Shruthi-1 Build

Another day, another build. The Shruthi-1 4 Pole Mission kit arrived from Mutable Instruments a few days ago and the remaining parts (resistors, capacitors, etc) turned up yesterday. Too inpatient to wait for the latter, I soldered anything I could as soon as I had the kit.

By the time the remaining parts arrived, it looked like this:

Shruthi-1 PCBs partially populated

A couple of hours later it looked like this:

Analogue board

Digital board (top)

Digital board (bottom)

A quick test before putting it in the enclosure and then the most awkward part - putting the case together.

Done!

A final addition was the LEDs for the dog's eyes. These had to wait until this morning when I found some header connectors. The filters still needs tuning, but other than that, it works.

Effects

I still haven't got around to doing a video of the MIDIpal, but the effects PCBs finally arrived a few days ago. I brought the boards for a Gristleizer and an EchoBase delay from http://musicpcb.com. Prior to this and in need of something to occupy me, I drilled a case for the Gristleizer, mounted the pots on a piece of stripboard and did some of the wiring. I opted for small desktop format cases rather than stomp boxes.

Prepared case

Once the PCB arrived, it was quickly populated and wired up. I ordered the wrong trim pots, but they fit with some leg-bending and the LFO speed pot has the wrong taper. Anyhow, it works and I'll change the pots at some point.

The Gristleizer PCB

PCB mounted and wired

"Completed" Gristleizer. Yes I drilled a hole in the wrong place.

Having completed the Gristleizer and before starting on the EchoBase, I decided that laser cut front bezels would look good. I designed one, along with a drill template for the EchoBase in Inkscape and will do also design a new front panel for the Gristleizer.

Initial EchoBase drill template

I built and tested the EchoBase outside the case as there are several mods available that I wanted to experiment with before modifying the panel (see http://musicpcb.com/pcbs/echo-base-delay/). I went with a diode lift switch, along with substituting the value of one resistor to cope better with "hot" signals as I will be running synths through this.

EchoBase guts

Finally, the case was drilled (with the deletion of the effect LED as the LFO LED is dual purpose) and the internals mounted within.

The completed units

I intend to do several more effects and also build a power supply for them in a matching case, rather like a DIY version of the Boss Micro Rack series from the 1980s. In the meantime I'll get the bezels made and build the Shruthi-1.

MIDIpal

This wasn't supposed to be my next project, but I am still waiting on parts for the audio effects units.

I have intended to get a MIDIpal for a while now, but was put off by the surface-mount soldering involved. I finally bit the bullet and ordered one and built it over the last few evenings.

The MIDIpal is a tiny MIDI processor, which can serve as an arpeggiator, a simple step sequencer and delay, among other functions. It is Open Source hardware and available as a kit from Mutable Instruments.

This was my first experience of surface-mount soldering and it actually turned out easier than expected, though I applied too much solder to the ATMega328p MCU, resulting in a short between VCC and ground. Solder wick fixed the short, but left rather a lot of burnt flux behind. As for the resistors, LEDs, diodes and capacitors - soldering was actually quicker than with through-hole parts.

The completed MIDIpal in it's transparent case. Despite the mess around the MCU, it works!

Uploading the firmware using a USBtiny ISP.

I'll post a video once I have had a chance to play with it.

x0xb0x.

I built this in a few days, whilst waiting to acquire some rare transistors to finish the 9090. The 9090 took weeks.

The x0xb0x is a clone of the infamous Roland TB-303 "Transistor Bassline", designed by Adafruit Industries and originally supplied by them. Kits are currently available from several sources. I got mine from http://www.x0xsh0p.de.

The underside of the main PCB. This is split into two sections - towards the front is the synthesiser, using mainly original '80s "rare parts" and at the back is the sequencer. The ATmega for the latter is missing in this shot.

The top of the same PCB, with buttons and LEDs for the sequencer in the foreground and potentiometers for the synth at the back.

The main PCB mounted in the case, and wired to the IO board which contains the MIDI, DINSYNC and USB interfaces, CV and Gate out and the audio jacks. The power supply is also on this board.

The completed x0xb0x.

9090

A few photos and a brief (and bad) video of my 9090 drum machine. This is a clone of the Roland TR-909 voices, without the sequencer, designed by Trevor Page. Yes it is attached to a piece of cardboard, but this is temporary! For more information on the 9090 see: http://www.introspectiv.org/

I intend to build a sequencer, based on the MidiBox Seq V4. For more on this visit: http://www.ucapps.de/ (MidiBox) and http://www.synthage.com/ (the sequencer control surface).

Board 1 part completed. This contains the power supply, noise generator, bass, snare, low tom and mid tom drums.

Completed board 1

Completed board 2 comprising high tom, rim shot, hand clap, hi-hats and cymbals, plus the MIDI interface. The three large ICs are EPROMs containing the samples for crash and ride cymbals and hi-hats. All other voices are analogue.

The rather temporary card panel with potentiometers attached.

Close up of the EPROMs on board 2, also showing some of the rare parts - three types of long discontinued Japanese transistors.

The 9090 in action.