Filter brewing for the Soekris R2R

Yes . I'm aiming for aliasing/imaging free, time and phase coherent filter with flat response from 20 to 20kHz. Current DAC architecture is forcing upsampling so I'm trying to find way how to do it right. There are tons of other solutions for example, external upsamplers, perfect FIR sinc filter with millions of coefficients but somehow they doesn't work for me.

Well that would go a long way explaining why the original NewNOS had audible distortion and yours doesn’t. Well played sir.
 
Unfortunately, it is still too quiet for me. Even this filter with +9 gain.

Gain is lost on first stage with FIR1 NOS filter, then I recover gain on IIR stage and FIR2 stage but I can’t do more. Filters are level matched to be comparable.
Or maybe I missing something.


Well that would go a long way explaining why the original NewNOS had audible distortion and yours doesn’t. Well played sir.
Thanks. There are still few variations to test but I will need remove some filters from set to make room :)
 
If your filters are fed 48 kHz material, they roll off just the same as 44,1 kHz right?

Experimenting here with first doing software upsampling from 44,1 to 48 kHz, then feeding it to the dam over I2S. Not normally my cup of tea but interested to find out if this improves the RPi clocking (see the dam1021 thread).

Would you expect any anomalies?
 
Gain is lost on first stage with FIR1 NOS filter, then I recover gain on IIR stage and FIR2 stage but I can’t do more. Filters are level matched to be comparable.
Or maybe I missing something.



Unfortunately, I do not know how to create filters at all. I'd like to just check out what you're trying to do. The TNT filter sounds + 17dB louder compared to yours.
The problem is that it sounds much quieter than the CD player.
 
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Experimenting here with first doing software upsampling from 44,1 to 48 kHz, then feeding it to the dam over I2S. Not normally my cup of tea but interested to find out if this improves the RPi clocking (see the dam1021 thread).

So I've been trying realtime upsampling to 24 bit 48 kHz on my Raspberry Pi streamer, using the speexrate_best ALSA plug.

Though I cannot rule out any placebo effects, I think the sound is slightly thinner and a bit more metallic. Though still good.

Call it dogma but I would much rather do the upsampling on the dam. So I am now thinking of putting a Kali reclocker before the dam, to at least have a stable 44,1 bit clock. See the dam1021 thread.

This has nothing to do with your filters gumisb, they seem to handle 48 kHz just fine.
 
The problem is that I have a tube preamplifier and it generates a little noise at higher volumes. Therefore, too low volume at the output from the DAC is inconvenient for me.
Besides, I have the impression that using this filter the DAC loses Dynamic.

NOS filters by definition have higher THD and by proxy lower DNR. The question is if you subjectively appreciate that THD. For the objectively "best" I think you should opt for linear filters.
 
So I've been trying realtime upsampling to 24 bit 48 kHz on my Raspberry Pi streamer, using the speexrate_best ALSA plug.

Though I cannot rule out any placebo effects, I think the sound is slightly thinner and a bit more metallic. Though still good.

Call it dogma but I would much rather do the upsampling on the dam. So I am now thinking of putting a Kali reclocker before the dam, to at least have a stable 44,1 bit clock. See the dam1021 thread.

This has nothing to do with your filters gumisb, they seem to handle 48 kHz just fine.
If you want to play with jitter try this software DeltaWave Audio Null Comparator DeltaWave Audio Null Comparator | DeltaWave documentation
Generate wav test files from REW for example and then play/record them to compare. At last it should allow to control what changed 😊
 
There are many types of audiophiles. The objectivist would agree with you. The rationalist might point out that there are even order harmonics that some find pleasing to the ear. The subjectivist could say to let your ears be the judge.

Are you suggesting that low THD and good DNR are less pleasing to the ear?
I care about the best quality of music playback. I even have the room acoustically adapted and you suggest to me it's a matter of taste?
Why bother with filters at all when you can listen to music on the kitchen radio or on your smartphone?