I posted this initially in this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=93421.0 Rick suggested I start a dedicated thread for posterity
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DIY reverbs are pretty rare, and small-sized ones using readily available parts are rarer still! Most use the Belton brick, which contains three PT2399s. I wanted to see how good (or how lame) reverb could sound using only two PT2399s, and I wanted to make it fit in a 1550B (equivalent).
It has tails switching (naturally) and there's a trim pot to adjust the delay of the second PT, which produces some (not very useful) sounds ranging from bathroom to hall. I have it set on 17.5k, where it will probably stay. There is a bass-cut switch that filters out the bass before it reaches the delay lines, for a less invasive sound.
Sound clip: Starts with max reverb and the bass-cut off. Then I reduce the reverb and put the bass cut on for the second half of the clip, and increase the reverb again. I'm very pleased with the sound- it's a lot better than I was expected for just two delay lines and no modulation. You wouldn't use it for studio vocals or anything obviously, but for 'ordinary' guitar I think it was well worth it!
w w w.freewebs.com/valvewizard2/Equinox.mp3
(remove the spaces from www)
The schematic looks a bit busy because its all jammed onto one page, but operation is really quite simple. Here's a sketch to show how it works. The signal is filtered and then passed to two delay lines in parallel. The outputs are mixed, filtered, and fed back to the start. The longer delay line gets a bit of extra filtering to mimic the loss of treble you get with longer reflections/more air time. Then the wet is mixed with the dry in the usual way.
Full schematic and PCB layout etc. are here:http://s81.photobucket.com/albums/j207/merlinblencowe/Equinox%20Reverb/The pedal etching didn't come out so good. I will be redoing this eventually...
Thanks also to Rick for sending me an enclosure!
