GMS784 Quad LFO/VCA in 2MU

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burdij
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GMS784 Quad LFO/VCA in 2MU

Post by burdij » Thu Jun 27, 2019 10:47 am

My first module was the GMS782 Dual LFO/VCA which was two LFOs and two VCAs in a 2MU module.

Image

I have developed a new version of this module that includes four LFOs and four VCAs but still housed in a 2 MU panel. The new module uses a similar circuit to the previous version with some improvements. Each oscillator has a voltage control frequency input with 1V/Octave response, a sync input to restart the waveform, and three frequency ranges 0.015 Hz to 400Hz and two lower decades down to 0.00015 Hz.

Image

Each channel also includes a linear response VCA the input of which can be one of the three VCO waveforms or an external input connector. The CV input of the VCA has an attenuverter to allow scaling on the control voltage input.

This picture shows the stuffed boards for the oscillator:

Image

Here the oscillator is making some (sine) waves:

Image

There are still a few days left to take advantage of the Mosquito Days sale in the synthstore. 15% off or free domestic shipping on selected modules. The sale ends at midnight June 30 central daylight time.
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ba1
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Post by ba1 » Fri Jun 28, 2019 11:26 am

Looks nice!

Can the VCAs be used independent of the LFO?

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josaka
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Post by josaka » Fri Jun 28, 2019 11:55 am

burp..

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burdij
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Post by burdij » Fri Jun 28, 2019 1:00 pm

ba1 wrote:Looks nice!

Can the VCAs be used independent of the LFO?
The external VCA input is selected by the waveform switch so you can choose the VCA with an external input or one of the VCO waves through the VCA per channel. Its the curse of not having enough I/Os.

I am looking at putting ribbon cable connectors on the rear board to bring out all the waveforms and VCA outputs (and inputs?). Minimally, if you needed access to the separate waveforms, some kind of simple breakout panel could be used. I am thinking of some kind of modulation matrix-like thing on the outputs with routing options as a future project.
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While website and store updates are in progress, access the Grove Audio Synth Store
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ba1
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Post by ba1 » Sat Jun 29, 2019 5:51 pm

Cool. When is this going to be available?

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Post by burdij » Mon Jul 01, 2019 8:07 am

I am waiting for an order of rotary switches to come in for these. The module will be in the store in about two to three weeks. I am planning an introductory sale special on this product as well as a couple of other new things too. 8-)
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While website and store updates are in progress, access the Grove Audio Synth Store
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Post by josaka » Mon Jul 01, 2019 8:41 am

are the Sync/Freq CV inputs normalled on the Quad LFO ..?

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Post by burdij » Mon Jul 01, 2019 9:31 am

josaka wrote:are the Sync/Freq CV inputs normalled on the Quad LFO ..?
I hadn't planned to normal them but this could be ordered as a modification if desired. Normalling so many inputs might present a loading issue with regard to the device driving the input.
Knobcon 7 - 2018 Photo Album
While website and store updates are in progress, access the Grove Audio Synth Store
Tesla Science Center http://www.teslasciencecenter.org

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ba1
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Post by ba1 » Tue Jul 02, 2019 1:00 am

How fast or slow can the LFOs go?

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Post by burdij » Tue Jul 02, 2019 9:10 am

The frequency range over 3 decades is one cycle per 111 minutes to 400 Hz. In the normal (N) mode, the range is one cycle in 66 seconds to 400 Hz.
Knobcon 7 - 2018 Photo Album
While website and store updates are in progress, access the Grove Audio Synth Store
Tesla Science Center http://www.teslasciencecenter.org

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