CV'19 - a multi waveform LFO CE-2/Pork Barrel

[Lurktastic]

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

[jimilee]

Wow! You have been busy, very nice.

[Bio77]

Wow, that's all kinds of awesome!  Great build.

I'd be interested to hear the square wave LFO.  Since it never passes through the origin, I wonder if it ever sounds in tune?   Maybe at faster speeds? 

[zombie_rock123]

Awesome build! That second demo with all the reverb, tasty as!

[Lurktastic]

Thanks guys! I'm glad to hear ya'll like it

I'd be interested to hear the square wave LFO.  Since it never passes through the origin, I wonder if it ever sounds in tune?   Maybe at faster speeds?

Hmmm interesting question! If you like, I can record a demo using all the non-sine/triangle waveforms

[diablochris6]

That's phenomenal! Love it, man. I might try that with something I built.

[Lurktastic]

Wow, that's all kinds of awesome!  Great build.

I'd be interested to hear the square wave LFO.  Since it never passes through the origin, I wonder if it ever sounds in tune?   Maybe at faster speeds?

I've recorded a demo showcasing the square, ramp up and ramp down waveforms. Later in the sample, I "distort" the waveform using the "Deform" control on the pedal. This control basically alters the dutycycle of the selected waveform. I found that on ramp up/down, altering the dutycycle can make the "gliding" of the vibrato more apparent (best heard around 0:55 onward).
Anyway, I've found the most useful waveforms to be either the sineoid, triangle and lump/valley waveforms (or the variations thereof). The various possible waveforms can be seen on page 3 of the TAPLFO pdf.

[soundcloud]https://soundcloud.com/user-584389416/cv19demosquareandrampwaves[/soundcloud]

0:00-0:04 - clean
0:04-0:33 - square 40% mix and 100% mix
0:33-0:55 - ramp down 40% mix and 100% mix
0:55-1:25 - ramp up 40% mix and 100% mix

That's phenomenal! Love it, man. I might try that with something I built.

Thank you very much! What effect are you going to try it with?