X-VCS3 the extended VCS3 clone

Last modified : march 31st, 2005
La même chose en français ff

This provisional page is dedicated to the building of a clone of the famous EMS VCS3 synthesizer. As I included some extra features I called it the X-VCS3 standing for the eXtended VCS3 !

The EMS - like control knobs
The EMS control knobs are produced by Cliff Components and can be found in different brands : no metal insert, sanded aluminium inserts, shiny chrome inserts.
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I purchased these knobs at Electro-Value in the UK for a very reasonable price (£0.38 each). Unfortunately, they are no longer in business. This is not exactly the EMS style (sanded aluminium insert) but I think this is an acceptable compromise. The next step is to paint some inserts in order to mimic the colour scheme in the EMS synths.
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The colour inserts were obtained by painting them with special paint markers. These are really great to use and provide a nice enamel finish. As an alternative you may use those enamel paints used for plastic models.
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In order to paint the inserts, these have to be removed from the knobs. I used Steve Thomas' technique. The knobs are placed in a dish filled with hot water from the tap. After one minute or so the glue is soften enough to make it possible to extract the metal insert with a Xacto knife. This must be done gently in order to avoid scratches on the metal surface. One or two layers of paint will be necessary in order to obtain an even glossy colour. Then the inserts are glued to the knobs with neoprene cement.
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Eventually, this is what one gets!

The EMS - like vernier dials
Well, I spent quite some time surfing the Internet before I found suppliers for the exact 36mm vernier dials I was looking for. Eventually I found different places where these are available : Ocean State Electronics and Mouser. The part number is : 45KN100 for Mouser (http://www.mouser.com) and VD1122-10 or VD1122-100 for Ocean State Electronics (http://www.oselectronics.com/ose_p101.htm)
v vc
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Once again the vernier dials come only in one tint : black !
Therefore, I had to paint them using the same blue paint marker as for the control knobs. I used some adhesive tape to define the circular zone to be painted. Only one layer was necessary.

The patch panel
The patch matrix was real problem for me. I only know three places where to purchase one : Ghielmetti in Switzerland, Infolite in the USA and Hinton Instruments in the UK. What is for sure, is that I won't to pay US$680 (€533 or £350) for such a device (22x22 patch panel) ! Therefore I decided to build a patch matrix using the Steve Thomas' technique based on 2.5mm jack sockets. It is time consuming, tedious and hard on the eyes but the cost is something like three to four folds less than the original stuff !
Hopefully by the beginning of 2005, I eventually found a second hand Ghielmetti 20x20 patch matrix. I purchased it from the psychedelic dutchman Rude66 for a very reasonnable price (3.5 times less than a new one)

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Here is the matrix. The external dimensions are a quite big (20cmx20cm) and I will have to crop it in order to integrate it in the lower panel. I originally planned a 22x22 patch matrix and I also need now to change the design of my lower panel.
The making of the patch panel... To be continued...

The front panels
My ideas was to design a faithful copy of the upper front panel of the VCS3 and design a completely new lower panel since in the first hand, I use a homemade patch panel that occupies a bigger space than a genuine Ghielmetti or Sealectro patch panel, and in the second hand it hosts extra modules.
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The upper panel design:
Because I had no VCS3 at hand I had to recreate this panel completely from scratch. In fact, I searched the Internet in order to collect as many pictures of the VCS3 as possible. Knowing the exact size of the control knobs I extrapolated the measurements from the pictures and eventually came up with this.
Click here to download the 1:1 drawing of the upper panel in PDF format.
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The lower panel design:
I tried to design this panel in such a way that it is conform to the EMS style. It is greatly inspired from the organisation of the controls in the upper panel.
Click here to download the 1:1 drawing of the lower panel in PDF format.

The making of front panels... To be continued...

The cabinet
For the making of the wood work I used 90cmx15cm beech boards (2cm thick). Once again, I had no VCS3 at hand, thus I had to figure out the dimensions of the cabinet. After various attempts at extracting these from pictures, I eventually asked Steve thomas to perform measurements on his VCS3.

The making of the cabinet... To be continued...

The electronics
Some of the original schematics are available on the Internet, these are :
Module schematics
 Internet location
Oscillator 1 (sine, saw) 
 Hinton Instrument EMS-MOD page
Trapezoid envelope shaper 
 Hinton Instrument EMS-MOD page
Output module 
 Hinton Instrument EMS-MOD page
Noise + Meter 
 Stefan Sundberg + other modules
Ring modulator (Marjan Urekar) 
 Marjan Urekar's schematics
PSU (to be avoided ! use 7812 & 7909 instead) 
 Hinton Instrument EMS-MOD page
VC Reverberation (adapted by JH) 
 Jürgen Haible
Mods (Graham Hinton), sync, buffering.... 
 Hinton Instrument EMS-MOD page

The other original schematics (Osc. 2 & 3, VCF, input, Joystick) are not available unless you buy a copy of the VCS3 manuals from some specialized companies.
One schematic very much sought after is the diode ladder VCF. It is possible to find schematics of "EMS-like" VCF using diode ladder, they work pretty well but are not the original stuff. These "ersatz" can be found at Stefan Sundberg's site and also at HyperReal Music Machines or at E-Music DIY archives.
You may also check these : Masa921 japanese site (closest to EMS VCF than the previous) and Tom Gamble's version (VCF 6c) at EFM. You may as well try the PE Minisonic2 design which is close to the original one ( Julian Bunn's Minisonic2 page or Anders Sponton's C.A.G.)

Eventually, I have purchased a copy of the full service manual, I scanned the schematics and decided to make them available. You can download them here.
The meter
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I used a small  signal meter that I purchased at Maplin's (www.maplin.co.uk, ref. LB80B at UK£3.99).  Its technical parameters are 250µA FSD and 675ohms internal resistance.
The original number scale is 0 to 5 over a lime green background. It's quite easy to substitute another scale on a white background. The plexiglass covers is fixed only with two thin transparent adhesive tapes. I printed my own scale (0..10) with a laser printer on a printable label (white sticker). After removing the plexigless cover, take out the green plastic scale that is slightly glued (use a sharp knife).  Stick the new scale, put the cover back in place and seal it with the adhesive tapes.

The making of the electronics... To be continued...

Related links
EMS site : http://www.ems-synthi.demon.co.uk/
Hinton mods site : http://www.hinton.demon.co.uk/ems/emsmods.html
Jürgen Haible's Synthi/VCS3 clone : http://www.oldcrows.net/~jhaible/tonline_stuff/hj_synclon.html
Steve Thomas' Synthi/VCS3 clone : http://monopole.ph.qmw.ac.uk/~thomas/synthdiy/index.htm
EMS Rehberg :

Acknowledgments : I wish to thank Jürgen Haible and Steve Thomas for their advices and help.
The background picture was borrowed from http://www.musiccontrol.co.uk/