Crunchboy!

master keeper · Post by **master keeper** » Fri Mar 24, 2006 4:18 pm

This amy answer some of yuor (shit, too many beers in the sun

)questions! It's from a previous post at the marshall forum...

It's modded per these specs:

Split cathode V1a 250uF/820,V1b .68/820
All coupling caps are 0.022uF except
bright channel coupling cap is 0.0022uF
bright cap on vol pot is stock RI
470k mixer resistors
470pF mixer bypass cap
Bypass cap on V2a is .68uF
33k/556pF tone stack combo
47k NFB resistor at 4 ohm tap
220k bias splitter resistors
0.1 uF cap on presence control
100uf fizzy cap
filtering: 16, 32, 50uf
****** 2" DRAKE OPT
power tubes: TESLA EL 34 (early '70s)
preamp tubes: TESLA E83CC, 2x MINIWATT ECC83
All changed caps are SOZOs!

You barely get your credit card between the opt and the power tubes

original PCB...

master keeper · Post by **master keeper** » Fri Mar 24, 2006 4:25 pm

In addition to the above I remember that we removed a cap or resistor (don't ask what or where, I don't remember!

)stock to the RI that was meant to bleed off high end and prevent oscillation. Once removed the amp was a bit angrier!

rockstah · Post by **rockstah** » Fri Mar 24, 2006 5:31 pm

this is a great spec - i love it - basically a 69 here with lower filtering.
something to try since u are running the 4 ohm tap with this spec to get a little juicier/thicker would be to change the 820 ohm on v1b to a 2.7k and change feeback resistor to 100k.

for whoever it may concern,

Mark

Crunchboy · Post by **Crunchboy** » Fri Mar 24, 2006 7:42 pm

Thanks, MK. I really like the sound of your tweaked RI, so I'd like to keep this info in my files. If you remember anything else, please add it.

Now let's hear some more clips of that bad girl! And the "real" one, too!!

bmf5150 · Post by **bmf5150** » Sat Mar 25, 2006 9:25 pm

wow!!4 ohm tap,tons of gain!!

rockstah · Post by **rockstah** » Sun Mar 26, 2006 2:34 am

master keeper · Post by **master keeper** » Sun Mar 26, 2006 4:59 am

Not so much gain as one may think actually. The 2" tranny opens up the sound a bit and has less compression than the standard size!

mightymike · Post by **mightymike** » Sun Mar 26, 2006 8:16 am

Can you use the 4 and 8ohm taps while using a hotplate?
I keep forgetting

I'm thinking of trying that, and uping my NFR to 100k from the 47k, to get a little more dirt. Other than split cathode, I'm set up ****** Spec (or stock 67 spec) right now on my Amuminum 12000.
I think I'm going to get those crappy new Sensor Mullards out of there too.

I might even try 69 Values for Slope and Treble cap just because
I like the way they sound on strat clean better. (More recognizeable tone.)(even on the JTM45/100)

I'm still tweaking it.

rockstah · Post by **rockstah** » Sun Mar 26, 2006 1:21 pm

mike,
yes - putting you feedback wire on 4ohm tap has nothing really to do with what ohm you run your amp at - mine is at 16 ohm with a 16ohm cab with feedback on 8 ohm tap .

and 69 all the way man.

Mark

mightymike · Post by **mightymike** » Mon Mar 27, 2006 4:17 am

all the way?

You have a double 50's all the way around?
.002 after the first stage
.022 in the output

47 or 100 fizz

presence cap .1 or .68

Up until I started messing with 12000 series, the 69 spec was my favorite
(69 spec with the exception of a .022 after the first stage)

I even like the 69 tone stack on my JTM 45/100. It does
something to the strat tone that I like. It's a recognizeable signature sound.

MacGaden · Post by **MacGaden** » Mon Mar 27, 2006 6:13 am

mightymike wrote: I even like the 69 tone stack on my JTM 45/100. It does
something to the strat tone that I like. It's a recognizeable signature sound.

That´s the "Hendrix Mod" on the Hendrix/Dickinson Marshall HW that just came out.

BashCoder · Post by **BashCoder** » Mon Mar 27, 2006 7:39 am

mightymike wrote: I'm thinking of trying that, and uping my NFR to 100k from the 47k, to get a little more dirt.

Put it on a pot! I've been having fun with that mod.

mightymike · Post by **mightymike** » Mon Mar 27, 2006 6:51 pm

Tried the different taps, and I like the 8ohm tap.

Didn't realize they were doing the Dickenson spec on the JTM 45/100 reissues. I just tried it from Dan's layout, and remember people arguing tweather or not the Dickenson amp was BS, so I figure I'd try it.

rockstah · Post by **rockstah** » Tue Mar 28, 2006 11:37 pm

hey Mike, what didnt you like about the 4 ohm tap?

Mark

bmf5150 · Post by **bmf5150** » Wed Mar 29, 2006 5:08 pm

8 ohm is my favorite as well!