Upsampling DACS: Take the Pepsi Challenge

I have read many of the discussion boards here over the past year or so and I was especially interested in this particular discussion as well as the analog vs. digital discussion found in another emotionally-charged confluence of differing opinions. Below my preamble I have included a plagerized excerpt from a Soundstage review. I think it is very noticable that many people understand what they themselves have learned but have trouble conveying it to others with the same depth of understanding that they themselves enjoy. Whether they are right or wrong is irrelevant to them because they KNOW the gospel according to them. That being said I offer this thought for consideration: What sounds great to your ear might be mud to another's ear. It is the perception of the truth and not the truth that matters to us when listening. Do you hear some things for the first time when changing cables or do you just notice them for the first time because you have gone into a VERY active listening mode instead of a somewhat passive listening mode because you heard the source so many times before? I agree with Carl that digital is theoretically better at sound reproduction than vinyl, but keep in mind that CD technology is relatively new as music reproduction time lines go and it is really almost barbaric when compared to what will be heard from that technology within 10 years. Remember seeing the first Edison recordings that were made on the laquer tubes? Compare that to today's vinyl. Problem with vinyl is that, although it can still be optimized, it is a technology whose time has come and gone. It will be surpassed by the digital domain. I do disagree with Carl however in his observations about women, finding them overgeneralized and sophomoric (and yes I am a guy). There are differences between brain usage between women and men, to some degree, and women might be more attuned to certain areas of stimulation than men. However, I take exception with anyone who thinks that a man and woman can not be moved just as passionately by music or hear/appreciate the same dynamics. Just not true. Totally gender neutral. There are women who are just as scientifically curious as any man - ever hear of Madame Curie? I work with them every day and they are EE's and physicists. Depending on your system, you might not be able to tell the difference between those drums being played across the street for real or being played on a good recording through an optimized system. You know they are real because that kid is banging away, making msitakes, playing along to music he has playing, etc. You can tell from the acoustics right away. But if a really talented recording engineer went into that space, recorded that kid banging away with all the echo, attack, and decay - then you did an A/B listening test - I think you'd be hard pressed to tell the difference. The reason we know this is true is that it has been done before and more than not were fooled. But the music reproduction system would cost you upwards of $100k. As the digital technology advances, the breakthroughs in software and hardware will bring much of that front end cost down. The problem with digital vs. vinyl is that most people hear a pure "streaming" data set when listening to vinyl. It is infinite in its attack, transients, harmonics, etc. So vinyl picks up the harmonics and decay from transients better than digital - up till now. As you read through the information below, you will see why Carl is right in theory but the author teaches the lesson with great KNOWLEDGE and the ability to impart his knowledge to others. Here it is: Data-word length Some background. Here’s what a random 16-bit data word looks like for CD audio: 0011011000101110 There are 65,536 different values represented by the 16 digital bits (2 raised to the 16th power). Each of these values represents a voltage in the analog output signal. If the DAC IC outputs two volts maximum, then each different value for the 16 bits represents .0000305 of a volt (this isn’t a precise analysis, just a general conceptual overview). 0000000000000000 = zero volts 0000000000000001 = .0000305 volts 0000000000000010 = .0000610 volts 0000000000000011 = .0000915 volts 1111111111111111 = 2 volts If you increase the word length from 16 bits to 24 bits, the number of different voltages you can represent increases from 65,536 to 16,777,216 (2 raised to the 24th power). Each step in a 24-bit word would represent .00000006 volts, still using our 2-volt output model, compared to the .0000305 volts for each step in a 16-bit word (using the same 2-volt output example). You can see that the granularity in voltages representing the musical signal is incredibly fine when the data words are 24 bits long. Take an example where the audio signal wants to be .0000455 volts (still in our 2-volt example). With 16 bits available, software has to decide whether to make this voltage become .0000305 or .0000610 volts. There is no way with 16 bits to make a voltage that is .0000455 volts. But in the 24 bit world, you have an extra 256 different voltages available between .0000305 and .0000610 volts. One of them will be almost exactly .0000455 volts. Twenty-four bits is really higher in resolution than any consumer analog or digital audio products can achieve due to limitations in current electronic technology. Most digital products with claimed 24-bit performance lose probably three to four bits in the noise floor. But nevertheless, it is advantageous and comforting to have a digital standard that actually exceeds the capabilities of performance in consumer audio components. I’m not sure you would want to listen to music that requires all 24 bits to reproduce anyway; the loudest sounds would be as loud or louder than the loudest noise you ever heard in your life, well beyond the threshold of pain. The quietest sounds would require the total silence of an anechoic chamber to be able to hear them. What 24 bits brings to the table is headroom and footroom, which make digital audio more forgiving and easier to work with and offers an improvement in resolution even if limited to 20 or 21 bits of effective resolution. The circuitry in the D2D-1 creates a higher resolution digital audio bitstream by analyzing sequential groups of 16-bit data words and generating interpolated (best guess) 24-bit data words to replace the original 16-bit words. The process does have some margin for error, but it is vanishingly low. Keep in mind that in converting 16-bit audio to 24-bit audio does not increase the resolution of the reproduced audio. You can’t have more than 16 bits of resolution when you start with 16 bits of data, but the higher resolution digital bitstream can be more optimally transmitted and processed to make small improvements in sound quality.

