jerry amp

Postby tigerstrat » Thu Jan 18, 2007 2:30 pm

Jerry used GOBS of reverb in his Fender preamps (and his Mesas).

Otherwise, I suspect he probably would have just gone ahead and switched to the Alembic F2B in 1973 like Bob and Phil did.
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Postby strumminsix » Thu Jan 18, 2007 5:50 pm

DreamNightWind wrote:
If he ran his preamp at "clean" levels (this sounds right to me, though I don't know), it weakens the argument that says the reason he didn't use power tubes was to be able to drive the preamp hard without introducing serious clipping in the Twin's power amp.


Not necessarily. The input of the preamp, the gain stages, the PI all come into play. You can run a hot signal into your preamp using a padding of sorts or lower output tubes and not clip it.

However, if the signal was too hot going into the poweramp that may clip it. Or maybe the signal was too low going into the poweramp and by the time it was raised enough it was clipping.

Lots o' factors in the equation...
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Postby betteroffdeadnc » Fri Nov 09, 2007 9:41 am

Hey Guys,
I have a question. Does anyone know if Jerry's Twins had the output circuitry removed? I mean, if he wasn't using the amp to drive speakers he would have to remove the power tubes to prevent the output transformers from self destructing and potentially shorting out the whole amp. So if he removed the tubes he would have probably removed the OT, since why would you carry a few lbs of iron if you weren't going to use it. So If the tubes and the OTs were removed from his amps, the operating voltages of the preamps probably went up since the preamp voltages are determined by the overall current pull through the voltage divider chain in the power supply. Does anyone know if he had this modified or ran the preamps hot?

-s
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Postby waldo041 » Fri Nov 09, 2007 10:36 am

betteroffdeadnc wrote:Hey Guys,
I have a question. Does anyone know if Jerry's Twins had the output circuitry removed? I mean, if he wasn't using the amp to drive speakers he would have to remove the power tubes to prevent the output transformers from self destructing and potentially shorting out the whole amp. So if he removed the tubes he would have probably removed the OT, since why would you carry a few lbs of iron if you weren't going to use it. So If the tubes and the OTs were removed from his amps, the operating voltages of the preamps probably went up since the preamp voltages are determined by the overall current pull through the voltage divider chain in the power supply. Does anyone know if he had this modified or ran the preamps hot?

-s


i believe the output tubes were all that was removed. appears all to be there, probably as a backup if needed.

http://i60.photobucket.com/albums/h36/w ... an0001.jpg

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Postby betteroffdeadnc » Fri Nov 09, 2007 10:47 am

That could be a significant factor in his amp's sound then. You can do a similar, but less significant, thing by removing the 1st tube of the normal channel (assuming of course that you're playing through the Vibrato/Reverb channel). I find that it sounds better in most 2 channel Fenders.
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Postby tigerstrat » Fri Nov 09, 2007 12:00 pm

waldo041 wrote:
betteroffdeadnc wrote:Hey Guys,
I have a question. Does anyone know if Jerry's Twins had the output circuitry removed? I mean, if he wasn't using the amp to drive speakers he would have to remove the power tubes to prevent the output transformers from self destructing and potentially shorting out the whole amp. So if he removed the tubes he would have probably removed the OT, since why would you carry a few lbs of iron if you weren't going to use it. So If the tubes and the OTs were removed from his amps, the operating voltages of the preamps probably went up since the preamp voltages are determined by the overall current pull through the voltage divider chain in the power supply. Does anyone know if he had this modified or ran the preamps hot?

-s


i believe the output tubes were all that was removed. appears all to be there, probably as a backup if needed.

http://i60.photobucket.com/albums/h36/w ... an0001.jpg

peace,
waldo


In 73-74 shots, you can also see that the trannies are all there.

I doubt weight would be a factor since they had crew to move everything.

I also doubt that backup was a consideration, since if a Mac failed they would go to a backup Mac rather than insert the Twins power tubes.

They probably left the output circuitry in because A) it would as you said raise the voltages, where they didn't want/need them raised, B) it would be more work to take them out; and possibly even C) easier to resell the amp with them intact.
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Postby betteroffdeadnc » Fri Nov 09, 2007 12:05 pm

Just removing the tubes raised the voltages.
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Postby GratefulPat » Fri Nov 09, 2007 1:15 pm

he used the mesas when he practiced backstage before shows in the late 80s early 90s, i believe the studio at times also
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Postby tigerstrat » Fri Nov 09, 2007 1:35 pm

GratefulPat wrote:he used the mesas when he practiced backstage before shows in the late 80s early 90s, i believe the studio at times also


Where did you get this backstage info? What Mesa? I always thought he would either use that tiny Fender Harvard (although that pic is clearly mid-70's), or- as seen in Justin Kreutzmann's home video of Jerry playing "Crazy Fingers" in the dressing room- no amp at all.
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Postby tigerstrat » Fri Nov 09, 2007 1:40 pm

[quote="waldo041
http://i60.photobucket.com/albums/h36/w ... an0001.jpg

peace,
waldo[/quote]

Jerry's Mutron III and Octave-Divider are barely visible in this pic, on the floor and nearly buried in confetti!
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Postby strumminsix » Fri Nov 09, 2007 2:33 pm

GratefulPat wrote:he used the mesas when he practiced backstage before shows in the late 80s early 90s, i believe the studio at times also


Ya, where did you hear this?

Always heard a Harvard as well.

Seems unlikely he'd play a Mesa to warm up then a Fender live.
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Nice photo...

Postby Tennessee Jedi » Fri Nov 09, 2007 2:36 pm

Gee Bobstar and Donna look real chummy in that shot.
I thought Jerry sounded un-plugged on the Crazy Fingers video.
What a great sounding guitar. :cool:
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Re: Nice photo...

Postby tigerstrat » Fri Nov 09, 2007 3:53 pm

Tennessee Jedi wrote:Gee Bobstar and Donna look real chummy in that shot.
I thought Jerry sounded un-plugged on the Crazy Fingers video.
What a great sounding guitar. :cool:


Yep...a little too chummy :x
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Postby GratefulPat » Fri Nov 09, 2007 5:13 pm

too my knowledge yes mesa, then fender, depending on the year i guess. just some different you tube vids ive seen him on the mesa...
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Postby GratefulPat » Fri Nov 09, 2007 5:15 pm

i could be wrong though
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