To anyone reading this:
I got a new phone a couple weeks ago and can't seem to find the permission setting that allows Blogger to see my photos or files. So if this post is the most recent one on here, that means I'm an idiot and STILL cannot figure out how to add my layout drawings to posts.🤦
However - even a quick perusal of dub tunes will reveal two things: 1) a love of effects like tape delay, spring reverb, and filtering, and 2) a DIY aesthetic that was born on an island where the access to gear was limited and interest from outsiders was not really a concern - at least not at first, anyway...
So much of the gear these folks used was repurposed from old military equipment, or just straight up built from scratch using whatever parts they had. The high pass filtering from a passive box that King Tubby constructed and used A LOT is just such an example of this. As is the "dub siren" - which is basically a single-oscillator drone synth with some really wild tweakability.
This is the layout for one of those synthesizers that I adapted from a schematic that was originally drawn by Jacob Lysgaard. The majority of the conversion to stripboard was done by Nabble/Guitar FX user Alex80.
I simplified a few of the functions, eliminated a couple of the switches, rewired a couple of the pots and also added a power cut function to the siren on/off switch - because otherwise noise WILL bleed through.
The end result is VERIFIED, and will give you some pretty nasty siren-ish sounds. This thing has a really wide pitch range and is super loud with the volume maxed. The mod rate and shape knobs will have no effect when the mod level knob is fully counter clockwise, effectively turning the modulation off. I'll include the original schematic at the end of this post, but it contains quite a lot of stuff that I eliminated or changed, including two different LEDs for bypass status and modulation rate following.
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:
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.
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!!!
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.
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.
