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Old 2nd March 2015, 04:24 PM   #271
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I do not use potentiometer, the gain is always 0 dB.

If you are using volume potentiometer, you should use this NOS filter (-15 dB F1) to avoid saturation at +15 dB.
Attached Files
File Type: txt NOS-15.txt (1.9 KB, 28 views)
File Type: zip NOS-15.zip (539 Bytes, 21 views)
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Old 2nd March 2015, 06:03 PM   #272
TNT is offline TNT  Sweden
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Quote:
Originally Posted by zfe View Post
...
Second the NOS filter of pos (FIR1 and FIR2 8 taps 1)
Attachment 469181
...
I changed my mind again. I don't want ot listen to violins with this on top.

//
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Old 2nd March 2015, 08:36 PM   #273
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Quote:
Originally Posted by zfe View Post
P.S. I have the impression your answers get a bit ... hmm tense
I'd say terse, not tense.
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Old 2nd March 2015, 08:57 PM   #274
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Quote:
Originally Posted by oneoclock View Post
Well , this is the NOS no-filter that other people likes.

The correct filter NOS that people are asking, previously proposed by Soren. I think it's not right to put NOS filter: one sample and seven 0.



With 11025 Khz. or 22.050 kHz. sinus see bad. With lower frequency signal is more nice. With audio signal the NOS output is more similar original audio. And one sample and seven 0 see bad, no similar to original audio.

I 'm not very interested NOS filter, if I have a good filter oversampling , without saturation or rounding errors. But they are people likes NOS without oversampling filter.

In case I use NOS, I prefer with an IIR filter that amplify the fall of 16 kHz due to rectangles reconstruction. (a sync in frequency). (3 dB. 20 Khz.)
Thanks for posting up the quote from Søren, I couldn't find it when I looked.

From zfe's posts I can see the single coefficient is the main issue with the NOS filter I did. I'm not particularly interested in using NOS personally, and only gave the filters a cursory listen to ensure there wasn't obvious audible clipping.

I've been playing around using the Octave's least squares FIR algorithm to generate filter coefficients. The resulting filters are linear-phase and steep roll off but have very low levels of passband ripple and better stopband rejection than the default 44.1khz filters. I think they sound fairly good, but probably not much different to TNT's efforts.

Last edited by spzzzzkt; 2nd March 2015 at 09:06 PM.
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Old 2nd March 2015, 09:10 PM   #275
derekr is offline derekr  Barbados
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I've not listened to the most recent (last two or three days) filters nor have I revisited the NOS files yet but, after trying the first nine or ten files on this thread, I am leaning to Paul's 1021SA1. Has excellent shimmer and sheen on cymbals, very good separation of instruments and very good detail. Background seems 'quieter/blacker' and voices have good microdynamics. Have to go back and listen to other DAC and filters again to confirm but only caveat is a nagging thought that there's a touch of darkness (small lack of warmth, maybe?) on voices and midrange. But I could live with this filter....

Subject to correction the 1021SA1 was posted on another thread I think but what are it's 'characteristics', Paul? i.e what were you trying? (Save me wading through the other thread, please.)

Might be an idea too, to repost it and 1021SA2F2v1 in this thread (if it indeed was not) just to consolidate the filters here.
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Old 2nd March 2015, 10:39 PM   #276
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Quote:
Originally Posted by derekr View Post
I've not listened to the most recent (last two or three days) filters nor have I revisited the NOS files yet but, after trying the first nine or ten files on this thread, I am leaning to Paul's 1021SA1. Has excellent shimmer and sheen on cymbals, very good separation of instruments and very good detail. Background seems 'quieter/blacker' and voices have good microdynamics. Have to go back and listen to other DAC and filters again to confirm but only caveat is a nagging thought that there's a touch of darkness (small lack of warmth, maybe?) on voices and midrange. But I could live with this filter....

Subject to correction the 1021SA1 was posted on another thread I think but what are it's 'characteristics', Paul? i.e what were you trying? (Save me wading through the other thread, please.)

Might be an idea too, to repost it and 1021SA2F2v1 in this thread (if it indeed was not) just to consolidate the filters here.
Good question! I think that was an attempt at a steep roll-off apodizing style filter. The SA was "super adopizing" but the filter was made with linear phase so doesn't have the minimum phase characteristic that Peter Craven used in his apodizing filters. So effectively it's only "sort of" apodizing. The idea was to have the filter -100dB at 21-21.5kHz, but this had the effect of rolling off gently down to 10kHz. I was trying to ensure that this filter eliminated the effect of any other filters, but it softens off the mids in the process. v2 changed the filter corner so the filter was down -80 or -100dB at near to 22050 so there was less impact on the mid-range. The F2 variant had a modified FIR2 with gentle roll-off.

