Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: anon get an old ps amp and modify it.... -- 1107745319 View Thread

Re: Design Challenge!!!

2/8/2005 4:14 PM
Dr. Photon
Re: Design Challenge!!!
Use the same power amp and PI for both. use either a marhsall or a Fender blackface PI (they're so similar). I'd personally go for the Marshall. Then wire the sockets up for EL34n and provide a good range of bias adjustment so that the amp can take either 6L6 or EL34.  
For the clean channel, just lift the front end off of a Fender Blackface. For the dirt channel, pick your favorite dirty preamp, I'd suggest either the plexi (the kind where you jump channels together) or the 2204 style (with the high-low inputs. with some creative wiring of a switch, you can rig a switch to select between the "plexi" and the "2204" cascade-circuits.  
If you don't have zillions of jacks, I'd just leave off the "low" input on the Fender, and I'd also leave off the low inputs on the Marshall plexi circuit (and you can save a jack by using just one for the plexi type circuit and internally jumpering them).  
This will take 4 12AX7s. one for the Fender Preamp. One for the shared PI, and two for the Marshall preamp. I'm not sure how you would want to do the channel switching. Personally, I would have a footswitched relay or a front panel toggle that switched the input of the PI between the channels. with this, you could remove one of the jacks and internally parallel up the input to the Fender and the Marshall preamps. If you want both channels to be "live" at a time with you using a stompbox ABY switch, use some mix resistors when you go into the PI.  
As for reverb, that is a complication. it really depends upon where you want the reverb. I'm temped to say just build the fender standalone reverb unit and you can hook that up to either input (reverb on OD?!?!), or between the outputs of the preamps and the input of the PI (a simple unbuffered EFX loop would be useful.  
to keep in budget, do not buy new iron and chassis. I suggest getting an old organ amp, unloved hifi amp of little value, unloved cheap guitar amp, PA amp, or some random thingies from a surplus shop or hamfest and make due with them. Huge savings there. Your passive components should still be new, however.