Barton Visits The Lower West Side

For some time now I’ve heard the name Barton Musical Circuits in relation to the DIY modular synthesizer scene.  The trouble is that there is so much stuff out there I find myself inundated with a wide variety of vendors, products and technologies that I sometimes hear something then forget about it a short time afterwards having moved on to something else.

Fortunately the other day while surfing I came across a site which I had never found before.  It is a vendor called Modular Addict.  Intrigued by the name I began to check out their site.  Modular Addict officer a substantial number of DIY kits in multiple formats.  Under their Multiple / None format I found the Barton line of PCBs.  These boards were designed for the Eurorack format, however, it was my intention to modify them for the Moog Unit (MU) / Dotcom  format.  The boards can operate at 12 or 15 volts which is perfect as Dotcom utilizes + / – 15 volts.  The boards even support an MOTM style power connector.

I purchased three types of PCBs;  The BMC018 Analog Drum module, the BMC030 Guitar Interface module and the BMC034 Switched Resistor Voltage Controlled Filter module.  I figured this was a good place to start.

The boards arrived quickly and were packaged very well.  The cost of the boards was very reasonable which is great for something you’ve never tried out before.  I looked up some videos on the modules on YouTube and liked the sounds and functions the modules produced.

Documentation for the boards is available for download and is clear and easy to follow for the most part.  A bit more detail on the flying wires could be helpful but overall I was able to determine how to wire the jacks from the photos provided.

In order to accommodate the MU format I did have to wire the potentiometers with flying wires rather than using the PCB mounted potentiometers indicated in the documentation. This required an added level of complexity to the build but in reality is wasn’t difficult at all.

One thing I did notice from the photos was that the Ground (Earth) pins on the input / output jacks were not connected.  Personally I like my gear to be Grounded so when I wired up my modules I connected the Ground pins together and then to a ground point on the PCB.

I started by building the BMC030 Guitar Interface.  The build went quickly and easily and after a couple of hours I was testing the board with my modular.  It worked very well allowing me to change the sound of my bass guitar with the filters and other toys in my modular.

For my build, though, I had to design a panel suitable for my Dotcom style cabinet and modules.  I chose a 2U panel so that I could use the large knobs associated with MU / Dotcom style builds as well as having the components spaced out comfortably.  Once I had a design I used corrugated cardboard and a printout of the panel to create a mock-up.  This allowed me to test my layout and ensure things would fit.  As it turned out this test showed me that a couple of items needed to be moved a couple of millimetres one way or other.  I have made those changes and the panel is now ready to be sent to my silk screen guy to have a screen made.

IMG_6518.jpg
2U MU Version of Barton Musical Circuit’s BMC030

I did take the liberty of slightly modifying the name of the module from Guitar Interface to Instrument Interface as I plan to plug things other than guitars into it.  Just for fun!

Next I moved on to the BMC018 Analog Drum module.  This is a cool little module which allows you to create some really cool bass drum and tom sounds.  Coupled with some noise you can also create some interesting snare drum sounds.

Once again the build went quickly and smoothly.  The module tested out perfectly and I can definitely see adding a few more of these to my modular for some cool electronic drum sounds.

I created a 1U panel for this module which I mocked-up out of cardboard like the first module.  This time no adjustments were necessary.

MU Version of Barton's BMC018 Analog Drum Module
1U Version of Barton’s BMC018 Analog Drum Module

One question that did arise was Barton’s use of 10 Ohm resistors in place of Ferrite Beads to reduce power supply noise.  An interesting discussion sprung up from this subject on MuffWiggler’s Forum but in the end, for this first build at least, I decided to stick with the documentation and go with the resistors.  So far they seem just fine.

Next up will be the BMC034 Switched Resistor VCF.  I have several filters now and I’m very excited to try out another.  The different flavours filters give a modular make for a wildly varying sonic experience and I plan to add a large number to my setup.

Once I complete the next build I’ll post a write-up.

So in a nutshell;  modules by Barton Musical Circuits, in my opinion, are quite a nice addition to my modular rig.  I really like them in the MU format I have modified them for but even as Eurorack modules they are a great add-on.  I would also highly recommend them for beginner DIY builders as you get an easy build with some excellent features when you’re done.  Oh, and Modular Addict….. excellent place to deal with!

 

 

Cat Girl CGS01 Sub Oscillator

Actually the full name of the module is the Cat Girl Synthesizer CGS01 Sub Oscillator / Harmonic Sequencer…. but that is one heck of a long title.

The CGS01 is a tremendously powerful module whose capabilities are often not completely understood.  Truth be told I have yet to fully understand the module’s abilities but I hope to pass on what I do know with this article.

Several CGS01 modules have been built here in the studio.  The build is actually quite easy. That is they are easy up to the point it’s time to connect the flying wires.  Once you get the trick of where everything goes, though, the modules are a snap to build.

For the CGS01 builds the boards were purchased from Synthcube.com.  At the time of this writing Ken Stone, the board designer and manufacturer is no longer selling the boards through his site but his product line is available from Synthcube.com (at very reasonable prices I might add).

Cat Girl modules are among the most unique of the DIY modules out there.  First of all they  provide a wide and assorted array of features which are not otherwise available in modules by other manufacturers.  If the features are available Ken has put interesting spins in his version.  Second, CGS modules are frightening to build.  When I first came upon the CGS site and read Ken’s FAQ and disclaimer I practically ran away screaming in fright.  As a new DIY builder his warnings are very valid.  With some research and the excellent support of users on forums such as Muff Wiggler and Electro-Music I was able to successfully build several of his designs.

