Quote from Spritzer:
Upsampling started because Phillips had designed 14bit dac's which was the original CD standard. With no time to make new chips they upsampled instead. Arguably a far better ploy than what Sony did back in the day. It is essential with delta/sigmas to decrease the error rate. Saying that OS messes up the treble is simply not true though, that's like saying analog has higher resolution than Red Book. In fact, how could OS do that as it is just a fixed multiplier?
Plenty of DAC's that don't brickwall, in fact many high end dacs play with the brickwall and offer different slopes. Removing it all together is a bad idea though and substituting for it with passive components is even worse. That could be just me though as I believe in proper engineering, not hocus-pokus BS. It's also nice to leave part tolerances out of the equation for unit to unit consistency.
Quote from Wikipedia:
There was a long debate over the use of 14-bit (Philips) or 16-bit (Sony) quantization, and 44,056 or 44,100 samples/s (Sony) or approximately 44,000 samples/s (Philips). When the Sony/Philips task force designed the Compact Disc, Philips had already developed a 14-bit D/A converter (DAC), but Sony insisted on 16-bit. In the end, 16 bits and 44.1 kilosamples per second prevailed. Philips found a way to produce 16-bit quality using its 14-bit DAC by using four times oversampling.
The reason Philips oversampled was they had already designed an early 14 bit DAC, as you say, BUT this does not prove that the Sony DAC of 16 bits was below par to the Philips, and is probably the opposite in actual fact. All this does not have anything to do at all with Delta-Sigma chips and errors. The oversampling architecture (OS) was created by manufacturers to be able to design an effective HF filter at 20k-22.5k range that was 'deemed' required to block out sonic wave shadows are artifacts measured on oscilloscopes but in the upper human hearing range. This filter implementation has been proved by many leading DAC manufactures as false and not required, and lead to reduced sound quality proved in exhaustive listening tests as apposed to measurements. It is quite incredible how after 25 years or more of CD and the oversampling architecture of mainstream DACs, that manufacturers are finally listening to the SQ they actually hear, as apposed to a wave read out.
On Oversampling affecting the sound quality, many owners and reviewers prefer the Perfectwave DAC with OS tuned off, as do many owners of the Esoteric K-01. There is a change in the sound in those machines when changing the OS rates, so clearly it DOES affect the sound. We all used to think digital is digital, a copy is perfect, speaker cables are just wire etc etc. Time and again it isn't Many reports show upsampled digital is not bit perfect, and in real time, and then down sampled back to 16 bit? Errors, blurring, it all affects the SQ. I use the comparison of a 72 ppi image - upsampled to 288 ppi, then downsampled back to 72 ppi. Compare it with your original, and the OS image is not as sharp or as clean.
On Oversampling there are three camps
First camp stick to OS and think it sounds best.
Second camp have found NOS and maybe not sure how it works, but love the SQ and stay with it.
Third camp is those who have climbed halfway up the mountain, and decided to stop, and say they know it all, and slate NOS DAC designs without hearing any or many of the better ones out there.
I am in camp 2. I nearly left CD for good as I was so fed up with the digital sound and 'hi-fi' presentation. I am so glad I listened to NOS tubed DACs.
So, I must say it again, NOS DACs do NOT reduce the high frequency of RedBook. In fact, NOS DACs with the Brickwall filter removed should do the opposite? Also Tubed DACs do NOT guarantee soft sound quality or 'tubey' presentation. Some of the best audiophile amps available are tubed designs. Or is the BHSE crap now?
And finally, please guys, lets try some NOS DACs and make our minds up with quality experience preferably in your own system. It could be a revelation to you?