can test tubes found in guitar amps and is not too expensive?

I was thinking of an eico 667 but I have no experience with any tube testers so your opinions are wellcome.

Thanks

Andrei, Enzo is always right. If you are trying to repair an amp, replacing the suspected tube is the best way to go, the cheapest and the quickest way.
Also, sometimes a tube tests OK on the tester but it may have problems.
That said, I haven't had the oportunity to try any of the Eico testers, but the 667 looks very good indeed. If I understood it right, it has the option of testing both sides of a double triode tube (12xx7) with a simple turn of a switch or something like that, and believe me, that is very important unless you like to spend a whole afternoon to test a few tubes.

Good luck in your search.

[Dudeski]

If the tube has no flaws..It should be around 50 on your TV7 ..
A friend of mine who has thousands of old tubes and really is deep told me 52/53
Average new is 1600 mhos (transconductance) and 1.2 gain anything above 1.2 ma at 250 volts..that's gain ,and you have a really nice thick "brown sound" particularly with a mullard.
Then of course,you check for shorts and noise.
But this is the standard
Check this link out..http://guitaramplifierblueprinting.com/12ax7.html
Read especially after it says "inconsistencies" to understand values..
Others might disagree..but I love this article.
Good luck

[hylaphone]

Just wanted to add, the TV-7 is a great tester but probably not an accurate one for high Gm, low bias tubes like ECC83
It's been a while since I used mine but isn't the signal voltage something huge like 5VAC?
Would probably want that well under 1V to avoid driving the tube into cutoff