Dub Siren

This little monster is a Dub Siren I made for DJ DRM (Aaron Schultz) of Bastard Jazz Recordings. If you’re unfamiliar with what a dub siren is you might guess by its name that it sounds like a siren. There are many varieties and a good deal of folks make their own:


But the tying thread is that they are usually just square wave oscillators with minimal tone and a couple controls to vary the speed and pitch of the siren. Check the sound samples at the bottom of the page for an example of this one.

This dub siren revolves around a couple of 555 timers and has four main controls. A speed control which changes the speed of the siren, a pitch control which changes the, well, pitch of the siren. A range control which changes the siren’s range and lastly, a modulator which, when engaged, alters the smooth sweep of the siren to a more asymmetrical ambulance type siren. There are two LEDs: one that flashes in synch with the clock cycle so you can see the speed in the dark and another that oscillates gently when the momentary switch is engaged. Both RCA and ¼” jacks are available and the RCAs are only active when there is not a ¼” jack plugged in. This was to prevent ground noise from accidentally coming into the circuit by inadvertent contact with the jacks. Check the full build on Flickr by the link below.

More photos, comments, and the schematic can be found on Flickr here:


Sound Samples:

Dry, without Effects

Wet, with effects

Tone Generator

This is a square wave tone generator based around three 555 timers wired up as oscillators. I took some inspiration from the dub siren and figured if two were good then three would be better. This was mostly true. Several unlabeled pots control the oscillators impact on each other and then two signals are mixed at the final stage. Just as a note I get these pots by buying damaged internal boards of Mackie mixers. With a little time you can remove these great center detent pots for pennies. A schematic isn’t available right now but I will get something together and post soon.

There were a couple problems that I didn’t really notice until after the circuit was wired up. I used a pot to control the balance of the two signals going into and additive mixer at the output. This causes large swings in output volume depending on how far from center the pot is. When jamming it all in the box with a battery something happened  and one pot has no impact on the sound. These problems aside, the tone generator makes some great chirps, bleeps, bloops, and squeals.

I’ve recorded a string of the sounds you can generate with this tone generator, chopped it up into a couple dozen samples and included them for your use. If you end up using them in something I’d love to hear what you do.

You can see the complete set of photos here on Flickr

FB 383 Freebass Mods

Back in 1997 a company called Music and More (MAM) created a tb303 clone called the MB33. They licensed their design to another company called Freeform Analogue Technologies who dubbed the same clone the Freebass FB383. I guess it’s a clone of a clone? Both were identical and affordable during a time techno was all the rage and everybody and their brother HAD to have a tb303. Despite the overused sound and the long past death of techno these little boxes still have a good deal to offer…. Especially at current prices…. Originally around $400… I picked mine up for $10.00 on eBay, albeit broken. Due to poor manufacturing many of these guys are broken these days and don’t produce any sound however, you can still tap into their analogue resonance filter to add some nice tone to just about any instrument and add a excellent tool to your studio. The mods that follow show you how… and it will cost you pennies.



Assuming you’re familiar with the FB383/MB33 you’ll know there is an external input on the back to patch a signal through the filter section of the unit. Assuming your unit works you know that when you connect a signal the internal synth is disabled which makes racking the unit a major hassle. By adding a filter on/off switch you can keep your unit racked and patched to a patch bay and use the filter easily. If your FB383/MB33 doesn’t work, like mine, then it’s basically a signal on/off switch. I plan on making a cv input for the oscilator and when i do, this mod will still be neceassry if i want to rack the unit.
Filter On-Off

The photo above is a shot of the finished mod. You can see more details, photos, and descriptions at the link below.

The Full Flickr photo set here.



As with most external filter units, you need to trigger the envelope section before you will hear any sound. So if you have an input signal patched and the envelope is not triggered you hear nothing. To do this you have to supply a voltage to the bias input of the Operational Transconductance Amplifier (OTA). Instead of applying a direct voltage I opted to use a pot to drop the voltage at the base of a transistor controlling flow to the bias input… drop the voltage and current flows to the bias input. With higher voltages you get some gritty distortion which isn’t so bad in some cases. I soldered one lead of the pot to ground and one to an easy to reach lead on the end of a 0 Ohm resistor. That’s what you see in the photo above.
Filter Trigger

As before, you can see the full set of photos by the link below.

