Question about tubes (can you make a dod250 tube driven?)

KorovaMilkBar · March 27, 2009, 01:10:54 AM

i was just cruising things boards for a second and i was wondering to myself if there was a way to rig an overdrive pedal (to be specific, a dod 250 yellow clone from GGG) to be distorted by tubes. i guess to make it quick.

1. how do tubes distort? is it just like the diodes in the dod 250?

2. if so, would i be able to wire tubes into the diode circuit to add tube distortion. do they need to be powered more than the pedal can put out by itself(battery powered)?over

i have a ton more questions and would love to know more about how tubes work. i guess i will cruise the FAQ and see if there is anything there that can help.

so ya, can i add tube(s) to my dod 250 clone?

svstee · March 27, 2009, 01:37:47 AM

You can use tubes as diodes, but that is not going to get you the "Tube" overdrive sound you are looking for.
If you are interested, check out the build guides over at AX84, the info is for amps, but the theory documents do the best jobs of explaining tubes I have seen.

KorovaMilkBar · March 27, 2009, 02:54:00 AM

so what would i have to do? do i need to add more power or voltage to the tubes or can i use diodes and tubes in the same circuit? i was thinking of making some sort of franken-drive with tubes, tone and possibly expression jacks. so what is it that i need to make it possible?

petemoore · March 27, 2009, 11:37:50 AM

Switch/diodes across the AC signal [after DC blocking cap] between output and Gnd.
Make the tube produce a voltage which exceeds the threshold voltage of the back to back diodes.
I never understood why this wouldn't work to get a clipped signal shape, and is easy enough to try, right across the volume control or with a 250 diode/output type configuration.

aziltz · March 27, 2009, 04:12:20 PM

Tubes probably clip closer to the way cascaded FETs clip, not like diodes in a feedback loop.

KorovaMilkBar · March 27, 2009, 04:20:06 PM

i did just find this thread

http://www.diystompboxes.com/smfforum/index.php?topic=63479.0

im still a little new to the whole schematic reading thing, but apperantly this project doesnt even need a circuit board. can i just solder everything using wire and it should work? im just trying to get this right before i try anything like buying parts, but i might take on this project and see how it is, than i might go on to house the tube boost and dod250 inthe same housing and throw some more mods on. so ya how does this sound as my next project?

aziltz · March 27, 2009, 07:46:04 PM

start small grasshopper.

i suggest doing a kit first. especially if you don't have electronics experience.

i have alot of electronics experience in reading schematics and building but it was still the best thing i did to get started. Building a BYOC kit or other really shows you good techniques to CONSTRUCT your project, especially getting it into an enclosure in a way that will last.

KorovaMilkBar · March 27, 2009, 11:30:57 PM

i have made a pre-assorted kit before from General Guitar Gadgets (if i didnt mention that, i dont remember). thats the dod 250 i have now. i think i have settled on trying out the project in the thread i posted. it seems simple enough and i do just want to try an experiment with tubes just to learn more about them. i have a few parts ordered like the tube. i am gonna try to stop by a components store and see if they cant help me. thanks for all the advice and yes i am gonna try and start small with this tube project and if it sounds good i will see if i can house the tube boost with the dod 250 (definitely need something bigger than right now) and than that will probably be exactly what i am looking for!

Lurco · March 28, 2009, 05:25:19 AM

Joe Hart · March 28, 2009, 09:37:16 AM

Perhaps design a 250 using discrete components (instead of an IC use transistors and stuff to replicate the IC postion), then replace the "important" transistors with tubes? Kind of like what people have done with amps where they replace the tubes with transistors -- just backwards. Maybe?
-Joe Hart

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Question about tubes (can you make a dod250 tube driven?)