Filter brewing for the Soekris R2R

By phase coherency I presume you mean phase linearity.
The default filter Soren already implemented is also phase linear, with a shallower slope.

Minimum-phase filters imply phase shifts, linear-phase filters imply preringing.
Audibility of both of these phenomenon is still questioned, especially at these frequencies.
The steeper the filter, the more pronounced the phenomenon.

Pick your poison ;)
 
In defence of NOS

Would be nice to try a NOS filter on the DAM. Some interesting thoughts contained in Cees' 'paper' within this link. 6moons audioreviews: Metrum Acoustics Pavane

I built the Soekris DAC using various low-noise power supplies from diyinhk for the isolated input and even the bipolar J2 (which is still working fine) and using an R-core trafo. I still find the sound from a NOS DAC superior - more 'real' - although I think that, because of the ability to change filters, the DAM has huge potential. Onward spzzzkt, pos and other filter contributors - thank you for your efforts and please keep going.... please include NOS filtering in your efforts.

Incidentally, arguably the best improvement in sound quality occurred when I tried the DAM fed directly by the i2s out of a lowly Raspberry Pi running Volumio, completely eliminating the USB (an Auralic Aries) and SPDIF inputs. This was using the first minium-phase filter from spzzzkt.
 
Still waiting an a serial adapter
am familiar with the real dynamic sound of nos
I hope nos and/or partial nos continues to be part of filter development

I have also ran a rpi with Ians fifo reclocker it will be certainly better than regular pc to usb to i2s
I think rpi to dam dac will suit alot of people
 
Derekr, Nige2000 : TNT would (will) say you it's impossible because the FIFO ! :D

So maybe here we have a hint : FIFO can be sensible, in the spirit of what DIMDIM said and that I translate to the amount of jitter due to its buffer capacity ? Sorry off topic in this thread.

Does Volumio play Stream NOS or is it able to upsample itself if you ask it?

Raspberry is said to have layout problems for speeds above 192 K hz... ?!

It's certainly something to check with 384 K hz material for a testimonial in the implementation thread.

Was the difference with an AC traffo vs your Regs big enough ? What is the most interressant at ears : a shunt regs ?

Sorry again for the off topic, certainly need to answer on the other thread to let it go with digital filter here.
 
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Still waiting an a serial adapter
am familiar with the real dynamic sound of nos
I hope nos and/or partial nos continues to be part of filter development .....

+1

As NOS is essentially an oversampling filter bypass there isn't much that can be done to develop it further.

The measured with white noise, the frequency response of the NOS "filter" is essentially flat out to about 70kHz. I think my audio interface is starting to roll-off at this point, so don't believe there is a need to do additional corrections.

cheers
Paul
 
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Good ! I believe because the room and time delays with walls interactions : NOS is not the same when listen to with headphones vs Floorstanders. The room have to help a little in the highs with NOS acting like a pad of interface.

Certainly a mixed way to find between NOS and FIR filter like TotalDac made ? This is not to said than upsampling can be bad but it seems to involve a huge work to find something which sounds pleasant !

Paul, did you find a better dynamic with NOS ? Especially in the low end and medium ? Cant it rock now ? (bass string, percussions, drums ?)

Totaldac is using a FIR to compensate for HF roll-off. I haven't specifically tested the frequency response with a swept sine, so I can't say if this is necessary on the DAM. The white noise testing seems to indicate that the response is flat.

I'm not sure if I'd say it was more dynamic. The sound was thicker, and worked well on some material.

Where I felt struggled was on bottom heavy tracks. Out of interest I listened to Method of Defiance's "The unfathomable depths where dreams lie". You can preview the track on Juno if you really are curious... The Only Way To Go Is Down by Method Of Defiance on MP3 and WAV at Juno Download On this type of material the NOS filter sounded congested and confused.

Basically the filters are there to download, they take a few seconds to upload to the dac. If you are curious about how they sound - have a listen.
Talking about the differences in sound between filters is like using interpretive dance to explain the design nuances of Frank Gehry's Paper Bag building.
 
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NOS sounds best to me so far, but I like the sound anyway. Coming from MHDT and Metrum models this is the same presentation but better. Except- I am having a little more glare than with other DAM filters. A lot more glare than with MHDT.

Has you been trying this same NOS filter but playing a 16/41 already upsampled with Sox at 384 Khz to compare if hearable differences ?

(I can stay on topic sometimes :D.... btw I listened this afternoon a TDA1541 DAC in NOS with 16/41 materials and it can sounds clean... to me, but have not tried with Sox yet to push it at 192 or 384 !)
 
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NOS sounds best to me so far, but I like the sound anyway. Coming from MHDT and Metrum models this is the same presentation but better. Except- I am having a little more glare than with other DAM filters. A lot more glare than with MHDT.

In the case of the Metrum Acoustics DAC there is a mild 70kHz (first-order) filter just before the signal is sent to the output-terminal.

The DAM1021 has a hardware output filter set at 270khz, and a final software filter which is -80dB @ 240kHz.

Modelling a 1st order filter with a 70kHz corner frequency in rePhase indicates that the Metrum will be -0.31dB at 20kHz, -1.23dB at 40kHz, and -3dB at 70kHz (obviously, as the corner frequency is the -3dB point).

It is easy enough to create this filter and the output should be more like a Metrum, in terms of frequency response anyway.

The filter is minimum-phase but it will make little difference.
 
