Does anyone have a comprehensive list of Jerry amp mods?

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Does anyone have a comprehensive list of Jerry amp mods?

Postby RiverRat » Thu Oct 23, 2008 1:51 pm

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Postby Emoto » Thu Oct 23, 2008 1:57 pm

Tons of stuff here: http://www.dozin.com/

Waldo, is that your site?
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Postby Tennessee Jedi » Thu Oct 23, 2008 2:01 pm

Waldo, is that your site?

Its Dozin's site - he's a big Boston fan I hear ...
:cool:
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Postby Emoto » Thu Oct 23, 2008 2:07 pm

Tennessee Jedi wrote:
Waldo, is that your site?

Its Dozin's site - he's a big Boston fan I hear ...
:cool:


I suspected it might be. I had discovered that one before I found this one,
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Postby RiverRat » Thu Oct 23, 2008 2:35 pm

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Postby jeffm725 » Fri Oct 24, 2008 11:37 am

there are 3 people you need to talk to and listen to when it comes to the Fender Amp mods and they are all very knowledgeable:

in no particular order:
Waldo
Jonarobb
Joe martin

The first 2 are obviously active participants on this board, the 3rd (Joe) I can give you his number
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Postby jonarobb » Fri Oct 24, 2008 11:50 am

jeffm725 wrote:there are 3 people you need to talk to and listen to when it comes to the Fender Amp mods and they are all very knowledgeable:

in no particular order:
Waldo
Jonarobb
Joe martin

The first 2 are obviously active participants on this board, the 3rd (Joe) I can give you his number


I defer to Wald, he really came through with the specifics along with another brilliant Gearheads group member named Buck. Between the 2 of them they came up with the most comprehensive list to date... Great guys, and great info. I don't know Joe but have heard great things about him as well.

And RiverRat, btw, it's the 100k plate loads that get the Dale metal films, not the 220k's...
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Postby RiverRat » Fri Oct 24, 2008 3:28 pm

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Postby Dozin » Fri Oct 24, 2008 3:37 pm

If we could put a good list of mods for the Twin I'll add it to the web site. I need to revisit the Twin myself. My buddy just picked up a 74 twin and we need to do some work to it. So, I guess I'm back into it and this is good timing to get it done.
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Postby jeffm725 » Fri Oct 24, 2008 4:34 pm

RiverRat wrote:Yep....Duh.... Tanks Jonarobb

I had 220K on the brain from something else I was working on...It filtered through and made it's way into that last email I sent... Sometimes I type messages when I am dealing with other stuff and the things get jumbled.

Jeff, I'd love to get Joe's #.... I'll PM ya either way cuz I need a connection for some of the Blue Belden cable...

Buck Webster and Waldo have been a huge help so far... and they don't even know it. Plus, I will be posting to Gearheads this weekend seeking the same info.


Rat..PM me for Joes number anytime, he LOVES talking this stuff...I Have about 800 feet of the Belden on hand right now, so I think I can probably cover whatever you need :-) ...just sent a few out with neutrik ends to another rukind member last week, I think he was pretty happy with 'em. You probably just need cable, no plugs, right? (I think I have maybe 1/2 dozen of the old fat right angle np2rc's right now and a couple straight np2c's)...anyway just send a pm anytime.....

also, I am VERY interested in the front street mods, (or alembicization) of the twin (my twin doesnt have those done..yet) so if you can keep me abreast of your findings, and changes I would be very interested in seeing the differences and audible changes.

Also, didnt jonarob just do some of those mods? You want to chime in with your findings there jason? I think you already might have but I cant remember what thread it was in,.

as an addendum, I kept purely gearheads recommendations off this thread earlier, but I have to concur that Buck really knows his stuff. There are some others over there that are tube amp geniuses as well.



Dozin', your site is always one of the most definitive sites for, uh well, just about everything, so you might as well get those latest amp mod specs up there :smile: ...Thanks for all the work you have put into it over the years.

B :o
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Postby waldo041 » Sun Oct 26, 2008 4:44 pm

Dozin wrote:If we could put a good list of mods for the Twin I'll add it to the web site. I need to revisit the Twin myself. My buddy just picked up a 74 twin and we need to do some work to it. So, I guess I'm back into it and this is good timing to get it done.


Dozin,

i've pretty much noted on the schem and layout over at gearheads the majority of changes. the thing to remember is that the babbs amp was pulled from a pool of twins at Front Street, and while jerry "might" have used it, we still have never gotten under the hood of his twins. also, for the most part jerry's twins were stock. that said, i have tested and played all of the mods. as a matter of fact i loved them all so much they are all still in use.

here is a list of knowns that he did have.
1) individual channel preamp taps
2) metal film plate load resistors

and these are very good mods that probably were done to "clean" things up on jerry's amp and ARE shown on the babbs amp.
1) vibrato leg snip - eliminates the vibrato and increases output. by snipping the leg you also elimnate any noise from the unused portion of the circuit.
2) cap material change of the 10pF cap, parallel with 3.3meg resistor, on the vibrato channels 3rd gain stage from ceramic to silver mica. ceramic can drift causing a more dramatic treble boost.

lastly, the alembicization input mod is NOT shown on the babbs amp, but is a good possibilty that it was in jerry's twins. it eliminates noise on the input by removing the 68k input resistors on input 1. input 2 stays stock. here is the possible clue for this mod, Jerry ALWAYS used input 1 on his twins whether it was the blackface or the silverface.

as for tubes, forget power tubes, once jerry had the preamp taps to an external power source his power tubes were removed. as for preamp tubes, it is well noted that they went to military surplus sales and bought all the tubes, caps, resistors etc,etc they could. so he probably had some american made RCA, Phillips, or GE tubes in the preamp slots. and being in the preamp section they could probably last a long long time. i would shoot for the cleanest, less noisy tubes you can find.

also, i would like to thank buck for all he has contributed. we collaborated quite a bit before posting what we discovered and while i cannot speak for him, i would say that we both enjoy the fact that people like "you all" are getting a chance to use the info. my amp sounds great and i hope you guys get the same feeling i do when you play yours.

peace,
waldo
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Postby RiverRat » Tue Oct 28, 2008 12:44 pm

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Re:

Postby waldo041 » Thu Oct 30, 2008 6:06 am

RiverRat wrote:Any thoughts on a source for 25uF caps... I was looking at F&T's, but I think they are only rated for 25V.


LOW ESR Cathode Bypass capacitors. that is what Healy stated. You should be able to search Mouser, Allied or any other with the term Low ESR and then find the values needed. i believe the Cathode Bypass Voltage ratings is 25v so those should work.

peace,
waldo
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Re: Does anyone have a comprehensive list of Jerry amp mods?

Postby RiverRat » Thu Oct 30, 2008 1:08 pm

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Re: Does anyone have a comprehensive list of Jerry amp mods?

Postby waldo041 » Fri Oct 31, 2008 11:26 am

RiverRat wrote:I'm a bit more intrigued about the Alembicized Inputs, reading up on some stuff and getting the impression that this would be an ideal location for a switch from Carbons to Metal Films.


iirc, the whole point of wickershams alembicization input mod is to eliminate the input resistors, no matter what material they were. any resisitor in that position will be susceptible to noise, albeit smaller chance with metal films, but none the less susceptible. with them you have no chance of it and the whole point of the mod.

peace,
waldo
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