Tuesday, September 10, 2013

SLMSX2 (MFOS Soundlab Mini-Synth MKII 2-Voice Poly Synth)

The past couple of months I have slowly been designing a 2-Voice Poly Synth. At it's core, it is 2 MFOS Soundlab Mini-Synth MKII's.  I've spent a lot of time tweaking ideas on how to implement everything. Pretty much all of the parts are there, I just need to put it together. Easier said than done.

It starts at a Mutable Instruments MIDIpal.  Eventually I will try to tweak the MIDIpal code so it only has some of the apps, like Dispatcher (of course), arp, seq and maybe some others. Keep it simple. The MIDIpal will be connected internally to 2 chained midimplant's (MIDI to CV) which will be wired to each Soundlab. This is how the polyphony will be achieved.  I will have MIDI IN & THRU jacks mounted on the rear of the case. 

The front panel will have both Soundlabs mounted side by side. There will be a 3rd panel to the left of the 1st Soundlab that will be home to the MIDIpal as well as some other cool stuff. This "Master" panel will have the following, top to bottom:

  • MIDIpal
  • LFO
  • S&H
  • Cutoff & Resonance knobs
  • Mixer and master out volume

The LFO, S&H, cutoff & resonance will be global controls. 

The LFO will have 2 rotary switches.One waveform and one destination. It will also have PWM knob and an amount knob. 

LFO Waveform switch:

  • Sine
  • Triangle
  • Sawtooth
  • Reverse Ramp 
  • Square 

LFO destination switch:

  • OSC 1
  • OSC 2
  • OSC 1&2
  • Filter (cutoff)
  • OSC 1&2 + Filter

The S&H will only have 1 rotary switch which will be the same as the LFO destination.  Along with the normalled destinations, they will also have banana jack patch points.   Noise from the 1st Soundlab will be hardwired to the S&H input.

Next is the filter cutoff and resonance knobs. These will be connected to a series of 4053 IC switches. There will be a Poly/Mono toggle witch will route both Soundlabs cutoff and resonance to either the Poly global knobs or their dedicated knobs via the 4053's. The global pots are 2 dual gang potentiometers with a 5% tolerance.  In theory this should work, but I haven't breadboarded it yet. There will be an unused switch at each pot which I will use to drive 2 LED's that will show which state the synth is in (mono or poly). 

Lastly is the global mixer. As each Soundlab has a dedicated output, I will wire them to switching jacks. When not used, the outputs will be sent to the mixer where I will have a pot to mix the volume of each Soundlab as well as the final volume output. It will go through a stereo mixer where I can pan each synth. The final output will be wired to 2 jacks at the rear of the case. The Left will be normalled to the right, unless a jack is plugged in for stereo effects. 

Each of the synths CV & Gate jacks will be normalled to the midimplant unless a jack is inserted, which will break the connection from the midimplant. 

I am also adding a circuit to each oscillator to give it a Triangle wave. 

Finally, I want to add a D-Sub connector (ala minimoog voyager) to access additional inputs and outputs for each Soundlab. It will connect to a separate box with the jacks and pots (again, ala minimoog voyager)

The case will have a sheet metal base and wood sides. I'm planning on cutting, bending and drilling the sheet metal myself. I may take it to be professionally painted, price being the biggest factor.  Ill probably screen print the panel descriptions myself as well.  I'm still on the fence if this will be the only one or if I will make them to order. As it is now, these will not be cheap. Just for the 2 Soundlabs, it's close to $1K without build costs.  If you are interested in buying one, leave a comment bellow and I'll keep you posted as this progresses.

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