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Messages - sethwitz

#1
First, here's a quick and dirty demo video I made:


Description of The Circuit

This is "a PT2399 based delay with envelope controlled pitch modulation that does chorus, vibrato, doubling, or slap-back delay" created by Aleph Null (original post on the madbean forum here). After viewing their demo video and looking at the vero layout, I was set on making my own version of this pedal. I love a good doubler/slapback sound for thickening up solos and riffs, and I figured it would be nice to have a dedicated effect for this very purpose. (I don't like fiddling with the settings on my delay pedal in the middle of a performance.)

Build Process

I made this directly from the vero layout provided by Aleph Null. It was an exceptionally simple build, and all of the parts are things many DIYers will already have on hand or will be able to obtain with ease. In general, building pedals on vero has been mostly fine for me.

There have been a few cases where vero didn't work out because of the size/complexity of the overall circuit. That's definitely not the case here. There's plenty of space to place components, there aren't too many cuts or links that are needed, and the layout is small enough to fit inside of a 1590B.

Quick note for anyone considering making this pedal: the vero displays a "100nf" electrolytic capacitor, when it should actually be labeled "100uf."

Modifications

I'm not at the point in this hobby where I can confidently identify what parts of a circuit would lend themselves to modification. Nonetheless, I made a few tweaks based on some feedback provided to me by Aleph Null. First, I switched out the B2k "Detune" pot for a B5k. This enables more wacky pitch-bending action with the "Detune" knob. I chose to do this because I play single-coil guitars, and more intense pitch-bending is triggered the harder you strum/pluck/pick. A B2k pot will probably work just fine if you're driving a louder signal into this pedal than I am.

In addition to this, I tried another modification that Aleph Null suggested. The additional gain on tap via the "Boost" knob is excellent, but I wanted to figure out a way to tap into that gain without increasing the overall volume very much (like a Speaker Cranker/Electra pedal). I've been especially inspired by the Rec Head pedal by Bleak District Electric and was hoping to turn the "Boost" knob into more a "Saturation" knob. Aleph Null suggested removing the 100k resistor before the Output and adding in some diodes front-to-back. I looked at a schematic for the Speaker Cranker and tried to copy-paste that into my build. I still get a fair bit of volume boost, so I didn't get the effect I was hoping for. I may return to this another time and try to modify it more, but I'm nonetheless happy with how the pedal sounds.

Enclosure Design

So enclosure design is the part of making pedals that I enjoy the least. Drilling and getting all of the parts into the enclosure is already hard enough for me as it is, and when I get to the point where I know a circuit works and sounds good to me, I'm usually driven to simply box it up as fast as possible. Most of my pedals are bare aluminum enclosures. However, I wanted to take the time to make this look a teeny bit nicer than my usual pedal. (Spoiler: I messed up quite a bit throughout this process).

The first error that I made had to do with the I/O and 9v drill holes. Given how poorly I spaced the drill holes out (even after doing my best to take precise measurements), I had to sand down portions of the jacks themselves to make it all fit. In the end, the jacks are all so close that I have to be very careful with which cables I use to plug into this pedal. If I use pancake jacks, then getting the power connected requires squeezing things in pretty tight.

In addition to messing up those drill holes, the holes I drilled for the pots came out quite uneven. I'm inclined to think that my drilling is the issue (rather than the marking/measurement). I've been using a step drill bit with a power drill. I imagine a drill press would give me a much better result.

Finally, I completely messed up the paint job that I was at one point very pleased with. I thought the paint and clear coat had dried enough for me to box up the circuit. Unfortunately I was wrong. The paint got scuffed up, and so I tried to patch things up by spray painting and clear coating again. Foolishly, I was both too impatient and lazy to remove the circuit and all of the off-board components. I opted instead to mask everything as best as I could with some painters tape and then paint again. The results were meh.

