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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Sun May 22, 2011 8:00 pm
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Darn tubes sound good even to "10." Not running hot. Leads me to believe that maybe the bias meter is not accurate. Going to borrow my friend's bias tool and double check the bias.


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Sun May 22, 2011 8:06 pm
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A bias pot would have little affect on tremolo, as the tremolo speed and intensity are AC, and the bias voltage is DC. But, the intensity pot does lower the bias voltage when turned up though, with or without having a bias pot. The '65 PRRI schematic that I'm looking at, shows a bias pot. So, did the originals have a bias pot, then none on the SF, then the RI has one? Or is the bias pot only on the RI?

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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Sun May 22, 2011 8:20 pm
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Yeah, you're prolly correct. I'll give these a shot. If they fail... back to the Hytron's.

Thanks, for your comments.


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Sun May 22, 2011 10:25 pm
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Vintage Princetons and Princeton Reverbs (both BF and SF) did not have the adjustable bias pot -- it's an add-on for the re-issues (useful, but FMIC could've sweetened the pot by fitting a standby switch as well).

Arjay

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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Mon May 23, 2011 10:55 am
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I tried 2 different pairs of TS 6V6 in my DRRI. The first pair sounded very sweet, similar to the RCAs, but a month later one of them developed a rattle. I then got another pair to keep as a spare, been running the RCAs... I could never get the new pair to sound good! Both were biased around 20 mA. I even took both pairs to my amp tech to test, both looked good. I never thought to bias them really hot to see if it makes a difference. I left the tubes with the amp tech cause I was very disappointed with the way they sounded, but I kept the first pair with the rattling tube.

Doubt I'll be buying anymore TS tubes... I did try a pair of TAD 6V6GT-STR, just so I can have good sounding tubes as spare, very happy with the results! They sound even closer to the RCAs I love.


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Mon May 23, 2011 8:04 pm
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Yeah, I've gone through 4 pairs of TSRI 6V6GT reissues in various amps. They all need to be biased above 28mA to sound good. You bias them below 25mA and it almost sounds like Class B biasing. Very cold. Sterile.

The whole thing reminds of the 6P6S tube. There was a big do it about it's tone. But, unfortunately, it was found that it could not handle over 350 VDC on the plates. Had a lot of runaway tubes.

Problem is, the crazy NOS tubes that these old guitar amps were built around were way over built. And new production doesn't seem to be. At least the TSRI can take 415+ VDC plate voltage.

Will keep you posted.


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Mon May 23, 2011 9:05 pm
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BMW2002Ti wrote:
...NOS tubes that these old guitar amps were built around were way over built. ...


I remember RCA would routinely use/recommend their tubes in their own equipment and other applications where the specs of the tubes would be greatly exceeded, and they worked very well with no problems handling the excess (very high Plate voltage for example). My dad was an engineer in charge of safety testing (among other things) at RCA here in Indy and I got to see some of the fantastic things that they would do to test the equipment, very brutal extreme testing that the tubes and equipment had to be able to handle. I don't think that very many of the new manufacture tubes would be able to withstand the abuse that the old ones could take.

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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Tue May 24, 2011 5:23 am
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The Deluxe Reverb puts more onto the 6V6s than spec'd doesn't it?
I've seen audiophiles talking about us amp boys and laughing at how we're pushing 6V6's over the limit....I know voltage is higher now than in Leo's days but they were over spec back then,isn't that right?


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Tue May 24, 2011 6:13 am
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Look at original GE's 6V6GT data. 285 VDC on the plates for Class AB1? Some amps put that much onto 12AX7's.


http://www.guitaramplifierblueprinting. ... /6V6GT.pdf


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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Tue May 24, 2011 8:02 am
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And that 285VDC yields but 14 watts in the AB1 application.

Leo definitely pushed this tube's envelope. Bottles engineered and built less sturdily would've self-immolated in the AB763 Deluxe Reverb.

Arjay

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Post subject: Re: BAd news about a pair of TungSol 6V6GT reissued tubes.
Posted: Tue May 24, 2011 9:12 am
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Retroverbial wrote:
And that 285VDC yields but 14 watts in the AB1 application.

Leo definitely pushed this tube's envelope. Bottles engineered and built less sturdily would've self-immolated in the AB763 Deluxe Reverb.

Arjay


basically he couldn't have used 6V6s in the DR circuit for example. So if the tubes couldnt take it.... the DR in its form never would have been. Along with many other amps of the day that used 6V6s. They counted on the robust nature of those tubes..


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