Build Your Own Clone Message Board

Inspired by gtr2's build at madbean's forum, I decided to try my own hand at crafting a circuit for the BTDR-2 reverb module. This is essentially the smaller version of the big Belton Brick. Quite a bit smaller, actually. I believe gtr2 is working on a 1590A layout for all you masochists.

I plan to do one that will fit in a 125B or 1590B. Board-mounted pots. Two controls: Reverb Level and Damper (high cut).

The module is available in Short, Medium, and Long decay times. I'm currently working with Medium, but I also have a Long module (haha!) that I will test as well. Medium sounds very hall-ish. I think Short would be more like spring.

Anyway, what I've got working now is simple and sounds quite nice. It's approximately 20 passives and a quad op amp. It could be scaled down to a JFET and a dual op amp, but the space savings wouldn't really be that great, and the JFET (buffer) would require additional passives to bias, so it would end up being more complex. Plus VREF wouldn't be buffered, and that might introduce noise. So quad it is!

Here's a shot of it from last night's first test run:

Nice work. I've got half a dozen Beltons. Ooops. Planning to do a bipolar powered reverb for my modular system including voltage control of depth and regen using a LM13700.

Sounds like a cool project, Rick.

I think "phase 2" for me in this project will be to do one with stereo outputs. Of course, it can't really do stereo in, but have two outs is kinda nice sometimes.

Phase 3 is going to be to integrate one of these little guys into my Valve Jr.

Two knobs on a valve jr? Blasphemy!

Seriously though, I'm digging phase one, two, AND three.

There's going to be at least three: Volume, Reverb, and Damper.

My old VJ had had three knobs and two switches. You can trick one out pretty decent. Spinnin rims!

Excellent! Into all the bi-phases as well

and circuit boards will be available when?

good question. I'm working on a layout now. And trying to decide how many features to add. I think I might keep it simple and go with a Reverb mix and tone control and leave it at that.

But I'll post the schematic soon so people can just build one on vero or perf if they want, or someone else could do a PCB layout.

gimmegimmegimme
If anyone got a good source for the modules in Europe, please let me know

I'm 99% sure this one is good to go. I made some changes on the board that I then re-applied back to the schematic. So unless I goofed up on that, the attached schematic is good.

I've tried this with the Medium and Long decay bricks. The Long can definitely get some cool ambient spacy sounds going on. And with the tone control at min, it's really bright (either brick type). The only difference I can hear is the decay time.

There is some curious modulation in the wet signal. It almost sounds like there is an LFO in there set with the depth really low and speed pretty slow. I swear I can hear it, though. Or maybe the internal VREF is sagging? I don't know, but I'm 99% sure I hear it.

You guys knock yourselves out doing vero layouts and whatnot. I've ordered a couple prototype boards for myself (and for testing). This could be another group buy thing, but I'm not sure people want to drop $18 on a reverb module. Us DIYers are cheap!

One question F: What is this gap?

IC 4 and 11 right

I would imagine its the Vss and Vdd connections for the TL074.

Yes.

as in pin 4 and 11

Yes.

In Eagle, most op amps (and other ICs) are setup so that the positive/negative voltage supply pins are separated from the main schematic symbol. This makes it a LOT easier to draw both the main circuit and the power supply sub-circuit.

Use the "Invoke" tool to make the power pins appear. Check out this tutorial and look for the section "Dealing with Hidden Pins (Power and Ground)":

http://myhome.spu.edu/bolding/EE4211/EagleTutorial4.htm

It's for an older version of Eagle, but most of it is still correct.

Thank you sensai

If you do a group buy, I'd definitely be interested.