Up and Over sampling EXACTLY the same thing

I agree, Phild... we need to evaluate equipment on how it sounds and not (for the most part) on the technology used to get there. As far as your new DAC, digital filters have no doubt gotten better (and I believe will continue to get better), but in the end the performance of the product is purely dependent on the designers skill in implementing the whole package (digital and analog).

The method is the same for both up/over sampling. I think some manufacturers latched on to the high rez format buzz words of 24/96, 24/192 and just performed a small integer (or non-integer in the case of redbook CD to 96 or 192) up/over sampling in the first digital filter, followed by a standard 4x or 8x up/over sampling in the second digital filter. As the article states, if you add another digital filter it WILL change the sound for better or worse, depending on the computational power and sophistication of the filter. I also found it interesting that using two digital filters in series is a cheaper way to achieve a certain technical spec.

Is anyone else troubled by the statement in the article, "but the public really wants something like this. It's like trying to sell a seven-year-old on Santa Claus -- it doesn't take much selling."? It ticks me off!

Hellosimplymusic, I agree that the misconceptions regarding up/oversampling have reached critical mass and that the marketing hype will likely continue.

I wouldn't say I understand the technology well. I am not an EE specializing in digital design, although I am an engineer. That said, I do not think this is conceptually difficult to understand.

Judit, I wrote that to mean that I feel purchasing a piece of equipment based on the marketing hype is not likely to result in sonic satisfaction. The component may sound better, it may not as well. Our ears will ultimately determine our satisfaction, notwithstanding certain short-term psychological effects (eg. this "should" sound better affecting it "does" sound better -- not sure what this phenomenon is called?).

I am not familiar with the VHS/Betamax story, but I have heard it to be very interesting. Something along the lines of Betamax being technically superior, but marketing and timing resulted in VHS winning out. Is that essentially correct?

Ultimately, I think we all want better sound. Some may be quite content with knowing their ears tell them it is better while others want to know how/why as well. For me, I want to hear the differences for myself and know how/why also, probably the engineer in me coming out. But, no matter how interesting I find the technology, if it doesn't sound better I don't want it. And BTW, I don't consider "upsampling" new technology. Better filter design, yes, upsampling, no.

I have not heard any of the new formats (DSD or 24/96). They likely offer greater "potential" for sonics, but without a sizable library of software and clearly better sound, I probably will stay on the sidelines. I also have hope that significant improvements in Redbook CD will continue as long as 16/44.1 software is still produced. This, I believe, is good for us all!

This is interesting. Despite Wadia's previous efforts at dispelling the marketing hype of "upsampling/oversampling", they now have embraced it. (See quoted text below)

Or have they? They use the words "upsampling" in describing their process, but they don't "upsample" to 96kHz or 192kHz (non-integer or "asynchronous" up/oversampling). They actually use a 63X (~2.8MHz) oversampling. Is Wadia being disengenuous now or are those (mfg's and reviewers) who have been touting "upsampling" as something new and fundamentally different the ones who have been disengenuous?

I actually applaud Wadia in this. They have made efforts to inform the public that up/oversampling are the same, but it clearly has not worked. Plan B: Give up trying to point out the marketing hype and dilute it by embracing the terminology. If every mfg uses the term "upsampling", then is there any marketing advantage by touting it? Not a bad plan I suppose.

BTW Martian, Wadia use a 12th order polynomial spline curve fitting to interpolate the extra data points.

Wadia Technical Bulletin, March 2001: Up-sampling and Wadia Technology
Digital up-sampling has been getting a lot of attention recently, and for good reason: up-sampling can provide tremendous sonic benefit. At Wadia we have been incorporating patented, high-performance synchronous up-sampling systems into our CD Players and Decoding Computers since 1988. We welcome the new attention being paid to up-sampling and would like to explain the technology behind it.

What is up-sampling?
Up-sampling is the process of mathematically generating digital samples to “fill in the blanks” in a digital data stream. Up-sampling increases the digital data rate, reducing the demands on the analog filters used to smooth the signal during digital to analog conversion. Well-executed up-sampling can have a dramatic sonic benefit, resulting in a more realistic and natural musical presentation. However, up-sampling cannot somehow magically recover information not captured in the original recording.

Can up-sampling convert a CD into 96 kHz?
Some products use asynchronous interpolation to increase the data rate from a CD to 96 kHz or 192 kHz. While this process does increase the number of samples, it does not recover any additional information that would have been captured during a true 96/192 kHz recording. In fact, asynchronous interpolation discards the original CD data and can actually reduce the clarity and detail of the original recording.

Why is Wadia’s DigiMaster up-sampling better?
Wadia’s patented DigiMaster system, by contrast, uses a synchronous interpolation process to preserve the entire original signal and provide up to 2.8 MHz data rate – almost 30 times the data rate of 96 kHz up-sampling systems! The DigiMaster system uses 12th-order polynomial Spline curve fitting to generate up to 63 new samples for each original sample. Music lovers and audio reviewers around the world have agreed that Wadia’s innovative up-sampling process realizes the most compelling and engaging musical performance available.

What is the future of up-sampling?
Wadia has continued to refine and improve the DigiMaster system for over 12 years, expanding the possibilities for high-performance digital audio decoding. We firmly believe that consumers who desire the most advanced up-sampling technology in the world need look no further than Wadia.

Martian,

If you like how the Belcanto sounds, what's the problem? The sound is the most important part, at least for me.

Upsampling and oversampling are indeed the same thing. Both are sample rate converters. Both increase the number of samples by some factor (2, 2.18, 4, 4.35, 8, or whatever). Both will need interpolation to assign a voltage (amplitude) value to the newly created samples. Although a separate process, both may increase the word length from 16 bit to 18, 20, or 24 through the appropriate use of dither (basically white noise). Both may use a dac of various resolution (18/44.1, 24/96, 24/192 or whatever).

As Charles Hansen (research director for Ayre) said in the article I posted above, "Upsampling and oversampling are the very same thing and anybody who tries to tell you differently is misstating the case... And there's nothing unusual about putting two digital filters in a row -- virtually every digital filter is a cascade of 2x stages, because it costs less than accomplishing the entire filtering process in one go".

The reason why turning off upsampling on a capable player changes the sound is that you are taking one of the digital filters out, Particularly if it was designed to utilize the computing efficiency of two digital filters, it is likely to sound worse with only one. Again, Charles Hansen: "upsampling almost always makes a difference, and it can make an improvement".

In the end, it's the sound that matters. If it sounds better and the mfg happens to market using the "upsampling" hype, then fine. I do appreciate mfg's who talk straight about the topic though and if two products sounded identical (or maybe I should say the final subjective value I assign to the two products are the same), I will award the straight talking mfg with my business. That's just my philosophy.

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.