Custom Half-width Buchla Modules

I was asked to design and build a pair of custom half-width Buchla modules for some clients. They each had two half-width slots spare in their custom built cases and wanted to fill the spaces with Euro to Buchla CV and gate translator modules.


The brief was simple (and the same for both clients): 5 channels of 1V/oct to 1.2V/oct CV translation and 5 channels of gate boosting to Buchla levels; the Buchla stepped pulse was not required, just big pulses (10V or more).

This was a great opportunity to use the Synovatron Proto range of prototyping boards which accomodate 5 channels and offer stackability if more circuitry is required than will fit on one board; see below.

The Proto range of boards

As the Proto boards are designed primarily for Euro there was space on the 4U Buchla front panels to add some extras in the form of a passive attenuator. Here are the front panel designs that we agreed on:-

CV and Gate modules

To keep costs down it was decided not to have panel marking as the functions are obvious.

The CV module design used a straightforward precision amplifier with gain of 1.2000 (yes that accurate), 1M Ohm input and 0 Ohm output impedances. The gate module used comparators and output and LED drivers. The outputs each have diodes in series allowing them to be wire-ORed by just connecting outputs together (common to Buchla, wish it was used on Euro).

The CV module electronics fitted nicely on a ProtoJax board with plenty of space as you can see:-

For the gate module I decided to put the input comparators and sockets on the ProtoJax board and output buffers and LEDs on the ProtoXp board and stack them together (it  probably could all have been put on one board but it was simpler to make use of the space). The stacked ProtoJax and ProtoXp boards can be seen here:-

The gate board was powered from an MTA connector and the CV board took its power from the gate module (hence the 10-pin ribbon headers for a linking ribbon cable); this was at the client's request as they only had one spare connector (these are very low current modules and daisy chaining them didn't cause any crosstalk issues). 

The finished panels looked pretty good; they were made by Schaeffer using Front Panel Designer http://www.schaeffer-ag.de/en/front_panel_designer/the_idea/.

  
If you are interested in the Proto range of PCBs or in having a custom module built then please contact me at synovatron@btinternet.com

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).

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 up 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.

Modular in a tool case

I had a day free on Saturday and set about putting a modular in a tool case. To be exact it is a Doepfer A-100 DIY kit #1 fitted to a Halfords engineers tool case. The point of this was to have an easily transportable demo system so I can take to shows, meets etc in order to show how lovely my CV Tools module is and to let people have a play.

In a follow-on to my cheap DIY store front panels post a few weeks back I used anodised aluminium angle strips in the construction from Homebase - the case is bigger than the 6U 84HP of the rack kit.
(Note to non-UK readers Halfords is a motor accessories store and Homebase is a DIY store)

Here's the case

Prep the case - remove separators, tool panel and unecessary fixings.

All done, ready to start serious modding

This will be powered by a 15VAC supply so a nice big hole for an XLR connector

XLR in place (EDIT: this is eventually replaced by a plug version as a power lead with exposed pins is bad karma)

A bit of judiscious foam cutting to neaten it up

Markout and drill the regulator boards fixing points - 4 x M3

Regulator screwed in place

I used M3 washers to spread the load - the case is just hardboard with a thin aluminium veneer

Position the bus boards and drill mounting holes - long M3 screws with tapped spacers fitted

All electrics now in place. Note this is temporary - there will be wiring to a front panel power switch on the next installment!

Next make the rack end pieces out of 10mm x 20mm anodised aluminium angle strip. These make the rack the perfect width to fit the case.

Similar to above I made top and bottom strips to fill the gap - I used 25mm x 25mm anodised angle, again an almost exact height fit - starting to look good.

Here's a view showing the fixings (ok I drilled a hole in the wrong place. Motto: measure twice, cut once!!!).

As I said a near perfect fit in the case. At this point just resting on the foam and not screwed in. That's in the next installment.

Loaded with modules and powered up. Take no notice of the modules selection, I've since changed it to a more coherent set.

Even a nifty scope showing VCOs, Synovatron DioDe and CV Tools in operation - now that's a waveform!