My first build was the CGS01 Sub Oscillator / Harmonic Sequencer which had some very intriguing features.  Rather than acting as a single sub oscillator which would play a note one or two octaves below the main oscillator’s note the CGS01 has a variety of divisions of the primary input note.  Further a combination of two inputs could be multiplied and divided then mixed together to produce even more interesting sounds.

In addition to these sound contorting features the CGS01 could alter control voltage inputs such as LFOs.  The output of these mashups could then be fed into an oscillator’s 1V/Oct input to create bizarre sequence effects.  This is a way cool feature!

IMG_6386.jpg
2 CGS01 Modules Built an Ready for Wiring

The largest number of components on the board are resistors, primarily in the mixer section. A few capacitors and some diodes (and 2 ferrite beads) make up the remainder of the small components.  There are 9 integrated circuits used but none of them are particularly expensive or difficult to obtain.  In short;  building the PCB is a snap.

Wiring the board to the outside world is a bit trickier.  There are a number of variations which can be done depending on how large a panel you wish to use, how many potentiometers you want and how complex you want your options.

panel_subosc
Ken’s 14 Potentiometer Design
panel_subosc2
8 Pot Alternate Layout

To keep things within reason and to reduce the footprint of the module I decided to go with Ken’s alternate layout with replaces some potentiometers and a 5 position rotary switch with some toggle switches and a reduced number of pots.  I utilized a combination of Ken’s panel layout and one done by Kindredlost from Muff Wiggler to create my panel design which I silk screened onto a Q132 Double Blank panel from Synthesizers.com.

IMG_6478.JPG
My Test CGS01 Panel

The wiring diagrams on the CGS site are a bit confusing when it comes to wiring up this alternate panel layout so I created my own wiring diagrams for reference.

CGS01 - Page 2

CGS01 - Page 1

As suggested in Ken’s documentation I did not tie the flying wires together in my build to prevent cross talk so from the back the module is a bit less tidy than I like but we do what works rather than what is pretty.

IMG_6467.jpg
The CGS01 Wired Up And Ready To Test

 

Describing the features of the CGS01 doesn’t do the module justice so please watch the following demonstration video for more information.

So to summarize;  Great module.  Not as scary a build as you might think.  Incredible features with a multitude of possibilities.  Try one out!

Stroh Dual Gene Splicer DIY Build

Last week I received a Stroh Dual Gene Splicer kit from Synthcube.com.  This versatile module is actually two boards mounted in a single width (1U) MU panel.  The panel is by Caleb Condit and is laid out clearly and cleanly.

IMG_6455
Complete Dual Gene Splicer Kit from Synthcube.com

 

Each Gene Splicer provides two inputs which are mixed together and then sent to both regular and inverted outputs.  A control voltage can be used to pan between these two inputs.  Either audio or  control voltages can be input into the input ports.

If you’re new to DIY and looking for an easy place to start then this is the module for you.  The board consists primarily of resistors with a few diodes, capacitors and a single Integrated Circuit.  The interface to the outside world is through ten 1/4″ jacks.  There are no potentiometers.  Both boards are identical and can be built quickly and easily.

IMG_6458
Both PCBs Almost Completely Populated

Once the boards are complete it’s time to wire the jacks, install the board mounts and connect the power.  I used a single ground wire connecting all the jacks together then connected the ground to the ground on one of the PCBs.

IMG_6460
1/4″ Jacks Mounted and Ready to Wire

Rather than wiring headers onto each board I opted to solder wires connecting the power pads.  The board uses +/- 15 volts plus ground.  There are pads for both MOTM and Eurorack style power connectors.

IMG_6462
Power Wires Run Under The Boards

The kit comes with an MOTM to Dotcom power connector convertor but I opted to wire my own Dotcom style power connector directly to the board setup.  After soldering all the power wires to the board I connected the remaining flying wires to the 1/4″ jacks.  There are only 5 per board and the wiring went very quickly.  I opted to run the wires through the underside of the board to keep the build more clean.

IMG_6463
The Dual Gene Splicer Wired Up And Ready To Test

With the wiring all done the board was ready to test.  For testing I have a separate power supply which I use on untested modules prior to connecting them to my modular’s actual power supply…. just in case.  Once I confirmed the module was working I installed it in my cabinet.

IMG_6464
The Dual Gene Splicer Mounted In The Cabinet

The kit itself comes without documentation, however, the docs for this and other Stroh modules can be found here on the Muff Wiggler Forum.  The Bill of Materials is available in this thread.

To see the features of the Stroh Dual Gene Splicer check out the following video…

 

 

Sometimes Chaos Is Better!

There’s a saying with modular synthesizer users; You can never have too many VCAs.

Over the past few months I’ve really learned that’s true.  One corollary I’d like to add is that those VCAs should not be the same.  Having a variety of VCAs provides a wide range of sounds as each VCA adds its own subtle difference to the sounds it is processing.  As of this writing my modular has five VCAs; a Cat Girl VCA 3+, a PAiA 9710, 2 Oakley Classic VCAs and of course, a Synthesizers.com Q108.

IMG_6441

But this post is not about VCAs.