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It is easy enough to create this filter and the output should be more like a Metrum, in terms of frequency response anyway.

OK, this one is badly distorting at high volumes. I'm not sure if it's messing with the Hypex amp, or similar but it's pretty ugly beyond about V-10.

I'd advise not to use and I've requested mod's delete the attachment.

The original 1021NOS.skr seems to be fine so I'd use that in preference.
 
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Is it possible to have a FIR 1 NOS from 10k/15 K hz then a FIR 2 with digital EQ from 10/15 K but with a stronger roll of ? Stronger but stil with a few -DB roll of per octave ? - 1.5 to - 3 DB ???
Why not try something non conventional which impact the ears range directly ! When I listen to an old 16/44.1 chip like the Philips, I can't really hear a lacke of micro informations .... I'm not sure it's straight right to 20 k hz in a 0.5 DB drift range....

Have to say I'm always with the stock filter as I haven't bought an USB to serie RS232 convertor !
 
Has you been trying this same NOS filter but playing a 16/41 already upsampled with Sox at 384 Khz to compare if hearable differences ?

(I can stay on topic sometimes :D.... btw I listened this afternoon a TDA1541 DAC in NOS with 16/41 materials and it can sounds clean... to me, but have not tried with Sox yet to push it at 192 or 384 !)

I use cds so no access to Sox. I did add a 6111 tube buffer to the direct output and the signal has cleaned up nicely. NOS is giving me the tone I am looking for and no drawbacks so I will use it as reference.

I am moving on to output stage and will start a new thread.

Thanks for the great work on the filters guys we all appreciate it!
 
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Is it possible to have a FIR 1 NOS from 10k/15 K hz then a FIR 2 with digital EQ from 10/15 K but with a stronger roll of ? Stronger but stil with a few -DB roll of per octave ? - 1.5 to - 3 DB ???
Why not try something non conventional which impact the ears range directly ! When I listen to an old 16/44.1 chip like the Philips, I can't really hear a lacke of micro informations .... I'm not sure it's straight right to 20 k hz in a 0.5 DB drift range....

Have to say I'm always with the stock filter as I haven't bought an USB to serie RS232 convertor !

Perhaps you should spend the 10-15 euro on a USB -> Serial interface. It seems a bit pointless endlessly speculating about variations when you haven't listened to any of the modified filters.
 
Ah, I just tryed to follow the comments that's all :D. Sorry if you get upset with it !

I'm a little busy on some other dacs building... And my Dam1021 is always for sale in the swap meet section http://www.diyaudio.com/forums/swap-meet/269283-sale-soekris-dam1021-0-02-a.html, have to fax to my bankeer to decide if it's worth to buy a USB to serie adapter (and ask for a little more to buy a Valium tablett to let it work ! ). The first listening just give me the envy to finish first my others dac as this one is too much time consuming ! .... And before trying the other digital filters improvements (more listening sessions, etc !)

What can I answer to you Paul :) ? Thank you for sharing ! Your efforts are much appreciated and far above my personal skill...BTW I updated the memory aid first page for new readers http://www.diyaudio.com/forums/digi...oekris-s-dac-implementations.html#post4184471

At least it seems this DAC is a good war tool as well :eek: ; You will excuse me about this off topic but your message called for an answer !
 
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OK, I am a noob at DACs and have been reading to try to understand. If I understand correctly, the DAM has no filter when fed 352.8 or 384 kHz input. Reading the John Swenson posts about upsampling externally using SoX, it seems like the interpolation filter used by SoX would have quieter alias' than upsampling of zeros added in the Dam as described by Soren. I'm not sure how rephase works.

I was wondering if any of you filter kings have compared a high res sample (192 or greater) with the NOS using 44.1 that you have been experimenting with? The hi-rez sample should sound cleaner, in theory, than the NOS, even if it was upsampled using a program like SoX.

My current concept is that the DAM Dac is an excellent choice when used with externally upsampled music, but I haven't gotten far enough to try any hardware.

Thanks in advance for you comments and experience.
 
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Ah, I just tryed to follow the comments that's all :D. Sorry if you get upset with it !

I'm a little busy on some other dacs building... And my Dam1021 is always for sale in the swap meet section http://www.diyaudio.com/forums/swap-meet/269283-sale-soekris-dam1021-0-02-a.html, have to fax to my bankeer to decide if it's worth to buy a USB to serie adapter (and ask for a little more to buy a Valium tablett to let it work ! ). The first listening just give me the envy to finish first my others dac as this one is too much time consuming ! .... And before trying the other digital filters improvements (more listening sessions, etc !)

What can I answer to you Paul :) ? Thank you for sharing ! Your efforts are much appreciated and far above my personal skill...BTW I updated the memory aid first page for new readers http://www.diyaudio.com/forums/digi...oekris-s-dac-implementations.html#post4184471

At least it seems this DAC is a good war tool as well :eek: ; You will excuse me about this off topic but your message called for an answer !

Not upset, but without hearing what the different filters sound like in your system it's as useful as picking your favourite flavour of ice-cream on the basis of what someone thinks is good. I hate aniseed, banana and passionfruit but you might love Pernod, so are you going to avoid Pernod ice-cream because I don't like it? Following someone else's opinion - no matter how stridently it's expressed - might well deprive you of something you will enjoy...

As pos says "pick your poison" but you can't do that without listening....