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Old 16th February 2015, 04:51 AM   #41
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Default Move comparative tests

The second test is a 19K test tone. Again no calibration, this was just set to the same level as the white noise.

Same order of appearance as above.

MB1 is a bit cleaner in the audio band than Søren filter. The MPSRO shows the obvious image at around 24kHz which is not present in filters with steep roll-off for anti-imaging. It's also has a lot more junk in the audio band. It's worth noting that the worst case additional junk is around -80dB on the test tone.
Attached Images
File Type: png MB1_19K.png (222.9 KB, 576 views)
File Type: png 1021Default_19K.png (183.2 KB, 534 views)
File Type: png MPSRO441v2_19K.png (198.8 KB, 493 views)

Last edited by spzzzzkt; 16th February 2015 at 04:56 AM.
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Old 16th February 2015, 05:19 AM   #42
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Default Why not NOS?

Hmmmm. Let me see.

It's not pretty.
Attached Images
File Type: png 1021NOS.png (136.6 KB, 519 views)

Last edited by spzzzzkt; 16th February 2015 at 05:21 AM.
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Old 16th February 2015, 05:28 AM   #43
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Nice set of measurements
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Old 16th February 2015, 05:45 AM   #44
TNT is offline TNT  Sweden
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spzzzzkt is right on the money.

These 3 filters are all steep. They are also symmetrical i.e. they have equal pre and post "ring" around a pulse.

MB1=nuttall - data1
MB2=Taylor - data2
MB3=Cheby(chev) - data3

In the pulse plot, all three are actually in there in one and the same plot.

Group delay over frequency (derivate of phase) is constant for all three filteters - only one shown. These should have excellent time coherence or as usually expressed "phase correct".

This is what I have but I (get) answers on any questions.

btw - don't forget to pull the serial connector when finished loading and starting to listen - you don't want your computer earth in your D/A.

I liked MB2 a lot. Had the best experience so far with this filter. I think MB1 and MB2 sound considerable cleaner than the what I had listen to earlier. The soft roll off filters has a trail of quite nasty hf that is not music but maybe clarity. MB2 was to me more mechanical somehow - not as much music. MB2 made my muscles around the ear relax.

Yes - tonality is a game of matching components but cleanness and coherence can't be. Many of the latest trend tall/narrow speakers do suffer from lack of energy in the warmth/chest band du to less coupling to the room. More baffle area cures this but also some EQ would.

I still feel that the D/A is not as clean in the upper regions as I would have wished - at times it has a little grey hash. See if the unbuffered output provides a solution. Also for these filters I need to hear them over loudspeakers - hopefully this week.

Thanks to Mikael B for designing these filters which he says are all text book filters with a little tweak with windowing.

Filter thumbnails left to right - MB1, MB2 and MB3
//
Attached Images
File Type: png nuttall_1016_8.png (17.8 KB, 518 views)
File Type: png taylor.png (18.1 KB, 205 views)
File Type: png ChebyWin.png (17.1 KB, 187 views)
File Type: png IR 1_3.png (19.5 KB, 214 views)
File Type: png grpdelay.png (11.3 KB, 201 views)

Last edited by TNT; 16th February 2015 at 06:10 AM.
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Old 16th February 2015, 05:53 AM   #45
TNT is offline TNT  Sweden
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Quote:
Originally Posted by spzzzzkt View Post
Hmmmm. Let me see.

It's not pretty.
No - what is it?

//
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Old 16th February 2015, 06:04 AM   #46
TNT is offline TNT  Sweden
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If you experience loss of output level, one possible reason could be that you did not change the "numbercoefficients" parameter implying that not the whole filter is executing. Sören to confirm that this would be the consequence...

-- Format:
-- signature, samplerate, interpolationrate, type, numbercoefficients, multiplier

//
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Old 16th February 2015, 06:57 AM   #47
zfe is offline zfe
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Quote:
Originally Posted by TNT View Post
No - what is it?

//
NOS (see title)
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Old 16th February 2015, 07:26 AM   #48
TNT is offline TNT  Sweden
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Quote:
Originally Posted by zfe View Post
NOS (see title)
Ah! Urrk.

//
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Old 16th February 2015, 07:37 AM   #49
TNT is offline TNT  Sweden
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Quote:
Originally Posted by TNT View Post
spzzzzkt is right on the money.

These 3 filters are all steep. They are also symmetrical i.e. they have equal pre and post "ring" around a pulse.

MB1=nuttall - data1
MB2=Taylor - data2
MB3=Cheby(chev) - data3

In the pulse plot, all three are actually in there in one and the same plot.

Group delay over frequency (derivate of phase) is constant for all three filteters - only one shown. These should have excellent time coherence or as usually expressed "phase correct".

This is what I have but I (get) answers on any questions.

btw - don't forget to pull the serial connector when finished loading and starting to listen - you don't want your computer earth in your D/A.

I liked MB2 a lot. Had the best experience so far with this filter. I think MB1 and MB2 sound considerable cleaner than the what I had listen to earlier. The soft roll off filters has a trail of quite nasty hf that is not music but maybe clarity. MB2 was to me more mechanical somehow - not as much music. MB2 made my muscles around the ear relax.

Yes - tonality is a game of matching components but cleanness and coherence can't be. Many of the latest trend tall/narrow speakers do suffer from lack of energy in the warmth/chest band du to less coupling to the room. More baffle area cures this but also some EQ would.

I still feel that the D/A is not as clean in the upper regions as I would have wished - at times it has a little grey hash. See if the unbuffered output provides a solution. Also for these filters I need to hear them over loudspeakers - hopefully this week.

Thanks to Mikael B for designing these filters which he says are all text book filters with a little tweak with windowing.

Filter thumbnails left to right - MB1, MB2 and MB3
//
Should have read: MB3 was to me more mechanical somehow

//
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Old 16th February 2015, 08:02 AM   #50
pos is offline pos  Europe
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Ok so those filters are basically brickwall filters (so called "windowed sinc"), using 3 different windowing algorithm.
This is the simplest possible LP filter design you can do with FIR.
The final shape (steepness and ripples "floor") is dictated by the chosen window.
Similar design to what Soren originally did use, but with more taps which allows for steeper slopes with the same ripples floor...

Attached is an example you can play with (choose different windowing algorithms and generate to see the resulting curve, and also maybe change the filter frequency).
Those that work well in this context are Nuttall, Blackman-Nuttall, and Blackman-Harris.
I don't have Taylor and Chebychev windows in rephase so cannot try these, but I can add them for the next version.

Funny thing is that people wanted a shallower slope and no preringing, but now the steepest linear-phase (ie tons of preringing) filter is preferred
Attached Files
File Type: zip DAC 44,1kHz brickwall.zip (1.1 KB, 75 views)
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Last edited by pos; 16th February 2015 at 08:05 AM.
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