Up and Over sampling EXACTLY the same thing

Martian, while I agree that the term "upsampling" is generally used in conjunction with 96kHz and 192kHz, both non-integer multiples of 44.1, I disagree that there is any fundamental difference from oversampling. I do believe that 96kHz and 192kHz are used specifically to wrap the manufacturer (and convince the consumer) that this is somehow as good, the same, or close to the same as the higher resolution format DVD-A (true 24 bit, 96kHz recordings).

"Sample rate conversion" simply means changing the sample rate from one rate to another. If you recorded a concert at 88.2 kHz DAT, the sample rate conversion was a simple 1/2 of the original rate to burn it to redbook CD. Most DAT's, however, are 48kHz or 96 kHz, so the sample rate conversion to Redbook CD is a non-integer conversion.

The "bits and pieces" (pun intended) of actually changing the sample rate are the same whether it is a non-integer or integer change. Extra samples are created and voltage values are assigned for these extra samples based on interpolation of samples before and after. Several techniques are available for the digital filter designer to choose from, one of which would be a linear interpolater. But an interpolation algorithm based 2nd order, 3rd order, or sine function can be used as well. This is the same for both integer and non-integer sample rate conversion (over/upsampling) and is just one of many factors a digital designer must consider.

I will leave you with this Wadia quote from the article you linked:

When used to convert a CD signal to a higher sample rate, the process of sample rate conversion is mathematically synonymous with over-sampling. Whether this process is performed in a digital filter housed in the same chassis as the D-to-A converter or in a ieparate chassis has little bearing on performance. Any advantage that can be claimed for a rate-conversion system can equally be achieved in a sophisticated over-sampled system such as the Wadia DigiMaster.

The concern with the Redbook standard that Up, Over or Down sampling miss...is that the biggest concern with all of your/my/our CD players is still where it was when we were all buying Sonic Frontier, Levinson, Classe DAC's and things like the Genisis Lens and SF Ultrajitterbug...the two areas that really have big impact on your sound, gentlemen, is jitter and the audio section of your player.

Why isn't this addressed(marketed) by CD/DAC manufactures..well it's because the cures are expensive. It is much easier to buy the latest Burr-Brown DAC...(which is a chip) and tout that, rather than do the serious structural/transport/receiver work that is the jitter end, or speak of the jfets or tubes(let alone the wire, caps, resistors..etc. that we all worry so much about in pre-amps etc.) or whatever in the audio section. Go to look at the ad/flyer on-line for some of these older DACs and see where they address jitter and the audio section.

Most of our/your most used source piece..the CD player has no better jitter than prior generation units and usually poorer audio sections..even very $ players are using op-amps for the audio signal. Kinda silly to worry about the tube vs. SS or silver vs. copper wire..etc. when the audio signal in most systems is starting in an op-amp that none of you would think much of if it was the audio section of your pre-amp!

So, my friends, up and over...is a new chip to put into a player or DAC that is easier to do and market..than the more costly..and harder to do improvements in jitter and audio signal quality.

Wadia oversampling advocating:

«...Any advantage that can be claimed for a rate-conversion system can equally be achieved in a sophisticated over-sampled system such as the Wadia DigiMaster.»

I can follow you. But at the same time it's clear that the interpolated curve resulting from an upsampling (non-integer sample-rate converting) system isn't identical with the curve from an oversampled interpolation – after smoothing by the low pass filter. Though we can't say which one is better or more adequate, there is a difference. It can also be deduced from the reviewer's (Andrew Harrison) judgement, which btw. clearly favors the «upsampling» dCS against the «oversampling» Wadia. No deciding argument, of course, due to the very different devices.

Interesting points:

Sony only quit making Betamax players THIS year (2002).

Also, the Ayre CD player upsamples to 1.4112 MHz which is more than any other player that I can think of off the top of my head.

The Ayre player does sound fabulous though.

See my review of the Ayre CX-7 here at Audiogon.

KF

I'm going to try an isolation transformer to my CDP. Probably a more effective tweak than all this "up" and "over" hype.
Jon Risch has some interesting designs at his geocities site. No toroidial transformers, use EI (?) transformers instead..