Analog Modular
Welcome to my DIY synthesizer website. The name Pugix (and the graphic toon) belonged to an online gaming character that I used to play and has nothing to do with synthesizers.
My most recent activity:
Old Fashioned Drone
Just an old fashioned drone, made with modular Tetrazzi, Zeroscillator, an LFO, a sample and hold, and some envelope generators.
Two of twelve sample and holds
Here is a CGS SSG board, assembled as a dual S&H with a one-shot circuit. It’s the first of six identical boards.
A while back I posted about a ‘quartussy‘ project I wanted to do. Since then I have extended the design to six sections and enhanced the block diagram to include a VCA between the first sample & hold output and the CV input to the VCO. I’ve tentatively decided to call this project the Quantasise, indicating six quantized things. There will be more about this project as it develops. Each section will have a VCO, a VCA, and two sample & holds (S&H). That’s 12 sample & holds total. This post is about the sample & hold circuits, which are made from CGS SSG boards.
The SSG (Smooth & Stepped Generator) has two virtually identical sections that can each function as a VC slew, VCO, or Sample & Hold. The S&H function is implemented by pulsing the track and hold function. A pulse releases the hold for a moment, allowing the output to slew towards the input and then hold again. The minimum acquisition time obtainable with the selected capacitor (about 0.28 milliseconds) is relatively long for a S&H, but it works just fine for my purpose. No external rate pot is needed, because the trimmer is capable of setting the rate for the shortest acquisition time. I selected a 47 nf polypropylene capacitor for the integrator. This capacitor is Mouser part number 505-MKP20.047/100/5 (WIMA MKP2D024701C00JSSD). I have not tried to measure the droop rate of this S&H, but for this use I’m sure it will be acceptable.
In addition to the two S&H circuits, each SSG includes two one-shot pulse generators. One of these is used to drive two S&H circuits, as shown in the block diagram. More about this in a future post.
Stand Alone Power Supply
I built a stand-alone power supply that delivers +/-15 volts @ 800 ma to use as a bench supply for testing modules under development, and also to use as the external supply for a new stand-alone synthesizer I’m building. The supply is Power One HAA15-0.8-AG. Two jumper wires near the output posts must be cut to change the output levels from +/-12 to +/-15 volts. These are labelled VW1 and VW2.
The enclosure is Hammond 1458VD3 (Mouser 546-1458VD3). The top and bottom are vinyl-coated steel, with ventilation slots, and the front and back have painted aluminum panels, easy to machine. I mounted all parts on the front panel, with the Power One supply fitting nicely in the rear of the box.
I used the same Schurter AC Power Entry as on my portable cabinets. It’s very convenient, having the AC inlet, dual fuse, and power switch all in one unit, Mouser 693-4304.6090.
The red and yellow LED power indicators are in chrome bezels I had lying around. I put a 2K resistor in series with each.
Red and yellow banana jacks output +15 and -15 volts, with two black banana jacks for ground. The outlet that will supply the stand-alone synthesizer uses a high quality 4-conductor locking connector that includes earth ground as well as plus, minus, and supply ground. The connector shown is a female panel mount. The corresponding connector on the synthesizer will be a male panel mount and the cable will have mating male and female connectors. These connector Mouser part numbers are:
- Panel mount female 523-C01620G00310012
- Panel mount male 523-C01620C00310012
- Cable end female 523-C01620D00310012
- Cable end male 523-C01620H00310012
Asheville Butoh Festival 2013
I was in Asheville, North Carolina, last week, visiting my friends David Linton and Claire Barratt, and was invited to join in an improvisational piece to be shown at intermission at the BeBe Theatre, during a performance for the Butoh Festival. David and I had practiced with a setup that included his zither and my Tetrazzi and Cocoquantus. The piece, designed by Claire Elizabeth Barratt, involved the use of a number of instruments set out in a space to be played by wandering musicians. This video captured a part of it. Because of the complexity of the overall resulting sound, I decided to omit the Cocoquantus and just use Tetrazzi. We all wandered about slowly, playing instruments at will. I wasn’t the only one playing Tetrazzi.
The Other Studio
The dining room table has been taken over by Ciat-Lonbarde stuff. I also set up the RCF powered monitors in the room. Combined with the Macbook Pro and the firewire interface, it makes a complete recording studio. Tetrazzi and Roland Mobile Cube are in the background of first picture.
Shown below, clockwise from lower left: touchpad, gong, origami, gong, Cocoquantus, Plumbutter, Tetrazzi, Shbobo Shnth.
Shbobo Shnth
I was lucky to snag a first-run Shbobo Shnth, Peter Blasser’s just released computer music device. It is tiny at 4.25 x 4.25 x 1.25 inches. It features:
- 4 touch-sensitive wood barres
- 8 control buttons
- 2 touch-sensitive antennae (on the back side)
- 8 LED indicators
- A microphone input
The output is through a stereo mini-jack.
Shnth is programmed in a language called shlisp. The programs load from a computer via a USB cable, which also serves to charge the internal battery. Shnth can be disconnected from the computer and played with the currently loaded program. Programs can contain a group of separate ‘situations’, which represent different patches.
Here’s a quick demo, using one of the supplied programs, called ‘vancouver’, which has several different situations that I stepped through to demonstrate.