PolyLAB Update 1/23/2014

List of things competed:

• Prototype Case built
• LFO, S&H, Globals PCB, Saw2Tri, Midi2CV, Power Supply & Transformer all mounted
• Globals Panel Prototype built
• MIDIpal LCD and Encoder installed and mounted to Globals Panel

To Do:

• Wire it up!

I built a quick-and-dirty power buss board, but I did order a PCB.  Just waiting for that and 1 10k Pot for Voice 2 Resonance.  I ended up going with the Midimplant MIDI2CV with a MIDIpal for the dispatch to achieve poly.  The nice thing about the Midimplant is 1 board has 2 independent midi2cv's.  Each can be assigned a MIDI channel and have their own V/Oct & Gate.  Wish I had read the spec more clearly before I ordered a 2nd one.  Guess one can never have too many midid2cv's.

Hopefully 1 more month and the prototype will be complete!  Then, this spring I'll try my hand at bending aluminum.

Official PolyLAB Page Added

Added a PolyLAB page to the top.  In it you will find a full description of what it is and where it's at.  I will update is as progressions are made as well as posts on the home page.

PolyLAB Update

The main globals PCB arrived and has been populated. Just missing 1 capacitor. So far the Portamento and gate led drivers have been tested.

Next PCB, which should arrive this week is for the 2 MIDImplants (although I probably could have used only one. It pays to read the manual fully first, kids).  It's also got a 5v power supply for the MIDI thru. 

Other than that, I should have a working prototype within the next month or 2. The case is going to take a while as I probably won't be able to bend the metal or paint until the weather warms up. Oh wells. 

PolyLAB Update 11/15/2013

Think I finally decided on a the MIDI 2 CV.   Hexinverter.net has a DIY MIDI2CV that pretty much fits the bill.  The only issue is it cannot chose how many voices for poly.  It's either 1 or 4.  But, there is a version of software over on muff's that allows to select how many voices, among other things.  At first I was just going to hardwire it under the panel, but I decided that I would wire switched jacks and normal everything for 2-voice poly, but when a cable is inserted, it will break the connection.  Should be pretty cool.  While I'd like to have a custom one built, I don't know how to write code and it would probably be a lot more expensive to pay someone to build it for me.

The Globals panel is pretty much laid out.  I just ordered that last remaining parts needed.  Now the big challenge is getting the case designed and built.

PolyLAB Update 11/12/2013

Lastest and possibly final PCB revision.

Here's what we got:

• Mod Bus (Osc 1, Osc 2, Filter, PWM).  Each destination is global.
• 2 Portamento's, each with their own amount knob and symmetry (slide in, out or both).
• Master Audio Output Mixer
• 2 Gate LED Drivers

Probably going to order up the boards next week.  Hopefully I can get it built and tested by the end of the month.  

Now, to find someone willing to write code for the polyphony dispatch & MIDI 2 CV....

PolyLAB Update 10/31/2013

Welp, the global cutoff and resonance knob switching has been completely redesigned.  The amount of parts needed for something so simple was just bugging the hell out of me.  So, I ended up ditching it all together and going with simple rotary switching.  Now it will have independent controls for each.  The Cutoff and Resonance will each have a 6-pole 2-throw Rotary switch which will send it either to it's local pot or the dual gang global pot.  The nice thing about this is not only is it waaaay more simplistic, but it will allow individual control of each parameter, such as if I want to have control of but cutoffs but with 2 different resonance amounts.  I'm thinking that could be a pretty neat feature.

I finally wired up the Saw to Triangle PCB to my working Soundlab.  Holy crap!  The low end that comes out of this thing now is incredible!  This synth absolutely needs this added to it!  I'd highly suggest adding this to yours if you have one.  The circuit is easy to wire up to some perfboard.  I used a 3PDT toggle to switch between the 3 waveforms.

