You may have read that here at Lower West Side Studio we have a number of Moog Slim Phatty synthesizers polychained along with a Moog Little Phatty Stage II for what is (at this writing) a six voice polychain.  I’m hoping to max it out at sixteen some day.

I’ve named the unit Phatt Bastard and you can read more about it here.

The Moog Phatt Bastard Polychain

Handling multiple machines in a MIDI chain has its challenges.  One of these is keep all the patches on each machine synchronized.

When polychained, each Phatty in the chain is set to the same MIDI channel.  MIDI commands sent from the controller of the chain, in my case a Little Phatty, to each machine on which they are acted upon.  System commands controlled through the Master switch must be performed on each machine individually.  These global functions include MIDI setup, tuning, clock setup, etc..

Saving presets is easy though as the Write button will activate the Write function on all the units in the chain thereby performing the save across the board.

So here’s what happened…..

I’ve collected a group of patches I really like from a number of Phatty patch libraries.  I’ve had the factory libraries from both Slim and Little Phattys plus several libraries available online.  I saved each patch via Sysex Librarian and then, once I had all the patches collected, I sent them one at a time  back to the chain.

Sending sysex commands to the polychain is easy as the commands filter down the chain to each machine.  This means that sending the patch once updates each machine simultaneously.  Switch the controller to the next patch, send the next Sysex patch, repeat….etc..

NOTE: Only have machines that you want to update turned on in the MIDI chain.  Sysex Librarian sends commands down the pipe to ALL machines and you never know if an update for one type machine will blow up another.

Once I had the patches loaded up to my liking I used Sysex Librarian to receive a Bulk Dump from my Little Phatty (remember, this is the main controller in the chain of Slim Phattys).

This is where the problem started.

A few days later I loaded one of my older libraries into Phatt Bastard.  When I wanted to switch back to the new library I created I went to Sysex Librarian and sent the dump file back to the chain.  The trouble was it was a dump from a Little Phatty being sent to five Slim Phattys.

Everything seemed to work but…  Some machines wouldn’t play sounds in some of the patches.  Some machines wouldn’t play any sounds at all.  Patch names were garbled in some cases.  Some machines would then would not respond to MIDI commands from the controller.

I used the Factory Reset option in the Master menu and restored each machine.  I downloaded my patch file again (remember, this is a Bulk Dump and not an All Preset Dump).  Same thing but this time Slim Phatty #5 was stuck on patch 86 which had a garbled name.  No controls would respond.  Reboot.  Same thing.  Re-flash via USB.  Same thing.  Number 5 – Dead.  No response.  Re-flash via MIDI (not in the chain – directly from my MIDI I/F to #5 MIDI IN).  Still locked.  Patch 86.  Garbled name.  No response from any control.  Tried flashing from a different machine via USB.  Same thing.

Meanwhile I figured out that the dump file was sending something that the Little Phatty liked but upset the Slim Phattys greatly.  The other machines were set up back in their polychain with factory default patches.

So now the panic is setting in.  Number 5 is dead.  Locked up.  Not responding to anything.  I can re-flash the firmware over and over (SlimSystem_v3_21_690.hex ) but it still comes up locked.  It looks like this might have to go into the shop…

Just before I grabbed the screwdriver to remove #5 from the Phatt Rack I thought “what if I flashed the Slim with the firmware I have for the Little (StageSystem_v3_21_691.hex)”.  What would it hurt at this point.  So I did….

…and what happened was that #5 was alive!  Alive but reeling like a bar patron after last call.  The patch names were all messed up BUT I could access the controls.  Even the Master menu was baffed – But pressing the Master button at least DID something.

The next step was to re-flash the firmware with the Slim firmware again via USB.

After this flash #5 started up but all the presets still had messed up names.  This time, however, I was able to access the Master menu and perform a Factory Reset.

TADA! Good as new.

I’m guessing that the lack of a checking routine in the firmware loading software let the Little Phatty firmware code slip by the Slim Phatty’s detection.  Because the machines are so close in function they likely share a huge slug of the same codebase.  This is why #5 didn’t simply curl up and die.  Updating #5’s firmware to the Little Phatty kick-started just enough of the OS to break the lock on the controls.  Once that was done the bootloader and one more firmware update did the trick.

I don’t know if this will work all the time but it worked this time for me.

One last note;  Of my five Slim Phattys all but one have Bootloader v1.1.  Number 4 has version 1.0.  I’ve tried to update the firmware using the same file I update the other Phattys with but with no success.  In a couple of cases I’ve had strange things happen to #5 and #6 after I’ve sent MIDI dumps of preset banks to the chain.  I’ve long suspected that perhaps they fixed something in that 0.1 update that makes MIDI work properly.  I have therefore moved #4 to the #6 position (the end of the chain at this writing).  All the machines preceding it are v1.1 so IF the 1.0 loader had something to do with the problem, hopefully this will help correct it.