Hello GPCB community!

It’s been a while since my last pedal build, and after returning to the forum and seeing some of the gorgeous combo builds done by members over the last several months I decided I wanted to get back in on the fun.  My first build was a Civil War variant Muff I posted a while ago, and I’ve done a few single pedals since then, but my goal was to do something a little bigger.  So today I present to you: Dark Echos.  The build components include:

BMP Op Amp with Roto Tone Deluxe for 4 diode clipping options.  Position 1 was populated with the original diode schematics: triple pair of 1N914s matched.  I used a Si/Ge pair in position 2 with a N914 and N270.  Position 3 has asymmetric clipping with two silicon N4148s and one silicon N4001.  Position 4 has a double pair of Schottky BAT46 diodes

Ancestral Apparition with the Accutronics BTDR-2H long decay brick.

Easy Order Switch toggle between the Op Amp and the AA.

Emerald Ringer, stock build, with all components tested and within 1% of spec.  Diodes are matched N914s with Vf = 0.595

Stage 3 boost with SW1 capacitor switch.  I used the standard J113 transistor and biased it by ear, which got me at 5.12 V.  I then adjusted it to read 5.25 V, dead center between the recommended 4.5 and 6 V.

Graphics were a bit of a creative journey.  I wanted to have some tie-in with the PCBs used, so there were ideas like ghost ship, green ghost, siren’s echo, etc.  Nothing was really speaking to me until I stumbled on the ghostly silhouette and used that as the centerpiece.  I then found the Motel King font, which invoked old 60s Twilight Zone themes, which let to the black and white color pallete.  That led me to the TV static gradient, which then led to a tutorial on how to ‘glitch’ the text.  All of it tied together with the echo waves and, with a nod to the Op Amp grit, Dark Echos was born.  Graphics were compiled using GIMP software, printed on a water slide decal, and hit with clear acrylic rattle can spray at the end.  I used a 1590DD enclosure.

Things I learned:

1. This was my first combo build, so I learned a lot. I really had fun with the Roto Tone and trying out different clipping options.  The Guitarpedalx.com primer on clipping diodes was a great reference for understanding diode forward voltage and for pre-plan diode combos.
2. Measure everything with a DMM before populating the board. Mistakes were made.
3. I spent more effort trying to keep wires short and tidy. Unfortunately, this was initially built without the Easy Order board, then revised once I received one.  That led to less than ideal space to incorporate the new wiring, and things got a little sloppy at the end.  Be patient, wait for all your parts, then begin.

Things I really like:

1. The Op Amp is such a great PCB. Amazing distortion and fantastic mod options.  It’s one of my favs and sounds great.
2. The Ancestral Apparition reverb was a new one for me. I really like modulation effects and have been blown away by the warm sonic honey oscillation of a Dr. Phybes I previously built.  The AA delivers as promised- great echo, lots of expansive headroom, and all adjustable.  Very cool.
3. Stage 3 boost. Such a small, inexpensive board and provides easy boost adjustments right on the pedal.  I’m probably going to put some kind of boost effect on every pedal I make in the future.

Things I would have done different:

1. The different diode options on the Roto Tone result in different sounds (good), but at different volumes. Totally expected- that’s how they work- but in hindsight I’ve got Position 1 and 4 noticeably louder than 2 and 3.  I would have arranged the board by high to low volume, 1-4-3-2.  That way when I make a switch from 1 to 2 or 2 to 3, I know to make a simultaneous adjustment of the boost to compensate.
2. The Emerald Ringer and I are still feeling each other out. Initially I thought there might be some component problems- at that point of my build I was getting a little cross-eyed.  I had a spare PCB so I rebuilt the whole thing and swapped them out.  No significant change.  I occasionally get some unexpected note truncation and warble.  From what I’ve read the octave is an acquired taste and may not be for every playing style.  I’m going to keep at it and see if we can find an understanding.

All it all, it was a super fun build and I’m really happy with the way it looks and sounds. The purpose of the day was to learn about combo building and develop a deeper understanding of how things work, so I say it was a success.   I’ve got a couple other combo builds in the planning stage, so let me know what you think.

Happy modding!