Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: korni on August 09, 2020, 03:49:32 pm

Title: JCA20HV doom mod?
Post by: korni on August 09, 2020, 03:49:32 pm

Hi all!

I've been thinking of modding my JCA20HV more into doom territory, think of Sleep - Dopesmoker.
Now, I know, I won't get there 100% but only getting close would be great, so I'd love some input on the mods I'm thinking of doing (attached schematics).

1. Does the cathode follower and this sort of phase inverter rule out the Orange/Matamp sound?
2. From what I've read the cathode follower has a specific distortion, so maybe I should cut traces and jumper it making it plate driven TMB amp?
3. Do I need Cathodyne PI for this? [I'd rather not mess with the PI and leave it as it is]
4. Is it even worth trying? There was a company, Hovercraft Amp, modding these to doom sounding amps (Dwarvenaut 20) but I've only ever seen youtube videos so not sure.. :help:

Title: Re: JCA20HV doom mod?
Post by: shooter on August 09, 2020, 04:40:51 pm

here's a good read on your cathode follower;


http://www.valvewizard.co.uk/dccf.html (http://www.valvewizard.co.uk/dccf.html)


once read, back out til you find phase inverters, good reading
as to "your vision", no clue  :icon_biggrin:

Title: Re: JCA20HV doom mod?
Post by: korni on August 10, 2020, 01:16:36 am

Quote from: shooter on August 09, 2020, 04:40:51 pm

here's a good read on your cathode follower;


http://www.valvewizard.co.uk/dccf.html (http://www.valvewizard.co.uk/dccf.html)


once read, back out til you find phase inverters, good reading
as to "your vision", no clue  :icon_biggrin:

Yea, that's where I got the idea, that it might be too different from what old Oragne amps have.
My only experiece is building (not designing) pedals up to this point, so I'm trying to wrap my head around all this.
Thanks anyway  :smiley: