Holy Island Audio modified Casper Electronics Echo Bender!!!

Here's an all ready wacky circuit made a touch wackier by Gwion of Holy Island Audio Effects in Wales. The main tweak they've added is... AN EFFECTS LOOP - so you can cram even MORE craziness into the noisy fuzzed out repeats this thing is known for.

 I'm an admirer of Gwion's work, and have also drawn up a layout for a three oscillator drone synth that Gwion came up with that is quite evil. That one can be found on the Dirtbox Layouts blog.

The only modification I made to the Holy Island schematic was to the power supply: I used a 1n5817 protection diode in series with the 9v instead of a 1n4001 in parallel. Everything else is as it is on Gwion's schematic - which is really only a tweaked version of the Casper Electronics EchoBender. Which is a PT2399-based delay+noise design that, as far as I can tell, has been kicking around the DIY building community for over a decade.

Oh! I also changed the labeling of one parameter. The part of the circuit labeled "wet" on the schematic is called "efx" on my stripboard drawing. I gag a little when folks use the word 'wet' in reference to reverbs and delays. Sorry, I'm neurotic and weird. It can't be helped.

Someone on Dirtbox asked if I had drawn this up after I mentioned it in the comments of another post. Aside from sending this to Gwion, I realized that I hadn't shown it to anyone else... OR built it up yet. So this drawing is still UNVERIFIED.

The switch wiring is a little different from the traditional ways of connecting a 3PDT in true bypass. Gwion has the effect loop send fully grounded with the extra connection to lug three of the stomp switch.

ALSO: I feel I need to clarify the wiring on the switched send and return jacks on the effects loop. If you are using the "Cliff" style mono jacks there will be 4 lugs on each of the two jacks that need to be connected. All of the sleeve jacks (next to the jack nut) need to be connected to ground. There is a pad labeled on the board for that. You can just daisy-chain link all of them together then run one wire to that pad on the board. However - the tip lug connections are a little less obvious. The lugs that are connected to the large metal pieces on the top of the jacks are the ones that get wired to the board. They are the lugs that will be in contact when you insert the 1/4" cables for whatever pedal you want to put in the effects loop. The lugs that are on the other side of the jack are the ones that get wired to each other (referred to as "send N" and "return N"). The idea is that they will form a direct 'through' connection when there is no pedal inserted in the effects loop.

Feel free to comment and tell me how I have screwed this up! Here's the original schematic from Holy Island:

 

STFU, simply: DIY noise gate circuit

 

Here's another one that is, until I have time to build it on my own, UNVERIFIED.

I drew this from a schematic that someone named Matthes posted to FreeStompBoxes a couple of years back.

The more that I have gotten into using fuzz pedals with synthesizers and drum machines, the more I have grown to appreciate a good noise gate. Currently, I make the most out of the gate circuit in the Boss 1/2 rack RCL-10 compressor - but I'd like to be able to make one on my own that doesn't require obscure, out-of-production components or expensive THAT ICs.

This one that Matthes came up with seems to fit the bill. A single channel op amp (TL071) an NPN BJT (2n3904) and a P-Channel jfet (j175) are all pretty easy to come by. And yes, you are seeing that correctly - the 2n3904 has the collector, not the emitter, going to ground.

The drawing on the left is made for amplifier FX loop send and return jacks - so that you can place this gate between the preamp and power amp section of your guitar amplifier. This is the designer of the circuit's preferred method of use.

However, I included a modified version (the drawing on the right) for placing it in front of your amp's input. In this version, the sidechain out connects directly to the amp FX loop send (the source of the jfet) and the FX loop return becomes the output. Which is all according to the designer's notes in the FreeStompBoxes post thread.

I'm attaching the schematic from the original post, and will also attempt to link to the thread on FSB.

fuzz... BASS fuzz!!!!

 This is a drawing of AionFX's "Penumbra" project - which is an amalgam of the best parts of the Zvex Wooly Mammoth bass fuzz and the Vexter series Mastotron.