I would like to add the statement; You can never have too many VCFs.

Filters, like VCAs and Oscillators each have their own unique characteristics.  Sometimes you’re looking for a rich, creamy filter.  Sometimes it’s a raspy biting filter.  Sometimes it’s a warm and fuzzy filter.  In any case having a variety of filters to choose from just expands your creativity pallet.

Presently in my coral of filters I have; a Yusynth Minimoog clone filter, a Dotcom Q107 State Variable filter, a Synthcube / Moogah SEM filter, a Cat Girl Steiner / Synthacon filter, a DJ Thomas White Triple Low Pass Gate and (the actual subject of this post) a PAiA 9730 filter.

IMG_6442

As I add components to my modular I’ve learned that certain modules have a high degree of precision to them while others tend to have less.  Synthesizers.com modules, for example, have an almost surgical quality of beauty to them.  They have a degree of perfection I can always count on.  I know what to expect of them (most of the time).  PAiA modules, on the other hand, are different.  I’ve described them to others as modules with a handful of sand thrown into the works.  They have a certain degree of unpredictability that has a type of charm all its own.  You can never be 100% sure of what you’re going to get when you throw them into the mix.

Migrating my FRAC sized PAiA modules to MU (see previous posts) was a great thing for my setup.  I now incorporate them into far more patch setups than when I was limited to the number of 1/4″ to 1/8″ patch cables.  Because the 9700 has the basic building block component modules for synthesis I have a PAiA feature available through all portions of the sonic creation process.

The 9730 filter is an interesting beast.  It is sometimes maligned for its unpredictability.  The 9730 can often mangle a sound beyond what you thought you would expect due to functional limitations and / or anomalies.  I won’t get into those specifics here but you can Google them if you’re interested.

One “Fix” offered by PAiA is a resistor addition modification to minimize oscillation of the filter.  This involves tacking in a couple of 4700 Ohm resistors to IC3 on the board and resetting the scale trim pots.

IMG_6439

I performed this process and used it for a couple of months.  During that time I found I used the 9730 less and less.  It became so un-interesting.  The filter worked but without its wild unpredictability it left me flat and bored.  If I wanted a bland filter I would have searched out a bland filter (although why the hell would I do that ; ).  All my filters have unique characteristics which make me love them all.  Having worked with them for a while I now have a good idea of where to go when looking for a particular sound.  When looking for a wildcard I’d go to the 9730 (before the mod).  After the mod, however, it was just another filter and not a particularly interesting one at that.  Removing the modification changed all that.

My bandmate in my electronic band Fizzbin once said to me that he chose some of his effects pedals and synths based on their unpredictability.  He explained that not knowing what was coming could sometimes be more fun then simply dialling in a sound.  He’s right!

Un-fixing the PAiA was the best mod I’ve made in a long time.  I’m excited to have my out of control, whack-job filter back.  I wouldn’t have it any other way.

 

2015 – The Year In Review

I know 5 months into 2016 is a bit late for a Year In Review article but hey… better late than never.  2015 was a very interesting year to say the least.  Musically a lot of stuff was going on while some… not so much.  So here goes;

Drums / Percussion

Another slow year for the drum kits.  Once you have all the toys you need there isn’t room for much more.  I’m still using my Gretsch Renown Maple kit for studio use and my Pearl Exports (now 35 years old) for live shows.

I’ve played around with heads this year settling on a set of Evans Hydraulic Black for the Gretsch batter heads and continuing to used Remo Pinstripes on the Pearls while using Evans Hydraulic Blues on the resonant heads.  I tried the Hydraulics on the Pearl batter side, however, the sound doesn’t carry well in live situations.  In the studio the Hydraulics work great, especially for recording.

I also scored a great deal on a Pearl hi-hat stand for my gigging kit.  Pawn shops are awesome for gems like this and now I don’t have to tear apart my studio kit hardware when I gig.

IMG_5894
Setting Up For A Gig At Piper’s Sports Bar

 

IMG_6149
The Black Evans Heads Look Awesome and Sound Great

Electronics

2015 was a HUGE year for electronics as I have shifted my focus to DIY gear.  It started with stomp boxes from Tonepad.com.  These guys have some great clones of really excellent pedals.  I began with a Ross Compressor pedal which, after a bout of using bad solder, worked out really well.

Building electronics was something I did early on in my computer career.  My mentor Dave taught me how to build Apple 80 column clone cards, Z-80 cards and Hayes 1200 bps modem clones.  He was a strict teacher and my soldering skills are really good thanks to him.

Incidentally, if you’re into music DIY and haven’t checked out Small Bear Electronics then you’re missing out on some awesome stuff!

While I enjoy building stomp boxes I really put my skills to use in a new area which came to the studio;  Modular Synthesizers.

Modular Synthesizers

I’ve always been a huge fan of modular synthesizers.  There’s something about all those knobs, plugs and cables that appeals to me.  The sounds they create are astounding and in 2015 I finally got into them big time.

It started early in the year when I built a PAiA 9700 from a kit.  PAiA has been around for a long, long time as a DIY supplier.  I first learned of them back in the ’70s when I saw their Strings ‘n Things keyboard.  PAiA also created the first drum machine which was used in Peter Gabriel’s Games Without Frontiers.  It was only natural that I’d test my skills on one of their modular systems.

