Equinox: Easy PT2399 Reverb

[merlinb]

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 .

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!

[askwho69]

nice any chance to hear this beautiful circuit?

[Mark Hammer]

merlin provided a link.  It just doesn't show up because he inserted spaces in the URL.

w w w.freewebs.com/valvewizard2/Equinox.mp3

[frequencycentral]

Easier way to the soundclip: http://www.freewebs.com/valvewizard2/Equinox.mp3

What a great little circuit! Viva DIY!

Edit! Will someone please put me out of my misery and tell me which Zeppelin song that is?

[artifus]

hi rick - that link just takes me to this very thread - is just me? and good work merlin! (i'd heard the clip on t'other thread)

[frequencycentral]

hi rick - that link just takes me to this very thread - is just me? and good work merlin! (i'd heard the clip on t'other thread)

It works fine for me. I keep telling Merlin to use dropbox (hint hint). Name the Zep song please.....

[artifus]

hmmm... no go here, i'm trapped in a mobius loop! could be chrome. removed the spaces and had a listen and it's bugging me too! on the tip of my tongue - i can almost here a vocal coming in singing 'oh, baby, baby, baby...' but that doesn't really narrow it down much!

[slacker]

hi rick - that link just takes me to this very thread - is just me?

try copying and pasting the link into a new browser tab or window, that works for me.

Sounds great.

[artifus]

ta slacker - got there in the end the long way round. a direct click in chrome returns to this thread but highlighting the link and right clicking 'go to..' gets me there. most odd.

[nick d]

           "Baby I'm Gonna Leave You " off the first album .

             Love the sound of this pedal - might just have to build it !

[frequencycentral]

           "Baby I'm Gonna Leave You " off the first album .

Thanks! Playing it right now.......

[WhenBoredomPeaks]

The Rebote 2.5 already sounds kinda reverbish with short delay time and lots of repeats, i think i bookmark this thread.

[Skruffyhound]

Good God, I actually have a backlog of about five Merlin effects I have to build. I better get my house finished soon or at this rate I'll never catch up.
Sounds great, again, thanks Merlin.

[Mark Hammer]

That sounds really nice for such a small parts count.  Would make an excellent addition to a small DIY amp.

[Earthscum]

well, no soundclip for me. Anyways, I spotted something (may have been mentioned already), ultra-thin trace connecting C24's ground leg.

[merlinb]

well, no soundclip for me.

Just put the URL into your browser and remove the spaces from WWW...

Anyways, I spotted something (may have been mentioned already), ultra-thin trace connecting C24's ground leg.

Fixed.

[Mark Hammer]

I'm curious about the manner in which you have the ins and outs of the two 2399s connected.  Is there some of the feedback of the one going into the other?

[merlinb]

I'm curious about the manner in which you have the ins and outs of the two 2399s connected.  Is there some of the feedback of the one going into the other?

Not sure what you mean? It is as described in the sketch schem. The first on-board opamp on the first PT is arranged as a low-pass filter as per the data sheet, and overall feedback is also injected here. The output from this opamp is also tapped off and send to the second PT via R12. The second on-board opamp is not used.

The second PT includes the output low-pass filter, also as per the data sheet. The delayed output from the first PT is also mixed in here via R14. There's only one feedback resistor, R19.

[Earthscum]

Just put the URL into your browser and remove the spaces from WWW...

tried that. Firefox and opera are both returning me here or to searches that link right back here. Even pasted direct "go here"... Short of doing some kind of hack, I don't think it's working, and redirects really tick me off, no offense meant to you at all. Just, I guess, writing code and such in the past has made me nitpicky about universal functionality.

[deadastronaut]

@merlin:  dropbox