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Author Topic: Exact Info on CV Ins and Outs  (Read 144 times)

Lunatic Sound

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Exact Info on CV Ins and Outs
« on: January 03, 2018, 03:55:34 pm »
Hello friends,

this one has been bugging me a lot as well:

I canīt seem to find any proper explanation on where exactly the CV ins and outs come from / go to and how they work. I really wish, I had a huge manual for real nerds explaining everything to the last detail...

So by playing around with it, I came to the conclusion, that the CV Out always send whatever you feed that particular destination in the matrix, but not the actual value (so to speak, knob position) of the knob, that the destination targets. Right?

Wouldnīt it be logical and cool, to send the knob position + the modulations on the corresponding CV Out, so that the other e.g. Filter I target will move just like the MB Filter does and I could move them by hand as well? Or am I missing something again?

And also, are those ins and out DA and AD converters, or is the analogue signal really fed through?

I am sorry I always have more than one question per topic, there is just so much to ask...

DrJustice

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Re: Exact Info on CV Ins and Outs
« Reply #1 on: January 11, 2018, 07:58:20 pm »
(also with reference to this thread)

...
So by playing around with it, I came to the conclusion, that the CV Out always send whatever you feed that particular destination in the matrix, but not the actual value (so to speak, knob position) of the knob, that the destination targets. Right?

Wouldnīt it be logical and cool, to send the knob position + the modulations on the corresponding CV Out, so that the other e.g. Filter I target will move just like the MB Filter does and I could move them by hand as well? Or am I missing something again?
Yes, that's right. The outputs from the matrix is just that; only the matrix modulation signal, not the related knob position. The knob position and the matrix columns are combined internally in the MxB.

It could have been the way you describe, or the way it is... It's a design decision. In a way it gives more flexibility since you can tap a modulation signal from the MxB without it being affected by the related internal parameter value. If you need a knob on the MxB to control something external through CV as well as internally in the MxB, you can assign macro knobs in the matrix to do the job.

Quote
And also, are those ins and out DA and AD converters, or is the analogue signal really fed through?
The inputs goes straight to the analogue voice card, so they work at audio rate. The outputs are tapped from the corresponding points on the analogue voice card, but the voltages are generated digitally by the modulation matrix.

It's also worth noting:
 - the CV inputs and CV outputs are mixed internally in the MxB in the analogue domain, so whatever you plug in AND assign through the matrix will affect the MxB
 - the MxB keyboard will affect the VCO 1 and 2 pitch outputs, i.e the keyboard is to be considered a modulator in this instance
 - the pitch bend wheel will not affect the VCO 1 and 2 pitch outputs

I agree that the manual is a bit thin on the ground in some areas.
« Last Edit: January 12, 2018, 03:04:23 pm by DrJustice »

Lunatic Sound

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Re: Exact Info on CV Ins and Outs
« Reply #2 on: January 12, 2018, 12:27:18 pm »
Wonderful! Thank you!

Where do you know this stuff from, actually? :)

Do I get you right, when you say the outputs are generated digitally from the Matrix, that for example the LFOsī analogue signal is ad-converted for routing and then converted back to analogue at the outputs? Does that mean, it is not being routed "analoguely" to the MBīs own destinations either? That seems kind of weird to me.

Good point mentioning the macros, keeping their existence in mind I can indeed understand the design choice to not include the knob positions in the outputs better.

I also quickly checked, if an input signal being fed into a cv-in is being sent out the corresponding cv-out, which it is not, regardless of how the Matrix is configured. That would have been a way to see, how fast and frequency-linear the ins and outs work...



DrJustice

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Re: Exact Info on CV Ins and Outs
« Reply #3 on: January 12, 2018, 03:00:22 pm »
Wonderful! Thank you!

Where do you know this stuff from, actually? :)
Hypothesis -> experiment -> theory - we need to perform some science to fully unlock the mystery of the matrix ;D

Quote
Do I get you right, when you say the outputs are generated digitally from the Matrix, that for example the LFOsī analogue signal is ad-converted for routing and then converted back to analogue at the outputs? Does that mean, it is not being routed "analoguely" to the MBīs own destinations either? That seems kind of weird to me.
That is the case for the envelope follower, mod wheel, aftertouch and expression pedal 1 and 2 - they are analogue sources read by AD conversion.

The remaining modulator rows (LFOs, envelopes etc.), the converted signals mentioned above and the the matrix itself are digital. Then there is DA conversion for columns 1-12.
« Last Edit: January 12, 2018, 10:42:27 pm by DrJustice »

Lunatic Sound

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Re: Exact Info on CV Ins and Outs
« Reply #4 on: January 15, 2018, 03:30:34 pm »
So do we (meaning most probably you, Dr.Justice) know anything about the converters, its samplrate most importantly?

DrJustice

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Re: Exact Info on CV Ins and Outs
« Reply #5 on: January 15, 2018, 04:56:04 pm »
So do we (meaning most probably you, Dr.Justice) know anything about the converters, its samplrate most importantly?

Yes we do :)

The LFOs have frequency content to 4 kHz, e.g. the saw has a nice saw-type spectrum going all the way to 4kHz, and I can't see any aliasing. The reconstruction appears to be perfect, so sample rate and bit depth is more than adequate - very good in fact. We're looking at a sample rate of 8kHz or more.  The dynamic range, or perhaps rather S/N ratio, appears to be almost 100dB. Also the LFOs go to 80Hz and the shortest envelope times are ca 2ms.

Edit to add: the bit depth is probably 12 or 14 bit since there are DACs with both depths on the voice board.

« Last Edit: January 19, 2018, 08:15:35 pm by DrJustice »

Lunatic Sound

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Re: Exact Info on CV Ins and Outs
« Reply #6 on: January 19, 2018, 08:02:59 pm »
You are awesome, man.

 

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