Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: jasperok on June 30, 2009, 09:55:30 am
-
I got my hands on a dual distortion pedal that runs 2 12ax7's for bass guitar.
I dont know what the deal is with it - i dont even know how theres enough power to run the 2 tubes
it draws 1.3amps and runs at 24volts (12v power supply with a voltage doubler circuit inside)
Anyway - short story is i reallly realy dislike it - it just sounds as rattty as hell.
I know its a long shot but are there any know preamp/overdirve/dist tube pedal layouts as its a really good base to use for such a project given it holds the tubes and the pedal box is big enough etc.
what would you do withit?
-
Is it homegrown or factory made? Schematic available?
If you are working on a guitar application, here are a couple of threads that might give you an idea or two:
http://www.el34world.com/Forum/index.php?topic=5448.0
http://www.el34world.com/Forum/index.php?topic=5055.0
I dinked around with various permutations/combinations of the Hotbox, Bottle Rocket and Doug's tube pedal but never really got it exactly where I wanted it. Then again, I never ended up with a true to any one schematic layout.
Got tired of modding it and I had a handful of other pedals (General Guitar Gadgets kits) in que so I turned my attention toward those and haven't picked the tube version back up.
If I was starting over again I would build the Bottle Rocket plan with Doug's power supply. My version that was the closest to that was very decent.
The Bottle Rocket plan appears in one of the threads above and Doug's tube pedal project is in the Library of information.
Cheers,
Dave O.
-
http://www.el34world.com/projects/tube_box.htm :evil5:
Your wish is Dougs command!
One of these days I plan to build up one Myself.
-
depends on what you want ... distortion, preamp, reverb, vibrato ...
distortion and preamp have been done lots; there's the hoffman project on this webpage as per previous posts or, if you wanna get heavier, the soldano super lead overdrive in a box:
http://www.schematicheaven.com/newamps/soldano_supercharger_gto.pdf (http://www.schematicheaven.com/newamps/soldano_supercharger_gto.pdf)
otherwise, with two tubes, you can build just about anything in a box; marshall preamp, fender preamp, vibrato, reverb (external tank, of course) etc. think complete gut. you can build on terminal strips, and all the other stuff (jacks, footswitch, sockets, etc.) are easy to get. dunno about two thinks - are the tube sockets chassis or pcb mounted, and what does it have for a power transformer?
good luck, and i would certainly enjoy working through a pedal build with you, as it is on the list of things to do in the future (i think a tube-driven vibrato pedal would be a thing of beauty ...).
-
I just got something like this to work. Mine powers up and makes sounds, Now I needs to work to get the sound "right". But I did prove the concept. I powered it as below:
Power the pedal with a 12VAC (yes "AC") power cube. Then inside you use a 12V 1000ma transformer and run the 12VAC right into the secondary and you cam make a 160VDC B+ supply. Split some of the 12VAC off and run the heater in the 12AX tube. AC wall worts are hard to find but you can open up a DV unit and by-pass the rectifier. I salvaged the rectifier from the wall wort and placed it inside the peddle to make a DC heater circuit. A Wall wort also provide the source for the salvaged 1000ma transformer. With two tubes you can make anything. If you don't like pedals make a direct box for recording, or a "guitar tone box" so you can play through a home stereo or boom box. Or make a "head phone amp" for practice. Or an "input expander" so two or three guitars can play through one amp