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Parameter Values

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Parameter Values

Postby geebake » Thu Oct 25, 2012 7:05 pm

Hello,

Let me preference my question by stating that I'm completely new to analog synthesis (or modeled analog synthesis for that matter) and I'm not a keyboard player - at all!

Recently, I purchased a Gaia as a fun toy. I have to admit that I'm pretty blown away and am absolutely having a ball with it.

To get started with patch programming, I bought Fred Welsh's Synthesizer Cookbook. It's been very informative for me. In one section, he includes programming values for a number of different instruments. In order to make best use of these, one must know general parameter values. Resonance frequencies. Oscilator speeds, etc. As far as I can tell, the Gaia really doesn't give the user any way of knowing what the true values are. At least not in the sense that x value on this particular control represents x actual value. Welsh's book does include tons of calibration wavs that will help determine this values in a rough sense. I suspect that the better your ears, the better your results will be. Being new to this, I don't think my ears are very good at this.

He also outlines how to use audio analyzer software to get these values a bit more precisely and I will try that sooner than later.

However, it occurred to me that I must not be the first Gaia user that would like this information. So I thought I'd ask if anyone here knows where a good copy of this data can be found. I hope this isn't a question that has been asked a dozen times. I searched the forum and found no similar posts.

Any insight would be greatly appreciated.

Thanks!

Greg
geebake
 
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Re: Parameter Values

Postby Grauw » Fri Oct 26, 2012 2:52 pm

Hi geebake,

As far as I know you’re the first who asked this question :).

Could you be more specific as to what controls you’re interested in knowing the values of? I could perhaps give answers for individual cases, but you need to give some direction :).

The manual also contains a lot of information if you know where to look, btw.
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Re: Parameter Values

Postby geebake » Fri Oct 26, 2012 3:14 pm

Thanks for the response.

What I'm trying to find is the specific real world values represented by the 'percent' values of various controls.

For example. I'd like to know exactly how many HZ the LFO is running at at a given value. Or perhaps how many dbs does output drop when the amp is dropped by x percent.

I have actually begun to use a scope plugin to determine most of this and I will post my findings here.

All of the time based values are pretty easy to measure in a DAW. I've also been able to get pretty accurate measurements of the amp behavior. Of course, dbs are only relative in that case.

The only thing I'm having trouble measuring at this point is the frequency cutoff of the filter. I have instructions, but am having trouble putting it into practice.

Like I said, I will post my results once completed.

I do realize that in the real world of synth programming, this is probably pretty silly. Most guys have the experience and ears to develop patches without this. But what can I say, I write code for a living and always like things better when I can put a number on them!

Greg
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Re: Parameter Values

Postby geebake » Fri Oct 26, 2012 3:25 pm

And I thought I might add this.

I've been reading this book "The Synthesizer Cookbook" written by a guy named Fred Welsh. It's essentially a manual for reverse engineering sounds - both synthesizer sounds and those of acoustic instruments. There's excellent information about how to analyze sounds through harmonic analysis - using a scope plugin in a DAW for example.

Again, this may well be easy stuff for more experienced guys, but it's been a godsend for me.

You can check out his site here:

http://www.synthesizer-cookbook.com/index.html

Greg
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Re: Parameter Values

Postby geebake » Mon Oct 29, 2012 8:24 pm

I don't know if anyone care about this but here are some of my initial measurements. These values were measured using a variety of techniques in SONAR X2. I may not have the values exactly right, but they are very close.

LFO
Percent Seconds Hz
10 6.1 0.16
20 1.9 0.53
30 1.05 0.95
40 0.77 1.30
50 0.56 1.79
60 0.42 2.38
70 0.3 3.33
80 0.18 5.56
90 0.1 10.00
100 0.04 25.00

I measured this value in an effort to match the velocity of specific oscillations. It was measured by measuring the distance (in time) between two known points of a single sine oscillator. These measurements are only as accurate as I am with a mouse, but they should be very close. Conversion to HZ is 1/value in seconds.

If you have the wherewithal, graph that in the spreadsheet app of your choice. Interesting (to me) how logarithmic it is.

Oscillator Level
Percent db Adjusted
10 -47.5 -38.6
20 -36.5 -27.6
30 -29.5 -20.6
40 -25 -16.1
50 -20.5 -11.6
60 -18 -9.1
70 -15 -6.1
80 -12.6 -3.7
90 -10.5 -1.6
100 -8.9 0

This requires some explanation. Here, db isn't really an accurate representation of what is being measure. Relative amplitude would probably be a better explanation. I measured the maximum output (as reported by SONAR - using an oscilloscope plug in) of a single sine wave oscillator - varying the amp level to the percentages listed. I attempted to get the 100% value to zero db, but was unable, hence the adjusted column. Think of that as the effective db changes by percentage of the level control.

I worked out this value because I wanted to be able to understand how oscillators mix. Knowing these numbers, it should be possible to determine numerically how the amplitude of multiple oscillators are mixing.

ADSR
Percent Sec Sec Sec
A D R
100 33 16.8 12.5
90 12.5 6.2 3.4
80 4.75 1.9 2
70 2.6 1 1.125
60 1.4 0.6 0.675
50 0.84 0.35 0.39
40 0.45 0.2 0.25
30 0.24 0.11 0.15
20 0.14 0.06 0.1
10 0.075 0.04 0.065
0 0.015 0.01 0.05

All of these values were determined by recording samples and measuring (in time) the appropriate value - again in SONAR. There could be some inaccuracy, but they should be pretty close. A measurement for sustain is not meaningful and was therefor not included.

I still need to work out a good method for measuring filter values (cutoff frequency and resonance), but I'm working on it.

I realize that more experienced synth programmers can probably set these values by ear far better than I can with numbers. But I do think knowing these values has some value. It's particularly effective for trying to reverse engineer patches from other synths.

Greg
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Re: Parameter Values

Postby geebake » Mon Oct 29, 2012 8:25 pm

Grrrrrrr. I tried to line up all those tables nicely. I'll try to figure out a better way.

Greg
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Re: Parameter Values

Postby Grauw » Wed Nov 28, 2012 12:41 pm

Very nice :), please keep posting your findings if you like.

Being a programmer myself I understand the more... mathematical approach to sound :).

At some point in the future I think it would be nice to add your real-world numbers to the Gaia tool’s output.
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Re: Parameter Values

Postby geebake » Wed Nov 28, 2012 4:41 pm

Excellent Gruaw!

I've been on vacation for a while and dropped the ball a bit, but will get back to this shortly.

Sheesh! I need to fix all the typos too! In my defense, it was late at night when I worked all that out.

Greg
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