Tesseract — Distorted Reverb

[Aleph Null]

I managed to cram it into a 125BB with top mount jacks! The Chaos Control has been moved to the outside of the box. I took some liberties with the control names.



I had to get a little creative with jack placement. The extra height of the 125BB is definitely required for top mount jacks.



The finish is ink jet on printer paper. I used acrylic as a fixative, then Mod Podge to adhere the print. More acrylic went on after that for the clear coat. The enclosure was quite rough, so I had to do some serious buffing just to get the "distressed" look you see on the sides here.



I wanted a little more chaos, so I substituted a B25k for the recommended B100K pot. It's still more subtle than I had anticipated in some settings. I may also find a way to bypass the resistor in the feedback loop (R27) for even faster swell speeds. I built this initially with a short Belton brick, thinking it would be more versatile. That may be, but the short brick would not self oscillate at all in this circuit.



Some of the larger caps are bent forward to accommodate the jacks. I was having flashbacks to failed 1590A builds as I boxed this! Still, I'm glad I went with a smaller enclosure.

Thanks, DiabloChris666, for making this PCB available.

[alanp]

Wow, that looks like fun!

[stringsthings]

Looks good!  I still have to box mine up.  One failed attempt at a 1590BB.

[flanagan0718]

Stunning Build!!!

[diablochris6]

Breathtaking build!

The trimpot was mostly meant to be a set and forget kind of deal. Once you find where it can feed back, leave it alone. Since folks are adding it as an outside control, I would drop the pot value, even to something like 1K or 5k. Even then, it really starts singing when you have the depth and gain up pretty high.

[Aleph Null]

Breathtaking build!

The trimpot was mostly meant to be a set and forget kind of deal. Once you find where it can feed back, leave it alone. Since folks are adding it as an outside control, I would drop the pot value, even to something like 1K or 5k. Even then, it really starts singing when you have the depth and gain up pretty high.

Thanks for the compliment!

I have a Grind Customs Tenebrion with freak-out switch and a hidden trim pot, so I wanted something a little different from this build. The Tesseract definitely does have a character of it's own.

I'm considering putting the chaos pot in parallel with Recycle and R27, as this would reduce the total resistance in the feedback loop to below what is achievable currently—something like a maximum resistance of 20k with a 25k pot and zero at full clockwise. This would allow for swell at lower Depth settings and just make the Chaos Control more powerful, I think.

I'm a little concerned about bypassing C24. I'm assuming it's there to block DC voltage when adjusting the Recycle pot? If so, I should be fine bypassing it right? Maybe I'd get some crackle if I turned the Recycle or Chaos Control while pressing the Chaos switch?

[Aleph Null]

Ok... I spent a little time pouring over the schematic.

It looks like I should be able to put the Chaos Control in parallel to Recycle and R27 by moving just one wire: I can desolder the wire that connects to the lug 2 Chaos control pad and then connect it to the bare lead between R27 and D1.

I'll be sure to report back once I've had a chance to experiment!

[Aleph Null]

Ok... I spent a little time pouring over the schematic.

It looks like I should be able to put the Chaos Control in parallel to Recycle and R27 by moving just one wire: I can desolder the wire that connects to the lug 2 Chaos control pad and then connect it to the bare lead between R27 and D1.

I'll be sure to report back once I've had a chance to experiment!

Update: Doing the above breaks things. I get sound, but no reverb or gain. I think doing this grounds the first gain stage through lug 1 of the Chaos Control or something.

I installed a momentary 3PDT (because I had it on hand. I'll replace it with a DPDT at some point.) One pole for the Chaos switch and another to short past R27. This makes self oscillation attainable at a broader range of settings.

The downside is the momentary 3PDT switch is nowhere near as smooth as the SPST...and it's probably not as mechanically robust.

[diablochris6]

Ok... I spent a little time pouring over the schematic.

It looks like I should be able to put the Chaos Control in parallel to Recycle and R27 by moving just one wire: I can desolder the wire that connects to the lug 2 Chaos control pad and then connect it to the bare lead between R27 and D1.

I'll be sure to report back once I've had a chance to experiment!

Update: Doing the above breaks things. I get sound, but no reverb or gain. I think doing this grounds the first gain stage through lug 1 of the Chaos Control or something.

I installed a momentary 3PDT (because I had it on hand. I'll replace it with a DPDT at some point.) One pole for the Chaos switch and another to short past R27. This makes self oscillation attainable at a broader range of settings.

The downside is the momentary 3PDT switch is nowhere near as smooth as the SPST...and it's probably not as mechanically robust.

I believe another option could be to have R27 attach to the junction between R10 and R11 instead of at the gain stage and maybe decrease R27's value to 10k (or maybe less for more gain on the feedback path). It wouldn't keep distorting through the clipping stage, but you might be able to get more of a wash out of it.

I appreciate your endeavors on making this circuit better!

[Aleph Null]

Ok... I spent a little time pouring over the schematic.

It looks like I should be able to put the Chaos Control in parallel to Recycle and R27 by moving just one wire: I can desolder the wire that connects to the lug 2 Chaos control pad and then connect it to the bare lead between R27 and D1.

I'll be sure to report back once I've had a chance to experiment!

Update: Doing the above breaks things. I get sound, but no reverb or gain. I think doing this grounds the first gain stage through lug 1 of the Chaos Control or something.

I installed a momentary 3PDT (because I had it on hand. I'll replace it with a DPDT at some point.) One pole for the Chaos switch and another to short past R27. This makes self oscillation attainable at a broader range of settings.

The downside is the momentary 3PDT switch is nowhere near as smooth as the SPST...and it's probably not as mechanically robust.

I believe another option could be to have R27 attach to the junction between R10 and R11 instead of at the gain stage and maybe decrease R27's value to 10k (or maybe less for more gain on the feedback path). It wouldn't keep distorting through the clipping stage, but you might be able to get more of a wash out of it.

I appreciate your endeavors on making this circuit better!

That's an interesting idea and something I might test. I do like the washed out distorted sound, though—that's one of the most appealing aspects of the design to me. It acts as a natural limiter for the Chaos. Plus the right settings get an almost shimmer-like effect. Probably something to do with all the extra harmonic content created by the distortion.

I think "making the circuit better" is generous, but I'm glad you see it that way. It's a really compelling design and I'm enjoying exploring it.