EMS Synthi A - Mark I

Shots via this auction.

Details:
"This is a Mk I EMS Synthi A from 1971, the first version of the EMS popular briefcase model. About a year later came the Mk II, also known as Synthi AKS. Mk I is rarer due to its short production run. According to Robin Wood at EMS about 300 were made. Electronically it's identical to the first version of the VCS3 which was produced between 1968 and 1972. Mk II intruduced a number of modifications:
* The PSU was redesigned, Mk I PSU is too weak to power a KS (the blue/black touch keyboard of the AKS) DK1 and DK2 can be used though.
* The output amplification, reverb driver and ring modulator circuits was redesigned.
* The patch matrix was reconfigured, Mk I has two individual outputs per oscillator Mk II has only for each of osc 1 and osc 2 only osc 3 has two outputs. In my opinion the Mk I configuration is much more useful.
* Some switches were added for AKS compatability.
* Prestopatch socket was added. With some work it can be added to a Mk I as well.
I think all Mk I Synthis and VCS3 came with the beautiful "Morning Mist" coloured front panel. Later on, most of them had uncoloured metal finish.

I have owned this synth for three years. When I bought it from a guy in Berlin I was told that this particular unit was originally owned by Manuel Goettsching of Ash Ra Temple and used by him as well as by Klaus Schulze, but i have not been able to confirm this so i can't be sure.

Together with Magnus Danielsson I have restored it internally. All electrolytic capacitors and all but two potentiometers have been replaced. Some failing transistors has been replaced with "new old stock" transistors of the same kind that was used by EMS during the 70's. Many trim potentiometers has been replaced for greater precision. The PSU has been re-organized. One of the transistors there produces a lot of heat. This one has been moved from the circuit board and mounted to a larger metal area inside. Many Mk I Synthis and VCS3 has been ruined due to this transistor being mounted on the board, it has the potential of burning off the traces of the circuit board. The synth is fully working and electronically in great shape. Though, due to its age I cannot give any guarantees and it is sold as is. But I would not expect it to fail anytime soon.

One thing is missing, there is only one speaker inside. However these can be bought from Robin Wood at EMS.


I have made two small modifications:

1. The panel switch for the built in voltmeter has been replaced with a three way switch so that it can be turned off when routing signals that way.

2. Voltage control for the waveshape of Oscillator 2 has been added via one of the microphone inputs (route out via meter and in via mic 1 with a patch cord).

Both are fully reversable in case one would prefer it to be original.


The panel graphics are worn in some places, it is unavoidable due to the screen printing method used on this synth. It is mostly numbers around some of the knobs that is worn out.

I have collected a large number of very rare spare parts for the Synthi, these are included in the sale:
3 x PA234 output and reverb amps for Mk I
2 x TAB101 ringmodulator IC for Mk I
A bag of BC169 transistors
A bag of BC258 transistors
1 x original joystick
3 x Red switches used on Mk I
1 x key for the briefcase
19 x Original knobs i various colors
3 x dials for the KS-keyboard
1 x Panel keyboard connector.
14 x extra pins (totally 34)

Also included is an original service manual containing all schmatics and trimming instructions for Synthi/VCS3, KS, DK1, DK2 + additional Mk I schematics not usually included. Original "Book of sounds". An almost complete original user manual, cover and first page is missing"

via Johan