 Next installment will add a power switch and fixings to anchor the rack to the case. It will also make use of all that front panel space top and bottom for passive and buffered mults, bus access, simple LFOs, gate logic, 3.5mm to 6.25mm/RCA adaptors, etc etc (the thought of the lovely goodies that will get built in is going to keep me awake a night - so sad!!)

Here's a short clip of it working:-

Cheap DIY front panels from UK DIY store!!!

Tone's Top Tip for July

Whilst wandering around my local Homebase DIY store I noticed a rack of metal and plastic extrusions. In there was a range of 2mm thick aluminium clear anodised strip in 10mm, 15mm, 20mm, 25mm and 30mm widths i.e. approximately 2HP, 3HP, 4HP, 5HP and 6HP respectively (note that the online links wrongly refer to it as flat tube and not all widths are listed online). The strips are 1m long and cost between £4.50 and £8.00 each. They have a similar finish to Doepfer front panels but with a slight vertical graining. Here's a pic of 6HP and 4HP strips.

If you are OK at cutting and drilling they are a cheap solution to narrow DIY panels. Good dimension info here. I guess they are available in most large DIY stores so it's worth having a look next time you are there.

First review comments and user's video for the CV Tools Module

Over half of the first batch of CV Tools have been sold, many in kit form. Here is some feedback from a few kit builders and module users:-

"Finished the CV Tools module. It works as advertised ;) No warts!

I must compliment you on your kit. The packing and organisation of components are as good as I've ever seen. Documentation is on the money for newbies ... All in all, I'm extremely satisfied ..." Steven H (VICMOD)

"An excellent simple tool. Great for cascading polyrhythms. Really easy to use and very surprising differences depending on where you tap the signal." Stephen R (VICMOD)

"...I was really impressed with the documentation and the way everything (in the kit) was bagged/labelled...CV Tools seems like a real Swiss Army Knife. I can already think of countless ways I'll be using it with my Oberheim SEM ... and humble modular." Alex M

"Tinkerbell lives!  Tonight I patched a triangle wave LFO into channel 3 of CV Tools and took the slew output into a quantizer (A156) set up to run minor arpeggios.  I can control the range of the arpeggiaic ascend/descend and even build in rhythm just using pots 3 & 4 - then out to two VCO's tuned apart. Out through a digital delay and reverb in ProTools and  . . . instant magic - fairy dust!  What fun . . " George B

Also check out this thread on Muff's entitled Some thoughts on the Synovatron CV Tools
 

Just to keep things balanced some people have expressed a lack of enthusiasm for the front panel, some about the font and some about the fact that the graphics is on a matt laminated laser printed vinyl overlay. The beauty of the overlay is that multiple colours, shades and fading effects can be easily implemented, the down-side (for me) is they are expensive and difficult to fit accurately. 

The solution is that the second batch of CV Tools will have a standard screen printed front panel (something like TipTop Audio quality). I will be offering either a very low cost swappout or a low-cost retro-purchase to existing users who would prefer a more conventional graphic - I prefer happy customers over a few extra £. Hopefully you'll come back for more!

Here is the current overlay panel next to the artwork that will be taken to the screen printers (where there is grey it will be the brushed anodised aluminium showing through so it will look a bit better). Any comments, likes and dislikes gratefully received - I will give the artwork to the screen printer in just over a week's time.

New generic front panels for DIY kits

I now have stock of a range of 4HP and 8HP front panels to suit the Synovatron DIY Prototyping Kits. These can be purchased with the kits as an option or separately. 

The 8HP panel suits DIY Kit 1 and has two variants, one to suit a column of jacks (8.2mm holes) and a column of pots (7.5mm holes). The other variant has 3mm pilot holes to give you the flexibility to mix and match front panel components by drilling out to suit jacks, pots or switches, or left as is for 3mm LEDs.

The 4HP panel suits DIY Kit 3 and also has two variants, one to suit jack sockets (8.2mm holes) and the other with just 3mm pilot holes so they can easily be modified to larger diameters for jacks or switches or left as is for LEDs.

