More info on CD upsampling...please

[resperc]

I am seeing some DVD players available that offer CD upsampling from the standard 44.1khz to frequencies as high as 176.4khz. I am pretty sure this does not raise regular CDs to meet the quality of DVD-A or SACD. However, there must be some benefit (hopefully not just marketing). I am still a little confused on how this will help. The CD will still be a 16-bit source, right? What are your experinces with CD upsampling? If it will make my regular CDs sound better...I am all for it. Please shed some light on this issue. Thanks

[Bam!]

Hi

here's the delio with what I think.

There are fifferent qualities of DACs......yes the specs say one thing but the sound says something else.....just like the power ratings of amps......cinema receivers especially....


So for me....I would much rather listening to let us say Naim cd5i that is a 16 bit and makes the cd sing....than let us say a DvD player like samsung or whatever that says upsampling 192khz with a cheap DAC colors the sound....usually resonates......just not my cup of tea...

The max music cds can be upsampled IMO is 24/96......cause so far I've never heard a good 192khz upsample.....


Just my 2 cents.

[aud19]

I agree. If you want upsampling get something like this Most mass market players will just add cheap DAC's so they have the stats but more likely than not won't sound all that great. Now if higher end players start coming with DAC's similar in quality/performance to the DAC1 built right in well now that would be something to spend your money on... Though it would likely be fairly expensive.

Jason

[Kevin P]

"Upsampling" is similar in ways to the "oversampling" craze in the 80s/90s. It's a way to convert fewer bits and samples into more. In the case of oversampling, this was done to simplify filter design. Upsampling is used to convert lower resolution sources (such as Redbook CD) into bitstreams compatible with modern 96/24 or 192/24 DACs.

Oversampling was always a power of 2 upconversion, 2x, 4x, 8x, 16x, etc. For 2x oversampling, the DAC simply interpolated a sample (by averaging the two samples) in between two real samples, essentially adding 1 bit of "resolution" to the bitstream. 4x does this twice to add 2 bits, 8x does it 3 times, etc. Each level of oversampling doubles the sampling rate, shifting the quantization noise further into the ultrasonic range, allowing gentler analog filters to be used.

Upsampling is a bit more sophisticated, since it isn't a simple doubling of the sample rate. Instead, it converts one resolution to another (much like a scaler does with video). Upsampling is more likely done as an economy measure, since most devices nowadays have either 96/24 or 192/24 DACs, and since it's cheaper to make a DAC support a single resolution rather than multiple (especially odd resolutions like 44.1/16), upsampling is used to allow a native resolution to be fed to the DAC even if the source isn't operating at that resolution.

So does it sound better? It depends on the implementation. A 44.1/16 DAC with a high quality filter can sound as good as, if not better than, an inexpensive 96/24 DAC fed an upsampled 44.1/16 signal. It all boils down to how accurate the upsampling algorithm is, and the quality of the DAC and filters.