BUILDER'S NOTE!!! The "pinch" control is shown here as it is laid out on the AionFX schematic. However, that will make the gate close as you turn the knob counterclockwise. I don't like this, so in order to wire it so that the knob works in the 'proper' (clockwise) direction, swap Pinch 2+3 to the pad where 1+2 currently is. Then swap Pinch 1 to the pad where 3 currently is. The gate will still have the same threshold - the knob will just increase the gate as you turn it up instead of down.

It's basically a silicon fuzz face with no low end loss. Bass guitars, synthesizers, whatever - it all sounds awesome coming out the other end of this beast. 

The transformer and jfet form a switchable "pickup simulator" (designed by Jack Orman) that tricks the fuzz circuit into thinking it is the first pedal in your signal chain by mimicking the impedance it would get directly from the output of your guitar pickup. So that you don't necessarily have to keep it first in your signal chain.

The "pinch" control is a really simple, REALLY effective noise gate that clamps down and releases fast.

As always - if you want something neater than stripboard, you should head over to AionFX and buy a PCB or kit from them. Aion's kits were how I got started making circuits - and I managed to make their HM-2 project work back when I barely knew which end of the soldering iron to hold... Their build documentation is super thorough and laid out in a clear and sensible way.

BUT if you still wanna take a swing at this one, just know that I have yet to build this up. So until I decide to pick up my iron again, this one is UNVERIFIED as of the posting date of 1/27/25.

EDIT: this layout is posted over at Dirtbox as well, and was just VERIFIED AS OF 3/14/25 by Magus Fremar!!!

Boooooring... but SUPER useful utility circuit: an active buffer+signal mute with optional boost and dedicated tuner out

 First post in a few months since I've been busy building a "DAW-less" rig to make sequenced/electronic music with. I'm also deliberately taking time off from soldering, since I use leaded solder and probably have more of the stuff in my blood than I should after 4+ years of almost daily circuit building.

BUT since I am currently having to build quite a few of these things (seven in total) to properly mute all the channel strips on my mixer (some of them pop when I feed them too hot of a bass signal), I thought I might share my layout.

This is, essentially, a standalone active mute switch with an optional dedicated tuner output. I adapted it from a GuitarPCB design, and if you fancy something neater than stripboard, you can buy kits from Müsikding or PCBs directly from GuitarPCB.

This drawing includes some suggested modifications from GuitarPCB - most notably, the gain boost pot - which can be omitted and replaced with a simple jumper for just slightly above unity. The 470nF capacitors are my preferred values for maintaining low end integrity. The original build doc calls for 220nF caps in those four positions.

Any dual op amp will do - TL072's work fine. I've been using NE5532's in order to keep it clean and safely allow for the jump to an 18v supply (just use caps that are rated to a minimum 35 volts!).

You can also use a 3PDT stomp switch, of course - but only two columns of lugs are necessary - which is why the drawing is for a DPDT stomp.

The original build doc calls for a common-anode, bi-color LED but I've no experience with those, other than I have read that they can be kind of on the dim side. I've got horrible peripheral vision and need my LEDs to be visible from space, so I went with two standard 5mm diodes for separate active and mute indicators.

Also - if you don't want the dedicated, always-on, tuner pedal out - you can just omit the polarized 2u2 capacitor, as well as the cut that is just to the right of the cathode of that cap. One less 1/4" jack to solder!

The original goal of the designer of this circuit was to allow you to still use your tuner while totally removing it from your signal path. While replacing it with a decent, modifiable buffer/signal driver. As it is designed, the tuner is always on and pitch detecting - you just choose whether or not you want your signal active or muted.

It's a pretty simple utility build that works great, with NO popping or signal bleed. It's definitely in the "I didn't realize how badly I needed one of these until I built it" category for me.

Yes, it's SUPPOSED to sound like that: my modified version of the Synthrotek DIRT filter

 While I personally refuse to make the jump to the Eurorack/500/modular gear universe, I am not against appropriating some of the more common sounds that exist there. Especially the ones that can be easily modified to work with a negative center +9v DC power supply.