The Full Flickr photo set here.



This one is pretty self explanatory. There is a resistor in place that restricts the resonance a bit. By bridging this resistor you can get some nice thick resonance and even some self-oscillation. Instead of simply bridging it though I added a switch to allow for ‘normal’ and ‘boost’ modes for a variety of applications.
resonance boost

As with the previous mods… photos and details by the link below.

The Full Flickr photo set here.

When initially looking into information on the FB383 I immediately figured out that nobody has any. Nobody. There was virtually no information available on the net with the exception of a brief background on MatrixSynth and some information on possible mods (for a fee) at Circuitbenders.uk. Of course there were reviews at typical locations like hyperreal and harmony central but other than that it was limited. I managed to track down someone familiar with MAM products through the company that ate them, Musonik, and figuring that somewhere someone would have service manuals, design specs, part sources, etc. I was wrong. Nothing.
Circuit Overlay

So given the good number of these machines out there and the likelihood that there were a fair number of folks in need of a signal flow diagram I made a high resolution circuit overlay of the Freebass FB383 (MAM MB33). It’s not a schematic but it’s about as close as you can get. I’ve found it immensely useful and have it available here for any and all to put to good use. Enjoy!

The full high resolution (7920×1587) image here.

AD633 Ring Modulator

This is a Ring Modulator or similar sounding effect box based around the AD633 (Analog Devices Four Quadrant Analog Multiplier). The original design is taken from Roman Sowa. His website has further details on his design and the schematic I used as a starting point. The above photo shows the finished version albeit without knobs. This is mostly because I, despite better judgment, bought pots from Radio Shack, and didn’t want to waste them. As you can see the shafts are just a bit long. No matter; they work.

I made a few modifications. The first was to remove the option to select AC/DC coupling. I felt that I had no need for DC coupling so I hard wired it up AC coupled. Secondly I added some gain on the clean channel. The clean signal was coming through a little light which I personally didn’t like. Lastly, I added a LED meter on the output volume which you can see in this picture. Using a LB1403N I made a level meter which increases as you turn the volume up. This doesn’t actually monitor signal level but the position of the pot. There’s no real purpose other than I like blinking, flashing, pulsating and adjustable lights on all my gear. Who doesn’t? It’s wired through a dual ganged pot with a trim pot to adjust sensitivity. The detailed photos can be seen at the full Flickr photo set.

From a distance the paint job looks OK but as you can see in the first photo there’s definite room for improvement. Wet sanding, Clear Coat, and Polish would definitely help but it’s not a bad first run. The fluorescent paint however had a tendency to get ‘powerdery’ and presented some problems. Check the sound samples below to hear what it sounds like.

Many more photos and comments on the build can be found on Flickr here:
AD633 Ring Modulator

Sound Samples:
Before & After Number 1
Before & After Number 2
Before & After Number 3
Before & After Number 4

DJ Paul Digs Fuzz


This is my second design from scratch that I put together for DJ Paul Diggs. He mentioned to me he wanted to add some fuzz to his Fender Rhodes and this seemed like a great chance to take a stab at an original design. Well, almost original. The distortion circuit is a portion of a larger circuit which I found on the web but unfortunately did not document. The remainder however, the sweepable low pass filter and second tone control I added in myself. Overall this is a pretty versatile sounding fuzz box with a pretty wide range of tones. It utilizes diode clipping so it still can be a little harsh although with the filter and clean/dirty mix you it can be tweaked for a nice sound. This is hopefully only the first version, I’ll be working with Paul to refine the tone and the layout to hopefully make this a perfect compliment to his Rhodes and bring about the sounds of classic rock years gone by like those from Joe Zawinul and the likes of Weather Report… though that’s just my taste, I’d bet it will end up a bit different.