Here's a wiring diagram for the 3PDT:

Here's some pics of it in place.  Double sided sticky foam is great!:

PolyLAB Update 10/22/2013

Slowly coming along.  I think the PCB design is finished.   I crammed everything onto 1 board.  It will have the following:

• Modulation Destination Switching
• Cutoff & Resonance Switching (for global and local controls) with a Mono/Poly Switch and LED indication
• Portamento

The Portamento was an addition I just did last night.  There are 2 on the board actually.  1 for each voice.  There will only be 1 Amount Pot.  It will be asymmetrical, meaning there will be a switch to choose between slide into note only, slide out of note only or slide in and out of note.  Should be a pretty cool feature.

PolyLAB Update 10/11/2013

So much for keeping the PCB costs down.

The global Filter Cutoff & Resonance pots were a bit more involved than I thought, but this is a section that I feel the synth must have.  Pretty nice looking PCB though.  I still have to go through and label everything, but I'm hoping this and the Mod Bus boards will be ready for fab next week.

PolyLAB Update 10/6/2013

Well, the more I looked at the design of the Mod Bus, the larger the part count was getting, so I scrapped the original idea.  I worked it down to just  3 CV Mixers and let the rotary switches handle all of the switching.

The LFO Wave Selector rotary switch stayed, but the destinations were reduced to OSC 1, OSC 2, Filter.  There is now 2 Mod Source/Destinations.  The Source will just be a standard Toggle switch between LFO & S&H.  Both toggles will wire to the Amount pot.  From there it will wire to the Destination Rotary switch to be sent to the Mod Bus Mixer PCB.  This is a much simpler design and will keep the PCB cost low.  With the previous design I was pushing the cost for 3 boards over $100.  This new design is about $25 for 3.

On Friday I put an order in for the Saw to Triangle Generator!  I also designed and ordered a small board for the rotary switches.  Instead of having to solder a bunch of flying leads, they will all be connect to a molex connector.  Nice and neat.

Now that the Mod Bus was redesigned, the Global Control Panel will have to be resigned.   I may also be replacing the 2 MFOS panels and putting both + the Global Panel on 1 piece of sheet metal.  I had a thought to redesign the layout of the 2 Soundlabs and move all of the patch points between the global control and the 1st Soundlab.  Oh, and I will be replacing all of the banana plugs with 3.5mm jacks.  The main reason for doing this is so I can connect it to my dotcom and eurorack modular easier.  Banana patching between different power supplies is a pain because it does not carry the common so I would have to have a dedicated banana plug that was wired to common to bind the commons between systems, as well as have a separate unit with banana to TS Jacks (I did build one, but with more than double the patch points, it's just not worth it to keep the banana jacks).

That's all for now.

Note the INPUT labeling is wrong. Instead of LFO or S&H it will just be 1 or 2 and its destination as both busses will be switchable between LFO and S&H. 

PolyLAB Update

Other than finally settling on the name, PolyLAB, I got the Global Modulation Panel figured out (hopefully).  here's a pretty 3D rendering:

I also worked Ray Wilson's design of converting a Saw Wave into a Triangle wave onto 1 board.  This will give each Oscillator a Triangle wave.  4 in total:

This was my fist time designing a schematic and PCB.  I took the crash course over the weekend (staying up until 5am reading tutorials).  Once I got past the initial fear of it, it's surprisingly not that complicated.  I found it to be way more intuitive that I had thought it would be.

Hopefully within the next couple weeks I can have everything wired up and tested.  The case is on the back burner for now.  I'm still pretty sold on the idea of bending the sheet metal myself.  On the fence with the paint.  Oh, speaking of which, I think I'll paint the MFOS front panels as well, so it's all uniform.  Gonna be doing a lot of silk screening.

Also, after I complete and get the first one 100%, I'll more than likely sell additional units.  At the moment, I only plan to do 2 more (as the PCB's are ordered in multiples of 3).   If I do any future batches, it would more than likely be in groups of 3.  

Poly Continum

Global panel design complete!  Wiring nightmare!  

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.