Where do we find such items? Can you give us some websites of manufacturors? What is SN, a company name?
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The biggest difference in sonics between some of these and "conventional" types of DAC's has to do with the type and quantity of filtering used. Less filtering equates to wider bandwidth, better harmonic structure, less phase-shifts with the resultant "lifting of veils". The drawback is the potential for increased ultra-sonic noise, potentially damaging your tweeter and / or amp. Sean
I agree with Sean, but I'd add a caveat that the ultrasonics appear to be more of a theoretical than a real-world problem. I have yet to hear of amp or speaker damage that could be attributed to them. In a similar vein, the "advantages" of oversampling for red book playback are theoretically real, but the extra circuitry required to implement it usually gets in the way of the music. As always, the devil is in the details.
I haven't heard a DAC yet that could equal the natural presentation of my Audio Note.
IMHO, the sonic differences between various DACs stem from the analog filtering and amplification circuitry that follows the DAC. There are theoretical advantages to oversampling, perhaps not always realized because of inferior analog outputs.
A little history...Oversampling was a Philips idea (which they didn't bother to tell Sony about) so that they could use a good 14-bit DA instead of the flaky 16-bit ones that were common when CDs were introduced. Everyone agreed that the 14-bit Phillips ran circles around the Sony units.
Gliderguider: I agree with what you said about ultrasonics, but i wanted to be honest and fair as to the pro's and con's. Like you, i've never heard of anyone popping an amp or tweeter that was directly related to this phenomena. As a side note though, Philips evidently thought that this was serious enough to allow one to select the hinge frequency for filtering on their SACD 1000's. They specifically mentioned "potential for damage to amps and tweeters" when selecting the 50 KHz ( maybe it was 40 KHz??? ) filter. I ran mine at the highest setting with speakers that were flat out to 23 KHz and an amp that was linear out to 80 KHz and capable of over a kilowatt of output per channel with nary a problem for about a year. Sean
Are you quite sure that it's the DAC reconstruction (analog) filter that is responsible for the degraded sound in oversampled/upsampled systems??
I feel that it is the over/upsampling (digital) filter - the one that various manuf. use to do the estimation - that is largely responsible for the degraded sound. By the time it gets to the reconstruction filter, the sound is botched already & the analog filter cannot fix this. Yes, it can degrade it further! However, I still feel that the principal damage is done in the digital domain.
Afterall, over & upsampling were used so that the manuf. could get away from designing a nearly brick-wall filter, which had a transition band from 20KHz-22.05KHz.
It's those estimation (digital) filters that change the harmonic structure of the sound. The algorithms are manuf. dependent & you might like one manuf's & hate another's.
(In the Scott Nixon tube DAC he uses the output tube as a filter by just relying on the vacuum tube's natural freq. response characteristic to low-pass shape the music signal).
I've improved my Ack! significantly by replacing the 3.3 mF AuraCaps with Dynamicaps, a pair of 5 mF and a .01 bypass per channel. It really opened up and the bass improved big time. I use it with an EAD T1000 with a Mapleshade/Insound Zepher dig link. Extremely open yet smooth, dead silent with wonderfull dynamics; the best I've heard.