Saturday, 12 July 2014

Eurorack DIY Prototyping Cards Rethink

The Eurorack DIY Kits have been quite successful and when the last DIY1 PCB was sold several weeks ago it provided a great opportunity to reassess the PCB design rather than just reorder more of the same.

What has emerged is a revised and rebranded Eurorack prototyping solution that is more usable and more elegant than before. The revised product revolves around three PCBs in the Synovatron Proto series: ProtoPotz, ProtoJax and ProtoXp

The new Proto PCBs' holes line up with each other to allow each board to be stacked one on the other using header plugs and sockets; allowing power and signals to be routed between boards without resorting to linking ribbon cables. Here is an example board stackup; this all fits neatly behind the Synovatron 8HPJ front panel (8HP wide with pot and jack holes):-

ProtoJax, ProtoPotz and ProtoXp boards stacked together

Examples of headers and sockets used to stack the boards


ProtoPotz is the direct replacement for DIY1 PCB (as used in DIY Kit 1 and DIY Kit 2). It is designed to hold up to five 16mm P160KN series pots using brackets. What's new about it?
  • Plated-through holes for robustness and convenience, essentially it's a double-sided PCB. 
  • Better supports the A-100 bus with dedicated positions for 10 or 16-way open or boxed headers, small electrolytic capacitors and protection diodes (to protect against reverse power connection.
ProtoJax boards with 5 pot brackets are available from Synovatron for 7.50GBP + delivery + VAT @ 20% (UK/EU only). ProtoJax will also be supplied in DIY Prototyping Kit 1 as a replacement for the original DIY1 PCB.

ProtoPotz pot breadboard PCB
Here is the range of pots available from Mouser that Synovatron recommends for use with ProtoPotz:-


ProtoJax is an evolution of DIY2 and DIY3 PCBs. It is designed to hold up to five Cliff CL1384 3.5mm mono jacks. It is almost identical to ProtoPotz except it has footprints for jacks instead of pots and another two rows of breadboard holes. What's make it more advanced than DIY2 and DIY3 pcbs?
  • Larger breadboarding area. 
  • Supports the A-100 bus similar to ProtoPotz.
ProtoJax is available from Synovatron for 7.00GBP + delivery + VAT @ 20% (UK/EU only). It will not replace DIY2 PCB in DIY Prototyping Kits 1 or 3 except as a requested option.

ProtoJax jack breadboard PCB


ProtoXp is a completely new PCB. It is an eXpansion board designed to add more breadboarding area to ProtoPotz or ProtoJax boards. It's features are:-
  • It has a cutout that allows the A-100 bus ribbon cable connector to fit without fouling on the ProtoXp board. 
  • The same ±12V power bus structure as the ProtoPotz or ProtoJax boards.
ProtoXp is available from Synovatron for 5.00GBP + delivery + VAT @20% (UK/EU only).

ProtoXp expansion breadboard PCB

 What else?

Data sheets will be prepared for the Proto series PCBs and download links will be posted online over the coming days.

DIY2 and DIY3 boards will be available for the foreseeable future. These can be used on their own or with the Proto series boards but the PCB holes do not align exactly so a linking ribbon cable is the best way to pass power and signals around between Proto and DIY series boards. Consequently the price of DIY2 and DIY3 PCBs will be discounted while stocks last. 

Sale price for DIY2 is 3.75GBP + delivery + VAT @ 20% (UK/EU only). Was 5.00GBP.

DIY2 jack breadboard PCB

Sale price for DIY3 is 5.00GBP + delivery + VAT @ 20% (UK/EU only). Was 6.75GBP.

DIY3 jack breadboard PCB

Please contact Synovatron for order enquiries, delivery costs and quantity/combined order discounts.

Sunday, 30 March 2014

Website updates

Due to being very busy trying to keep up with orders and developing new modules this blogsite has been sadly neglected. I was thinking I'd get round to putting up a proper grown-up website but that will not happen for a while yet as it requires careful consideration; I hope to setup an e-commerce type site with a basket and checkout facility. So apologies this is long overdue - I have updated details and pricing info for DIY Kits (Prototyping Kits and CV Tools Kit). More will be added to the DIY Kits page over the coming months including front panels and PCBs that can be ordered separately. I have also updated the Adaptors page and added a CVGT1/cvgtMM page.

