Things are always changing and Lower West Side Studio is no exception.  It’s what keeps things fresh.

Recently I was thinking about the fate of my Moog Sub 37.  I really enjoyed the synthesizer but lately I found I just wasn’t using it for that much.  The sound was good but menu diving and a poorly constructed software editor made creating sounds less than fun.  It was much easier to create sounds on my modular.

Then I became interested in the Sub 37’s Polychain feature.  Polychaining allows multiple synthesizers to be connected together to increase the overall number of voices you can play simultaneously.  The Sub 37 has this feature as did its predecessor’s the Little Phatty and the Slim Phatty.  We’ll get into more detail about polychaining later on.

I started looking around on the Internet to see examples of polychained Moog Phattys.  There were some very nice setups.  I ultimately came across Pete Brown’s 6 voice Slim Phatty polychain.  The sound was really incredible and having a polyphonic Moog synthesizer would offer a lot of new sonic possibilities.

Even better was the fact that each of the Phattys have control voltage inputs for Pitch, Volume, Filter and Gate.  There were a lot of possibilities for interfacing them with the modular systems we have.

I was hooked on the polychain idea now.  I would build a large polychained synthesizer consisting of Moog Phatty voice modules.  And I would call it….. Phatt Bastard.

Building Phatt Bastard

At first I thought I’d chain a few Slim Phattys off the Sub 37.  There were a few problems with this.  The biggest problem was that the patches in the Sub 37 and the Phattys were different.  Further, they couldn’t be exchanged between the two synths.  No surprise there as the Sub 37 has more  features that the Phatty series.  Next, the control interface of the Sub 37 differed from the Slim Phattys.  This wasn’t a huge problem but more of an inconvenience.  The patch memory layout also differed between the two machines.  The Phatty can store one bank of one-hundred presets.  The Sub 37 has sixteen banks of sixteen presets per bank for two-hundred fifty-six presets.  Selecting the appropriate Phatty bank / preset combination with the Sub becomes a bit of a math puzzle.

I decided to start the project by hunting down a couple of local Slim Phattys to start the chain.  Kijiji was very helpful in this respect.  The Slim Phatty is a discontinued product and must be purchased from either old inventory or pre-owned.  I know of one in old inventory but the vendor wants almost 50% more than it can be had for on the used market.

The first two Slim Phattys were obtained from Toronto and Montreal.  I hooked them up with the Sub 37 and was immediately impressed and depressed.  Impressed that I was playing three-voice polyphonic chords on Moog synthesizers.  Depressed because matching the Sub 37’s voice with the Phatty’s was a pain in the ass and never quite sounded the same.  This made for awkward sounding runs and chords (although it wasn’t all bad).

Then something wonderful happened.  I’ve always been a huge fan of Sequential Circuits / Dave Smith Instruments Prophet series of synthesizers.  Since I first heard their distinctive sound I was floored and that sound was something I wanted in the studio.  As it happened a fellow on Kijiji wanted to trade a DSI Prophet 08 for a Moog Sub 37.

I was right there and made the trade.  I’m glad I did as lately, with Moog’s release of the Subsequent line of synths the used Sub 37 market is booming with tons available for sale and prices bottoming out.  As for Lower West Side Studio – a Prophet had arrived and things would never sound the same.

So now I’m controlling my two-voice Moog Slim Phatty polychain with whatever keyboard controller is around.  A Roland A-300 Pro.  A Yamaha DX7 II-D.  A Native Instruments Komplete Kontrol S61MKII.  I kept going back to the A-300 Pro though and quickly threw together a template of MIDI CCs to control the chain.  Meanwhile another Slim Phatty was inbound from South Korea and one from the UK.

4 Moog Slim Phattys Polychained Together

The best way to sculpt sounds was to control the chain through a “Phatty” interface.  To this end I looked for a Moog Little Phatty Stage II.  The Little and Slim Phattys both share the same panel interface and more importantly patches.  I found a wonderful used Little Phatty from Calgary and soon it was controlling the chain.

Rack ’em Up

The next step was to rack up the Slim Phattys and work out a way to integrate everything with my existing system.  There were also a few details to work out.

Each Phatty would act as a voice in the system but each Phatty also had its own Audio Output to deal with.  This was handled through the addition of a Behringer RX1602 line mixer.  The RX1602 is a simple mixer with 8 stereo inputs .  I’ve got each of the Slim Phatty’s plus the Little Phatty all mixed into the RX1602 and then that stereo output passed on to my Mackie Onyx mixer.

