Friday, May 10, 2024


The NTDD is a PT2399 based dual-delay(DD) processor, and analog Dub-Siren circuit. 

There are two PT2399 delay chips in series with independent delay time controls on the X and Y axis of the "TIME" joystick(Left). 
The delay-mix and feedback-amount are controlled together by the "ECHO" knob. The "REGEN X2" switch enables the output from delay-chip 1 to be fed back to its input, as well as to delay-chip 2's input. When disengaged, only delay-chip 2 will have feedback(echo). 
The Echo and Feedback circuits are designed more for experimental exploratory noise, and less for traditional audio processing. 
The delay times can go very low and become very distorted, and the feedback is set very high to allow maximal feedback and self-filtering with the use of auto-leveling. 
An optical compressor is used to prevent feedback runaway, while allowing lower signals to regenerate continuously. 
An internal trimmer resistor can be used to adjust the sensitivity of the compressor.

The "Dub-Siren" consists of a square-wave VCO, gated envelope generator and LFO. 
The envelope generator is active while the "GATE" switch is held, and the "ENV"(envelope) knob determines the Attack and Release time when the Gate switch is pressed and released. 
The three position switch below the Envelope knob determines the Envelope knob's range. In the upper position, the Envelope knob will have a fast attack, and the knob will only change the release time of the envelope. In the center position, the Envelope knob range will be split between Attack and Release. Increasing the Attack time will in-turn decrease the Release time, and vice-versa. In the lower position, the envelope will have a fast Release time, and the ENV knob will only change the Attack time.
 By default, the envelope generator controls the volume of the square-wave VCO, but can also be used to modulate either the Pitch of the VCO or the Rate of the LFO with the "MOD" 3-way switch. In the center position, the MOD switch is "OFF".
The LFO modulates the Pitch of the VCO. 
The LFO can be set to Square-wave or Triangle-wave with the "SQR-TRI" switch. The LFO Depth and Rate are controlled with the X and Y axis of the right joystick. 
The LFO voltage can be offset with the "BIAS" knob. While the LFO depth is set to minimum, the BIAS knob can be used to change the pitch range of the VCO independent of the LFO.

The NTDD also comes equipped with;
 Volume knob(VOL)
Power ON/OFF switch with LED
1/8 inch(3.5mm) input jack
1/4 inch line output jack
5.1mm DC adapter(9V tip-positive)
Built-in speaker
3XAAA battery compartment.

The concept for the NTDD came to life while I was working on my big SUZUKI PK-37 project. 
I had been experimenting with different delay chips, and started to think about what I should do with tall these PT2399's I had laying around. These days I would prefer to use higher quality digital effects processors for my synth builds, so what to do with all these chips? I though it might be nice to have something weird to compliment the NTSH mini noise synth. The PT2399 may not be the best quality delay, but they can do some pretty freaky stuff when you mess with the filtering, feedback and sample-rate time. I thought it might be interesting to have two delay chips in series and have separate delay times and feedback. I had never tried it before, and wasn't sure it would even work, but with a little experimentation, I was able to get a pretty decent signal through both chips, albeit a little alias-y. One thing I really wanted to include was a self leveling circuit in the feedback path. I love being able to crank the feedback, and not have to worry about turning it back down before it runs away and starts clipping really bad. I have experimented a lot with compressors, compander chips, and auto leveling circuits with envelope followers of all kinds. Most of the time I usually end up scrapping them because they are either too strong and oppressive, or too weak and choppy. I built all the usual stuff trying to tame the feedback with envelope followers and filters. I tried OTA's and JFET's, but everything that worked had too big a footprint for the tiny box, and would probably require a lot of fine tuning. in the end I tried out these old cheap vactrols I had bought years ago. They come in handy sometimes, but are usually too inconsistent to rely on. They worked really well with my full-wave rectifier/follower circuit. They worked so well that I didn't even need any rectifier/follower circuit. Instead I just sent the signal to a comparator circuit that drove the vactrol, and there was no warble, and the the response was beautiful! When the input signal passes a certain threshold, the comparator sends out short pulses to the vactrol, which attenuates the input. The vacrols have just the right amount of lag to keep it subtle but effective, and the variation from one vactrol to the next makes no difference in the performance. Perfect! Sometimes things just work out like this, and I think this circuit was just meant to be.


After a few iterations of the dual delay circuit, I kind of wondered if the whole thing offered enough to be a standalone device. I had intended for the NTDD to be a signal processor for the NTSH, and the continuous feedback did give the NTDD some stand-alone quality. I just wasn't happy with it as-is, so I thought of ways I could add to the design. I thought it would be good to have at least some kind of VCO. I really wanted to keep it simple, though. There is really not a whole lot of space to work with, and I knew I would be super limited for controls. I thought maybe a simple dub-siren would pair well with the lo-fi delay. I was able to come up with a simple dub-siren scheme that was both simple but still pretty dynamic. I was able to fit it all in with some extensive designing. While the dub-siren was the inspiration for the circuit, I would have to say that it is more of a drone synth in practice, due to its limited ranges and control. It has a special character of its own, and I'm sure it would sit well in some more experimental dub music. 


