Topics

Howdy folks!
Long time lurker here. I finally built something I thought was noteworthy and/or impressive enough to share. I did build a couple other pedals over the years but I might post those in a seperate thread later.

DISCLAIMER: the name of the pedal is by no means meant harmfully, offensively or in a jesting manner. It is a nod towards COVID-19 though, because I built/developed most of it during the quarantine of 2020 and it was one hell of a release from cabin-fever at times. Inspired by the ZVEX Lo-Fi Junky, I dreamed up the idea of a BBD Chorus/Vibrato unit controlled by the TAPLFO v3 chip in late '19.

After studying the TAPLFO chip's inner workings and required circuitry, I adapted it to feed a Madbean Porkbarrel (2019 version). According to electrosmash the LFO of the regular old Boss CE-2 puts out between 2~7ish volts, so I figured I could utilize the circuit displayed on one of the last pages of the TAPLFO pdf. I drew up my own schematic (see below) for easy reference, made a layout and tested it on the scope. I can say the layout (see below as well) I made is definitely verified, although it can probably be improved upon in terms of space and/or component placement.

Anyway, I simply tied the depth pot's number 3 lug to the Porkbarrel's Depth number 2 pad hoping it would work straight away - and it did! The MN3101 accepts all waveforms! The sawtooth and squarewaves sound a bit janky though, but that may also be because I still have to swap the LFO amp's IC out for a TL061 (for lower power consumption), or maybe it's just a feature/sound of the BBD's clock frequency suddenly being shifted dramatically. I don't have enough knowledge about BBD's to know what's causing this.

Another issue is the depth pot. It's a 100kB and it seems to have all of it's "depth" tweakability bunched up near the end of it's travel. I figure I'd have to swap it out for a lower value and a different taper. I guess a 10kA would work. The wiring could've been done better in terms of neatness, but it's not noisy and sounds crystal clear, so I guess it's fine the way it is.

I also decided to omit the Speed multiplier rotary switch (labeled "RSW2 Multiplier" on my schematic) because I figured I'd mostly be using the speed pot by itself.

Anyway, I'm super proud of this build. It fired up straight away the first time I powered it on and I'm REALLY happy with the sound of it. It's got everything from subtle vibrato to the weirdest chorus effect one can think of. Also very applicable to synths I think... it can get very deep and lush on the highest depth settings, and a bit reminiscent of a flanger on the lower depth settings.

Enough of my rambling, here are some photos! Sound demos can be found below as well. I've added some timestamps to indicate what settings were used.
The sound demos were recorded using Amplitube and a Fender Player series Jaguar.








Gut shot! The two small trimmers on the back of the speed pot were added to dial in the range of the pot. I'm glad I put those in there, because they were definitely needed to give the control a manageable range.


Schematic. Apologies for my handwriting.


The TAPLFO layout I cooked up.

[soundcloud]https://soundcloud.com/user-584389416/cv19demonoreverb[/soundcloud]
(please forgive my butchering of the first two songs)
0:00-0:09 - clean
0:10-1:04 - triangle mode, medium depth, medium rate 35% mix
1:05-1:38 - sine mode, medium depth, medium rate, 35% mix
1:38-2:02 - sine mode, medium depth, medium rate, 100% mix
2:02-2:16 - sine mode, more depth, more speed, 100% mix
2:16-2:46 - sine mode alternate waveform, medium depth, medium speed, 40%ish mix
2:46-2:57 - sine mode alternate waveform, max depth, medium speed, 40%ish mix
2:57-3:05 - triangle mode alternate waveform, max depth, medium speed, 40%ish mix
3:05-3:34 - sine mode alternate waveform, max depth, more speed, 100% mix

[soundcloud]https://soundcloud.com/user-584389416/cv19demodrenchedinverb[/soundcloud]
0:00-0:14 - clean
0:14-0:36 - sine mode, medium depth, medium rate, 40%ish mix
0:36-0:45 - sine mode, medium depth, medium rate, 80%ish mix
0:45-1:47 - sine mode, maximum depth, medium rate, 100% mix
1:47-2:15 - sine mode, maximum depth, medium rate, 40%ish mix


Thanks for reading and listening! I hope you enjoyed

Good day/good morning everyone!

Yesterday I finally got the last parts in for my Sunking build. I still had an old board laying around and decided to populate it. Made a nice looking enclosure for it and all. Fired it up yesterday and... well it works, but the gain pot doesn't do much. I get a slight change of volume when the pot travels around it's midpoint, but other than that the gain level stays more or less the same - pretty low. The Level and Tone knobs work properly though, as does the bypass. I wired the circuit to be buffered bypass.
I implemented a couple of mods. One being the obvious clipping switch as described in the build documents, the other being a capacitor switch which switches between ~4nF, ~7nF and ~14nF. The cap switch works properly, I can easily hear the difference between different settings. The clipping switch however, just like the gain pot, doesn't do much of anything... which is logical of course because there's hardly any gain produced.

I've tried debugging it a tonne yesterday, spent a good 4 hours measuring/checking values, continuinity, voltages etc. So far everything seems to check out. I also reflowed a couple of suspect solder joints around the gain part of the circuit, namely around IC1B. I even tried connecting the dual gang pot in reverse and tried swapping the gangs around but to no avail.

Could one of you be so kind as to take a look at this? I'm at a complete loss, I don't know what the issue could possibly be...
Here's the build document. The board I'm using is the 2015 version.
Below are the voltages on all the IC's, which seem to check out when comparing them to the build document. I've also included pictures of the component side and solder side of the board, below the table displaying the voltages.
As you can see, I paralleled some capacitors on the solder side of the board, and put some resistors in series on the component side of the board. I did this because I didn't have the correct values on hand. I did this for:
-R7, making a ~423k out of a 33k and a 390k.
-R15, making a ~392k out of a 390k and a 2k.
-C3, making a ~390nF out of 68nF and 330nF.
-C7, making a ~82nF out of a 47nF and a 33nF.
-C9, making a ~390pF out of a 39pF and a 330pF.

Code Select Expand


IC1 - TL072CP
1 -  4.55v
2 -  4.55v
3 -  3.48v
4 -  0v
5 -  4.54v
6 -  4.56v
7 -  4.56v
8 -  9.02v

IC2 - TL072CP
1 -  4.59v
2 -  4.55v
3 -  4.54v
4 - -8.78v
5 -  4.54v
6 -  4.55v
7 -  4.51v
8 -  17.33v

IC3 - 7660S
1 -  9.06v
2 -  4.43v
3 -  0v
4 - -4.44v
5 - -8.78v
6 -  4.58v
7 -  6.97v
8 -  9.06v







Thank you in advance!

EDIT:

Messed up the image links... fixed it...

EDIT #2:

I've also checked the bypass switch wiring, to see if it checks out with the schematic. In bypass, the buffer is switched and the output of IC1B (through C10 and R10) is connected to ground. When the effect is ON, the LED is switched to ground and no short exists between IC1B and ground. Figured I'd include this because the build documents state the following on page 6: "09/12 - Buffered wiring diagram corrected (pads 4 and 6 were originally shown reveresed)."

EDIT #3:

I'm aware the sleeve of the output jack isn't wired. I only have the sleeve of the input jack wired, using the enclosure to ground the output jack in order to avoid ground loops.