Roland SH-101 synthesiser.
Home-made modulation CV interface
I imagine everyone looking at this site knows about the SH-101. It's an all-time classic monosynth, very basic but with a cool onboard sequencer that helped make it the other acid machine (along with the TB-303 and the other other acid machine, the MC-202). It was also the first analogue synth I ever got to fiddle with in about 1988 in a music shop in Northampton. Somehow I got some money together after that and I found an SH-101 in the local paper for £80. I went round and bought it, it was from these two old-age pensioners who had it on top of an organ in their front room. Some organ salesman had really done a job on them unless they were secret acid-house heads. Later I bought another one from another ad in the newspaper for £90, those were the days! I sold it to the bloke from Bizarre Inc.
So you've basically got one oscillator with sub-octave and PWM, white noise, one LFO including random and noise waveforms, one envelope and that's about it. The onboard sequencer can be triggered from an external clock and you can program slide individually for each note which is what makes it sound acidy. Of course you can also do lots of other good bass sounds, lead sounds and effects. It's great for Dopplereffekt-style twittering squeaky high percussion sounds.
There's also a modulation-grip for the 101 which is a handle that plugs in so you can strap it on and pretend to be a guitarist. The grip has a wheel that lets you control the filter or pitch bend depending on the settings of sliders on the synth itself.
One thing the SH-101 is missing is a CV input to control the filter. I scoured the internet and found several mentions of modifications you can do to add a filter-CV input, but they all involve doing some fairly brutal stuff to your 101. I kept looking at the socket where the modulation grip plugs in. It says "modulation." I thought there must be a way to use it to control the filter, and there is. After experimenting with a kids' electronics kit, I made the little box pictured above. Using this box as an interface you can control the filter cutoff frequency or the oscillator pitch with an external CV. You can even plug in an audio signal and do filter FM or oscillator FM. If you use an external envelope and trigger it only on certain notes, you can acheive and "accent" sound similar to the TB-303 and make some very cool acid lines.
If anyone's interested I will post how to make one of these little SH-101 boxes or I might start making them to order. Get in touch if you want to know more.
All these sounds are SH-101 with no effects and other sounds as credited.
SH10101 - SH-101 sawtooth wave acid using the internal sequencer with some TR-808 samples from the K2000.
SH10102 - the same acid with added "accents" using my modulation box and an envelope from my modular..
SH10103 - the same sequence again, this time it's a square wave and the modulation box is affecting the VCO pitch instead of the filter.
SH10104 - a thin pulse wave with square-wave LFO modulation, the sequence is an odd number of steps long so it cycles out of step with the drums.
SH10105 - another typical SH-101 bassline with sub-oscillator and a bit of slide programmed in the internal sequencer.
SH10106 - some rubbish keyboard playing with a PWM sound.
SH10107 - slow filter sweeps with white noise and a random LFO fading in (sub-bass warning - watch your bassbins I'm teling you).
SH10108 - some funky sounds with various filter settings.
SH10109 - some FM hits using my modulation box - you never heard a 101 sound like this before!
SH10110 - weird FM bass using the filter box.
SH10111 - FM sweeps.
SH10112 - more FM tones.
SH10113 - a nice Detroity high sequence using the internal sequencer.
SH10114 - exactly the same sequence with different synth settings makes a nice acid bass.
SH-101 at Sonic State here
SH-101 at Synth Museum here
SH-101 at Hollow Sun here
SH-101 at Vintage Synth Explorer here
SH-101 at Music Machines here
SH-101 at Harmony Central here
SH-101 at Roland Clan here
Yahoo Group about the SH-101 here
Programming examples from Sound On Sound here
Roland manual downloads here