A (somewhat) stereo BTDR-3 reverb

[samhay]

Oddly, there seems to be some interest in stereo reverb circuits...

For some reason, I had convinced myself that the two outputs from the Belton/Accutronics BTDR reverb bricks are identical. This is not the case and if you play with headphones, or have a stereo rig with a decent spread between cabs, then it may be worth making use of the pseudo-stereo-ness of the brick's outputs.

This is my take on it:


(click for larger version)

You may have noted that it also has stereo inputs, thus making it a somewhat stereo reverb - Dry signal is stereo, while the reverb is pseudo-stereo as the BTDR only has a single input.

Dry signal is summed at IC2A and IC2B is a 2-pole low pass filter borrowed from my Space and Time reverb. Putting the filtering before the reverb saved another op-amp and a 3rd dual-gang pot.

It is buffered bypass and I am currently using a mechanical ON/OFF switch. This doesn't seem to be causing as much noise as I thought it might (switch bounce is not great when it comes before a delay), but the plan is to add a daughter board with a PIC and FET switch to do more elegant switching.

With 4 jacks and 2 dual-gang pots, I didn't fancy trying to get it in anything smaller than a 1590B, which I did via this vero layout, which is verified insofar as I have built it, and it works.


(click for larger version)

Sound clips to follow.

[bluebunny]

Nice one, Sam.  Yet another entry for that ever-increasing "to do" list.  <sigh>

[deadastronaut]

cool..nice work sam, .cant wait to hear it. 

headphones ready...

[Kipper4]

Me too can't wait to hear it. I've got a 3 brick laying around.
Thanks Sam

[notnews32]

You can't substitute a BTDR-2 (s,l or whatever) into this circuit, right? Even if you reworked the power filtering and feedback circuit?

[samhay]

Sound clip:

https://dl.dropboxusercontent.com/u/11996927/stereo_reverb_1.mp3

Recorded direct into my audio interface. I used a little compression before the reverb.
It is mono in and stereo out, but I switch to mono on the interface at ~ 1:20 for a couple of bars.
Mostly random knob twiddling and I left the mix on max for the entire clip. I probably should have recorded some more subtle settings, but at least you can get an idea of whether it will be sufficient for your experimental noise ensemble.

[samhay]

A BTDR-2 brick will drop straight into the circuit. You won't get the depth control though as this is on the brick.

It should be easy enough to add feedback (~depth) to this circuit with a BTDR-2 something like this (below). I wouldn't recommend this over the BTDR-3, but if you already have a BTDR-2 and/or can't get the BTDR-3, then this might be worth a try.


(click for larger version)

[deadastronaut]

cool...

stereo comes out nice...

[samhay]

Thanks. With some settings, it certainly sounds a little more interesting, and you can always sum back to mono if so desired.

The BTDR-3 is also a nice upgrade to the BRDR-2. As the depth control seems to control feedback around 2 different parts of the circuit, it gives a more useful range of control than the external feedback we have used in BTDR-1/2 designs - well worth a look.

[deadastronaut]

cheers sam,  i'll grab one to play with...

[samhay]

Just re-posting the schematic etc, after the dropbox public folder shutdown.

Schematic:

(click for larger version)

Vero layout:

(click for larger version)

which is a comfortable fit in a 1590BB along with 4 1/4" jacks and the BTDR-3 mounted on the solder-side of the board:


and a clip:
https://www.dropbox.com/s/j600dklj1f1fyvd/stereo_reverb_1.mp3?raw=1