Finally back in the workshop

A line from ‘Arnie’ in the Terminator movie of “I’ll be back” I can now change to “I am back!”  At the end of 2014 the takeover of the airline I worked for caused me to make the decision to go somewhere else before the airline ceased to exist. I ended up working in the United Arab Emirates flying nice new Boeing 777 and 787 aircraft all over the world and that provided some unique opportunities but kept me busy.   The flights I operated took me to lots of new places including Chicago, San Francisco, and Los Angeles and during those flights I managed to meet Rob Drinkwater at Chicago University and Mr E-mu himself, Dave Rossum in Scotts Valley, California. I had been in contact with Rob Drinkwater previously because the university has quite a large original E-Mu modular system and I was able to help them repair some of [...]

2021-08-17T16:30:23+00:00August 17th, 2021|

Voltage Controlled Filters – Low Pass & Multimode

Any analogue synthesizer is only as good as the Voltage Controlled Filters (VCF) that it has. Most of the classic analogue synths (MiniMoog, MemoryMoog, Prophet 5, Oberheim OBXa, etc) only had 24dB Low Pass Filters (LPF) which whilst giving a great sound were a bit limiting. One of my favourite filters was fitted to the Oberheim SEM synth module and this was a MultiMode filter giving High Pass (HPF) Band Pass (BPF) and Notch (NF) outputs as well as the usual Low Pass. In addition the filter had resonance on all the modes which meant it could create some very different sounds from those synths limited to an LPF. The design of the Oberheim filter was relatively straightforward using 2 transconductance amplifiers (CA3080s), which gives a 12dB response, and this type of circuit was also used on the Emu Resonant Filter as well as being the basis for the SSM2040 [...]

2013-12-21T19:48:22+00:00December 21st, 2013|
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