There was also the matter of control voltages.  Each Slim Phatty has the CV inputs on the back.  This is not very conducive to patching on-the-fly.  For this reason a Samson S-Patch Plus patchbay was added.  The Samson was chosen for its solid construction, good reputation, reasonable price but most of all for the fact that one of its designers had the brains to put the jack selection switch on the front panel where it can be changed easily – even if the unit is mounted in a rack.

The rack chosen for Phatt Bastard was a JamStands JS-SRR100 Rolling Rack Stand.  We’ve got one of these beauties holding a Mackie Onyx 1640i, compressors, EQs, a Mac and more and just love the convenience of the adjustable tilt and the wheels.  There are 12U on the top rack and 9 on the bottom.  With the Slim Phatty coming in at 3U this rack would seem perfect.  It sure would seem that way.

Bogey Guards the Phatt Bastard Prototype


With the Phattys all in their places and wired for sound with a three foot cable between each Slim and the RX160 plus a ten foot cable to the Little Phatty it was time to hook up the polyphonic chain.

Moog has a great video showing how to do the setup which is not difficult at all.

The crucial things to remember are;

  • each device in your chain MUST BE SET TO THE SAME MIDI CHANNEL.  It doesn’t have to be channel one (1) but whichever you chose make sure to set them all for that channel.
  • Each device’s device number must be unique and in sequence (e.g. 1 of x, 2 of x, 3 of x, etc…)
  • The maximum number of devices (x in the example above) MUST be correct.  It should be the total number of devices emitting a voice.
  • After setting up or changing your MIDI parameters, reboot your Phatty chain to ensure all devices are on the same page.

Another thing to consider is the length of your MIDI chain.  MIDI can have a nasty habit of dropping information along a long chain.  Often these drops are NOTE OFF messages leaving something in your setup wailing away for an unknown reason.

To avoid this I’m using one foot MIDI cables between the Slim Phattys with a two foot MIDI cable (thank you for the long jump between top and bottom racks.  This also gives me a little more leeway in using a longer cable between the Little Phatty and the rack of Slims.

To USB Or Not To USB

Moog’s Phatty line of synthesizers were their first to include a USB port.  This port can be used for MIDI I/O and to install firmware through Moog’s Phatty Loader application.  I briefly considered wiring all Phatt Bastard’s USB ports to a USB hub then back to the computer but what was the point?  All the firmware was up-to-date on the Phattys and any Sysex data that needed transferring could be done through MIDI.

In the end I decided that if a Slim needed a USB connection for whatever reason I would plug it directly into the computer’s USB port for the necessary chore then unplug it.

The Little Phatty was a different story though.  Phatt Bastard needed a way to communicate with the studio computer.  Whether it’s for Sysex transfers or MIDI communication with my DAW the chain had to talk to the computer.  The Phattys make this easy though as the USB port can have data forwarded to and from its MIDI DIN In / Out ports.

Further, and most important for my application, the Little Phatty can merge MIDI data coming from its MIDI IN port with data going out its MIDI OUT port.  This THRU / OUT merge can be extremely handy.

Keys Please

The Little Phatty keyboard is perfect for its design.  As a bass synth or ripping lead synth three octaves is just fine.  When you get into polyphony though it’s helpful to have a wider range of octaves to play through.

This is when I thought of combining the Roland A-300 Pro controller with the Little Phatty.  I connected the A-300 MIDI OUT port to the Little Phatty’s MIDI IN port and then the Little Phatty’s MIDI OUT port to the MIDI IN port of the first Slim Phatty in the chain.  With all the devices MIDI channels set the same everything worked great.  I could play both keyboards at the same time.  I could control features of Phatt Bastard with the Roland.  It seemed like a perfect world.

And then a note skipped.  I tested by repeatedly pressing a key and sure enough it seemed like one of the Phattys stopped working.  I sent an ALL NOTES OFF message and was good to go again.  Then a note dropped.  And so on….

Without going into huge detail there are a couple of things I’ve discovered.  First, a Phatty is not losing a note.  What is happening is at some point one MIDI trigger is firing off two Phattys at the same time.  Those Phattys will act as one device until an ALL NOTES OFF message is received to reset things.  Because two are acting as one the round-robin tracking performed by the polychain feature gets confused and thinks a voice is missing.

