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[shawnhar]

I'm trying to use the MS20 to ring modulate an audio signal, by routing the oscillator output into the modulation VCA input, and external audio to the MVCA control input. But this produces silence as opposed to the expected AM/Ringmod audio.

Am I misunderstanding how this ought to work? Anyone tried something like this or gotten it to work? Is this VCA perhaps unable to operate at audio frequencies?

Thanks!

[danatkorg]

[shawnhar]

Thanks Dan, I will have to give this another try then. Good to know that it makes a difference which way I wire the two inputs.

[shawnhar]

Hello again,

I spent some more time experimenting with this, but have not managed to get MS20 to ring modulate external audio.

Simple set up: start with a default MS20 patch, connect the filter output to MVCA input, and MVCA output to the main VCA input. As expected you will now hear nothing as the MVCA is at zero.

Now route external microphone to the MS20 audio input, and connect this input to the MVCA control signal. Playing and singing at the same time now does produce audio, with a very low signal level and no ring modulation type effects at all. It's basically working like a gate, so the volume of the synth oscillators comes from the mic level, but there is no change to frequency spectrum even when I alter the relative frequency of what I am singing vs. the synth oscillators.

As best I can figure, the MVCA must be very slow to respond to changes in the control signal, tracking this more like a compressor or gate rather than responding instantly to audio rate changes. This seems like more than just a low pass filter, as combining two audio signals in this way isn't introducing any kind of distortion at all.

Not really a problem as there are plenty of other ways to ring modulate audio in Kronos, but I'm intrigued as to why this doesn't work with MS20.

[danatkorg]

I just did a quick recording of me fooling around with processing audio through the MS-20EX. This is a live recording directly from the KRONOS USB output, using a vocal loop played through the USB input. EXi Audio Input goes to the MVCA input, and Osc 2 goes to the MVCA Control In. I use the mixers to implement some switching as described below. I modulated the main volume to compensate for the level differences between pulse and square, and used a stereo compressor on IFX1 to tame the output a bit, and also to boost the output by 20dB (!) to compensate for the attenuation through the MVCA.

The dry vocal comes first; then the MVCA with pulse input from Osc 2; then switch Osc 2 to square; then switch from using the direct vocal input to using the input through the ESP (saturation, yay!); then back to pulse, and then modulating frequency both with LFO and by playing notes; then bring in some gratuitous reverse delay and the obligatory filter sweep (pretty rough on that one, sorry). Note that the oscillators are pitched very low, so that some semblance of the waveform gets past the MVCA's integral LPF. The pulse has a much rougher effect than the square.

It's not art, but it was kind of fun to explore. MP3 audio file at the link below:

MS-20EX vocal processing mp3 example
_________________
Dan Phillips
Manager of Product Development, Korg R&D
Personal website: www.danphillips.com
For technical support, please contact your Korg Distributor: http://www.korg.co.jp/English/Distributors/
Regretfully, I cannot offer technical support directly.
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[shawnhar]

Thanks for the example, Dan. Some interesting sounds there! It doesn't sound quite like ring modulation to me, but certainly an interesting form of audio mangling.

I'm seriously digging the MS20 filters for vocal processing at the moment. Resonance nice and high, crank up the input signal level, set HFP cutoff low to boost bass frequencies, and awesome distortion ensures!