The Model 15
Complex VCO.

All-discrete Triangle core VCO

Two exponential VCF inputs with full +/- processing

Separate linear FM input

1V/oct input tracks to seven+ octaves

VC PWM input with offset control

VC Wave Morphing with manual offset

Ultra-thin 1.125" design
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In a head-to-head VCO comparison on, Per Wikström said of the Plan B M15:

On basic sound: "The winner is, with no doubt, the Plan B VCO. It has a sort of warm and still a bit glittering sound, especially in the triangle wave.

On FM modulation: "The Plan B shows its class. Increasing the amount of FM gives a big palette of rich and deep sounds from mellow to brute, without going into distortion or too metallic buzz.".

On overall performance: "Plan B VCO outclasses it's competitors in nearly all aspects"

Thumbuki test: Click here for an independent sinewave purity comparison performed against a Csound generated digital standard performed on the Thumbuki site.

You want fat...well how about OBESE?

The immensely popular Plan B Model 15 is an analog Voltage Controlled Oscillator (VCO) featuring an all-discrete component triangle wave core, two independent fully processed (+/-) VC inputs, a single 1V/Oct input, a dedicated linear FM input, sync, and independent Sine, Triangle, Saw, PWM and Wave Morph Outputs. 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 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.

Various component improvements on the Model 15 core have increased for 1V/oct tracking to seven octaves requiring only single pot adjustments for periodic calibration and none of the hick-ups associated with sawtooth core VCOs past the 3k limit. For imore informaiton of the Model 15's tracking go here (suggesed reading for those requiring wide-range tracking).

The Model 15 has been mechanically redesigned with it's electronics resting parallel to the faceplate, bringing the overall depth from over 4 inches in previous revisions to less than 1 1/8th inches with the Rev. 2.

Why is it called the Model 15 you ask? 2 plus 5 plus 8 = 15. Simple!

Waveform Images:
Sine wave output

Click on photo for larger image. Click here for audio sample
Triangle wave output

Click on photo for larger image. Click here for audio sample.
Sawtooth wave output

Click on photo for larger image. Click here for audio sample.
Squarewave output 50% dutycycle

Click on photo for larger image. Click here for audio sample.
SIne to Square morph 50%

Click on photo for larger image. Click here for audio sample.
Sine to Saw morph 50%

Click on photo for larger image. Click here for audio sample.

What you're hearing:

All of the samples above consist of a single Model 15 being controlled by either a step sequencer or single upswept envelope generator with the VCO taken straight to the speakers. No filtering, no VCA, etc. In the morph samples, another bank of the step sequencer was used to control the output waveform (the amount of morphing). A Model 14 crossfader was then incoporated to morph the CV source from the sequencer to an envelope generator. In the sine to square morph sample a third sequencer bank was used to effect the dutycycle of the squarewave (PWM).

Important Notice for Model 15 Rev. 2.5 and above:

Circuitry has been added which protects against damage to the unit when power is applied backwards..

Sound Samples:

here for a Youtube video of Velvet Acid Christ's HexFix demonstrating the Model 15's new Hard Sync.

Sine on Sine FM demonstrating it's transient response to a 'chiff'

Another Sine on Sine FM example

Another demonstration to it's unique response to chiff transients

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!)

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)

Sound Samples by Zoran Bosnjak:

The following were realized by Plan B customer Zoran Bosnjak incorporating a mixture of Plan Model 15's, a M13 Dual Timbral Gate and a custom Plan B Steiner filter:

sample 1
sample 2
sample 3
sample 4

sample 5

Sound Sample by Sean Price - totally sick - click here

"I was just driving the fm input on one model 15 with a drum machine and using another model 15 to FM the first. When drivin hard enough (ie; the fm input all the way up with the max volume I could get out of the machinedrum)it acted sort of as a bandpass filter with gnarley distortion. Increasing the FM input from the second VCO gave a wider bandwidth. I mixed in the original signal in the beginning, but afterwords its all coming out of the sine output on one model 15."

Model 15 demo tracks from REwire:

Model 25 Demo's from REWIRE:

sample 1

"This is a 2:07 Demo that was made using only the Model 15 Oscillator as a source for all sounds including drums. Only modulation to the osc was using it's own waveforms to cross-mod others, noise into the sine to make hi-hats and snares and lfo and envelopes to cv or the morph input."

sample 2

Model 15 Reference Guidelines:

Click here for a calibration procedure (tracking & waveform purity).

here for power connection instructions.

Click here for the Frequency Calibration MIDI test file.

Click here for Expo Board insertion guidelines (rev1 and 1.1 only).

Model 15 calibration procedure slideshow:

Additional Comments:

Click here for owner 's reviews of the Model 15

Production Modules:

Model 1 Protected Power Source

Model 9 Mixer/Attenuator

Model 10 Polyphonic Envelope

Model 11 Evil Twin Bandpass Filter

Model 12 State Variable Vactrol Filter

Model 13 Dual Timbral Gates

Model 14 Dual Voltage Processor

Model 15 Complex VCO

Model 16 Spectral Multiplexer

Model 17 Triple Event Timer

Model 23 Analog Shift Register

Model 24 Heisenberg Generator

Model 25 Multi-tasking Audio Processor

Model 26 Multi-tasking Control Processor

Model 28 Programmable Tap Clock

Model 29 Dynamic Mult

Model 31 Buffered Mult

Model 36 Leveler


Model 38 ADSR

Model 38A ADSR Expander

Model 39 Wave Splicer

Model 40 Headphone PreAmp

Planned Modules:

Model 18 Stereo Output Mixer Sub System:

Model 18 Stereo Mixer

Model 18A Expander (VC level/pan)

Model 18B Balanced Stereo Outputs

Model 19 Gate Delay

Model 21 MIlton Controller Series

Model 27 Digital Delay

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