ElectroComp EML-101 volt/octave conversion mod

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belltones
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ElectroComp EML-101 volt/octave conversion mod

Post by belltones » Wed Aug 16, 2017 6:42 pm

Hi guys, thought you might be interested in seeing this video I just finished editing demoing the mod we did on an ElectroComp EML-101 that allows it to accept 1 V/octave control voltage input! The mod shows off some of the also very cool normal capabilities of the synth too, such as the way the 4 oscillators can cross-modulate for FM effects.



This is a wonderful, early 1970s duophonic semi-modular synth with 4 oscillators whose usefulness with other gear is often limited due to its strange 1.4V/octave +4.6V offset oscillator scale, but we designed and added a circuit to convert incoming 1 V/octave CV to the synth's strange scale. The mod circuit can be switched on an off using a toggle switch that we added, which matches the synth's original switches.

This synth is so much fun!

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Christian » Wed Nov 08, 2017 12:51 am

The EML uses non-standard CV scaling, 1.2 V/octave. Of course, any modern MIDI-to-CV converters won't scale up properly.

A sequencer can be very useful to tune any synths from any musical temperament systems.

So I am not sure why you did this modification on the EML-101.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Rasputin » Fri Nov 10, 2017 2:15 pm

Christian wrote:The EML uses non-standard CV scaling, 1.2 V/octave. Of course, any modern MIDI-to-CV converters won't scale up properly.

So I am not sure why you did this modification on the EML-101.
I think your first statement answers your own line of questioning. Seems pretty apparent why someone would mod that.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by celebutante » Sat Nov 11, 2017 10:25 am

Easy solution (which I know isn't for everyone)... use Silent Way. AFAIK, it wouldn't care how wacky the synths scaling is.
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Re: ElectroComp EML-101 volt/octave conversion mod

Post by madtheory » Sat Nov 11, 2017 1:44 pm

Kenton Pro Solo can have scaling adjusted also. It will drive anything including the ElectroComp. Lots of happy VCS3 users as well.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Christian » Sun Nov 12, 2017 9:55 pm

I asked because the guy used a sequencer KORG SQ1 to demonstrate the mod, which is absolutely not necessary in that context of use.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by smallsynth » Mon Nov 27, 2017 10:41 pm

this is pretty cool.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Abstraktor » Tue Dec 05, 2017 8:43 pm

The Electrocomp 101 is actually closer to 1.4V per octave and even a Kenton Pro 2000 doesn't get close to a standard span. I know because I have both. ES Silent Way would do it, but only with specific audio interfaces (MOTU, for example). I think Belltones mod is a cool workaround. I tend to use the synth for non-chromatic stuff anyway, but the sound of all 4 VCOS together is massive, and it would be nice to sequence them melodically sometimes.
Maybe Belltones could publish the circuit? :)

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Abstraktor » Fri Dec 08, 2017 11:45 am

Just to clarify - I have an earlier version of the Electrocomp 101 which doesn't have the SEQ in, so external CV control is done via the EXT OSC CONTROL. Maybe the SEQ in will scale fine with a Kenton or Encore. :)

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by Christian » Sat Aug 04, 2018 12:11 am

Thank you for bringing this to my attention... that means this modification makes sense with the other version of the EML 101 that has the SEQ input instead of the EXT OSC CONTROL input. Mine has the EXT control jack.

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by belltones » Wed Aug 07, 2019 4:27 pm

2 years later---
PCBs and kits for this mod are now available!
The new improved design eliminates the need to add a new switch while also allowing Voice 2 /Oscs 3 and 4 to work 100% normally when no external CV is plugged in.

details here:
http://www.belltonesynthworks.com/blog/ ... available/

:D

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Re: ElectroComp EML-101 volt/octave conversion mod

Post by ppg_wavecomputer » Wed Aug 07, 2019 11:37 pm

Damn... this made me want an EML 101.

And I was so happy to have successfully quenched my gear-lust...

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