Saturday, 11 January 2014

cvgt MM Buchla Translator ModuleModules are now shipping

The first cvgt MM modules have started shipping to clients at the top of the pre-order list. If you want to be added to the list then please make contact on

I will build in small batches and work through the list in chronological order and will then contact you when your order is ready to ship. Only at that point will I request payment (see prices below). Please note that this does not form any contract between us and you are not in any way commiting yourself to making a purchase until such a time that you make a payment.
Initially the cvgt MM will be only available directly from me but if there is enough demand then it is possible they will become available at all the usual distributors in due course. 

The current variants are:-
  • Buchla-Euro (round or hex nuts on 3.5mm jacks; please select)
  • Buchla-Serge*
  • Buchla-BugBrand*
  • Buchla-Fenix*
*These are banana socketed variants and only the colour of the banana sockets is different (to match the target system); All are variants (inc. Euro) are to translate from Buchla to 1V/octave systems.

The User Manual is being worked on and will be ready very soon and will posted here in an update. Please checkout the Eardrill website for more info on the ModuleModule concept and other great products from Chris Muir.

The price for the cvgt MM is as follows:-
UK is 180.00GBP plus 9.00GBP delivery (prices include VAT at 20%)
EU is 180.00GBP plus 15.00GBP delivery (prices include VAT at 20%)
ROW 150.00GBP plus 13.00GBP delivery (import duties and taxes may apply).

Either one or two modules can be sent within the quoted delivery price for the UK but add 2GBP per exra module for the EU & ROW. 

It is estimated that it will take up to 2 weeks from registering on the pre-order list before your module is ready to ship and the shipping time from the point of payment could be 2 working days ( UK ) or 5 working days (EU/ROW).
Payment is by PayPal to
Bank transfer is available on request.

Euro variant
Serge variant
Euro (top), Serge (bottom)

Friday, 6 December 2013

cvgtMM - A ModuleModule version of the CVGT1

This project has kept me busy for the past few months. It was suggested some while ago that I do a ModuleModule version of CVGT1 to go in a Buchla (see my earlier post). My initial thoughts were that it was probably not the best solution as front panel space in a ModuleModule is quite restricted and Buchla real-estate is not cheap. However what I didn't consider was that Buchla can also talk to Serge, BugBrand, Fenix etc and Serge users seemed to want this solution. Consequently I set about designing (or redesigning) CVGT1 to fit in a ModuleModule form factor. Chris Muir from Eardrill produced a great interface document which defines just about all I needed to know for designing a ModuleModule (I'll refer to ModuleModule as MM from now on). 

Because of the smaller front panel space I had to lose some features i.e. scaling and offset on the Buchla to other synth CV channel but as it is in a Buchla and will interface to an external 1V/octave synth I've fixed the scaling at 0.8333 (1/1.2) and zero offset. The PCB design allows either 3.5mm jacks or 4mm bananas to be fitted; so one PCB can be configured to for Euro or Serge etc.

Clearly this design has PCBs parallel to the front panel unlike CVGT1 which has them perpendicular hence the change in jack style.  The PCBs had a completely new layout with all front panel related parts on the first board (Front Panel Interface Board) and most of the circuitry on the second (Main Board). Here are some design images of the variants (there are a few very minor tweeks to the graphic since this was drawn and you'll see a few variations in the prototype pics below).

I built a prototype and that's all working nicely. Aside from the new PCB layouts I had to make some changes to the pulse/trigger/gate circuits to run from ±15V rather than ±12V but there were no major changes. Heres a scope image of the Buchla compatible pulse I achieved:-

Here's the prototype with an ink jet printed plastic overlay on the front panel.

All components are conventional through-hole types - I may go over to surface mount if I get more orders than I can personally cope with but think I will still retain through-hole if anyone fancies a kit. You will also notice that the scaling trimmers are front-panel accessible (with a small screw driver) however these are for very fine trimming ±0.5%.

