Troglodyte — Self Oscilating Reverb

[Aleph Null]

Troglodyte is a versatile reverb capable of everything from short, bright, roomy reverbs, to dark, cavernous, infinite sustain, to full-on self oscillation. I was inspired by Grind Customs Tenebrion—my copy would just barely reach infinite sustain. Something about that particular unit full up was magical. I've also built Mad Bean's Moodring with a short brick and loved how that could go from short and bright to full-on runaway oscilation. I set out to make my own design with all the features from other reverbs that I loved, plus something that could do precise, controllable self oscilation and reverb swells.



The enclosure is a limited run from Love My Switches.



The Belton Brick is a big boy! It's soldered in place on top of the board so that it hangs over the bypass LED and leaves just enough room for the footswitches. I made sure to leave plenty of room for top mount jacks and to get a soldering iron in to the potentiometer lugs once the rest of the board was populated.



An input buffer feeds a PT2399 delay chip. This provides pre-delay of up to 300ms or so by way of the "Onset" control. I used pretty standard filtering on the delay input. The output stage of the delay does double duty as additional filtering as well as a gain stage to feed clipping diodes for the "Saturation" control. The saturated signal then hits the Belton Brick. One of the Belton 3's outputs feeds a tilt EQ centered around 1kHz and goes to the output mixer. There's enough gain on tap that you can get the wet signal well above unity with higher "Saturation" settings.

I wanted a "kill dry" option, but I didn't want to stop there, so I went for a "Dry" mix instead. This goes all the way from "kill dry" to "solo boost" with 14dB of gain available. This means I could set the unit for a boost to take a reverb drenched solo, or I could set it to cut volume for an ambient verse. I like having options!

The "Sway" control is the same envelope-controlled vibrato I used in my "Special Sauce" circuit, but tuned for longer delay times.

The crowning feature of this reverb, in my opinion, is the "Feedback" and "Swell|Delay" controls. The "Feedback" sends the second reverb ouptut back to the delay input allowing for momentary gushes of reverb, infinite sustain, or self oscilation. The feedback loop interacts with the other controls to create some surprising results. The "Swell|Delay" switch controls how the momentary foot switch interacts with the "Feedback" control. In "Damp" mode, the "Feedback" control is connected by default and is disconnected when the foot switch is pressed. In "Swell" mode, the "Feedback" control is disconnected by default and only engaged if the foot switch is pressed.

Here's a demo:

I have a few extra boards. If you're interested in building one, just DM me.

[Matthew Sanford]

That is a gorgeous sounding pedal you have created there! I do like the switch to add a bit of extra swell, that is a really nice touch!

[Transistor-Transistor]

That sounds wonderful! I love how you have a saturation control on there too I love slightly distorted reverbs 

[Rob Strand]

You should label your pot names on the schematic.

[cymazic]

Absolutely lovely sounding. Well done.
I really like the inclusion of pre-delay , saturation and sway. Definitely one of the nicest sounding PT2399 projects I've heard .
 I'd maybe consider putting some of those potentiometer dust cap thingies on your pots in case those Lumberg jacks decide to spin a bit later down the line . Looks like a pretty tight fit  

[Aleph Null]

Thanks for the kind words, everyone.

You should label your pot names on the schematic.

And give away all my secrets?!    I've updated the schematic drawing in the original post

Absolutely lovely sounding. Well done.
I really like the inclusion of pre-delay , saturation and sway. Definitely one of the nicest sounding PT2399 projects I've heard .
 I'd maybe consider putting some of those potentiometer dust cap thingies on your pots in case those Lumberg jacks decide to spin a bit later down the line . Looks like a pretty tight fit  

It's not as tight as the picture makes it look—though it is tight. The only dangerous pot is the "Decay" control and I have some electrical tape on the back of that. They don't make dust covers for dual pots as far as I know.

[moosapotamus]

Beautiful sounding reverb. Love all the controls, variability. Nice job!

[jorg777]

Beautiful!  Very useful.  I'm thinking Cocteau Twins and Boards of Canada.

[287m]

That sound! Nice sounding and layout.

Somehow, i remember troglodyte from fuzzlord, but that fuzz with bmp tone.

[John Lyons]

Did the schematic get taken down?
I don't see it here.

EDIT: Switched to Firefox and it shows up.

[PRR]

Did the schematic get taken down? I don't see it here.

Right before "An input buffer feeds a PT2399 delay chip."

It is on Flickr.com, the kind of pussies&porn cat-pictures site often blocked by corporate networks.
https://www.flickr.com/photos/bj_reames/54002827196/
https://live.staticflickr.com/65535/54002827196_dba49d74bc_c.jpg

[bean]

I already praised it on the mbp forum but I'll do it again here, haha. This is a very cool circuit and very smartly implemented. That gain pot and clipping before the BTDR-3 is novel. Plus the useage of the secondary output. Great stuff!

[Aleph Null]

Thanks for all the kind words, everyone. I have sold the last of the boards, but there's enough interest that I'm going to do a second run. Any one that wants a board, DM me by Thursday, September 26th, 2024. I'll place an order on Friday.

Boards are $10 shipped to the continental US. I'll include a printed build doc. If you live outside the US, I can still ship you a board, but shipping costs might be different.

[rankot]

Very nice pedal!

[Aleph Null]

I've got the second rum of PCBs in hand and I have a few unclaimed boards. If you're interested, DM me.