IMG_3273
The PAiA 9700 – My First Modular Build

I learned to create some incredible sounds with the 9700 and began to study the basis of synthesis itself.  From there I decided to move from the FRAC sized PAiA modules to the larger Moog Unit (MU) size modules which I’ve always liked the look of.

I discovered Synthesizers.com from where, in October, I purchased my first full size modular system.  I got only a few modules to start but the number of toys I added grew quickly.

IMG_5500
Synthesizers.com Modular Atop a Moog Sub 37

Following the addition of the “Dotcom” (as they are known in the community) I put my DIY building skills to use adding modules by Oakley Sound Systems.  Today the modular is quite different from the original version but you’ll have to follow the blog and read the 2016 Year In Review to learn about that : )

Incidentally, the PAiA and the Dotcom get along beautifully with some 1/4″ to 1/8″ patch cables.  In 2016 though there have been some format changes to the 9700 which you can read about in the blog.

Keyboards

Not much has been happening in the studio’s keyboard realm with the big focus being on modular synthesizers.  I should note, however, that I did take part in Moog’s Sub 37 Editor program.  Moog had been working on an editor for the Sub 37 synthesizer which has been released in 2016.  It’s quite a nice piece of software which opens up all sorts of possibilities with the synth.

I have to say though that while I really love my Sub 37 many of it’s features are “computerized” for lack of a better word.  Since working with the modulars I find I can accomplish more things more quickly without having to wade through menus and key combinations.

Software

Still working with Reaper and loving it!  They have a great upgrade cycle and terrific support.  I can’t recommend it more highly.

Bands

Coming of Age has had a great year performing many live shows at multiple venues.  We’ve done charity events and several private parties all of which seem to really have pleased the crowd.  Our repertoire of classic rock tunes has grown and everyone is having a great time.

Fizzbin is also expanding its musical field adding a number of original tunes to the list of songs we perform.  While we haven’t performed live during 2015 we are preparing an awesome show for the 2016 musical year.  Stay tuned!

So that, in a nutshell, was 2015 for Lower West Side Studio!  Sorry for the late entry but at least I got the info out there.  Keep on Rockin’!!!

 

System X ADSR – 5U Version

I’ve recently completed my build of a 5U version of the System X ADSR Envelope Generator by Frequency Central.  I have to admit it was a quick build and not very difficult.  I would definitely recommend it for those interested in getting into modular synthesizer DIY.

I ordered both the PCB and the panel from Frequency Central.  The panel is an MU style panel which sits perfectly in my Synthesizers.com style cabinet.  The panel design is by Caleb Condit.  The PCB is designed to accept either MOTM or Dotcom style power connectors with +/- 15 volts.

Board quality is quite excellent and very easy to work with.  The board is double layered and very clearly labeled.  The components are quite standard and I was able to build this project with items I already had in inventory.  The only items which I did not have were the potentiometers.  I ordered these from Tayda Electronics as they were not available at my normal component suppliers DigiKey or Mouser.  The parts arrived within a week though so the build wasn’t slowed down too much.

The module is very easy and straightforward to use.  As the name implies there are controls for each Attack, Decay, Sustain and Release.  There is also a switch for selecting Fast or Slow envelopes.  There is a gate input and both normal and inverted outputs.  These features together provide some very cool options for creating interesting effects.

IMG_6343
The Completed System X ADSR
IMG_6345
Populated PCB With Dotcom Power Connector
IMG_6348
Mounted In Cabinet

 

The following video demonstrates the use of the Fast / Slow switch on the Envelope Generator…

More PAiA 9700 5U Retrofits

The retrofit of my PAiA 9720 Dual Oscillator / Modulator went really well.  My Moog Unit (MU) style modular synthesizer is growing and the mix of different manufacturer’s brands of components lends to it an eclectic mix of sounds.  While I really love my Synthesizers.com components I’d like to mix up the sounds produced by my modular by integrating modules from a wide variety of manufacturers.  Having started my modular journey by building a PAiA 9700 I definitely wanted to include it in that mix of modules.

At first I integrated the 9700 with crossover cables.  The were cables with 1/4″ jacks on one end and 1/8″ jacks on the other end.  I got some really cool sounds.  The PAiA modules are grittier for lack of a better word.  They sound sort of like a handful of dirt was thrown into them giving them a more unpredictable sound and feeling.  Perhaps this is because of the use of 5% resistors throughout rather than the more conventional 1%.  It allows for far more drift from the designed specification.  Whatever it is I liked the result and wanted to integrate the PAiA modules more fully with my modular.

As mentioned earlier this conversion began first with the 9720 Dual Oscillator / Modulator.  This conversion brought the number of oscillators in my system up to five.  Having five oscillators in a system has allowed me to produce some damn cool sounds.  I intend to double it before I’m finished.  I was now left with the 9700K MIDI2CV8 converter, the 9710 VCA / Modulator and the 9730 VCF / Modulator.  The nice thing about the PAiA modules is that most include an Attack / Release (AR) or an Attack, Decay, Sustain, Release (ADSR) modulator (or envelope generator).  This flexibility gives the PAiA modules the capabilities of multiple modules.  While the cramming of features into a single module is more of a Eurorack thing it does sometimes come in handy.  The modulators are normalized on the PAiA modules which mean they are tied into portions of the modules circuitry without the need for patch cables.  This normalization, however can be broken through the insertion of a cable into the modulator’s output.

