stage center reverb

[iorr]

Hi,
Builded the reverb based on the pcb from GGG. It works pretty good but there is a lot of hiss  .
The main problem is by the outgoing RCA plug. Think this  cabel must be shielded. Are there any more cables which have to be shielded?

gr. Karsten

[Ashurbanipal]

I haven't built this one, but I did prototype a lot of circuits when building my reverb. You should probably shield both cables going to the springs. The spring box can also pick up noise. Move it around to see if the noise changes.

Shielding probably won't help much with hiss. I prototyped a bunch of things for my reverb, and settled with a .001 or .00047 (switchable) capacitor into a lm386 amp into the springs. This cuts lows to brighten up the sound and then drives the springs pretty hard to get a good signal into the springs to reduce noise. Then for the recovery something similar to what is listed here under "Signal Recovery Amp": http://members.tripod.com/~roymal/reverb.htm.

For yours (schematic: http://www.generalguitargadgets.com/diagrams/stage_center_reverb_sc.gif), maybe try:

1. Change C4 to .001 or .00047 to cut lows
2. Change R7 for more gain to the biggest resistor value that doesn't cause distortion, maybe 1M
3. Put a cap in parallel with R9 to cut highs in the recovery section, maybe .001, but whatever is the best compromise between cutting hiss and still having a bright reverb, There's not much high frequency content coming from the springs, so cutting highs here may help hiss and not cut into the reverb brighteness.

Running a compressor before the reverb can help as long as the compressor isn't very noisy.

[343 Salty Beans]

It's complications like this that lead me to settle for a normal, stock reverb rather than DIYing one  call me lazy. Reverbs are definitely up there in  the 'holy crap what do I have to TWEAK TO GET THIS RIGHT' project list.

[iorr]

Thanks,
I will try the changes.

Karsten

[Ashurbanipal]

'holy crap what do I have to TWEAK TO GET THIS RIGHT'

Yeah, that was my experience. I read many articles, looked at many shematics, prototyped several things, and nearly gave up until cutting the lows and then driving the springs really hard with a lm386 amp did thing in my setup. Increasing the gain of the opamp on his project may not be enough, not sure.