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Filter brewing for the Soekris R2R
Filter brewing for the Soekris R2R
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Old 17th April 2015, 08:04 PM   #771
nige2000 is offline nige2000  Ireland
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Join Date: Jun 2013
Quote:
Originally Posted by spzzzzkt View Post
Why is it worrying? It probably means that the power supply on the stock board is sufficiently good that your "improvements" make no difference.

The filters are not EQ. They are reconstruction filters that are essentially dead flat under 10kHz. The only difference that will effect bass quality is roll off between 13-20kHz which will make the bottom end sound slightly more forward.
not what i meant
if the optimum amount and quality of weight cant be gained with filters where can it be obtained
my power system has helped sq vastly
but its still a little short on weight
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Old 17th April 2015, 08:35 PM   #772
TNT is online now TNT  Sweden
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These, without the filter but with 38k on input, I think helped me in the weight department.

JG buffer - I2S over USB Audio

//
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Old 17th April 2015, 08:53 PM   #773
nige2000 is offline nige2000  Ireland
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Originally Posted by TNT View Post
These, without the filter but with 38k on input, I think helped me in the weight department.

JG buffer - I2S over USB Audio

//
ive +/- 5v direct from lifepo4 cells into the opamps for the 4v reference
doubt ill get much better than that
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Old 17th April 2015, 08:55 PM   #774
TNT is online now TNT  Sweden
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OK - haven't started to tweak the board yet. If ever...

//
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Old 17th April 2015, 10:16 PM   #775
nige2000 is offline nige2000  Ireland
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Originally Posted by TNT View Post
OK - haven't started to tweak the board yet. If ever...

//
That could be wise I already killed one board (silly mistake)
But would advocate a good DC supply and for the more adventurous something special for the 3.3v supply
The rest ain't so bad
Ac input was a car crash for me
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Old 18th April 2015, 02:23 AM   #776
spzzzzkt is offline spzzzzkt  Australia
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Quote:
Originally Posted by nige2000 View Post
not what i meant
if the optimum amount and quality of weight cant be gained with filters where can it be obtained
my power system has helped sq vastly
but its still a little short on weight
I'm aware the filters sound a little light on bass, but it's not something that I'm going to attempt to fix by adding 1-2dB of boost below 250Hz for example. The measured response at the outputs is actually dead flat in this range, so it's not actually a problem with the DAC or filters per se.

Ultimately the solution is going to come from understanding the reasons this is occurring rather than trying to compensate with add-ons. You'll just have to be a little bit patient.
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Old 18th April 2015, 06:23 AM   #777
TNT is online now TNT  Sweden
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Quote:
Originally Posted by spzzzzkt View Post
I'm aware the filters sound a little light on bass, but it's not something that I'm going to attempt to fix by adding 1-2dB of boost below 250Hz for example. The measured response at the outputs is actually dead flat in this range, so it's not actually a problem with the DAC or filters per se.

Ultimately the solution is going to come from understanding the reasons this is occurring rather than trying to compensate with add-ons. You'll just have to be a little bit patient.
Good.

//
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Old 18th April 2015, 08:09 AM   #778
spzzzzkt is offline spzzzzkt  Australia
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I've been trying to find a way to visualise the impulse in the time-frequency domain as I'm convinced this is more informative than time domain or frequency domains. There is a paper on the dirac site which indicates that only time-frequency domain adequately represents perceived frequency response.

This is a Wigner-Ville contour plot done with the time-frequency toolbox for Octave/Matlab from TFTB -- Time-Frequency toolbox

Filter brewing for the Soekris R2R-c128_100-png

This a plot of the C128_100 impulse. It seems to show similar information the STFT plots, but less cluttered. There is a mesh plot that can be done which show the impulse in 3 dimensions but it doesn't translate well to a static image.

I've done a bit of chasing on the bass issue, and still not sure exactly what is going on. I have a sneaking suspicion that going for minimal ring is part of the problem. C128_180 - which really crunches the side lobes - sounds pretty awful, to the point I won't bother posting. Going the opposite direction and using a kaiser window at beta=8 (which gives around 80dB attenuation to the stop band ala John Swenson Bottle Head) sounds pretty good, although it might be heading down the path of being overly forward. It is punchy and detailed, I won't commit to it being better in the bottom end. Sounds pretty decent on Pete Namlook & Material Object's "elektronik"...


Filter brewing for the Soekris R2R-k128_8-png
Attached Images
File Type: png C128_100.png (56.4 KB, 579 views)
File Type: png K128_8.png (55.9 KB, 573 views)
Attached Files
File Type: zip 1021filtNQ_K128_8.skr.zip (1.6 KB, 14 views)
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Old 18th April 2015, 11:15 AM   #779
supra is offline supra  Australia
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Join Date: Jul 2004
Location: Margaret River West Australia
Quote:
Originally Posted by spzzzzkt View Post
I've been trying to find a way to visualise the impulse in the time-frequency domain as I'm convinced this is more informative than time domain or frequency domains. There is a paper on the dirac site which indicates that only time-frequency domain adequately represents perceived frequency response.

This is a Wigner-Ville contour plot done with the time-frequency toolbox for Octave/Matlab from TFTB -- Time-Frequency toolbox

Filter brewing for the Soekris R2R-c128_100-png

This a plot of the C128_100 impulse. It seems to show similar information the STFT plots, but less cluttered. There is a mesh plot that can be done which show the impulse in 3 dimensions but it doesn't translate well to a static image.

I've done a bit of chasing on the bass issue, and still not sure exactly what is going on. I have a sneaking suspicion that going for minimal ring is part of the problem. C128_180 - which really crunches the side lobes - sounds pretty awful, to the point I won't bother posting. Going the opposite direction and using a kaiser window at beta=8 (which gives around 80dB attenuation to the stop band ala John Swenson Bottle Head) sounds pretty good, although it might be heading down the path of being overly forward. It is punchy and detailed, I won't commit to it being better in the bottom end. Sounds pretty decent on Pete Namlook & Material Object's "elektronik"...


Filter brewing for the Soekris R2R-k128_8-png
Yeah but like you said, the filters don't do EQ. Something else is causing weak bass, can someone do an output impedance/ frequency plot on unbuffered output.
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Old 18th April 2015, 11:24 AM   #780
bambadoo is offline bambadoo  Norway
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Join Date: Feb 2003
Location: West Coast of Norway
Have at least 5 dacs laying around. The dam has not weak bass in my setup. Initially I felt so. After playing some hundred hours this is not a problem. The bass is deep, powerfull and articulate.

With the latest "NOS" filters there is even more. ? Hard to describe.

Using unbuffered outputs.
AC 7.5V (50va trannie) direct into the dam.

Amplifer used for the time being has approx 10k input impedance

Last edited by bambadoo; 18th April 2015 at 11:46 AM.
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