EMS Synthi E - VCO sequenced with a Korg SQ-1

 The Synthi E is quite a rare synth.

I think there are only about 200 of them around.

I understand, the year of production was 1975. Designed by Tim Orr 

(Tim also designed the EMS Vocoder 5000, worked for AKAI & designed the Powertran Trancedent 2000)

The Synthi-E was produced as an educational tool and appears very simple at first glance.

Just one filter, EG, Oscillator, LFO, noise, inverter, VCA and mixer.

 

Apparently, "a complete teaching course has been built round it allowing teachers and students to learn the techniques and background of electronic music and its production". 

When I first bought this I didn't have a keyboard and the ribbon controllers were not functioning very well.

I'm sure there was a manual however it alludes me (as do the schematics).

 

 

Patching doesn't use a matrix. Just very simple cables. 

I only had a limited supply of the original cables, but discovered that 2mm banana cables also worked just fine. They have the added advantage that they are stackable.

 

 

From  what I can decipher from the internet, the general signal level at the patch nodes is  3V P-P.

This however, seems to vary quite a bit depending on which module you are talking about.

It should be safe however to patch 2Vp-p voltages. (I don't have any definitive data regarding this so do so at your own risk).

The Korg SQ-1 is ideal for this.

You can limit the voltage range to 1V, 2V and 5V/oct.

I found the 2V setting provides a good range of pitches 

 

 

Remember to also set the SQ1 to Negative (S-trig) gate.

You will need to ground the sequencer with the synthi. The scope output is prefect for this.

The sleeve is ground.

Here are the specs of the VCO:

Total frequency coverage: 1 Hz to 10KHz.

 

There are 3 waveforms available: Sine,Tri, Rectangle.

All three waveforms are accessible simultaneously and can also be
used as modulation sources.
Sine wave distortion: 5% THD (TYP)
Triangle symmetry (rise and fall): 3% at 1 KHz.
Rectangular wave mark space ratio voltage control range: 0 to 100%.

Two CV inputs: Width & Frequency

Interestingly, the frequency CV input has two flavors .. 1/2 and 2.

There is a trimmer to fine tune the V/Oct scaling.

Deviation of voltage control of frequency from ideal exponential law
Over musical range 100Hz—2KHz: .8% (B.S.L.)
Over audio range 10Hz — 10KHz: 1.7% (B.S.L.) 

General short term stability. Drift at 1 KHz: 2% per hour.

 

I really like the sound of the filter... squelchy ... almost acid like.

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If there are any mistakes, errors or omissions, do let me know.

Cheers J