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Post subject: TungSol re-issued 6V6GT (Russian made) update
Posted: Sun Dec 25, 2011 7:05 pm
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Rock Star
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OK... update. In the BFPR I just patched-up to work properly, I found that the 100K-ohm resistor that is just before the recitifer diode for the Bias Power supply, must be replaced with a 68-75 k-Ohm resistor to get an NOS Hytron 6Y6GTY to pass 20-23 mA of current each (at 425 VDC on the plates). There's just little room for a pot. And after the diode, a pot effects the Vibrato section (tube driven).

I tried a new TAD 6V6GT-STR and got 18-22 mA in same amp. Good tone. I then tried my last set of TSRI 6V6GT's. I got an varying bias of 28-36mA, same amp settings. This is prolly why the amp sounds a bit brown and overdrives a tad earlier with these tubes. They run hot. I bought them matched from the Tube Store. I used a Bias Probe on the tubes with DVM's on each tube.

Then, in less than 5 hours of playing--- one TSRI went dead. Zero mA. Sure enough, it showed "dead" on my Hickok. The amp still played through the one good tube--- which bias went to 40mA. And actually I would never have known that one tube went bad, without the meter. Kinda hard to see the tube's plates and grid through the back panel.

These must be incredibly poor construction or lightweight plates and not truly aligned grids---esp for combo guitar use.

Finally, I tried a set of US made BP TungSol-made 6V6GTA labeled Magnavox. 22-24mA. Played it all night long. At the end of 4 hours--- 22-26mA. I have never tried the JJ in this amp---due to a catastophic failure in a guys' $10K hi-fi amp--- last year, using these tubes. The whole output broad fried before the fuse could blow.

I recommend to look for NOS or good testing used US made 6V6GT's. For these old BF and SF PR and DR's. Esp if you are really going to push the amp or gig with it. The TAD-6V6GT-STR seems to be a good modern choice. As I have yet to hear a disaster using this tube.

Just my observation. YMMV. And all that jazz.


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Post subject: Re: TungSol re-issued 6V6GT (Russian made) update
Posted: Mon Dec 26, 2011 6:45 am
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Rock Star
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Joined: Wed Feb 17, 2010 11:38 am
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Location: Tennessee
Wow!
In other words...do not buy TS 6V6's...POS!
I wonder how many others who are less knowledgable about tube amps are having real problems with those tubes?....that could be really bad. :(


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