As with the 9720 module the 9710 and 9730 modules only require a slight modification to  support the Synthesizer.com’s +/- 15 volt power supply.  This modification involves first removing the R1 and R2 resistors and replacing them with straight wire link jumpers.  I just used left over pieces of component clippings for this.  While you can short the resistors by just wiring one end of the resistor to the other there will still be resistance on the circuit as some of the electricity will pass through the resistor so I opted to remove the resistors entirely and add the jumpers.

IMG_6258
R1 & R2 (Lower Right) Resistors Replaced With Jumpers

The second step in the power modification involved replacing the 4-pin power connector with a 6-pin Dotcom compatible connector.  The PAiA modules use +15 volts, Ground, Signal Ground and -15 volts.  To add the new connector I simply cut the existing 4-pin connector wires around mid-point and added my 6-pin connector.  Because the Dotcom power supply only has a single ground connection I soldered the Ground and Signal Ground cables together and then linked them to pin 4 (Ground) of the Dotcom connector.  Remember to remove pin # 2 on the connector you use so that it will mate correctly with the Dotcom power supply connector where pin 2 has been filled in for correct orientation.

I should note that I made and tested these power modifications prior to removing the panels from their original FRAC settings.  This way if for some reason the modules failed to function I far less troubleshooting to do than if I had modified everything at once and then tested.  Once I was satisfied that the modules worked with the Dotcom power supply I continued my modifications.

You may have noticed that I didn’t include the 9700K MIDI2CV8 module in the list of modules to which I made this power conversion.  This is because modifying this particular module is significantly different.  While the 9710, 9720 and 9730 modules sit downstream from the 9700K the 9700K itself is connected to the 12VAC wall-wart power supply and supplies the other modules with power.  In order to make the necessary modifications I referred to the Powering the 9700K MIDI2CV8 document provided by PAiA.  This document can be found here.  In a nutshell the modification involves replacing the power connector, rerouting a capacitor, removing the 7805 voltage regulator as the Dotcom supply has its own +5 volt pin required for IC3 (this reduces the power draw by a factor of 10), routing +5 volts to the board and modifying the existing power switch.  This last step is important as the switch cannot simply be removed. The 9700K requires a reset to get things going.  This reset was automatically accomplished with the switch was flipped to activate the power.  I replaced the switch with a momentary pushbutton switch.

IMG_6183
Note the Routing of the Yellow (+5) Line from the Power Connector

When transferring the 9700K to a new panel I decided to leave the board’s connectors in their original positions.  This meant drilling out the panel so that the board could simply be mounted in place while allowing access to the MIDI IN, MIDI THRU and DIP switches.  The tricky part was the DIP switch hole which is rectangular rather than round.  For this I drilled out small holes inside the rectangular area and filed it into shape.  My result is not perfect but it works ok for me.  Additionally because the functions of the output jacks varies based on the positions of the switches I opted not to screen the panel but rather refer to a cheat sheet for the functions of the jacks.

IMG_6186
Modified PAiA 9700K Mounted In the MU Modular

 

Speaking of panels…. Rather than pay wild fees to have a single panel screened by a printing company as I did with my 9720 I opted to have a silkscreen produced for each the 9710 and 9730 modules.  This worked out both good and bad.  The screens produced by Metro Graphics in British Columbia were excellent, however, my silkscreening ability is still lacking.  The results I got for the panels were acceptable for my own use but I wouldn’t produce them for sale until I’ve worked out the kinks.  Some things I’ve learned include; keep the screen about 1 – 2 millimetres off the panel itself.  Cover the area to be screened with a layer of paint prior to using the squeegee.  Apply EVEN pressure using both hands when using the squeegee.  Press hard.  In addition the acrylic paint that I’m using may not be ideal and I’m still searching for the best paint for the job.  As you’ll see from the photos the screening isn’t great but as I said… it’ll do for my personal use.

Once the power modifications were done and the panels screened and drilled it was time to  transfer the modules.  The biggest cost for the job was the 1/4″ jacks.  These panels have LOTS of jacks.  The 9730 has sixteen jacks and the 9710 has thirteen.  I used Switchcraft 112AX jacks.  These are 3 connector normally closed jacks.  I could have gotten away with 2 connector jacks for many of the connections but I got a better deal buying the jacks in bulk (for this project and several others I’m currently working on).  Two of the jacks are actually stereo jacks used on the 9710 VCA.  I began by connecting the jack’s ground lugs all together.  The PAiA FRAC modules have some funky methods of connecting the jack grounds to the potentiometers.  By linking all the jack grounds together it became much easier to connect the few pot grounds to the jacks then back to the board.

Once that was done I desoldered the flying wires connecting the 1/8″ jacks to the PCBs for each of the boards.  I should note that I did one complete module at a time rather than complicate things by doing the modules simultaneously.  Then I removed the potentiometers from the FRAC panels and separated the boards and panels.  For all but one connection (the Pan knob on the VCA) the potentiometer wires interconnecting one another did not have to be cut.  Only one or two ground wires linking the pots to the 1/8″ jacks had to be cut and these were easily reconnected to the new 1/4″ jacks as the jack grounds were all linked together.

