MPC Ren | Program Mixer's Filter section vs. 0-127 value.

Hi,

I was wondering why the Freq value in the Filter section of the Program Mixer goes from 0 to 127, and not from 10 to 19999 like the other filters in the Inputs and Sends.



I find it really confusing when I try to attenuate a certain frequency.

I don't understand the equivalences!

Thanks.

Anyone?

These are MIDI numbers versus actual frequency numbers. There is no direct correlation to frequency but you could do the math to determine which numbers equal which frequency.

You are better off just using your ears or strapping a spectrum analyzer on your output, crank the resonance and sweep back and forth until you see what frequency your peak is at on the spectrum analyzer.

free spectrum analyzer if you don't have one.

http://www.voxengo.com/product/span/

Airyck wrote:These are MIDI numbers versus actual frequency numbers. There is no direct correlation to frequency but you could do the math to determine which numbers equal which frequency.

You are better off just using your ears or strapping a spectrum analyzer on your output, crank the resonance and sweep back and forth until you see what frequency your peak is at on the spectrum analyzer.

free spectrum analyzer if you don't have one.

http://www.voxengo.com/product/span/

Thanks! (I find it odd, though... If this button plays with the frequencies, it should show frequency cutoffs like all the other filters...)

This is for MIDI key note numbers to frequency but it should give you an idea, each point out of the 127 represent a fix frequency point. The resolution is limited to 127 points. So calculate 20Hz to 20kHZ should be the range of the filter.

20,000Hz - 20Hz = 19980Hz
19980Hz/127 = 157.32 Hz steps.

So it's pretty bad resolution. Only recently they added smoothing which makes the filter travel through the steps in between but you still can't set it to any values inbetween the 157 Hz steps

Airyck wrote:

! Thanks!

DSTR / deStar wrote:

Airyck wrote:

! Thanks!

I added some more info to the previous post if you want to learn more about whats going on.

^^This chart has nothing to do with the filter setting. Its the MIDI note number and the related frequency of the key.

to OP:
You can only test the frequencies with the given method (crank up resonance and sweep thru the filter and make notes which number represent wwhich frequency (with a good spectrum analyzer)

peace

Yeah, MIDI note number thing was meant to be an example. It doesn't go all the way to 20kHz like the filter so the offsets will be wrong. You can use it in conjunction with the calculation of 157.32 Hz steps to figure out what setting in the filter is closest to what note.

You need to know the upper and lower frequencies of the filter, before you can create any chart.

That chart might be a good example of how to go about it, but the details are useless in this application.

Typically, the frequency cut-off in MPCs are 0-100. Most program edit params in the MPC Software go from 0-127. These are just arbitrary values when it comes to the filter.

With some of the filters, 127 value means no filter applied like the Low Pass 1 Pole and the MPC 3000 Low Pass Filter (others act differently). A value of 0 using the MPC 3000 Low Pass Filter should be approx 70 Hz if it is a faithful reproduction of the original MPC 3000 filter.

SimonInAustralia wrote:You need to know the upper and lower frequencies of the filter, before you can create any chart.

That chart might be a good example of how to go about it, but the details are useless in this application.

+1

also you need to know if the knob is linear. I doubt that. If this and Airycks calculation would be true, the step from 0 to 1 would be the calculated 157 Hz does this make sense on a filter cutoff knob

0 = 0Hz
1 = 157 Hz
2 = 314 Hz
3 = 471 Hz
4 = 628 Hz
5 = 785 Hz

within the rage of the first 10 steps you would set the frequency range from 0 to 1570 Hz. Not very useful or rather said a complete fail in programming if it is true.

The common way to set such a filterknob is to use many small steps for the low-mid frequencies and less but greater steps in the highs.

peace

You could still crank the resonance and take some measurements with a spectrum analyzer.

i dont get why yall are talking about 'measuring' this control.

first, are you gonna measure all 127 steps?
second, are you gonna keep this 'cheat sheet' of values to reference every time you turn the knob?

use yer ears. it was just a glitch not coding in the right value.
or enjoy using yer cheat sheets

Airyck wrote:You could still crank the resonance and take some measurements with a spectrum analyzer.

Can you?