12AX7 instead of 12AT7 in PI - deluxe reverb

Rodolphe

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Hello,


I have tried today one of the regular mod seen on the web for the DRRI:
pulling out the V1 for a bit more gain, and replace the 12AT7 set in PI by a 12AX7.
I must admit I quite liked the result as the amp kinda screamed right after that. It really enjoyed playing it cranked with my strat and les paul. it sounded more wild than with stock tube configuration.
on clean settings, it was maybe a bit less sparkly, more tweedy in fact.

I sent an email to my local amp tech letting him know about it.
His answer sounded a bit ironical to me as he said something like:
save up some money for new 6V6 tubes in near future and maybe a new OT...
and he finished his mail kinda joking about what can be read in the net/forums about amps.

what is you opinion about this?
is it safe to replace the PI 12AT7 by a 12AX7 in a DRRI?
will it hurt something or not?

regards
 

Neemo

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I wouldn't do it in my Drri....I did do a full tube swap and rebiased to about 71% sounds awesome to me, but something about changing tubes around to draw more or less current (or none) , or totally removing something from the circuit board kinda freaks me out
 

LHakim

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Totally harmless. Guitarists have been doing that for decades with no ill-effect on their bf/sf fenders.
 

Rodolphe

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Any amp tech to give me a final point of view?
 

mcphaul

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Quoting from "A Desktop Reference of Hip Vintage Guitar Amps" by Gerald Weber. [ame=http://www.amazon.com/Desktop-Reference-Vintage-Guitar-Amps/dp/0964106000]Amazon.com: A Desktop Reference of Hip Vintage Guitar Amps (0073999302257): Gerald Weber: Books[/ame]

Both of these are in the chapter "Ten easy mods for your Pro Reverb" not in a chapter about DRRI's but elsewhere in the book he goes on to say that most of the mods can be done on any blackface Fender.

I've done both of these, along with several others, to my Silverface Deluxe Reverb, but have NO experiance with the re-issues.

Pg. 146 for both of these

4. Improve Gain by removing the 12AX7 from tht normal channel....Removing the normal channel preamp tube will automatically re-bias the reverb channel for better gain.

5. Increase Gain and Dynamic Response by removing the 12AT7 phase inverter tube and replacing it with a 12AX7.


Visit his website Kendrick Amplifiers, Tube Amps, Guitars, Books, DVDs, and Tube Amp Parts ~ Welcome! and drop him an email with the question.
 

Batman

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Hello,


I have tried today one of the regular mod seen on the web for the DRRI:
pulling out the V1 for a bit more gain, and replace the 12AT7 set in PI by a 12AX7.
I must admit I quite liked the result as the amp kinda screamed right after that. It really enjoyed playing it cranked with my strat and les paul. it sounded more wild than with stock tube configuration.
on clean settings, it was maybe a bit less sparkly, more tweedy in fact.

I sent an email to my local amp tech letting him know about it.
His answer sounded a bit ironical to me as he said something like:
save up some money for new 6V6 tubes in near future and maybe a new OT...
and he finished his mail kinda joking about what can be read in the net/forums about amps.

what is you opinion about this?
is it safe to replace the PI 12AT7 by a 12AX7 in a DRRI?
will it hurt something or not?

regards
I've done both "Mods" with no ill effect on the amp; great tone!

The only other "mod" I would say is necessary is to re-bias the amp slightly warmer. Unless you are having issues, both the re-tube and replacement of the OT is unnecessary.
 

Rodolphe

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Quoting from "A Desktop Reference of Hip Vintage Guitar Amps" by Gerald Weber. Amazon.com: A Desktop Reference of Hip Vintage Guitar Amps (0073999302257): Gerald Weber: Books

Both of these are in the chapter "Ten easy mods for your Pro Reverb" not in a chapter about DRRI's but elsewhere in the book he goes on to say that most of the mods can be done on any blackface Fender.

I've done both of these, along with several others, to my Silverface Deluxe Reverb, but have NO experiance with the re-issues.

Pg. 146 for both of these

4. Improve Gain by removing the 12AX7 from tht normal channel....Removing the normal channel preamp tube will automatically re-bias the reverb channel for better gain.

5. Increase Gain and Dynamic Response by removing the 12AT7 phase inverter tube and replacing it with a 12AX7.


Visit his website Kendrick Amplifiers, Tube Amps, Guitars, Books, DVDs, and Tube Amp Parts ~ Welcome! and drop him an email with the question.
that's the exact answer I was looking for.
my amp tech often quotes Weber, so I guess he must have forgotten this book...:) :thumb:

thanks
 

Rodolphe

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I've done both "Mods" with no ill effect on the amp; great tone!

The only other "mod" I would say is necessary is to re-bias the amp slightly warmer. Unless you are having issues, both the re-tube and replacement of the OT is unnecessary.
well he already changed the Power tubes, but what he meant was "If you change the 12AT7 PI for a 12AX7, then save up some money for new 6V6 & OT"...

he's on the clean side of fender sound so I guess that for him looking for more OD is kinda weird
 

Splattle101

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I think it's more a case of a tech denigrating information gleaned from the net in order to:
1. Seem wise; and
2. Maintain a sense of dependence in a customer.

The fact is, if he was actually interested in helping you get what you want from your amp, he might've suggested these tricks himself. They're very well known (they're in Weber's books for goodness sake!).

And I'm still trying to think how a 12AX7 is a danger to your OT.
 

mcphaul

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that's the exact answer I was looking for.
my amp tech often quotes Weber, so I guess he must have forgotten this book...:) :thumb:

thanks
Glad to help.

If you really want to understand the mods and maybe take it a little farther, pick up the book.

I have also disconnected the Vibrato on mine to increase the tone and built a jumper to use the reverb send/return as an extra gain stage.

The Vibrato mod is always on mine and is great, the reverb mod is removable and is great with a Strat for a little more edge but is not for everything.
 

Rodolphe

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I 'm already reading books on tube amps to understand better what's going on, and i'm planning to mod my class 5. i 'think i'll do it on my own (with the help from the board) without asking him...
 


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