Peter Gambles' home page

Soundlab minisynth

This is some information about my Ray Wilson SoundLab minisynth, built in summer 2006.

It has the 1v/Octave mod, the fine tuner mod, and the modulate Osc1 with Osc2 mod, and uses tempcos in the VCOs. The stripboard layout is based on Andrew Sharp's layout from Ray's website.

The case is a cheap toolcase - thin plywood covered in very thin aluminium sheet. Messy inside, but I like the industrial look - and it's got a builit-in handle!


Photos of the SoundLab


Slide 'Ribbon' controller for Soundlab

I also built a 'ribbon' controller to control the Soundlab using the two CV In and External Gate jacks. The ribbon is in fact a long series of resistors mounted on lengths of stripboard. It's been described in several postings on the electro-music forum as 'the Slide'. I can't track down the original post so my apologies for not giving credit where it is due. The essence of the design is that by putting a conductor across the gap between two adjacent strips, you tap the voltage at that point in the resistor ladder.

The circuit controlling all this is one I designed - schematic to be posted below. It's based on voltage regulators providing a constant voltage source, rather than the current regulation Ray uses in his single bus controller. I'm sure his is the superior (and cheaper) design!

The hardware consists of a length of constructual timber, routed out to hold the circuit board, controls, output jacks, and battery, with the ribbon glued on top, partially covered by two hardwood guide rails. I haven't shown the actual contact device. Had a lot of trouble designing that: the current version is a little block of wood with a short length of 1/8 inch brass tube inserted in a hole drilled vertically through it, and a short piece of copper braid (desoldering wick) soldered across the botttom. Pressing the block down onto the guiderails makes the braid bridge the gap between the copper strips on the ribbon.


Photos of the Slide controller

Photo 1 shows the whole controller, viewed from the back. Nearest to you are the controls, and on the back the three output jacks (CV1, CV2, Gate) and the power on/off switch. The Gate out is self-explanatory. CV1 is the 'proper' CV out, which I feed into CV1 In on the Soundlab. CV2 Out provides a voltage than is carefully regulated to yield a note a musical fifth above than provided by CV1 - plugged into CV2 In on the Soundlab, the result is a two note power chord!

Photo 2 is a top view, showing how the riibon sits in the controller. Note the gap at the right hand side for me to hold the controller steady (I'm left-handed, so built it this way round. Any right-handers who wanted to copy the design might want to reverse things.)

Photo 3 is a close-up of the control panel. On the top row are (from the left); a six position rotary switch to select the range of the controller (that is, the choice of top and bottom voltages and thus frequency; two pots which set the top and bottom voltages when the rotary switch is in position 6 (this allows manual selection as opposed to the fixed ranges available in positions 1-5). On the bottom row are: on/off LED; press-to-make button which provides a +9v signal to the Gate jack (depending on the position of the Gate switch); a pot for Portamento; the Gate switch - a centre-off SPDT - this selects between a Gate signal being provided whenever the contact is in place on the ribbon, no gate signal, signal whenever the manual Gate button is pressed. The way the Gate is triggered affect the sound - easier to hear than to describe.

Photo 4 is a close-up of the stripboard ribbon.


Circuit board

Details of circuit to be posted here.


Sound clips.

Here are a couple of examples of the Slide controlling the SoundLab. They are mp3's, recorded direct into my Tascam four-track cassette recorder, burnt down to CR-RW on a stand-alone CD recorder, then edited into shape in Audacity, and finally converted from .wav into .mp3. Each consists of a few seconds of the SoundLab Oscillator 1, with the frequency adjusted by turning the Osc1 pot, followed by several clip using the controller on different settings. They are all dry (no effects, apart from putting a couple of seconds silence between clips). You can hear some glitches caused by the contact device, which is wearing out - I need to rethink that.

First set of clips.Just the one output from the Slide. The clips are:


Second set of clips Uses both outputs of the Slide to produce a two note chorus effect as described above. The tuning is not precise (though can be adjusted with the fine controls), so you can hear beats.



This page was written by Peter Gambles.

May 2007