Absolute top tier DAC for standard res Redbook CD

@gdhal 
  
For highest fidelity and accuracy of Redbook, I would recommend to do this

1) Use Roon with its default 3 dB reduction to eliminate the all too common  intersample over clipping errors.
2) Use Roon or another software to upsample the Redbook data to 192KHz and 24 bit
3) Select the Linear Phase Slow filter option of your DAC

This approach will minimize the filter affect on the CD audio band to a negligible level because you have pushed the anti-aliasing filter corner way up to 96KHz which is much farther from the audio band than 22 kHz which is what your DAC will normally use if fed redbook.

Hi @shadorne

Thank you so much for the recommendation(s). In the case of the filter option, I will change to linear phase slow as you suggest (even though I rarely listen to the Oppo directly at this point).

As to Roon, I’m not sure why I would need that. One major source of my PCM based music is lossless legs. This is a bit torrent peer-to-peer trading community web site: https://www.shnflac.net/index.php?page=torrents&search=&category=0&active=0

If you care to have a look at the source of the actual show/music, just click on a show and note the torrent details. While the precise lineage isn’t always available, the majority of the time it is.

For example, gd1970-09-20.sbd.boswell.smith.miller.clugston.flac2496

details are:

Source Info:
Master Soundboard Reels (borrowed by Peter Kafer) > Will Boswell’s reels @ 7 1/2 ips

Transfer Info:
Reel (Technics RS1506) > Tascam DA-3000 (DSF 1bit/5.6 MHz) > dBpoweramp 24/96 > Adobe Audition 3.0 > TLH flac2496

I don’t think there is anything I need to do here in the way of upsampling or otherwise altering the source. Am I correct in my thinking, or is there something I could or should be doing to further optimize the quality?
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By the way, @shadorne and at @audioengr

in appreciation of your kindness, I’d like to offer the gift of music. Feel free to pick something (a show) you would like, and I can make it available to you as a direct download (in flac or shn format).

http://halr.x10.mx/shows.html (grateful dead)

http://halr.x10.mx/other.html (all artists other than grateful dead)

The quality (sound and performance) of most shows is pristine :)

@gdhal

The logic for upsampling Redbook is well documented and justified. Redbook requires a Nyquist filter at 22KHz to prevent aliasing or image noise from 22 to 44 KHz from being included in the analog output signal. Unfortunately a sharp filter at 22 KHz is guaranteed to affect the audible sound due to the proximity of this sharp filter to the audio band. By upsampling you preserve the entire original digital information contained in redbook but you push the Nyquist far up to 96KHz for a 192KHz sample rate. This makes filtering so much easier and entirely benign. Going up to 24 bit also preserves the entire Redbook signal.

The key understanding is that upsampling preserves ALL the original information and so does an increase in bit depth from 16 to 24.

This is very different from down sampling which can alter the original audio (stuff is thrown away) and normally down sampling requires careful processing and filtering to preserve the audio (dithering being a very important processing step in down sampling, as simple truncation is highly distorting)

The key to understand is that upsampling is benign but it makes the job of filtering aliased or ghost frequencies much much more accurate. Every DAC must filter out these “aliasing” artifacts as it is inherent in sampling theory (to accurately capture a signal you need a minimum of two samples per wavelength) - anything that is sampled less than twice will appear as “ghosts” or aliasing artifacts (and these artifacts sit at frequencies above the Nyquist which is half the sample rate frequency). The sharp filters at Nyquist are essential to ensure these “ghosts” do not appear in the reconstructed analog output, however, a sharp filter close to the audible range is less than ideal as it affects the audible range also!

Apart from this sharp near audio band filtering issue due to the low sample rate, CD Redbook is a near perfect audio distribution format - especially when carefully produced. Only recently has analog equipment achieved the equivalent of 21 bit resolution making 16 bits a further limitation of CD redbook.

@gdhal 

Thanks for this awesome gift.

I would like to hear Tower of Power live in 1975.

This was their best line up ever with Lenny Williams on vocals and Chester Thompson on keyboards. They are probably the best band in the world to see or hear live! Sooo excited!!