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Sounds great! What's different in the 2017 version vs. 2015 version? I've got the 2015 pcb on my workbench and was just about to start populating the board. When I have time anyway lol.

Just to elaborate some more (because I would not dissuade you from building the 2015 version). You can incorporate most of the changes very easily. From the 2015 schematic:
Space pot is now 25kB
D2 is yellow diffused instead of green (subtle but slightly improved difference)
R23, R24 are now 1k
R37 is 1k5
R5 is now a 50k trimpot. R3 was changed to 1M in conjunction with this.
The I/O stuff is now centrally located at the bottom of the PCB for convenience but that's not important.

The bigger change is the Dwell control which now has a JFET buffer in the path (something I've been experimenting a lot with in delays). Use the schematic below as a guide. You'll make the pot 100kB, R31 4k7 and then replace C27 with the buffer circuitry. Overall it gives the dwell a bit more character, is a bit louder but remains controlled without the self-oscillation running away on you (you can hear this at the end of the demo).

Sounds great! What's different in the 2017 version vs. 2015 version? I've got the 2015 pcb on my workbench and was just about to start populating the board. When I have time anyway lol.

http://www.madbeanpedals.com/forum/index.php?topic=26750.msg259040#msg259040

ok, I'll omit C3. and do I have to jumper the two C3 pads?


thanks in advance

Never jumper anything that says "omit". You gonna blow it all up!

I prefer to wear my tube amps.

I wear a better guitar player when possible. But, uhh...back to back.

Yeah, omit it. It should have been on that list.

The BOM listed two extra 470k resistors that are not in the build. This was removed and the doc re-uploaded to the Projects Page.

Sorry about that. I updated the project doc with the removal of the two 470k listed in the BOM.

IC4 is obviously a big problem here but whether or not that's a bad chip or a solder joint problem is something you need to look at. It looks like you have correct bias voltage at pin3, but from there it goes out of whack.

First I'd start by pulling that IC out, and audio probe pin3 of IC4 (in the bare socket). That will confirm whether or not you have delay coming out of the PT2399. Assuming you do, you need to either swap in a new IC4 or look for problems with your soldering or micro-bridges between solder joints.

Center lug of the Timbre pot is the correct output, so you are good there. Impossible to say what the problem is without more information. A weak signal could be lots of stuff...wrong part, wrong voltages, bad transistors or transistors in the wrong way, etc. You need to do some investigating.

At first I thought maybe it was a bi-polar power supply in which case I guess the buffer and input of the gain stage could be directly DC-coupled, but that's not the case here.

Quoting from RG Keen's Technology of the TS:

The clipping stage is a fairly ordinary variable gain opamp stage with a few tricks to shape the amount of clipping and the frequency at which it occurs. The signal from the input buffer stage feeds the (+) input of the opamp section, so the output is in phase with the input. In all members of the TS family except the TS10, this is a direct connection from the coupling capacitor to the emitter of the input buffer. In the TS10 there is a 220 ohm resistor in series with the (+) input. In all models the input is biased to the 4.5V bias source with a single moderate value resistor, usually 10K; this seems not to make any difference in the sound.

But, I'm not sure if he's referring to the 220R resistor or 10k resistor "not making a difference to the sound". It seems to me a 10k referenced between the emmiter of Q1 and ground rather than to the bias voltage at the non-inverted input of the amp would make a very big difference and not sound good at all. But, I might be totally wrong about that.

It's easy to find out - just breadboard that input buffer and a fixed gain stage and see what happens.

IN = S (send)
OUT = R (return)
G = ground

There's only one -9v spot. The other one is labeled +9v.

Just chiming in to say this sounds deserving of the overused term "epic fail"! In the best possible way, of course.

A 2P4T would do it. You'd wire your effect input and output from the bypass switch to the two poles, then the circuit input and outputs to their corresponding terminals on the rotary.

That is crazy. Excellent work.