The Shagpile Deluxe - an expanded version [video]

I recently sold one of my Shagpile pedals, and on the same listing I got an enquiry from someone who wanted one with a wet/dry mix. The existing version doesn't currently allow for this, as it is a fixed wet/dry mix out of the PT2399, so I went back to the schematic to see what I could do.

It turned out to be relatively simple - the wet and dry outputs at pins 15 and 12 of the PT2399 were summed using a simple voltage divider of 2 10k resistors, so I replaced it with a potentiometer.

Easy! It almost seemed like too little an adjustment to be able to pass off as a custom or 'deluxe model', so I also replaced the 'release' switch on the envelope section with a potentiometer.

The switch chooses between going directly to ground and 250K resistance to ground, and similar to how it works on deadastronaut's version of the phuncgnosis, affects how long until the envelope closes, so you have more control over this.

Of course, now it had 4 knobs, so it needed to be bumped up to a larger enclosure (the design of the PCB didn't really allow 4 pots to fit) which also meant a redesign of the decal. An hour or so in GIMP and I came up with a horizontal 1590BB design.

I'm pretty pleased with the way it turned out - it's an uncluttered layout and makes perfect sense, while looking true to the original. Also used a lovely Plasti-kote matt finish lacquer on it, which feels way better than the usual high gloss stuff. It's also one of my neatest jobs on the inside too, especially considering more free-trailing wires than I usually like, due to the 'floating' pots.

Check out those white jacks! I have a limited supply of these but it seemed right to use them on this one.

Shipping this one tomorrow, and I hope the owner enjoys playing with this as much as I enjoyed making it. I did a little demonstration video:

The EctoVerb - a low-cost, Belton-brick-free lo-fi spacey reverb!

I love reverb effects, and I love building my own effects, but these two things aren't necessarily compatible as the only real option for DIY reverb, without going down the spring tank route, is the Belton (or Accutronics) brick.

They're a useful little brick, but not cheap, and instantly push your budget way up as they cost about £15. So I set about creating a reverb with multiple PT2399 chips, which apparently is all that's inside the BTDR-2H anyway.

My first design was based on two PT2399 chips set up in parallel, using an ultra basic configuration - using only LPF1 and OP2 to create a single repeat, and then a high-value resistor bridging pins 12 to 16 to induce the repeats (around 2M!) it's quick and dirty but it works!

I had 2 of these set up as below:

One with a short delay time and the other longer, with a 'balance' pot between them before ground for small adjustments. I also used a large pot (1M) with a 750K resistor instead of a 2M between pins 12 and 16 so I could dial in feedback amount.

It worked quite well, and I also used a series of jumpers (or a 3P4T switch, as above) to jumper the wet signal of chip 1 to the dry of pin 2, and vice versa, neither, or both, giving different reverb tones. 

It worked pretty well, but I struggled to hear the short delay tone when it came to the summing stage, it sounded a bit muddy, and I lost a lot of treble tone on the dry signal. So I went back to the drawing board.

Instead of running the chips in parallel, I ran the signal through the chips in series. This time I got a much better 'reverb' effect - a little delay before the effect came in which sounded much more convincing, and a more fluid, less choppy repeat sound. Very nice. Sound sample:

So as you can hear, some nice dwell (most of this clip is played with the delay mix quite low, straight into Ableton with a little saturation added) and it sounds a little bit like a spring reverb, but also strangely ghostly like an oil can delay or something. About half way into the clip I turn the mix up all the way to nearly 100% wet. It starts to oscillate a little bit and I've since increased resistance from the output of chip 1 into chip 2 to tame it a little bit.

 At some point in the late nights developing this, I used a JFET based buffer on the input with a wet blend to control wet/dry mix. The treble I lost on the input is now back and the mix works perfectly, from no reverb at 0 to complete drench at 10.

A video of it being played through an amp is here:


One thing I noticed is there's quite a lot of hiss, so that's something I'm still trying to iron out.  currently have very small capacitors across pins 15 and 16 so might tweak those for something larger. Otherwise, I'm pretty happy with it and have some boards on the way. It's a relatively low part count - around 20 capacitors and 12 resistors, one transistor and the usual 5v power management components for the PT2399s.

There are some kits available on eBay. The full build guide is available here.

EctoVerb!!!

Hyper Light 2 is ready

It's finished!

I made this handsome demonstration model and I have some more PCBs on for order. Let me know if you're interested in a fully built one.

A short demo video:

Hyper Light 2 Demonstration

Enjoy!
I noticed after uploading I mostly play this with the ring mod mix very low - I do turn it up at a few points though.

Boards are currently on their way to me and should be available soon.

Hyper Light 2: More Hyper, More Light.

Hyper Light 1 had a good response, so I've got the version 2 on its way to me!

New features:

• Modulation inputs for carrier frequency and time
• Almost no treble bleed!
• Improved feedback response (no lockup)
• Better mix knob (external this time)
• Onboard bypass indicator (I don't know about you but I think these are a godsend)
• Better solder pads (sorry the other ones were thin as a rake!)
• Optional SMD socket for the LMC567 as the DIP8 package is increasingly difficult to find

It's gonna be pretty! Oh and it's 1590BB now. It outgrew itself! If you're very clever it might go horizontally in a 1590B.

Shagpile envelope-controlled double tracking/chorus pedal

I've been designing this lately - the Shagpile - an envelope controlled double tracking/chorus pedal. Basically, instead of having an LFO control the clock speed of the second voice, it's controlled by a very wobbly envelope follower, so modulates in unpredictable ways rather than the smooth in-out of a chorus.

Two controls - flutter controls the gain of the envelope follower, taking it from barely a ripple to Clari-Not style huge wobbling. Tracking controls the delay time of the second voice, from barely-even-there to nearly a second later. When you strum chords with the tracking quite close and the flutter about halfway, it sounds a bit like a very wobbly chorus.

The single switch makes the second voice slide up in pitch or down in pitch.

Pics!

Just sent off for the second version of this in a prototype run, and they'll be for sale in the usual way and maybe even in a limited, full pedal version. Decal needs a little work, other than that I'm very happy with this oddball circuit.

No sound samples but you can hear it being played on all guitar parts in this tune:

HyperLight schematic

Sold a few kits now, time to post the schematic!  There's also a full build doc with BOM here. Enjoy. Welcoming any feedback on this schematic - suggestions always welcome.