I used the PAiA Illustration Supplement for each module to guide the re-wiring process.  I first connected the required resistors, capacitors and bridge wires to the necessary jacks before attempting to wire the flying wires to the panels.  This made soldering things in place much easier.  I then mounted the potentiometers to ensure everything fit into place nicely.  The next step was to connect and pot grounds to the jacks to ensure everything was grounded correctly.  Finally, following the supplements, I connected the flying wires to their respective sockets.  Once again, as with the 9720 VCO, the wire lengths were sufficiently long that they reached their target jacks without extension or replacement.

IMG_6260
9710 VCA Refitted

I did have to remove each module’s LED and add some flying wires to the PCB so the LEDs could be relocated to accommodate my panel design.  Just for kicks I used blue LEDs for the PAiA modules making it easy to locate them in the dark.

Once done each panel was tested using a bench power supply before connection to the modular’s Dotcom QPS1.  If I made a mistake the bench supply would take the hit rather than my production machine.  Fortunately each module worked perfectly and I installed them into the modular after calibration.

So now my modular has the added bonus of some PAiA modules plus I now have 2 MIDI to CV modules allowing me to run my keyboard to some oscillators and an external iPad based sequencer (I still don’t have a sequencer module) to other oscillators.  I’m very pleased with the result!

IMG_6263
5U 9730 VCF / Modulator
IMG_6265
9710 VCA – Note the Right Side – Apply EVEN pressure when Screening

 

IMG_6267

 

 

 

PAiA 9720 5U Retrofit

PAiA 9720 5U Retrofit

Last year I began my adventure into the world of modular synthesizers by building a PAiA 9700 modular synthesizer.  The 9700 is a DIY kit consisting of a MIDI to Control Voltage Converter, Voltage Controlled Oscillator / Modulator, Voltage Controlled Filter and Voltage Controlled Amplifier.  These are the basic building blocks of synthesizers whether  modular or all-in-one units.

IMG_3273
9700 Connected To Roland A-300 Pro MIDI Controller

There are several different size formats for modular synthesizers;

Eurorack is by far the most popular.  The modules are 5.06″ tall, utilize 1/8″ connector jacks (like iPhone headphones), are crammed with features and have very colourful and busy faceplates.  They also run on +/-12 volt power supplies.

Moog Unit modules or MU (or 5U) are based on the early Moog Modular synthesizers.  The modules are 8.75″ tall with varying widths.  MU modules use 1/4″ interface jacks (like guitar cords).  They tend to have a more uniform and conservative appearance as well as larger controls with more space between them.  Most modules have one or two specific features.  MU systems generally operate at +/-15 volts.

The PAiA modules are in FRAC format.  These modules are 5.25″ tall and like Eurorack utilize 1/8″ jacks while cramming lots of features and small controls onto each module.  These modules are designed for +/-18 volts but can operate at +/-15 volts with slight modification.

This is a very basic outline of the various modular formats.  For more information you can follow this link.

Each of these different formats can work together providing you use the correct cable types.  Each format, however, must have its own appropriate power supply.

Personally I prefer the Moog Unit format.  I like the clear, clean, consistent design of the panels.  I find the larger plugs and knobs easier to handle and I find their overall appearance quite impressive.  Late last year I began to build a new modular synthesizer by Synthesizers.com.  In addition to the Dotcom system (as they have come to be known) I also build DIY modules by Oakley Sound Systems, Yusynth, Cat Girl Synth, Moogah and others.  These modules provide the basis for a very powerful sound sculpting platform.

IMG_5775

I wanted to make my existing PAiA system part of that platform.  At first I tested the two systems together by cross patching them.   The two modulars work well together but what I really wanted was full integration.  While surfing the web I ran across a modular builder at Guitarfool.com.  He had created custom made panels for his PAiA 9700 modules and remounted the PAiA electronics into these panels as well as replacing the 1/8″ jacks with 1/4″ jacks.  I got in touch with him and he outlined some of the things he had done as well as providing me with his panel graphic.  Thanks for all your help Jeff!

The first module I wanted to convert was the 9720 VCO.  This module is actually two Oscillators and an Attack / Release Modulator.  I made some modifications to the graphic and had a panel screened.  I used a Synthesizers.com Q133 quad panel.  This ensured a consistent look for the modular and a proper size fit.

The next step was to prepare the 9720 to accept +/- 15 volts as output by the Dotcom’s power supply.  This involved removing R1 and R2 on the 9720 and replacing the resistors with a piece of wire.  You can also connect wires between the resistor points to short them out, however, leaving the resistors in place means that there will still be resistance along the electrical path.  Thanks to Scott at PAiA for clarifying this info.  Finally I replaced the power connector with a Dotcom compatible connector.  Both ground lines from the 9720 must be connected together then connected to the Dotcom’s single ground line.  With this done and tested the time had come to swap panels and jacks.

IMG_6112
9720 Modified For +/-15 (Note: Power Connector And Blue & White Wires In Upper Left)

 

IMG_6113
New Panel (Prior To Hole Drilling) Next To Existing 9720

 

Disassembly didn’t take very long.  Fortunately the potentiometers did not require having their flying wires desoldered which saved quite a bit of time.  Some of the pot to pot connections had to be severed due to length constraints then reconnected once moved.

Because the jacks were all being replaced I desoldered all the flying wires connected to each 1/8″ jack.

