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Filter brewing for the Soekris R2R
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Old 14th March 2015, 11:08 AM   #391
zfe is offline zfe
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Quote:
Originally Posted by TNT View Post
So would/will I. Half a dB will not do any harm. I would even trade some ripple below 20khz to get a more ideal stop band.

//
If you look at the frequency response of speakers and headphones (also the good,expensive...) you see variations in the range of some dB. So yes some 0.xx dB variation more, as only criterion, will surely not be the thing that makes the difference.
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Old 14th March 2015, 11:21 AM   #392
danny_66 is offline danny_66  Belgium
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Default Resampler-V DSP plugin for Foobar

I just found a very nice tool: Resampler-V DSP plugin for Foobar

It's a resampling/upsampling plugin for foobar with a very good interface.
It uses the SoX and SSRC library.

You can change the pass band, stop band, attenuation, phase and see the result in the graphs.
By adjusting the sliders you see live changing the graphs, very nice

To get to the GUI: Preferences, Playback, DSP manager, configure selected.

Regards,
Danny
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Last edited by danny_66; 14th March 2015 at 11:48 AM.
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Old 14th March 2015, 10:24 PM   #393
spzzzzkt is offline spzzzzkt  Australia
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Quote:
Originally Posted by TNT View Post
So would/will I. Half a dB will not do any harm. I would even trade some ripple below 20khz to get a more ideal stop band.

//
I'm assuming you realise we were talking about 88.2kHz and higher sampling rates?

It's worth reading Julian Dunn's paper "Anti-alias and Anti-imaging filtering: The benefits of 96kHz sampling rate formats for those who cannot hear above 20kHz."
http://www.nanophon.com/audio/antialia.pdf

Quote:
The production of pre-echoes from filter ripple was reported by Lagadec and Stockham [6],. They found the pre-echo due to a filter ripple of 0.2dB with a span of 23Hz corresponded with echoes of -32dB at 40ms - which was found to be quite perceptible even with untrained listeners.
cheers
Paul
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Old 14th March 2015, 11:42 PM   #394
TNT is online now TNT  Sweden
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I'm talking also 44,1. I dont mind +/- 0,3 dB ripple starting from say 15khz and goes -1,5 dB at 20Khz. Keep the phase within 5 deg to 15 khz,

Alias and mirrors be gone.

//
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Old 15th March 2015, 11:32 AM   #395
spzzzzkt is offline spzzzzkt  Australia
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Default SoX sinc tip

More a documentation post than anything else...

sinc -t flag sets the transition band in hz. From what I can determine the transition band is centred on the lowpass corner frequency set with -21k for example. If you set the transition band at 5000hz and the -6dB point to 21kHz the stop band will begin at 23.5kHz.

So if you wanted to make a minimum phase filter that is flat at 20kHz, and -80dB at 22.05kHz you'd do something like:

Code:
sinc  -a80 -p0  -21k  -t2100
Which sets the -6dB point to 21kHz and the start of the stop band to 22.05kHz. -p0 is same as -M, and -p50 same as -L

Setting the number of taps using -n flag works well IF you use either Minimum or Linear phase. Using any intermediate phase (-p1 to -p49) results in over 50% more taps than specified.

cheers
Paul
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Old 15th March 2015, 12:50 PM   #396
bambadoo is online now bambadoo  Norway
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Quote:
Originally Posted by spzzzzkt View Post
I might have to drop this CRaP™ seeing we already have Schitt doing scat routines...

Anyhow, one more dose to keep things "regular"...

This is loosely modelled on the Dac Magic Linear Phase setting.
The original is -0.1dB @ 20kHz, -10dB at 22kHz, and hits -140dB at some unspecified point - seems to be 23-24Khz.

Obviously this has to be called...
TotalCRaP™'s CRaP™Magic - linear phase (v1)
............
Been trying for a while now.
For me, with my ears, my hifi-setup i feel there are better filters "out there". Went back to what I have used for a while now. "music" started flowing again....
Seems that playing with filters are quite individual whether we like it or not?

Will try the other filters when I have the time.

BTW: Have also connected a 10k linear pot and testing the volume control. Works like a charm

Best regards.

Last edited by bambadoo; 15th March 2015 at 01:00 PM.
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Old 15th March 2015, 02:21 PM   #397
nige2000 is offline nige2000  Ireland
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whats the short list for filters to try for those that liked the "nos" filter?
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Old 16th March 2015, 05:33 AM   #398
jaffar is offline jaffar  Russian Federation
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Quote:
Originally Posted by danny_66 View Post
I just found a very nice tool: Resampler-V DSP plugin for Foobar

It's a resampling/upsampling plugin for foobar with a very good interface.
It uses the SoX and SSRC library.
Danny, thanks for the link!
Really useful tool, can't stop playing with the sliders
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Old 16th March 2015, 06:28 AM   #399
LeonBernieniv is offline LeonBernieniv  China
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Quote:
Originally Posted by spzzzzkt View Post
More a documentation post than anything else...

sinc -t flag sets the transition band in hz. From what I can determine the transition band is centred on the lowpass corner frequency set with -21k for example. If you set the transition band at 5000hz and the -6dB point to 21kHz the stop band will begin at 23.5kHz.

So if you wanted to make a minimum phase filter that is flat at 20kHz, and -80dB at 22.05kHz you'd do something like:

Code:
sinc  -a80 -p0  -21k  -t2100
Which sets the -6dB point to 21kHz and the start of the stop band to 22.05kHz. -p0 is same as -M, and -p50 same as -L

Setting the number of taps using -n flag works well IF you use either Minimum or Linear phase. Using any intermediate phase (-p1 to -p49) results in over 50% more taps than specified.

cheers
Paul
Thanks for these functional parameters, that's the way to get the compromise between phase, delay, aliasing and ringing, eg. 'rate -M sinc -p30 -22050 -t12k' .
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Old 16th March 2015, 06:29 AM   #400
spzzzzkt is offline spzzzzkt  Australia
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Quote:
Originally Posted by jaffar View Post
Danny, thanks for the link!
Really useful tool, can't stop playing with the sliders
Now you guys just have to work out how translate these settings in to filters for the DAM and it will be something more than a toy....
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