This time I actually took notes and threw together a schematic. I’m hardly an engineer and my understanding of analog circuits is elementary so I welcome suggestions and criticisms from anyone familiar with these types of things. As with the other projects you can see detailed photos on the build at Flickr.

More photos, comments, and the schematic can be found on Flickr here:

Paul’s Fuzz

Sound Samples:

Unfortunately I neglected to sample this box before popping it in the mail. Version II will definitely have samples. That will be better anyway.  Incedentally I’ve repalced this fuzz with a better one.. the Big Muff Mod.

Crash Sync

The Crash Sync is a John Hollis design who’s schematic can be found here. There are dozens of examples of these on the web.  They’re pretty popular among DIY enthusiasts and not terribly difficult to throw together.  John’s site has a number of great projects that center around Op Amps and are very affordable to complete.

I typically use whatever components I have available, either bought or raided from old gear, so when putting a project together there are some inevitable changes.  In this project I used different Op Amps and added in a bypass switch (with lights of course) to pass the original signal.  As far as I can tell using a different op amp hasn’t had a noticeable impact on the sound of this awesome little box. Lastly, like all of my boxes so far, I haven’t wired them up for use with a 9V… which is fine for me, but others might find it an inconvenience.   See the full flickr set for detailed photos.

Many more photos and comments on this build can be found on Flickr here:

The Crash Sync

Sound Samples:
Before #1
After #1

Before #2
After #2


This is a follow up to previous works of a similar grain by members of Master Mosquito, this track brings forward similar sounds of past tracks. Smooth and melodic synths backed with down tempo rhythms and crisp layered guitars which create an ethereal soundscape suitable for any listener. This is one of my favorites which compliments the similar track named ‘Tallboy’ nicely.  Much thanks to Aaron Schultz (DJ DRM) founder of Bastard Jazz, and Jamie Roberts for making this complete.

Master Mosquito – Regalt

Tall Boy


This work-in-progress is an unreleased (well, except for here)  follow up of past works of a similar grain by members of Master Mosquito. Emotive guitar styling with warm and sunny synth melodies carry you through this eclectic, spacious, and resonant track. Much like a Tallboy it’s good anytime in any situation. Much thanks to Aaron and Jamie for their hard work on this one.

You will find that the stripes included in this zip are not one-to-one matches with the final mix. As edits, adjustments, and rearrangements made I opted not to export the stripes a second time. Nonetheless, all the elements are there and ready to go!

Master Mosquito – Tallboy


Here’s what I wrote on the old site:

“Green” started several years ago and the initial melody was used in a song I co-wrote with a band that’s been long broke-up.  Out of respect for music in general I will never post the track’s roots; but eventually it was reworked into its current form. Pretty and melodic. Not bound by deadlines this will likely always be a work in progress as I’m constantly attempting to “fix” the drums. My perpetual dissatisfaction notwithstanding, please enjoy!

This still holds true.  The sounds in the beginning of this song are some of my favorites.


Oregano Crunch

This is the first distortion “box” I designed myself. Admittedly it was a haphazard process of jamming parts together with only minimal understanding of what I was doing. It uses a couple diodes and an LED as well as a couple of op amps to give this guy some seriously gut busting distortion.

Looking back I now know I have some bias problems which cause some unpredictable behavior but my poor design notwithstanding, this is well suited for sound-design/sampling. It however is not functional as a typical signal processor. I neglected to label the inputs and the knobs so I always have to f with it to get it working, an amateur move, but I think it adds a little something… like a what-the-hell-does-that-do kind of something.

The most noticeable feature is the enclosure. As you could guess by the name it’s all tossed in an Oregano spice jar. Even if you don’t like the sound you can’t deny it smells delicious.   Not to mention there’re some LEDs in there but, no battery operation.  I don’t know why; that would have been pretty easy to accomplish. I recently went back to draw up a schematic of this circuit. armed with more knowledge of what i was doing I realized half these components weren’t doing jack and i was just overdriving an unbiased op amp.

Be sure and check the full photo set on Flickr and listen to the sound samples below.

Sound Sample:  oregano_before, andoregano_after.