DIY Spider sequencer

While I’m still working on other non-synth things… after I got the Wasp running last year I started to fiddle with making a Spider-ish sequencer out of a Teensy 2++ board, and this is as far as I got at the time.

Compared with the original track the oscillators should be an octave apart, but I never got the chance to re-record it before we moved house and the DIY Spider fell to the bottom of a box, somewhere in our loft. You get the idea, anyway.

The 7-pin DIN sockets on the top of the Wasp aren’t MIDI, but more like a weird digital CV/gate. .

The pitch is set in binary, with four pins determining the note within the octave, and the fifth and six pins defining the octave. There’s a table in the service manual which helps to work out the encoding. A 2 bit number has three states so you can get an extra octave from playing it externally.

The seventh pin is the “trig”, but it’s not just a simple on = note on, off = note off, rather it’s a square wave running at about 48Hz.

Everything works at 5v, which made it simpler to use the Teensy 2++ rather than the spare 3.3v Teensy 3.0 I had kicking around, and the extra I/O came in handy.

Compared to the original I added an LED display for showing the current step, and I made the transpose buttons latching. I almost got the real-time record working (with a silly piezo sounder for the metronome), but that always seems a bit pointless on these sorts of sequencers. Or maybe I’m just shit at playing in time.

I hadn’t got round to adding a clock input – from reading the Spider user manual, it’s not immediately clear how this might work in real-time playback mode – probably not very well. Or just very slowly.

The pin out of the Wasp DIN socket goes something like this

1 – f (MSB) – orange
2 – e – yellow
3 – d – green
4 – c – blue
5 – b – purple
6 – a (LSB) – grey
7 – trigger – white

… as if you are looking at the back of the socket (with the soldering) with the ground at the bottom, from left to right. Here’s a photo:

Wasp DIN socket

The sequencer is alright but to be honest it’s more fun to play from the keyboard… never thought I’d ever say that about any synth. I must be ill or something.

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