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.

Vero Layout: The Gristleizer

Here's a really ugly vero layout I did for the classic 'Gristleizer' circuit, the first circuit I ever took a probe to and figured out how it worked. I learned a lot from the circuit, as it provides elements of electronics present in both guitar effects and synthesizers.

It certainly hasn't aged well, the filtering is pretty terrible and some settings are borderline inaudible, with some knobs not doing anything in 70% of their settings, and using 5 LM741s seems ridiculous, so this one uses a TL074 and a TL072, with the voltage doubler hidden off-board (I had this in console style case that I never finished). A lot of fiddly parts chained together.

I've built several of these now and they've all come off really well. FuzzDog does a great PCB if you're in the UK too: https://shop.pedalparts.co.uk/Gristleizer_-_Mad_Modulations!/p847124_15740439.aspx

Anyway, the layout:

I told you it was ugly!

I often wondered why nobody had produced a vero layout for this, and then as soon as I put pen to paper, I realised why. Too many jumpers, too many cuts and too many specific parts needed to commit to making this unless you really want to.

The schematic I made this from was a beautifully neat Eagle schematic which now seems to have been expunged from the internet. I have a copy but shan't post it here as I cannot remember where it was from and wouldn't want to host it without asking permission first. But if you fancy it, have fun building this.

Self-verified, as I had this working for a while, and it sounded near identical to the three I bought from Fuzzdog.

First HyperLight boards now available

Hello all,

I now have the first run of HyperLight boards on their way to me.

If you're interested in buying one they are here: https://www.ebay.co.uk/itm/282842216604

Here they are:

Pretty huh?

You can drop me a line at bluffchill@gmail.com and we can sort out PayPal stuff.

Update: with a bit of fiddling, it fits in a 1590B.

Schematic for you home brew types:

New Effect: Screaming Red Rabbit Fuzz

So here's a happy mistake!
Confessions up front. I was trying to make a Seamoon Funk Machine. I'm sorry.
Sorry that I was trying to make an auto wah pedal, and sorry for not succeeding.

Fortunately, I can bring to you, hypothetical reader, something else entirely. I present to you the SCREAMING RED RABBIT fuzz pedal.

And I'm posting the schematic AND a veroboard layout for you to make yourself.

The Screaming Red Rabbit is, while technically unassuming in its low part count and common components, a rather serviceable fuzz pedal. It's almost like a ZVex Fuzz Factory, in that it squeals with delight, self-oscillates, and generally won't behave its damn self.

There are four controls.

• Definition (envelope sensitivity)
• Density (envelope gain)
• Frequency (frequency of the low-pass filter, a sign of its origins as a 70s filter pedal)
• Volume (how loud it can do what it does)

I fiddled around with the bit in between the envelope follower and the filter op amp for quite a while until I found a decent combination, but got it to do some pretty wacky things on the way. At one point it was very nearly a tremolo. A horrible, horrible tremolo.

Schematic!

And a vero layout for you to chew on:

Your homework is to try making this, verifying my layout and letting me know if it sounds as awesome as mine (somewhere between a Prunes & Custard and a Smashing Pumpkins-esque op amp big muff) or if it is totally horrible and I am very wrong. Bonus points if you can identify the origin of the name I have given this thing.

Enjoy!

New Effect: The HyperLight Ringmodulated Delay

I've been working for a little while on a circuit called the HyperLight. It is a very basic lo-fi PT2399 based delay with a ringmodulator in the delay path. Your dry tone stays dry, the repeats come back in Dalek form.

I was inspired by the soundtrack for the game Hyper Light Drifter, by Disasterpeace, which is divinely atmospheric in a decayed future sort of a way.

After a lot of twiddling over the breadboard, I have a complete version. Thanks to OSH park, I have some boards for it as well.

The controls are delay time, modulator frequency and feedback. There is also a trimpot mounted on the board which controls how much signal is returned from the ringmod vs 'clean' delayed tone from the PT2399. There is also an optional switch which puts it into 'experimental mode' - that is, it redirects the delay time pin from pin 6 through a 47k resistor to pin 5 of the LM567 chip. It gives a much shorter delay and makes it sound more like a normal ring modulator, but with the clean signal still present. An image:

Introducing the HyperLight ring-modulated delay. Send your delayed tone into the glitchy virtual future. #diyeffects #ringmodulator #delaypedal

A post shared by Bluff Chill (@bluffchill) on Jan 9, 2018 at 2:03pm PST

And some sound samples:
You can get some pretty cool hypnotic twinkly robot noises behind your normal playing. Obviously being a ring mod type effect it handles single notes better than chords but can fatten up chord work in weird ways when using lots of distortion. But I liked it and I'd like to share the effect with the world.

I will very soon have boards for sale. I will also add a schematic, and if I get round to it, a tagboard layout.

Welcome to the blog!

Hello and welcome to the Bluff Chill Devices blog!

A little introduction: I'm a musician who dabbles in electronics - effects pedals, noise makers, synthesizers, etc. I enjoy designing my own circuits and modifying existing ones. I like to think my particular area occupies a fuzzy (pun) area between synthesizers and effects units. I became interested in this particular area after discovering the Gristleizer, building several, and then deconstructing the schematic to change things about it I didn't like. Posts on my work will follow.

I've just taken my first steps into producing some of my work for sale and would love to share my work with the circuit bending, guitar effect building world, and look forward to them being deconstructed and modified in turn by other members of the community.

Enjoy!