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Fisher Reverb - tone mod or param eq?

Posted: Wed Aug 10, 2011 8:32 pm
by HollowRootStudio
Hi all, been viewing the board for quite a while, but this is my first post.

I am awaiting a fisher reverb from devilbay (yay!) I'd like to have the most control over the reverb tone in the aux signal while dubbing from computer, through the mixer, and back to the computer. The question I want to throw out is... Does anyone know how difficult it is to mod the K10 by adding tone pots? I don't have a whole lot of experience modding, but I am interested in learning. Or would adding a 3-band param eq after the k10 be better to save the insanity of learning how to incorporate it into the K10?

Thanks ahead,


Posted: Sun Sep 18, 2011 1:59 pm
by ocoughi
there is certainly a way to incorpore a tone pot in the K10, but you have to understand the traveling of the signal inside the machine.
if you don't know about electronics, forget it! Tube stuff uses high voltage!! start from the beginning with easy stuff...
you can do an outside box with a passive eq inside. the most easy do do and very cheap is the "Big Muff tone control". you'll find a lot of schematics on the web. there is one Potentiometer, 2 resistors and 2 capacitors.
You can change the eq settings of this bigmuff tone using a freeware called "tone stack calculator" (in duncan amps page and only for PC). This freeware has also other Eq with 2 pots or 3 pots (fender, marshall eq's....)
here is some links: ... neControl/

Peace and Diy...

Posted: Mon Sep 19, 2011 2:14 am
by HollowRootStudio
Thanks for the input Manu. That's just it though - my feet are wet with a recent diagnosis and successful repair of a Copicat Tube Tape Echo. I know how to discharge power caps and test transformers. I have no problem soldering in caps and resistors. And I am very careful when working with high voltage. I don't understand how the signal passes through very well however. Still, I'm down to go for a tone mod if I had help. If you, or anyone, knows how to do it and can be patient enough to explain it, I will do it. Especially if it can help me understand signal flow better and have a more versatile piece of gear. :)


Posted: Mon Sep 19, 2011 9:49 am
by ocoughi
ok so it won't be a problem if you find the schematics. Dr Zee's webside had a clean schematics of it...
if i had in mind to do it, i'll put a tone control before the drive amplifier of the tank and a highpass filter after the tank... but where exactly....??? i don't even have a
the only thing i know and i did is modding this way an analog one (spring reverb). i had a lot of problems in term of pure electricity values and the signal is distorded in the i left it on a side of my lab and i learn with other easier stuff. but soon...

maybe it's a good thing to invest in a 2nd hand scop when you start to mod tube stuff...

repairing is another thing, a cap has blowed, you find the same value, you change it and that's done but modding is disturbing the electricity flow in the machine and make the things more complicated..
i don't know if you're more or less skilled than me but personaly a lot of electric reactions is a huge mystery for me!!!! but i'm learning.... these weeks i'm experimenting with transformers and inductors to understand them...(to do RLC eq's you know?...a poor man's pultec style HP filter in mind....)

Posted: Mon Sep 19, 2011 8:30 pm
by Neil C
Schematics from the manual on this site:

Dr. Zee's is a bit clearer, and contains some perhaps helpful info: ... matics.gif

Posted: Tue Sep 27, 2011 10:35 am
by ocoughi
Whow!!! Dr Zee is da ruller....
complete schematics for a custom space expender here: ... everb.html
i think you've got here what you need.
Peace, Dub & Diy.