From the original SynthMaker forum (2004–2014), with its members’ names and dates.
JuzamDJ ·
Hello, I am developing an equalizer in SM with RBJ 2x Peaking module (21 Hz for the Low) I try to analyze the armonic distortion in VSTpluginAnalyser, but presents problems in the low frequency, reaching levels of -85 dB for noise
How I can clean this up?
attached the OSM
Would greatly appreciate your help. ,thx
Sorry for my english
Dell ·
Hi.
The fluctuations at the end of the frequency scale are due to having a very narrow Q at 21 Hz. There are ways to remedy the problem like, using a low frequency filter not to agitate sub low frequencies below 10 Hz.
The distortion VST Analyser is detecting is falsely assuming anything beyond 0 dB is distortion. Since the frequencies around 20 Hz and below are bouncing about above 0 dB, VST Analyser assumes it is distortion. VST Analyser offers a lot of errors in measurements so don't rely on it too heavily for it to be always correct. Plug-ins will not offer distortion unless you design the plug-in to distort.
Cheers
Disco_Steve ·
not quiet true, all maths cause distortions due to rounding errors! The only way you can make these distortions less strong is to use doubles, another option is to dither each of the internal values of the values stored inside the filter, but this eats so much CPU it is not worth the effort. unless you REALY REALLY care about -90dB distortions during very abnormal settings.
one only needs to worry about this type of noise floor if your designing radars. you will never hear this distortion. and if you can hear this you have your gain staging VERY wrong!
helpful?
Steve
infuzion ·
Disco_Steve wrote: not quiet true, all maths cause distortions due to rounding errors! The only way you can make these distortions less strong is to use doubles,
Another good reason for 64bit audio! 😉
Dell ·
Disco_Steve wrote: not quiet true, all maths cause distortions due to rounding errors!
Right!
However as you mentioned..
one only needs to worry about this type of noise floor if your designing radars. you will never hear this distortion. and if you can hear this you have your gain staging VERY wrong!
helpful?
Steve
I've had to explain to many what VST Analyser is actually telling them due to feeling a distortion level under the threshold of hearing at low frequencies will be detectable by the human ear.
There are just too many variability’s to add to the equation that would create more noise that is outside the realm of VST Analyser.
For those who seriously want to tests plug-ins, invest in programs that you can literally measure yourself using your own means of test signals. VST Analyser is good for simplistic things as getting an idea of a frequency response. However, it cannot measure distortion correctly and will give the user false assumptions.
Cheers!
tor ·
I have sendt you ((JuzamDJ) a PM with a link to a example with double precision maths.
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