The first pre-production modules will be available in just over a week when the screen-printed panels are in stock. I have a number of interested 'customers' that I will contact soon and will start a pre-order list; please feel free to contact me to get on the list: It will be a 'no-commitment no money up front' arrangement as before with CVGT1 and I will poll all interested parties in turn when I have a module ready to ship to see if you want one. I have not finalised a price yet but guess it will be in the same ballpark as Eardrill's own range of single panel medium complexity MMs.

It will be interesting to see how this takes off, CVGT1 started slow and now there are 200 out there with bags of interest still.  I will do an update in the next week or so. Thanks for reading.

Tuesday, 1 October 2013

Another custom built Euro to Buchla Translator module

I was recently commissioned by a client to build a custom Euro Buchla interface module, similar to the two I previously built, but with offset switching. The previous two designs both had fixed offset and gain and were intended for use with envelopes, LFOs etc. In other words there was no 1V/octave to 1.2V/octave scaling required just offsetting to ensure the Euro signals stayed in the 0-10V range of the Buchla (you can refer back to my earlier post here).

This module is intended to be used alongside my client's CVGT1 module (which provides the ground reference connection) and adds more CV channels. My client uses Expert Sleepers' SilentWay software for pitch sensitive CV and was not interested in scale conversion as the software does the necessary recalibration however he also wanted the flexibility to be able to interface envelopes, transients and LFOs and so wanted to be able to DC shift signals when he needed to.

The spec was 4 channels of Euro to Buchla (scale of 1, 0V or +5V offset) and 1 channel of Buchla to Euro (scale of 1, 0V or -5V offset); so 10 connectors a 5 switches in 8HP.  

My 8HP prototyping panels proved to be difficult as the existing hole positions meant that the connectors and switches would have been too close to each other plus I only had a few left and found they were scratched; they got binned. I used Schaeffer for a quick-turnaround panel; not cheap but very well made. In a moment of madness I got 5 panels made, including engraving (which the original 2 modules didn't have).

Is anyone interested in a kit (complete but advanced level; a lot of work to do and needs good hand/tool prototyping skills, the ability to read schematics and suggested layout diagrams)?  I can make the full custom module if you prefer too. Prices around 80GBP for the kit and 140GBP for the built module - exclusive of VAT (UK and EU) and shipping.

Wednesday, 24 July 2013

Synovatron Ltd has become registered for VAT

My company Synovatron Limited, trading as Synovatron Electronic Music, has just become VAT registered (still waiting on the registration number). Consequently I have removed all pricing from this blogsite for the duration until I have had a chance to review my costs and the pricing of products; I don't want to just slap 20% on prices for UK and EU direct sales. I apologise for any inconvenience and will endevour to resolve this as soon as I can. In the mean time if you have any queries about prices, availability or anything else Synovatron related then please contact me at

Please note that Analogue Haven, Escape from Noise and Rhythm Active have some of my products (CV Tools, CVGT1, ASM2DB, DM2ASB) available and are unaffected by this new change of status.

Thank you for your patience
Tony Steventon

Tuesday, 25 June 2013

Some Preliminary Work on a ModuleModule Design

ModuleModule CV and gate/trigger translator

This is just a quick post to show what I have been doing with regard to the ModuleModule design I mentioned in my last blog post. More info will unfold over the next weeks but this is just to let several Muffwigglers know that I am progressing their ideas (albeit a bit slowly). These are just a first draft and the design will change. The idea is that there will be a common design that supports either Buchla/Euro or Buchla/Serge; the only difference being the connectors used. It's difficult fitting all I want in the smaller ModuleModule format - perhaps the trim pots will come out and I'll add scale switches as per the CVGT1 - your feedback would be valuable!

CV2 - a sister module for the CVGT1

This is another idea I've been mulling over which will complement the CVGT1 and is intended for non-pitch critical CVs and for audio level translation. Again it's just a preliminary idea and feedback is welcomed.