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.

[jessenator]

Dude. This is seriously great sounding. I might definitely need a board

It's making all the right sounds. I'm definitely digging the Swell/Dampen control. and the sway control... Seriously, I'm going back and re-listening. Total Planet Telex at 3'30" and I stinkin love it.

Good work, man.

[NorthCoast]

That sounds fantastic. It's nice to see someone put this much thought into a reverb.

[neiloler]

Dude, this awesome. I'd love to buy a board from you.

[jessenator]

Dude, this awesome. I'd love to buy a board from you.

wah hey! The legend returns

[neiloler]

Dude, this awesome. I'd love to buy a board from you.

wah hey! The legend returns

When there's a reverb this dope, it brings me back from the dead.

Or at least I'm getting more into pedals again. I credit Jessenator.

[Aleph Null]

That sounds fantastic. It's nice to see someone put this much thought into a reverb.

Reverb is one of my favorite effects! Glad you all like it!

[gordo]

Damn this is cool.  I'm pretty much a self-professed Belton brick hater but this sounds amazing!  Nicely done!

[madbean]

Now that is a fine design! I love some of the innovative features you used in this.

[Aleph Null]

Now that is a fine design! I love some of the innovative features you used in this.

Senpai noticed me! But, seriously, that means a lot coming from you.

Damn this is cool.  I'm pretty much a self-professed Belton brick hater but this sounds amazing!  Nicely done!

The Bricks definitely do have their limitations. Most of the things I didn't like about the Belton 2—the built-in modulation, the low density, and poor diffusion—were improved in the Belton 3. The density is still low, but I think that actually lends itself to the "infinite sustain" kinds of sounds.

[Aleph Null]

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.

[waldo_jeffers]

This sounds incredible. It covers how I wished the DBA Reverberation Machine sounded plus so much more. I'd love to buy a board, will DM!

[Aleph Null]

This sounds incredible. It covers how I wished the DBA Reverberation Machine sounded plus so much more. I'd love to buy a board, will DM!

That's an interesting comparison. Looking at the schematic, the DBA is doing the clipping after the reverb and it's doing it by overdriving a low-bandwidth opamp. The Troglodyte does the clipping before the reverb and is using diodes to ground.

I experimented with different clipping options—I even tried putting a non-selective octave tripler in that location—but I found a lot of the nuance of the distortion was lost. Symmetrical hard clipping provided the most harmonic content, which is how it gets the faux shimmer sounds. It doesn't have the same "wall of sound" effect that you'd get from clipping after the reverb, but you can still get some of that by engaging the feedback control and sending the reverb back through the clipping diodes.

P.S. The second round of PCBs are on the way!

[Aleph Null]

I have the second run of PCBs in hand and there are still a few unclaimed ones. If you're interested DM me.