NOS Tube Score (Expert Assistance Needed!)!

Great score!!! Those should last you a lifetime in your amps. They should all be better than any current offerings, use them all. Yes, the 12AT7's will be great for the PR reverb and PI posistions, don't be drawn into the internet hype about which ones won't last, there are way too many variables that could have occured for those conclusions to be made. Let your ears be the judge.

MikeY

 

They are all great tubes and probably test new. TRy the 12ax7's & 5751's in your amps,(they are basically the same tube. The 5y3 would work great in the champ,but it would be nice to test that one for sure. I fried a Champ circuit witha bad 5y3,it toasted the tranny. THe 12at7 should be great in the PR.

 

It's the JAN GE 12AT7s that don't tend to work well or last as reverb drivers, not the Philips or Sylvanias.

Regarding the rest of them, use your ears....that's the only thing that matters.

 

I bought a lot of 50 GE 6201/12AT7's a couple of years ago for a very good price. I tested evey one in my Eico 667 and in the reverb send position of my original '65 Deluxe Reverb. While they all tested good in the Eico, 22 produced noise in the Deluxe's reverb send. The quiet ones work quite well in that position and I have had one in there for over a year with no problems. The problem would be buying these from a source that doesn't test for noise and microphonics. The ones that are microphonic can be used without a problem in the driver/phase inverter spot.

 

That's only in the mid-'70s SF Fenders that run the reverb driver too hot. If you change the cathode resistor back to BF value, any decent 12AT7 will be fine.

 

With any small signal tube, the best thing to do is put it in the amp and listen. The tubes made in Poland may sound good. The Princeton Reverb's reverb send, V2 , will weed out any tube producing noise.

 

I'm pretty sure they have problems in BF and BF'd reverb driver circuits as well, though I haven't kept a detailed data base. But then again, I've only sold about 80,000 tubes and worked on 100s of amps so what do I know?

 

Could they necessarily be worse than tubes made in Russia or China?

 

That would have been news to Fender, I suppose, since GE was the stock OEM tube for them for quite a while in the SF era, immediately pre-Sylvania.

It's the amps with the 470-ohm cathode resistor on the 12AT7 that have problems with non-Sylvanias. These are mostly the SF amps with the pull-master, but not UL. They also have REALLY high voltage (440V or more) on the plates there. Going back to the 2.2K resistor makes the amp happy with 'regular' 12AT7s again and doesn't affect the tone. They d

Yeah. I propose that Aspen Pittman has sold a lot more tubes than that, and been inside more amps too. It doesn't mean I'm going to believe everything he says.

 

The anonymous poster strikes again.

 

Sylvania 12AT7 "Made in Poland" - this one is a rare bird. It's an RFT made actually in GDR. Most probably Sylwania placed an order with Telam or Polam who were unable to deliver on time and bought bulk from RFT, stamped and re-exported. Poles paid the Germans in ham and butter, Sylvania paid Poles in USD so Poles could buy Decca radars for ships they were building for Soviet Navy which soviets paid Poles in reprints of Lenins works which the Poles in turn immediately sold to paper recycling facilities and printed books for US publishing houses and got their USD back. Those were the days....

 

Well, considering the triode is kind of a distant relation of the light bulb....



rooster.