Warning - disclaimer

All modifications are at your own risk and I assume no liability for personal injury or damage to equipment or loss of use caused directly or indirectly by the use of any info shared in these pages.
Although these modifications are quite simple they should only be performed by those experienced in electronics with access to at least a good oscilloscope and frequency meter, some will need a recalibration of the Synthi. Do not attempt otherwise.

EMS PCBs are very fragile,
to avoid damaging the tracks do not use a too hot soldering iron (I set mine to 315°C).


As an EMS Synthi lover and (ab)user, I hope this page will help you in the improvement of your instrument
I experimented all the mods described here and my Synthis still work fine (even better).

Questions, advices, suggestions, improvements, feedbacks... are welcome.

Does your Synthi or VCS3 need a fix ? Or extra features ?
Do you prefer not to do it yourself ?
Are you looking for a rare Synthi component (PA234 / GEL234F1, MFC6070, TAB101, ME9002, selected 74150 or other TTL for the KS...) ? 
For a rare connector or special cable (umbilical, mains, CV/gate, pin-jack, modules "facilities"...) ?
For an original knob or meter ?

I'll be happy to help you.

I'm located in Belgium.

Feel free to contact me.

No hole ?

Many Synthi users dare not make mods because they're afraid to depreciate their valuable instrument.
Is understandable, but is a pity because the mods wonderfully expand the Synthi and open doors to fantastic new sonic worlds.

Here's an idea I think is worth to be shared. I'm surprised no one else had it before.

I did a few mods on my Synthis A MKI and AKS using push-pull pots instead of switches to avoid drilling holes in the panel.

LEDs in the spare anti-rotation holes left by the original pots (push-pull ones I used are smaller) show that the mod is active when the knob is pulled. 

This makes the mods fully reversible and preserves the Synthi's original appearance and value. 

Most mods are described on Graham Hinton's guide to EMS modifications, some are on the Synthi Forum, others came during discussions with other EMS Synthi users.
Schematics and more useful informations can be found on SamZen's website.
Is important for me to thank these sources, and Lorena Tesch for some pics.

Here are a few mods I did, but push-pull pots can of course be used for any other mod you plan to do.

Push-pull pots

Matrix MKI/MKII layout

Simple Random Voltage Generator and Sample & Hold

Voltage controlled shape on each oscillator and filter response

Hi/lo range switchable oscillators

Filter 18/24 db

Filter slew/unslew

Oscillator synchronization

Attack and decay time extension


"Synthi 2" interface for interconnecting two Synthis

Documents, manuals, dopesheets, links