PLAN B Model 15 VCO

Click on the rightside image for an explanatiion of what you're seeing

The Model 15 is currently availible through Big City Music. click here For info on the MILTON 16 x 4 Voltage Controlled Analog Sequencer, click here I do custom modules as well. Go here

Click here for power connection instructions Click here for 1V/oct tracking adjustment Click here for Expo Board insertion guidelines IMPORTANT!

Sound Samples: Sine on Sine FM demonstrating it's transcient response to a 'chiff' Another Sine on Sine FM example Another demonstration to it's unique response to chiff transcients Pulse output into it's own FM input (comes in midway in the sample) Saw wave output A sample of the unique sound of it's PWM (comes in midway in the sample) Another sample of the unique sound of it's PWM (this is REALTIME from a SINGLE VCO. Nope,. that's not two you're hearing!) PLEASE NOTE: Only 1 Model 15 was used in these samples and outside of the second FM and saw wave demonstrations, they are all real-time. CLICK HERE TO READ WHAT MODEL 15 OWNERS ARE SAYING

You want fat...well how about OBESE? The Plan B Model 15 is an analog Voltage Controlled Oscillator (VCO) featuring a triangle wave core, two independent fully processed (+/-) VC inputs, a single 1V/Oct input,, a dedicated expo FM input, sync, independent Sine, Triangle, Saw and PWM outputs and a Wave Morph Output. The VC Wave Morph is a vactrol-based (read: smooth) crossfade function via a manual pot setting or VC control and the morphs from Sine to either Saw or Square wave outputs. Due to it's triangle core and epoxy-sealed expo converter architecture, the sound replicates that of the Buchla 258 with stability better than .01% (less than 4 hertz drift at 1kHz over 24 hours) and boasts a frequency range of 1 to 20Khz and a maximum power consumption of only 40mA. Why is it called the Model 15 you ask? 2 plus 5 plus 8 = 15. Simple! From requests received on the A-100 Yahoolist and with Dieter Doepfer's full approval, Plan B is producing these VCOs in a 18HP wide +/- 12 volt DOEPFER FORM FACTOR. The model 15 will run on 15, although component changes are required. There is a one year warranty for parts and labor.

Sorry, no kits or alternate faceplate configurations will be sold at this time. Please expect a six week period after your down payment for delivery as components, faceplates and boards arrive TRACKING SPECS (Important): NEWS FLASH: Various component improvements on the Model 15 core have increased for 1V/oct tracking to SEVEN OCTAVES - with none of the hick-ups associated with sawtooth core VCOs past the 3k limit. An important note: the Model 15 has a TRIANGLE core. Because of that, the high freq compensation circuitry associated in saw core VCOs is unnessesary as there is no fixed charge time - the positive slew of the Model 15's triangle core tracks the oscillating frequency. Technically speaking, there are three sets of transistors in the Model 15's core that affect current. The accumulation of the resistor values which were previously spec'd in that core were keeping these transistors, most notably the current mirror and expo converter, on the bleeding edge of their linear region and within a 10th of a volt of the rail. The net effect was limiting the tracking range to about four octaves. A simple substitution of resistor values in the core has shifted the current variances well within the heart of these transistor's flat region, which has increased tracking to over seven octaves. Click here to hear a sample of the Model 15 tracking Note: The distortion you hear is due to the mp3 compression. The signal heard here is the triangle wave output of the Model 15 Click here to try this at home (download the mid file used in the above soundfile) While I have you....need an analog sequencer? My feeling is life is too short for Avis when you can have Hertz. Click here for MIlton

Model15 status (9/15) The bulk of the high volume components (knobs, jacks, vactrols, pots, faceplates, analog switches, transistor pair, chip tempco resistors, mechanical switches) have arrived. The faceplates are going out for drilling this week. The PCB sets (there are four boards per VCO - main board, expo board and 2 jack boards that the faceplate jacks mount to) have not yet arrived, but should the same week the faceplates return from the machine shop. The rest of the components are availible locally. Status Update (10/3): I have feceived word that the bare boards are completed and in transit to me. Once this happens, I'm then building two prototypes - one running from +/-15, one running from +/- 12 volts. I will use these two as my first article 'gold'; samples during the first production run. These two samples will be finished production units and will ship as well as soon as the first run is completed. Long story short, I will be in production of the MOdel 15 in one week's time Status Update (2/10/05): The Model 15 is shipping.

Controls: Frequency Fine Frequency (+/-10%) VC 1 Processing (full +/- attenuation - center being null) VC 2 Processing (full +/- attenuation - center being null) FM Level Manual Wave Morph Manual PWM Morph select switch (selects 'to' condition to either saw or square wave) Jacks: Freq VC Input 1 Freq VC Input 2 Expo FM Input 1V/Oct Input VC Wave Morph Input VC PWM Input Sync Input Sine Output Triangle Output Saw Output PWM Output Wave Morph Output

Waveform Samples (excuse lousy photography) : Please note: It took me hours to get these photo's (somewhat) in focus and in the process did not align the waveforms on the scope (D'oh!) - these waveforms are symmetrical!

Sine Out: Triangle Out: Saw Out: Square Out: Sine to Saw Morph 1: Sine to Saw Morph 2: Sine to Saw Morph 3: Sine to Saw Morph 4: Homer out: Inverted Homer:

OK OK OK...those two are a joke - the ones above that are the real deal however.

Recently posted on the Analog Heaven maillist: <name withheld> writes: Since I'm buying two of these new Buchla style oscs and a quad Lowpass gate as well as some PSIMS I feel so buchla-y and have a new question about the music easel.... My reply: Hmmm...out of respect for D. Buchla (which I have a ton of) and fairness -this VCO of mine, while timbrally quite close to a 258 as far as it's freq range, the 33:1 range of two of its processed VC inputs , the sine shaper circuit and characteristics (sound) of the FM - it's not a clone! If nothing else it does a bunch the 258 didn't. Triangle out, PWM out, 1V/oct in, selectable wave morphing, sync in Yes, it has vactrols - but the 258 didn't! There are other differences: My wave morpher is a VC cross fader, and not at all what Don did by forcing the sine shaper into other waveforms. Now, I will say that because of that the saw and square outs of the Model 15 are a bit cleaner, but the morpher doesn't do its job in anywhere near the same way and has its own unique quality which differs sonically from the 258's waveshaping. Not better, different. It took a lot of effort to get what I felt were some of the unique qualities of the 258 sound through other design means. For instance - none of the semiconductors are the same as what Buchla used. Yes, it's triangle core but so are a bunch of other VCO's - Wiard, Aries, and correct me if I'm wrong, and all of the CEM based VCOs . Yeah, I use the exact same sine shaper - but as anyone who owns Electronotes Volume 1 knows - that wasn't Buchla's circuit, either. I just want to be clear about this. What I don't want is to feel I'll have to duck down a hall if I ever see Don Buchla coming the opposite direction and I put a lot of effort into it so I won't have to!