I quite like these filters as they seem to recover more of the room ambience - but this may well be a side effect of the pre-ringing.
Attached Files
File Type: zip 1021SA1.skr.zip (4.8 KB, 47 views)
File Type: zip 1021SA2F2v1.skr.zip (6.8 KB, 41 views)
File Type: txt 1021filtSuperApo.txt (59.8 KB, 41 views)
File Type: txt 1021filtApo_SRFinal.txt (45.5 KB, 43 views)

Last edited by spzzzzkt; 2nd March 2015 at 10:42 PM.
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Old 2nd March 2015, 10:49 PM   #277
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Quote:
Originally Posted by oneoclock View Post
I think this is the correct filter NOS DAM1021:
Why is this so loud? Using passive volume control after direct output it is 90db at 7:00. Paul's NOS bypass v1 needs to be @ 5:00 for same output.
All other filters have been around 11:00 on analog volume control, except the original NOS which was 2-3:00.

Last edited by robertrowett; 2nd March 2015 at 10:58 PM.
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Old 3rd March 2015, 01:17 AM   #278
derekr is offline derekr  Barbados
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Quote:
Originally Posted by spzzzzkt View Post
Good question! I think that was an attempt at a steep roll-off apodizing style filter. The SA was "super adopizing" but the filter was made with linear phase so doesn't have the minimum phase characteristic that Peter Craven used in his apodizing filters. So effectively it's only "sort of" apodizing. The idea was to have the filter -100dB at 21-21.5kHz, but this had the effect of rolling off gently down to 10kHz. I was trying to ensure that this filter eliminated the effect of any other filters, but it softens off the mids in the process. v2 changed the filter corner so the filter was down -80 or -100dB at near to 22050 so there was less impact on the mid-range. The F2 variant had a modified FIR2 with gentle roll-off.

I quite like these filters as they seem to recover more of the room ambience - but this may well be a side effect of the pre-ringing.
Thanks for the explanation - it helps to get an explanation of what the filter is intended to do and correlate it to what you hear. Who knows, it may lead to a consensus - although that's not likely!

Reading your reply gives me the impression there was SA1, a v2 of SA1 and then SA2 - i.e, three filters? If that's so, could you post SA1v2?

And yes, there's an ease and naturalness to SA1 - I slightly preferred it to SA2F2 although I need to listen to F2 again. It also has good PRAT.
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Old 3rd March 2015, 04:05 AM   #279
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Quote:
Originally Posted by derekr View Post
Thanks for the explanation - it helps to get an explanation of what the filter is intended to do and correlate it to what you hear. Who knows, it may lead to a consensus - although that's not likely!

Reading your reply gives me the impression there was SA1, a v2 of SA1 and then SA2 - i.e, three filters? If that's so, could you post SA1v2?

And yes, there's an ease and naturalness to SA1 - I slightly preferred it to SA2F2 although I need to listen to F2 again. It also has good PRAT.
Sorry v2 was same as SA2. The other thing about the first version is that it was partly an experiment in convolving a 507 tap FIR filter with itself. This improved some aspects - such as lowering the level of the stop band, but also reduced the steepness of the rolloff - which might be considered a benefit. The process also increased the pass band ripple.

Current filter I'm listening to has a 0-19kHz Passband and stop band starting at 22kHz. This version has two identical filters convolved together. There is some low level ripple in the passband but is 0.03dB p-p in the worst case, and less than 0.01dB p-p at 10kHz.
Attached Images
File Type: jpg 19_22fqc2.jpg (122.3 KB, 439 views)
Attached Files
File Type: zip 1021filtLS19_22_c2.skr.zip (7.6 KB, 30 views)
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Old 3rd March 2015, 05:02 PM   #280
zfe is offline zfe
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One thing to keep in mind while filter testing, is that if you use the DAM volume control you probably will not hear if the filter induces clipping (which might be a problem for the DAM-preamp people).
One asset of the NOS (8x tap 1, gain 1) is that it can not induce clipping, combined with not beeing more silent, maybe therefore some people like it.
I e.g. like the attenuated stock soekris filter (and then compensated by the preamp) definitely much more than the unattenuated version.
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