Following PAiA’s build document for reference I first added the new 1/4″ jacks, connected the ground leads and then (after repositioning the potentiometers) began connecting the specialty connections such as the capacitors, resistors and cross connections between jacks.  I then ensured that all the connections to the potentiometers were back in place.  Finally I soldered the flying wires back to the new 1/4″ jacks.

IMG_6124
Rewired 9720 Panel

With the system rewired I first tested the module on my bench power supply.  I highly recommend a separate bench-test power supply to anyone doing DIY modules.  In case something has gone terribly wrong the bench supply will short out rather than your modular power supply and any of your modules.  Personally I think it’s worth the extra expense.

With the module tested and working it was time to install it in my modular.

IMG_6130
New Panel Integrated Into Modular

My inventory of 25mm knobs was low but I plan to replace all the knobs so that they match the rest of my modular.  The larger knobs are also much easier to manipulate than the tiny PAiA knobs.

IMG_6131
S.W.A.N. – Synthesizer With A Name

I’ve already designed a graphic for the PAiA 9710 VCA which is my next conversion project.  Before that though I have a few new modules to build.

PAiA VCF
5U design for 9710 VCA

EDIT:  VCO with nice chunky 25mm knobs

IMG_6200

 

Yusynth Minimoog VCF

So far 2016 has been a great year for DIY modules at Lower West Side Studio.  Following the successful build of a Moogah SEM VCF I built a module that I’ve wanted since the moment I saw it; the Minimoog VCF clone produced by Yusynth.

There is nothing like the sound of a Minimoog and that is largely because of its transistor ladder filter.  Yusynth created a circuit based on the original and, like many of his other modules, he has published details on how you can create your own PCBs and build your own modules from scratch.  Unfortunately he does not sell any of his products.

Fortunately for me I didn’t have to etch my own PCB.  Synthcube.com came to my rescue by having some of these PCBs in stock!

img_5942_zpspvqczkfd

The PCB quality was quite excellent.  Very well made and very clearly labeled.  The build documentation for the board, however, is pretty much non-existent.  Yusynth has a page on their site detailing the Bill of Materials along with some very detailed images of the board, component layout, off-board wiring and of course the schematics.  If you’re hoping for a step-by-step instruction manual though, Yusynth boards are not for you.  They are more of an intermediate to advanced build.  Yves detailed diagrams are excellent though and I had no problem putting the board together.

img_5962_zpsrlkzaqo6

While the Minimoog filter is not particularly complicated there are a couple of things to note; there are six BC547 transistors required and these must be matched pairs.  In addition the four 47nF capacitors must be matched to within 1%.  To match the transistors I built a simple breadboard transistor matching circuit.  I used a circuit based on Ian Fritz’s design.

After selecting the correct pairs of transistors and group of capacitors my build went quickly and smoothly.

Once I completed the build I came to the part of DIY synth module building I dread… the panel.  Yusynth provides images for producing silkscreens of the panel, however, presently my silkscreening process is not up to snuff.  This was horrible.  I had a completed, tested working module but no panel to mount it in.

img_5964_zpssbmi3ge6

Then I discovered Free State FX.  They are builders in the US who provide panels for a number of Yusynth modules including the Minimoog Filter.  While the Canadian Dollar is very weak as of this writing the Free State FX panel was still significantly less expensive then the panels produced for me by a local screening company.  I received the panel very quickly and the quality was really good.  I should note for all those who do not wish to build their own Minimoog Filter module that Free State FX produces a built version for sale.

img_6022_zpsqnpqnlxq

Mounting the board into the panel went very smoothly and it was soon connected to my modular for testing.  It works great!  I still have to run the calibration procedure to ensure it tracks volts per octave correctly.  Additionally frequency and emphasis adjustments have to be calibrated.  At this point though I’m extremely happy with the module.

One very nice feature about the Yusynth modules is that they run on 15 volts and utilize a Synthesizers.com power connector.  This makes for quick and easy installation in my modular synthesizer.  One thing I should stress is the importance of a bench power supply for testing modules before installation into the main system.  It costs a bit extra to have a power supply that only comes out for builds but in the event of a build error it can prevent your modular’s power supply and modules from being damaged.  I use a Synthesizers.com QPS2 desktop power supply for this purpose.

I’m very excited to have this module as part of my modular synthesizer.  I plan to add several more Yusynth modules to my rig in the near future!  Thanks to Yves Usson for the excellent design and to Synthcube.com for stocking the part.

UPDATE:

I’ve built another of these wonderful modules, this time for sale.  I created a video demonstrating some of the filters capabilities.  The module sold very quickly but the video is still very useful so I’m including it here.  Please contact me if you are interested in having one of these modules built for you.

Moogah SEM VCF

I recently completed a build of an Oberheim Synthesizer Expansion Module Voltage Controlled Filter work-alike produced by Moogah (Jeff Farr).  I picked up the panel plus PCB package from synthcube.com.

I’ve always been a fan of Oberheim gear from way back in the ’70s.  Geddy Lee from Rush was probably my first experience hearing an Oberheim (at least I knew it was an Oberheim that I was hearing).  In fact Geddy had a Moogerheim mashup.  One very cool feature of the Oberheim’s were their filters which, as I began to understand the workings of filters more and more as my modular synth experience grew, I decided I wanted to add to my modular rig.