Sound

The most important thing though, of course, is how the pedal sounds! I think it sounds stellar, although you ought to judge for yourself. I made a quick and dirty demo video with the intent of capturing some different sounds that this circuit can make. I think you can get a very nice slapback and double-tracking effect, as well as a quirky little chorus/vibrato thing too. The additional gain on tap with the "Boost" knob is an excellent addition too. This is precisely the kind of pedal I'd want to use when trying to get the double-tracked guitar sound from songs like "Let Me Roll It."
#2
I certainly can! I'm unfortunately not yet good at designing artwork for enclosures, so it'll likely be a plain spray-painted sort of affair. I'll try to get a build report and demo up this coming week.
#3
Thank you for providing such a detailed response—this was very helpful! I'm relieved to hear that the 33pf and B20k substitutions were alright to do.

I followed your suggestions and wound up swapping in a B5k pot for Detune and adding 3 1N60P diodes at the end of the circuit. The Detune effect is much more pronounced now when Lag is set to a minimum. And good call regarding the impact of the output of the guitar pickups by the way! I play a Tele with lower output single coils, so using a B5k made a very nice difference. I'm really pleased with the effect. I might even try seeing what kind of chaos comes out with a B10K in there.

As far as the Boost section is concerned, there's still a decent increase in volume when Boost is all the way CW, but certainly less so that with the stock set-up. I goofed and didn't realize that the 1N60P diodes I have are *not* the same thing as the germanium 1N60s that were used in the Speaker Cranker, so that probably explains the issue. I might play around with some other diode options to see if I can limit the volume boost a bit more, but I'm more inclined to simply add a master volume pot. :)

All in all, great circuit here. I'm really looking forward to boxing this one up and putting it on a pedalboard!
#4
Quote from: Aleph Null on August 08, 2024, 08:36:56 PM
Quote from: sethwitz on August 08, 2024, 06:47:23 PMHey there! I made your original version using the stripboard layout you provided. The circuit sounds really great! Not sure if you're looking for any feedback or not. Let me know and I'd be happy to share some additional thoughts.

I'm glad you like it! I'm definitely open to feedback.

Before I make any remarks, I'll note that I had to make two substitutions in my build based on what I have on hand:
  • I had to use a 33pf in place of the 20pf
  • And I had to use an A20K pot for the Mix control

I'm not knowledgeable enough to know how significant of an impact such changes would make, so my apologies if the feedback below would be addressed if those substitutions hadn't been made.

First of all, I love the sound of the circuit when the Boost is full CW. It reminds me a lot of the flavor you get when adding either tape or tube saturation to the signal (e.g. what you'd get from either an EP-3 boost or an Electra-style circuit). If possible, I think it would be really cool if this circuit made it possible to crank the Boost and get that same chewy overdrive/fuzz sound without adding more decibel output (kind of like a Speaker Cranker). I'm not sure how complex that kind of tweak would be, but it would be really sweet. Could also be cool to have a toggle switch to engage or disengage a decibel boost when the Boost knob is cranked. More parts/complexity though, of course.

For the 100% wet setting, I wasn't getting much modulation when Lag was set all the way CCW. I wasn't sure if this was because of the substitutions I made or if it has to do with the PT2399 chip I used. I've heard those can be somewhat different from chip to chip. Having made other PT2399 delay/chorus/vibrato pedals (e.g. the Deluxe Pitch Pirate), I'm familiar with the fact that there's only so much modulation you can crank out when the delay time is set to its shortest setting. Nonetheless, the modulation on this sounds exceptional when additional delay time is introduced. The vibrato is definitely chewy and the chorus very lush. If there's any way to bump the modulation at that shortest Lag time, that would be sick.

Overall, this is a really, really great circuit and I'm definitely going to box it up. I think I can fit it into a 1590B with top-mounted jacks. It really succeeds at each of the functions you've listed: chorus, doubler, slapback, and vibrato. Thanks for making this available!

PS: On your vero layout, I think you might have a minor typo. There's an electrolytic capacitor labeled as "100nf" and I think it's supposed to be "100uf."

Cheers!
#5
Hey there! I made your original version using the stripboard layout you provided. The circuit sounds really great! Not sure if you're looking for any feedback or not. Let me know and I'd be happy to share some additional thoughts.