I found this one on Synthrotek's site - the schematic I have included is lifted from the build doc for this modular filter kit that they sell under the name "DIRT". It's technically a low-pass filter with a whole lot of noisy possibilities. The resonance and bias are highly interactive with each other AND the cutoff control.

I modified their layout slightly, subbing a 1n4001 for the polarity protection diode (they call for a 1n4148 - which has a similar forward voltage drop) as well as eliminating the battery clip, adding an input pull-down resistor (1m to ground on the input) and a master volume potentiometer.

I tested the CV input using an Electro Faustus Dual Oscillator, and it made this thing stutter and bubble like crazy.

Once again - all credit is due to Synthrotek for the design + schematic on this one and if you use Eurorack units, you should buy a kit from them and build it. But if you want to make a super-noisy, unpredictable low pass filter for use in stompbox format - I can't recommend this one enough.

It's just a bypass switch. That's it. My version of the Demedash Incandenza clickless relay stomp.

 This is another layout that I posted over at Dirtbox but it is most definitely the thing I build+use more than anything else I make. It's a version of the Demedash Effects Incandenza relay bypass on/off switch that Steve Demedash came up with a few years ago.

No microcontroller required, super-low parts count, and absolutely no mistriggering. My stripboard drawing has pads marked for all four leads that come out of your standard true-bypass circuit: send, return, +9v, ground. So you can just slap this on to any circuit that you desire, that uses a true-bypass switch. Polarity protection is included on the switch daughterboard so you can omit that from the main circuit, too.

The relay is 5 volts, dual pole/dual throw, and non-latching. There are a couple other versions of this schematic floating around out there but this contains one pretty important edit from Steve Demedash himself: the 100 ohm resistor that is placed between the 555 chip and the relay itself. This limits the juice that the relay receives, as the chip puts out about 8v and the relay is rated to 5v. I've listed three different model relays on the drawing itself (and I may have mentioned a 4th - the Panasonic one - on the schematic), but just about any relay of the same size can be subbed provided you check the pin out and datasheet. All of the relays I have listed have a coil impedance of about 175-180 ohms. If the relay you want to use has a higher or lower value, you may need to raise or lower the value of the 100 ohm resistor on the layout, too.

I realize that building an entirely separate board for the on/off switch is something that a lot of folks may not want to do. But if you ALL READY like giving yourself a hard time by working on strip/vero, why not go the extra mile for a switch that is much more reliable than a mechanical 3PDT?

The AionFX/Traynor TS-50B preamp - CAN YOU DO ANY LESS??!!

 BUILDERS NOTE: MAKE SURE THAT YOUR ELECTROLYTIC CAPACITORS ARE RATED MINIMUM 35 VOLTS.

This layout is posted over at Dirtbox, but it is one of the best damn bass preamps ever, so I wanted to put it up here, too. 

To be clear - I did not draw a majority of this one. Anders/Fuzzhead did all the heavy lifting on this but he used an LTC1144 charge pump to create the bipolar power that this thing needs. While that chip takes DC voltage and does a really good job of converting it to +/- AC voltage, it only puts out about 20 milliamps of current.

Unfortunately - this preamp circuit needs WAY more. Like up around 100mA, if I'm not mistaken. So while the LTC1144 IC works, you will get a subtle, ever present whine from the supply.

AionFX, who did the schematic for this originally (it is one of their PCB projects, go buy one) suggests a kind of expensive (about $10-$12 each) power converter that does the trick, though.

So my layout takes Fuzzhead's drawing and incorporates that power converter, as well as the Zener diode and inductors it needs, and now this thing works perfectly.

Seriously - it's the loudest, clearest bass preamp EVER (and sounds great on guitar, too) and, dialed in right, you can get that characteristic Traynor TS-50B clang that just cuts through anything and everything. The first time I plugged mine in I was like "oh there's THAT bass tone" Jesus Lizard, Shellac...