#1
I was thinking of making a custom tube drive pedal and was wondering if my wiring would work. Here it is:

Input->Gain Pot->Tubes->Gain Pot->Output

What's missing that's necessary?
#2
It'd be more like this:

Input->Tube Preamp (containing gain controls)->Volume/Tone controls->Output

I don't like block diagrams because they over-simplify the circuit. But that's the point, I guess.
#3
Jim said it: Block diagrams oversimplify. Many schematics don't have clearly defined "blocks" because they have overlapping elements. But Jim said the basic idea.
Gear:
Schecter Hellraiser Deluxe
Boss DS-1
Crate GTD65

GAS List:
Mesa Boogie Dual Rectifier Roadster
#4
Big part of pedals with tubes is the power supply. Most use a 12ac to 220dc converter. There are plenty of plans out there. The hoffman amps site has the plans pics parts list etc for one.
#5
^you can have pedals where the only active component is the tube and run the plates on 9V DC. They sound decent.

Power off 12V DC, tap 12.6V DC for the heaters and use a charge pump for the plates maybe?
#6
Thats those starvation plate voltage set ups. You gotta have serious voltage to the plates if you want tube tone. Theres the plans for the "real Mctube II" floating around. It runs off 120v to the plates. But all the good tube pedals run off the 12vac wall warts. Ive been looking around for a while for a way to step up from 9v dc to plate voltage. Even sent some emails to companies that make transformers they all said if you want that kind of voltage you cant use 9vdc.
#7
^I have a schem that can get some crazy voltage from a 9v (nowhere near 120, but you may be able to keep stepping it up). I'll PM it to you if you want it. I can't legally post it.

edit: I gotta go now, but PM me if you want it.
#8
There are lots of 120V to 220V transformers out there.

I seriously beg to differ on your statement on starved plates means no tube tone. I have built and experimented with lots of starved plate designs and they definitely get that tube tone. They are warmer and have more feel and dynamics than transistor and op-amp designs.

150V DC is the so called sweet spot for your run of the mill dual triode in amps. Many classic designs though have 125V DC on the plates. Some go as low as 90V DC.

Anyways starved plate designs are great for more than looks imo.
#9
Quote by Invader Jim
^I have a schem that can get some crazy voltage from a 9v (nowhere near 120, but you may be able to keep stepping it up). I'll PM it to you if you want it. I can't legally post it.

edit: I gotta go now, but PM me if you want it.

Cascading charge pumps?

Problem with charge pumps is you loose current every time you step up the voltage. Tubes draw a lot of current.
#11
^I have a feeling that you don't quite know enough about electronics to be planning a custom tube build. You should look into building something easier to help you learn how circuits work.
#12
Quote by Sunburst PR
^I have a feeling that you don't quite know enough about electronics to be planning a custom tube build. You should look into building something easier to help you learn how circuits work.

Thanks I was just trying something simple with 1 tube and 2 pots, 'cause I don't really like tone controls.
#13
1 tube and 2 pots isn't enough, bro. You can do without a tonestack (according to kurt, they suck gain, but idk anymore about it than that), but a dirtbox is nothing without a preamp.

edit:

Quote by kurtlives91
Cascading charge pumps?

Problem with charge pumps is you loose current every time you step up the voltage. Tubes draw a lot of current.

Yes, but Idk about the current loss. It uses a 1044 ic. I've never built it, so I've never tested it. It puts out +17v then add another charge pump for +25v and another for +33v.
Last edited by Invader Jim at Sep 21, 2008,
#14
^any passive circuit including tonestacks eat up gain. Remember gain is the difference between the input and output voltage of a circuit.

That's a pretty common charge pump setup with the MAX1044. Neat setup only issue is your voltage goes up as current goes down.