The panels are made from 2mm aluminium and have a brushed, clear anodised finish.  The mounting holes (slots) are suitable for both Doepfer and Analogue Systems hole pitches.

These panels make the kits more complete and I will also offer a set of knobs in DIY Kit 1 to finish it off.

Kit 1 options: The soft-touch knobs can be ordered in white, grey, red, orange, yellow, green or blue.

Prices range from £5.99 to £8.99 if ordered separately, a bit cheaper if ordered with a kit. The knobs are £1.25 for 5 if ordered with a kit.

The panels will also include a set of M3x6 screws and plain washers.

Update:

Here's a 8HP pilot hole panel that I drilled out for a customer so he could mount a mult on the left and an OSC303 on the right (Note: he bought the OSC303 as a kit without front panel and jacks. There's no point in trying to do this if you have one DinSyncs's excellent clear blue panels). The jacks were drilled out to 8mm, the pot to 7.5mm and the switch to 6mm. Looks pretty sexy!

Tone's top tips:  

(1) Cover the panel in masking tape so the swarf doesn't scratch the front finish. 

(2) start with smaller drill sizes and work up to the final size else you may end up with odd shaped holes.

(3) Deburr holes on both sides with a countersink bit.

Preview 2011 - the next module

Here's a sneak preview of the next module on the drawing board with a working title of "Diode". I'll leave you all to guess it's function - hopefully if I've done the front panel design right then that should be an easy task for you. Answers on a postcard.....


What's happening with CV Tools? Just having a last minute ponder and double-double-check before I commit to copper (and expense). I expect the first batch of production models to be available by the end of January.


Here's a question: The colourful high-res graphic front panel designs are cheap and easy enough for me to produce for prototypes but will be a more expensive for a production run. 

Does a nice front panel in a range of bright and colourful styles interest anyone or are we only interested in function?

I'd be grateful for any comments.


This will probably be my last post in 2010 so I just want to wish you all a happy, safe, fun and rewarding 2011. Keep those analogue modulars throbbing out amazing sounds.... Tony

Update on front panel artworks

Just thought I'd give a little more detail on front panel artworks as there is already some interest.

The picture below of my module currently in development shows the CAD drawing for a 12HP front panel in the top left. The adjacent front panel overlays show an evolution from a very simple, flat looking artwork to more 'sexy' metallic looking and coloured alternatives with some apparent depth.

 
Edit 08/07/11: The following graphics, based on ink-jet/laser printable vinyl overlays, was attempted on the first off batch of CV Tools modules but has been withdrawn in favour of a standard screen printed panel for two reasons. The first was that it was not liked that much by customers; people saw it as a cheap label. The second was that it was expensive and difficult to apply accurately. I will still use the overlays for prototypes.Please read the following but note it has all been superceded by events.

My task is to make this a service that is affordable by streamlining how I go about setting out the pot scaling, legends, functional grouping (separating lines or boxes). A good place to start from is if you use Schaeffer Front Panel Designer to get the panel made then I can use the DXF file generated to align the graphics to the holes; obviously with as much description from you as possible about what you actually want to see.

The one-off 2mm anodised panel from Schaeffer cost me 27 Euros (about 23GBP, $35US but it is beautifully machined!!); I anticipate the cost of an artworked plastic overlay would need to be less for that size panel to make it attractive, including my design effort (that's why I need to streamline the process - the slicker I get the more viable it'll be!).

The hardest part is lining up the overlay accurately on the panel as the overlay is self-adhesive. I'm getting quite adept at this now as I have prototyped several overlay types. You do get several chances and I may include a spare.

I am still developing the technology as it needs to have great graphics, be cheap to make whilst still having good wear and scratch resistance properties.  This balance is not easy and I will still need to explore better processes and techniques so initially this will be for smaller prototypes with some caviats on how much abuse it can handle. The artwork is great quality though and the durability is reasonable but could be better. The price will reflect this fact. Having said all that I'm going to use it in my system as it stands as I don't tend to abuse my hardware.

Any suggestions and comments would be most welcome.