So what’s the solution?  Simple;  use one keyboard at a time.  This is not the ideal solution but basically tests have shown that at some point the Little Phatty’s MIDI merge feature where it blends its own MIDI OUT with whatever is coming in its MIDI IN port fails.  Playing either only on the Little Phatty’s keyboard or on the external MIDI keyboard seems to stop this problem from happening.  Adjusting the controls on the Little Phatty doesn’t seem to cause a problem no matter which keyboard is being played.

Well this now caused a dilemma as I could no longer use two small keyboards as one large keyboard.  All that aside there was still a coral of synthesizers that needed to be integrated into the setup.  Included in these are a Yamaha Motif XF6, Arturia MiniBrute, the new Prophet 08, an ESI-2000 sampler and oh yeah…. a dual-MIDI port modular synthesizer.


Here’s the picture that’s worth a thousand words…

LWSS MIDI Setup - March 2018.jpg

One excellent feature of the Roland A-300 Pro controller is its ability to merge incoming MIDI data with outgoing MIDI data much in the same way the Little Phatty does.  This merged-THRU has opened up some cool possibilities.  I’ve connected a DX7 II-D to the A-300’s MIDI IN port so that either keyboard can control any variety of synthesizers in the setup.  I’ve also got a set of PK-5A MIDI pedals here which belong to my bass player (hi Jim!).  I’ve wired them into the A-300 along with the DX7 via a MIDI Y-Cable.  Now anything coming out the A-300s MIDI out can be source of control.

To distribute the signal a MIDI Solutions Quadra Thru box is used.  It will take a single MIDI IN and distribute it to 4 MIDI THRU ports.  The box is inexpensive, powered by MIDI and works like a charm.  As you can see from the diagram each of the THRU ports are designated to a specific arm in the chain.

This setup also enables use of the Slim Phatty’s USB MIDI for two purposes; first it can be used with a Sysex Librarian or similar program to download patch data to Phatt Bastard. Patch data is sent to all Slim Phatty’s (and the Little Phatty) simultaneously.  The USB/MIDI interface also “listens” to the Little Phatty’s keyboard  and sends that MIDI data back to my DAW.

Having the A-300’s USB/MIDI combination allows me to record any MIDI data being sent from the PK-5A, DX7 II-D and the A-300 itself back at the DAW.  Between these two interfaces most of the MIDI data generated by the system is captured.

But what about the keys played on the Prophet, Motif and MiniBrute?  To capture note data (plus other CC data) from these machines another MIDI Solutions box was used, this time the MIDI Merge.  The Merge features 4 MIDI inputs merged to a single MIDI output.  Each of the synthesizer’s MIDI OUT ports are connected here and then sent to a Yamaha UX16 USB/MIDI interface.

I can then set my DAW, Reaper by Cockos,  to record data from  All MIDI Interfaces and select the channels I want depending on which instrument I want to record.  It’s a much easier way to map MIDI than by specific interface.


So Just How Phatt…

Right now Phatt Bastard is sitting at six voices.  I think this is an excellent start.  Dual triad chords are no problem but of course the voices will start to drop if you solo over a sustain.  The polyphonic Moog is an incredible companion to the Prophet 08 and the two sound absolutely wonderful together.  As fun as the Motif is I won’t even compare it to either of the analog synths.  Alone the Motif sounds fine but compared to real analog synths its samples don’t hold a candle.

My ultimate goal is to max out Phatt Bastard at sixteen voices.  That’s the maximum number supported by the operating system.  For now six voices is ok.  I’d like to take it to eight voices in the next twelve months.  Eight is a good number with a small amount of room to breathe.

Still even eight voices can be used up quickly and I’m very happy to know my Prophet 08 can be polychained with a second unit (or the desktop version) for a total of sixteen voices.

Up next is also the control voltage implementation.  Because each Phatty can be cv controlled on its own I’m not sure how to best use this.  As a giant polysynth?  As a bunch of monosynths?  As several small polysynths?  Only time will tell….

Phatt Bastard with EMU ESI-2000 (with Phatt library)


By the end of 2018 Phatt Bastard was up to seven voices!


Once up and running there isn’t much need to fiddle with the Slim Phatties so they were moved to a vertical rack system.