Gmkane, thanks very much for that info... Best answer yet to the question that drove me to start the thread. Thanks...

Gthirteen, you are more than welcome. Wonderful thing about this forum is that, with the collective knowledge and experience to draw upon, greater understanding will result in the truth. In my line of work, we use quite a bit of very sophisticated algorithm development. MUCH more sophisticated than that found in audio. But it is really hard to make digital theory easily digestible and therefore hard to bring it to a point where it makes sense to everybody. I think the author did a magnificent job in his explanation. Coming around full circle, you can see why Carl was right - digital has the infinite capability to produce more dynamic and "lifelike" quality of music than analog. But, as always, the science lags behind the enabling technology. Therefore, we will have to wait about 5 years, by my estimate, to begin to fully realize the promise of the CD. Biggest thing to remember is that the science of hearing and how the brain distinguishes sounds, transients, harmonics, etc. is really not well understood at all. Therefore, you and I hear (and "understand" music) differently. So it is catagorically incorrect to hold to one's opinion of perceived sound as an unassailable truth. It is THEIR truth but you and I might hear it much more differently than they did. Just take part in a speaker or interconnect cable double-blind study sometime. You will hear differences, sometimes, between various products. But can you really differentiate to the point whereby you say that "Number 1 is Nordost" and "Number 2 is Radio Shack"? Try it sometime. The results are going to amaze you and reveal new truths heretofor undiscovered. Therefor, you are the ultimate judge of the truth and you can only do that by comparing different equipment in your system. NEVER go by reputation. ONLY go by what pleases your ears. Music should just be equated with joy (not ego) whether you cry at an opera or bang your head with Kiss. I've done both and I am the better for it.

Gthirteen, you are more than welcome. Wonderful thing about this forum is that, with the collective knowledge and experience to draw upon, greater understanding will result in the truth. In my line of work, we use quite a bit of very sophisticated algorithm development. MUCH more sophisticated than that found in audio. But it is really hard to make digital theory easily digestible and therefore hard to bring it to a point where it makes sense to everybody. I think the author did a magnificent job in his explanation. Coming around full circle, you can see why Carl was right - digital has the infinite capability to produce more dynamic and "lifelike" quality of music than analog. But, as always, the science lags behind the enabling technology. Therefore, we will have to wait about 5 years, by my estimate, to begin to fully realize the promise of the CD. Biggest thing to remember is that the science of hearing and how the brain distinguishes sounds, transients, harmonics, etc. is really not well understood at all. Therefore, you and I hear (and "understand" music) differently. So it is catagorically incorrect to hold to one's opinion of perceived sound as an unassailable truth. It is THEIR truth but you and I might hear it much more differently than they did. Just take part in a speaker or interconnect cable double-blind study sometime. You will hear differences, sometimes, between various products. But can you really differentiate to the point whereby you say that "Number 1 is Nordost" and "Number 2 is Radio Shack"? Try it sometime. The results are going to amaze you and reveal new truths heretofor undiscovered. Therefor, you are the ultimate judge of the truth and you can only do that by comparing different equipment in your system. NEVER go by reputation. ONLY go by what pleases your ears. Music should just be equated with joy (not ego) whether you cry at an opera or bang your head with Kiss. I've done both and I am the better for it.

Gmkane, I have been reading this thread since it began, and made no comments, as I really cannot contribute. I do have a question though. In the CURRENT state of high end, home (two channel) audio, does the ULTIMATE digital transport, D to A, etc., have a better chance of reproduction of music than the ULTIMATE analog system, assuming best L.P.'s as a source (most of us cannot access master tape!) Mind you, I am including NO cost limit in the question. If you want to include a $30K digital, OK. Be sure to remember the $30K turntables (and above) and the phono stages required to complete their process. I would very much like to hear your opinion on this. I confess, in advance, that my prejudice is for L.P., as I have gone to the limit with both formats, and essentially agree with one part of your comment, where you say we are 5 years away from getting digital "fixed." If I am wrong in the way I read your comments, I apologize in advance. You seem to be very knowledgeable in the field, so I am eager to hear what you have to say.