I edited the post to add the useful information.
It couldn't be compensated, you're just making the assumption that the frequency is much higher than it actually is. You need to think in terms of 5hz, so the first harmonic will be -1db or so when you're playing 10hz.
Bandlimited impulse train - again
-
- KVRAF
- 12555 posts since 7 Dec, 2004
Free plug-ins for Windows, MacOS and Linux. Xhip Synthesizer v8.0 and Xhip Effects Bundle v6.7.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
-
- KVRAF
- 12555 posts since 7 Dec, 2004
sh-101:
Mixer / filter input:
- 560ohm, 10u (28.4hz)
VCA input:
- 1k, 10u (15.9hz)
Output:
- 100k, 2.2u (0.7hz)
Mixer / filter input:
- 560ohm, 10u (28.4hz)
VCA input:
- 1k, 10u (15.9hz)
Output:
- 100k, 2.2u (0.7hz)
Free plug-ins for Windows, MacOS and Linux. Xhip Synthesizer v8.0 and Xhip Effects Bundle v6.7.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
-
- KVRAF
- 12555 posts since 7 Dec, 2004
I get the correct results.
Are you using the correct filter and coefficients in the correct places?
Also keep in mind the measurements you take from your ms-20 are useless unless you want to model an old, worn-out ms-20 that is working nothing like it should.
Also important to note that capacitor and resistor tolerances can vary the cutoff significantly. By typically about 30% !
Are you using the correct filter and coefficients in the correct places?
Also keep in mind the measurements you take from your ms-20 are useless unless you want to model an old, worn-out ms-20 that is working nothing like it should.
Also important to note that capacitor and resistor tolerances can vary the cutoff significantly. By typically about 30% !
Free plug-ins for Windows, MacOS and Linux. Xhip Synthesizer v8.0 and Xhip Effects Bundle v6.7.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
-
- KVRAF
- 12555 posts since 7 Dec, 2004
Actually it'll be exactly -3db at 28.4hz, plus or minus the effect of the tolerance of the components.
The problem with trying to measure the first harmonic is you're using a Fourier transform, I assume. That couldn't be any less accurate.
You're better off measuring a software filter and ensuring you get exactly the correct -3db at the correct frequency. This is easy using a pure sine and measuring peak level.
Once you have a filter you know works, pass a pure pulse wave through it and match the two visually. Once you have a visual match, take the difference and measure the peak level, then adjust to minimize the error.
The best way to measure the circuit is to inject a pure sine into the mixer and probe after each filter, identifying the -3db point.
This is easy to do manually with a peak meter. Just start at a low frequency, then adjust upward until you get -3db peak.
Can all be automated of course.
With Fourier you need to worry about windowing and bin size and the effect on levels. The ripple will be much higher than 1db in most cases.
The problem with trying to measure the first harmonic is you're using a Fourier transform, I assume. That couldn't be any less accurate.
You're better off measuring a software filter and ensuring you get exactly the correct -3db at the correct frequency. This is easy using a pure sine and measuring peak level.
Once you have a filter you know works, pass a pure pulse wave through it and match the two visually. Once you have a visual match, take the difference and measure the peak level, then adjust to minimize the error.
The best way to measure the circuit is to inject a pure sine into the mixer and probe after each filter, identifying the -3db point.
This is easy to do manually with a peak meter. Just start at a low frequency, then adjust upward until you get -3db peak.
Can all be automated of course.
With Fourier you need to worry about windowing and bin size and the effect on levels. The ripple will be much higher than 1db in most cases.
Free plug-ins for Windows, MacOS and Linux. Xhip Synthesizer v8.0 and Xhip Effects Bundle v6.7.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
The coder's credo: We believe our work is neither clever nor difficult; it is done because we thought it would be easy.
Work less; get more done.
