Pittsburgh Modular Documentary Films Presents: Discovering the Microvolt Episode 5

Published on Aug 21, 2019 Pittsburgh Modular Synthesizers

"The fifth episode in a series documenting the features and functionality of the Pittsburgh Modular Microvolt 3900. This episode is an overview of the dynamic VCA section."

Discovering the Microvolt Episodes

nonlinearcircuits beat freq 2

Published on Aug 21, 2019 nonlinearcircuits

"Mainly controlled by 2 VCOs, which also supply the audio. Middle section is clocked by 2 LFOs."

via nonlinearcircuits

"The idea for this module came from a schematic that has been floating around the web for years - 'beat frequency indicator'

The idea is to feed the circuit two signals and depending upon which one had the higher frequency the ring of 4 LEDs would light up in a clockwise or anti-clockwide direction. The speed of rotation would indicate how close or disparate the frequencies are. If the signals have the same frequency then just one LED is lit.

The original circuit used 74xxx series ICs for the logic, so it was simple enough to find the CMOS equivalents (sort of), then add gates corresponding to the LEDs and use the spare outputs of one chip to feed pots to make sequences. Then for good measure a discrete XNOR circuit was added to give a psuedo ring-modulator output based on the 2 incoming signals.

In operation this module is quite unique; the CV signals return to 0 between each step, the length of each step can vary depending on the incoming signals. Gates come in spurts. The circular LED display jerks around, sometimes it completes several revolutions confidently and then stutters between two stages, sometimes it shimmers on one spot.

At both audio rates and clock rates, this module is quite unpredictable but always seems to be putting out useful signals.

PCB = USD18
Panel = USD20
assembled = USD160"

CLICK FOR MORE »

nonlinearcircuits 1U Signum 2

Published on Aug 21, 2019 cirtcele

via nonlinearcircuits

"In the simplest sense, this is a switching module. It is a little different though because it has 3 states rather than just on/off:
\operatorname{sgn}(x):={\begin{cases}-1&{\text{if }}x<0,\\0&{\text{if }}x=0,\\1&{\text{if }}x>0.\end{cases}}
In this case, the module uses approx 1V, rather than 0V, as the switching point, so that it can be controlled by gates. It is simple to bring it back to 0V for those who think it should be.
Also the '0' state is really a result of the diode voltage drops rather than any circuit design trickery.

The signal on the bottom input is fed to the switch of the Switch jack (oh yes) so the incoming signal can switch itself without any help.
The three states actually mean there is a flat spot at the switching point, so the circuit can be used for audio but at slow rates there is a click, so it is far better suited for CV processing.

This circuit originally was used as the nonlinear element in the Primal Hyperchaos and two of them in the Hyperchaos Deluxe. I quite like it on its own, so the Signum Hyperchaos brought the signum section to the panel where it could be used as a stand-alone module. This version drops the chaos and just has the Signum.
The switching is done by diodes rather than a dedicated IC.

The panels are available in white/gold and black/gold in both Pulp Logic and Intellijel formats. Please specify which colour and which format you want when ordering.

Also the PCBs are the same for both panel formats and use a standard Eurorack power connector. There is no provision for the Pulp Logic 3 pin power connector.

PCB and panel set = USD10
Assembled = USD55"

CLICK FOR MORE »

Midnight Jam #5 (Moog Sub 37 & Novation Peak)

Published on Aug 20, 2019 Plexis

"Little midnight jam with the Peak routed through the Moog.
Have fun :)"

Music From Outer Space - MFOS - Soundlab Ultimate w/ Expanders and Voice of Saturn

Note: Auction links are affiliate links for which the site may be compensated.

via this auction

"This is a custom built modular synthesizer comprised of the MFOS Soundlab Ultimate and two identical Soundlab Expanders. The case itself was made from old bleachers from the school the builder worked at (who is one of the recommended builders on the MFOS website if you didn't feel up to the DIY challenge). The main synth voice is normalized but can be repatched. The patch points are an interesting combination of banana jacks and 1/4" jacks. There is a passive multiple box included that convert 1/4" and banana cables in either direction.
The bottom of the unit was also signed and dated by Ray Wilson when it was sent in to have the envelope generators response curve tweaked (I believe to make them snappier)

Soundlab Ultimate Features
3 VCOs with Square and Saw Waveforms
Noise Source
External Input
5 Channel Mixer
Analog Lowpass Filter
Analog VCA
Attack and Decay Envelope Generator
Sample & Hold Circuit
Gate Repeater
2 LFOs with Square, Rising Saw, Triangle, Falling Saw Waveforms, and Low and High Rate Ranges
4 Attenuators
Soundlab Expander Features (per each side)
Attack Decay Sustain Release Envelope Generator
Analog Multimode Filter w/ Lowpass, Highpass, and Bandpass
Analog VCA
Ring Modulator (Analog Multiplier)
Signal Booster
Envelope Follower
CV Inverter
4 Channel Mixer

Also included are a bunch of banana cables (some stackable, some not) 3pin cables to link the power from the main Soundlab to the 2 Expanders, and a separately built project Voice of Saturn drone synth. The Voice of Saturn does work but is a little finicky, and seems to need some calibration as the ranges on the controls are very narrow. But it will be an interesting add-on to this system giving you 2 extra VCOs and 1 LFO."

CLICK FOR MORE »

Yamaha SY35

Note: Auction links are affiliate links for which the site may be compensated.

via this auction

"The SY-35 is an awesome sounding vector synth capable of some extremely interesting and evolving sounds. Although very rich and unique sounding, editing is focused around envelope times and preset sound generation, making this more of a musically focused synth that almost always sounds good!"

CLICK FOR MORE »

Blue Roland SH-101

Note: Auction links are affiliate links for which the site may be compensated.

via this auction

CLICK FOR MORE »

CRUMAR COMPOSER

Note: Auction links are affiliate links for which the site may be compensated.

via this auction

"Vintage Analog Italian Synth
Mono/Polyphonic synth, organ, strings.
Extremely RARE
Very good condition and perfect working order
Just serviced

It also has a breath controller input and a BBD Bucket Brigade Leslie effect.

Composer uses the same CEM chip to VCA, filters and envelope as the Memorymoog, Oberheim OBX, OBXa/OB8, SCI Prophet 5.
Less than 400 units were produced."

CLICK FOR MORE »

1977 ARP Avatar

Note: Auction links are affiliate links for which the site may be compensated.

via this auction

"Recently serviced and in full working order. Includes original guitar pickup and cable."

CLICK FOR MORE »

Trap 808 Kick Bass Tones Volca Kick

Published on Aug 20, 2019 Dj Puzzle

"Quick demo of the various 808 style Trap bass tones you can get from a Korg Volca Kick. #808s #trap #korgvolca This is by no means a song or full composition of course merely a short demonstration for those who may not know this side of the device. What I ended up doing was sampling some notes and creating sampler patches to use in Ableton live. I feel using this Volca as the sound source gives the samples that extra bit of analogue warmth that I wouldn't get from a soft synth. Not saying soft synths are bad just saying it's nice to have different sources and tones to use and it's also fun to experiment!"