7394370004_5cd37b0df5_b
Geddy and his Moogerheim

A very cool feature about the Moogah SEM VCF was that Jeff Farr got Tom Oberheim’s blessing for his design of Tom’s circuit.  The VCF is a 2-pole filter which runs at either 15 or 12 volts (based on a couple of resistors).  There is no V/Oct control voltage so like the original it will only track a few octaves.  There is also no control voltage for the resonance (like the original), however, there is an option to build this in.  The PCB includes locations for the appropriate circuitry, however, the pre-made panels do not include a location for the required potentiometer and input jack.

Wanting my VCF to be as close to the original as possible I opted for the build without the voltage controlled resonance.  There are presently two panel formats available for purchase;  Eurorack and Dotcom/MU.  Because my modular is Dotcom based I opted for the Dotcom panel with the 15 volt power option.

Synthcube.com, the online supplier of the board and PCB, has a nice panel designed by Caleb Condit.  The panel is made from anodized aluminum and illustrated using the metalphoto process.  It is manufactured in the US.  While I really liked being able to purchase the panel with the board both the design and illustration left me a bit flat.  The panel is painted with a flat black paint which tends to show fingerprints more than its Dotcom counterparts.  The white printing is more off-white and significantly less bright than silkscreened panels.  The design, while functional has more of a Eurorack disco feel to it.  I like my potentiometers labeled with numbers rather than cryptic shapes.  Please note that these are only my personal preference.  The panel is well made and just receiving a panel with the PCB was a blessing.  There’s nothing worse than having a circuit built with no panel to install it into.

IMG_6009
The finished SEM VCF (Centre) among Dotcom panels

The SEM VCF is by no means my first, second or even fifth build.  I am not a skilled electrical engineer by any means although I do have relatively good soldering skills.  That said I must point out that this project is definitely NOT FOR BEGINNERS!

Step 1 in the documentation reads “The PCB requires a trace cut to address a design issue”.  YIKES!  That was a new one for me and definitely a bit scary.  The documentation, however, clearly shows where the two traces must be cut.  It also suggests to use a continuity tester to ensure the traces are cut.  I cannot recommend this step enough.  Just because it looks cut doesn’t mean the connection has actually been severed.

Cutting traces often involves adding jumper wires to reroute the flow of those cut traces.  This board is no exception and two jumpers are added later on in the build at step 22 of the manual.  This is a bit of a tight solder to points on the op-amps as they are close to some SMT caps.

Speaking of SMT or Surface Mount Technology caps – these suckers are SMALL.  VERY SMALL!  Normally SMT components are installed by machines.  They allow us to have very tiny devices like cell phones.  Soldering them by hand is a difficult process but not impossible.  It takes patience and a steady hand.  As my first attempt I can say that while not perfect, I did ok.  There is a handy video from Colin’s Lab showing how to solder SMT devices.  In addition – get smaller tweezers than the ones shown below!

IMG_5992
Next to my index finger and tweezers – this thing is small!

 

The PCB quality of the the SEM VCF is quite good, however, unlike several other boards I’ve used the components aren’t marked by their reference numbers (e.g. R1, R2, C15, etc…).  They are, however, marked with their component values.  This makes it a bit trickier locating their positions especially as some of the labels are obscured by the through-holes drilled into the board.  Several of the labels are marked with dollar signs ($) to indicate that they are required for building the version of the board which includes the resonance control voltage.  Others are marked with asterisks (*) to indicate they are to be excluded for the CV resonance version.  Overall though I found it easy to locate the component spots and to populate the board.

IMG_5975

The documentation for the project is quite good with one exception;  it is only for the Eurorack build.  While there is reference to which resistors to install depending on your power supply’s voltage, 12 or 15 volts (step 8) there is no warning about soldering the potentiometers to the board for the Eurorack panel (step 18).  I didn’t catch this at first and had to desolder my potentiometers.  What a freaking nightmare.  All went well though and I attached flying wires to the three potentiometer locations for the pots.  While a separate documentation is not necessary for the 5U build of this project it would be helpful if the author could mention the slight differences in the builds for the reader.

IMG_5983
Pots soldered on before removal
IMG_5996
After desoldering replaced with flying wires

Obtaining parts for the build was not too tough, however, there are three 2N4302 transistors which are discontinued and a bit tricky to find.  I was able to find work-alike versions of these transistors from Small Bear Electronics.  Incidentally, Small Bear is an AWESOME source for components for many DIY projects!

Another VERY important note is that if you are using the provided spreadsheet Bill Of Materials there is an error on row 25.  The Poly Cap listed is 150nF (nano-farad).  It should be 150uF (micro-farad).  Big difference!  This is corrected in the Bill Of Materials contained in the build document, however, not on the spreadsheet.

As I mentioned earlier, having the panel to install the board onto immediately after it was done was a tremendous advantage.  Once completed I tested the unit with my bench power supply.  I cannot stress enough the need for a bench power supply.  If a mistake was made on the board I would much rather blow up a bench supply then the power supply in my modular and also risk taking some modules with it.  I use a synthesizers.com QPS2 desktop power supply.  I’ve also modified one of the power connectors to support a MOTM/Oakley style connector.  This allows me to test both Dotcom and MOTM/Oakley modules with no muss nor fuss.  The VCF utilizes an MOTM/Oakley style power connector.  Once tested I built MOTM to Dotcom connector convertor and installed the unit in my modular.

IMG_6003
Setup and ready for testing

So there you have it!  A very cool module built in about two days.