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.

Wednesday, 12 June 2013

June update

Delivery status
I am very happy to say there is a batch of CV Tools and CVGT1 modules heading stateside towards Analogue Haven; estimated to arrive on Monday June 17th.

Having succumbed to requests I am looking at producing the CVGT1, or a version of it, in ModuleModule format. I'm just formulating ideas at the moment but I'm thinking two variants - one for Buchla<>Euro and one for Buchla<>Serge. I think this makes more sense than having connectors for all formats on a very tiny but expensive piece of real estate; I'm happy to take onboard any comments here.

Friday, 10 May 2013

May update

Module Availability

A shipment of CVGT1 modules and CV Tools modules is in transit to Escape From Noise in Sweden (already in their Coming Soon page).  The shipment for Analogue Haven is still sitting here waiting on the bank transfer hopefully that will be very very soon.


This blog site is woefully out of date and I will endevour to bring it up to scratch soon but will be looking to have a full on grown-up website sometime this year.

Screws and washers

In the mean time I have been asked about rack screws. Yes I do sell them but I have not really advertised the fact.  With all my modules I supply 8mm long M3 cap head socket screws, nylon washers and a 2.5mm hex key. These I sell separately if required. In small quantities the cost is 0.15 GBP for a screw and washer, 0.75 GBP for the hex key. For larger quantities the price will drop. Shipping is extra. If you are interested then please email me at

This is what they look like fitted:-

Wednesday, 17 April 2013

April update on CVGT1 availability

All the production problems have been resolved and I have a shipment of CVGT1 and CV Tools Modules ready for UPS to collectwhich will be heading for Analogue Haven. I'm guessing they should be in the US around 23rd/24th April.

I'm now building a batch of CVGT1 Modules for Escape From Noise, Rhythm Active and Post Modular and will post details when those are about to ship out.

Saturday, 2 February 2013

Update on CVGT1 and CV Tools availability

I had expected to deliver shipments of CVGT1 and CV Tools modules by early January but unfortunately the manufacturing problems surrounding defective jack sockets and poor quality front panels have not yet been resolved; read on for the details.

The good things: I'm really pleased with the pcb manufacture (by Quick Tech) and surface mount assembly work (by Phase 1 Electronics) on the CVGT1 pcbs - 100% perfect.

I'm really sorry for the delay for anyone wanting CVGT1 or CV Tools modules; I will try as hard as I can to resolve the issues. CVGT1s especially are receiving lots of interest partly down to Buchla's reintroduction of their more accessibly priced Music Easel - now that is seriously retro!

Jack Sockets

The jack socket issue was discovered after I built about ten sets of CVGT1 pcbs. The problem was that it was either impossible or very difficult to plug into a socket; a basic requirement for a socket you'd think! The new whole batch of 1000 sockets that I started using on my production run for Analogue Haven, Escape From Noise, Post Modular and Rhythm Active were defective. I had to remove the sockets that were fitted and have reported the problem back to Cliff Electronics. I had to chase them as they were not forthcoming about my plight but am glad to say that a concerned quality manager phoned me last week about the issue.  Prior to that call I ordered another batch of connectors from them to tide me over which are perfectly good; so far I have not received a refund for the defective items but here's hoping.

Front Panels

The front panel issue was discovered when I unwrapped them and found most of them have scratches. I challenged the fabricating company who said that the scratches were down to either the anodising company or the screen printing company and you guessed it they said it was down to either the other two. So basically no one to point the finger at and no one claimed responsibility. I managed to get the fabricator to strip the panels, refinish them and get them anodised. They arrived last week and I inspected them before taking them to the screen printers but all were poor quality with blemishes, dings, scratches etc. (I'm not expecting to be invoiced and certainly will not pay it if I am!).

So the upshot is that I am unable to complete the module builds and am looking for a new panel supplier; preferably one who does the manufacture, anoding and screen printing, quality control and takes responsibility.

Tuesday, 1 January 2013

Wishing you all a happy 2013

2012 for various reasons has been for me a real struggle and so am hoping 2013 will turn out to be a better year. My wish on this first day of 2013 is that it will be a very happy and healthy year for you and your loved ones.

2012 saw just a few successes:-

The first was the power system and trunk-line modules I designed and built for Gregg Wilson's wonderful wall sized monster synth.

The second was the development, prototyping (including two custom built modules) and preproduction run of the CVGT1 Euro Buchla translator module which are now delivered to the pre-order list customers who are putting them to good use.

Related to the CVGT1 was my first foray into surface-mount boards - the preproduction run of 30 CVGT1 modules used through-hole components which meant that I could, and did, hand build those modules. However they were so time consuming to build that I got quotes for getting them made but the cost was was prohibitive; I was advised that surface mount assembly would be much cheaper and so I set about relaying the boards for surface mounted components.  This worked well and they worked first time albeit for the most significant financial commitment I have made in Synovatron to date. 

CV Tools may get the same reworking but will keep the through-hole version in existance for you DIY enthusiasts; the CV Tools DIY Kit has continued to be a succesful product with more plaudits about the kit presentation, clear instructions and ease of build.

The downside for 2012:-

Following a personal loss in July I took some time out and then I pushed very hard in the last 2-3 months to produce a large batch of CV Tools and CVGT1 modules for the end of 2012 but due to supplier quality issues it now looks like those modules will not ship to distributors until late January to early February

I had to reject two thirds of CVGT1 front panels due to scratches and had to reject a batch of 1000 jack sockets due to varying quality from stiff to non-functional (i.e. can't insert a patch lead); unfortunately many were assembled on boards before I discovered this. So all in all a huge amount of effort and frustration with no output but I have learned lessons from this. 3.5mm connector quality is certainly the hardest component problem that Eurorack manufacturers seem to face followed closely by front panel quality issues.

Another problem encountered but Eurorack users is the ease of misconnecting the power cable. 

This was brought sharply into focus by a client who reverse connected his RS-35 using one of my ASM2DB Adaptors and blew up the tantalum capacitors and a CA3046 IC on the RS-35; notably all the TL072 ICs survived as did the F-V converter chip

The connection instructions are clear but we are human and our capacity to f**k goes with the territory (hence the disclaimer in the instructions); I still do it even though I know to be careful. I have fixed his module for free as a goodwill gesture but it does worry me - my plea to all designers of new modules is use protection diodes.