Reverse Delay Mod

[Coley]

Hi,

I know  there are various delays like:
dano backtalk
DD-6
DD-5
Digidelay
Space Station

that also have a reverse function. Now, my question is: does anyone know what to do in order to mod digital delay for reverse? can it be done?

I have a danelectro PB&J that i would LOVE to be able to make go in reverse.
any ideas?

thanks,
coley

[Nasse]

I have Alesis Microverb I and it has reverse program. But I remember having read somewhere that programs in digital studio effects are somewhat "pseudo" reverse things, so that it sounds some way like true reverse tape but notes you play come out same order you play them.

[The Tone God]

That sounds more like a reverse volume effect.

I looked up the specs for the IC used in the PB&J and to make a long story short it would be almost impossible to do a reverse mod for it. Sorry.

Andrew

[Coley]

how is it done though?are there any other cheap digital delays trhat could be modded for this?

thanks,
coley

[The Tone God]

Depends on how the digital delay mechinsm work. The IC in the PB&J is a tightly intergrated collection of circuits hence the difficulty in doing the mod. With something like say a DD-5 most of the functions needed for the delay are done with seperate circuits.

There are a few ways I can see doing this. One such mod would need you to do something like tell the D/A converter to read the memory backwards. You have to sync the read and writes to the memory to make sure they don't collide.

It can be a messy thing to do. Its not for amatures.

Andrew

[Coley]

i see. thanks for the help man!
-coley

[moosapotamus]

The DD-5 already has a reverse mode, but it's a blend of the reverse delay sound and the straight sound. There's a mod for adding a switch to cut out the straight signal so you hear only the reverse delay sound.

~ Charlie

[Coley]

I know that analog man does that mod to DD5's...

is this a commonly known mod/ would i be able to find info on it somewhere? or does analog man try to keep his mod ideas to himself?

[moosapotamus]

I dug out a hard copy I made of a description that was posted quite a while ago. It should be in the archives, but... Anyway, it seems like the idea is to switch out C9 (3.3uF), interrupting the trace at that point. I guess that's the point in the circuit where the reverse delay signal and the straight signal are mixed together.

The PCB is double sided, maybe? Tiny SMD components. Cap is located on the side with more components, at on end of IC2. D7 is at the other end of IC2. (someone else's description)

So, if you can find it, you might be able to remove C9, get a normal size 3.3uF cap, and install a toggle switch to select between leaving the cap in the circuit for normal operation (reverse delay mixed with the straight signal), and breaking the trace at that point to hear only the reverse delay sound.

I can't say that this will positively work, because I haven't done it myself. But, it sure seems plausible enough to try.

~ Charlie

[sirkut]

Moosa, I went back and found this, someone I knew commented about it..basically the same thing:

"Here's the kill switch mod that people have been charging $50+ for.
First locate c9. It's a tiny surface mount cap.
Carefully desolder it using a solder sucker, or desoldering braid.
Resolder it on end. Place a switch in series with c9 and the circuit board.
It took me less than 10 minutes. "

So yes, its C9..I haven't purchased one to try myself actually but it appears this is correct. If you do try it, please give us results!