I designed and built several variations of the circuit until I had something that I thought would be  a good final product, but when I assembled the full prototype, I just didn't think it was ready yet, so I shelved it for a few more months, and started working on another big project. About a month ago, my long neglected laser cutter literally went to pieces, and the big project had to be put on hold. Once I had dealt with the laser crisis, I thought I should finish up the NTDD before diving back in to the big job. I made a few changes here and there, mostly just bolstering some of the circuitry inside, and putting in the BIAS control knob in place of a dedicated pitch knob, as well as putting in the square-triangle switch in place of a high-low VCO range switch. The tweaks to the design were a huge improvement on the overall layout of the box. The design was finally finished and ready to build.

Over the course of building and assembling six units, I have had to ask myself some hard questions about whether these are worth all the time needed to build them, considering how much I am able to sell them for. For now, I think it is more important to just make interesting new things, and get them out into the world and make people happy. At the very least, I'm doing something way more interesting than working in some awful kitchen again :D
The six I made will be for sale on my Etsy and Reverb shops. Get one while you can!

Saturday, December 2, 2023


Shortly after finishing the NTSH and NT05, I decided to start this project. I was looking for something to do that I could just slowly chip away at over the summer. I had been doing some reverse-engineering of some of my toy keyboards for fun. I started with a Casio MT-40, then moved on to the Casio SK-1 using Kicad to draw the schematics cleanly. After those, I needed a bigger challenge. I had been hanging on to this pair of Suzuki PK-37's for several years. The first one I found at the Goodwill bins probably ten or fifteen years ago. It was dirt cheap and was pretty busted up. The main-board inside was badly corroded, but I was able to get it to turn on and make some sounds. Aside from all of the hiss and noise that keyboards of this era tend to have, I really like the warm lo-fi quality of the sound and the classic home-organ features. It has some nice punchy analogue drums and a cheesy arpeggio

Thursday, November 30, 2023


New batch of NTSH mini noise boxes for sale at my FOR SALE page. 
Get them while you can!

Sunday, March 5, 2023



Circuit bending digital cameras has been a love of mine over the past decade or so. I recently picked up a new camera at the thrift store, and it reminded me that I really need to do a write up on it. 
In the mid 2000's, about the same time I started circuit bending my first Casio SK-1, I was really obsessed with this key chain camera I had. It had extremely low resolution and frame rate, and no display, but it could take video clips, and if you really abused the auto white balance, you could get the camera to glitch a few frames. At the time I thought this was the greatest thing I had ever seen! A few years later, my circuit bending skills had come a long way. I was the proud owner of a pocket oscilloscope, and I was using it on just about everything I could get my hands on. My little key chain

Tuesday, January 31, 2023


The NT05 is a "LoFi RhythmBox"

It consists of;

-Two voices; "Sine" and "Noise"

-Two 128 step pattern banks

-Eight selectable rhythms

-Two "Pad" envelopes

-One LFO

Saturday, January 28, 2023



The NTSH is a mini joystick noise synth.

It consists of; 

- one white noise generator

-one square wave oscillator

-one 12db resonant LP filter

-one Sample&Hold/envelope generator

Saturday, July 2, 2022


My old buddy Matt Wright contacted me recently and asked if he could buy my FUNKY GLITCH BUDDY. I don't know why, but it is hard for me to sell things to good friends... Do you give them a discount?.. Or just give it away?.. Either way, I didn't want to give up my funky buddy just yet, so instead, I would build him something unique as a friendly gift. Matt is a master guitar tech/luthier, so I wanted to make him something guitar shaped that he could hang in his shop and maybe be a conversation piece. 

Sunday, June 5, 2022


A friend of a friend contacted me in the summer of 2020 to have his EHX 16 Second Delay reissue modified. I had done some pedal mods for him in the past, so I was willing to give it a go, even though I was pretty bogged down with remodeling projects in my house. I was happy to be in my shop again and working with something other than drywall.. I didn't end up finishing the mod until the winter of 2021, but the owner didn't seem to mind the wait. Thanks Joe!


While cleaning shop, I came across an old friend. I built this little keyboard monster back in 2013. The FUNKY GLITCH BUDDY was an interesting concept, but it suffered from some pretty challenging design flaws that I had always wanted to fix, but never had the time. For one, the keyboard would draw so much current due to the fact that the keys were all infrared proximity sensors. There were a lot of 7400 series chips and opto-isolators in the design too, so overall this thing was pretty inefficient and noisy. Two of the voices were 8-bit LFSR noise generators which didn't particularly sound like noise. The third oscillator was a basic two transistor oscillator that I ripped out of a cheap organ toy, and had died some time ago. At the time of this build, I had just started using my CNC to engrave and cut my own circuit boards. This was my first project using the CNC, and the design and orientation was pretty sloppy. Everything was jammed together, and I never even took the time to draw out my schematics, so finding and fixing problems years later was difficult to do. Instead I thought it would be quicker and more fun to just completely redesign the circuit.

Saturday, June 4, 2022


I have been clearing out my workshop and getting rid of things I don't want or have time for, in the hopes of someday getting back to circuit bending and blogging again, but just for my own amusement.
I am making a lot of progress, and my workshop is looking great, but I have run into some things that are too precious to throw out but not worthy of selling in the condition they are in. I had been holding onto this Waddingtons Compute-A-Tune for at least a decade, and I couldn't bring myself to throw it out. It had some major issues and was not worth even trying to sell for $20...
The Compute-A-Tune is a very old toy keyboard that i think was only sold in the UK in the early 80's. The synthesizer is based around the TMS1000, which if I am not mistaken-was the first microcontroller!