Cathode follower ideas...

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FuzzFaceBuilder
Posts: 137
Joined: Wed Mar 26, 2008 8:22 am
Location: Honolulu, HI

Cathode follower ideas...

Post by FuzzFaceBuilder »

Hey everyone,

My project is very dumble-esque, but I have a question or two that doesn't require previous experience behind the goop. So I'm posting it here, hoping for suggestions from everyone...

The long and short of the build is that it's pretty much a JTM45/100 with the dumble 3 tube reverb circuit and all of the Dumble accoutrement (PAB/FET/Switches/etc.)

Because the Dumble platform has only 1 channel, I only need one triode to drive the CF before the tone stack. What do you guys recommend I do? Cascade triodes? Only wire up one triode of the 12AX7 (what a waste though :x )? All of the amps that used EF86 (and the like) sound "grainy" and seem to fatigue the ears after a while.

Also, what say all of you, MV or non-MV, and can you recommend a schematic/layout?

BTW, this amp is being built for a Stratocaster player (read: low output single coils) with Eric Johnson's dirty rhythm/Fuzz Face tone in mind.

Thanks a million everyone,
Hale :mrgreen:
John_P_WI
Posts: 1457
Joined: Wed Aug 15, 2007 4:29 pm
Location: Wisconsin

Re: Cathode follower ideas...

Post by John_P_WI »

Hale,

I am having a hard time following what you are saying here. Can you post a simple scheme. Are you saying that you want to use a Dumble pre + reverb into a JTM power amp? If so you don't need the cathode follower.

If it was up to me, I'd loose the cathode follower and have 4 gain stages with plate loaded tone controls. This is very flexible, especially if you set up 2 gain stages, volume (gain) 2 gain stages then master vol. This leaves one tube for the PI (assuming the JTM 45 platform). Done right, this will get all of the distortion qualities you want.


John
FuzzFaceBuilder
Posts: 137
Joined: Wed Mar 26, 2008 8:22 am
Location: Honolulu, HI

Re: Cathode follower ideas...

Post by FuzzFaceBuilder »

Aloha John,

The simplest explanation of the build is that it uses the entire platform of a 45/100 like THIS (with the dumble reverb circuit before the PI).

There is only one (normal) input with the dumble format, compared to the two separate channels (bright and normal) on a 45/100.

Here's a quick hand drawing with the grid resistor, CF, bypass cap, and plate resistor on a terminal strip around a noval socket. (Sorry, I drew it and took it with my Iphone).

I need to hook them all up but don't need both sides of the 12AX7. That's the question. What to do about using a 12AX7? Cascade triodes? Don't wire one side? Single triode tubes get grainy and strain the ears IME. What say you?


Thanks so much,
Hale :mrgreen:
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