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Is it better to up-sample in the software, before the Dac, or at the Dac, or not at all, and why?
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Our lunacies may be indulged a while longer
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I purchased the Wadia 121 Dac which upsamples to a crazy 1.4MHz.
Before I always felt like the music was being manipulated, it just didn't sound right. Granted there was an increase in some aspect here-or-there but the overall sound just was not coherent.
With the Wadia I never feel like the music is/has been manipulated. The tone and musicality is even throughout the frequency spectrum. Details, depth of soundstage, width, bass slam, speed, its all there in spades. No one aspect calls attention onto itself, so in this regard it does not sound like 'upsampled' music.
For the record I have tried both software and hardware upsampling many times in the past.
Dynobots Audio
Music is the Bridge between Heaven and Earth - 音楽は天国と地球のかけ橋
"Is it better to up-sample in the software, before the Dac, or at the Dac, or not at all, and why?"Depends if it's synchronous or asynchronous........ Asynchronous conversion is not as true to the original digitized signal as synchronous conversion, and I personally don't like how it sounds. Synchronous conversion is often known as 4x or 8x or 16x oversampling...... Used to be common back in the 1990s..........
Most upsampling is done at the DAC..... If done before the DAC, there is more high-sample-rate signal transmission taking place, which introduces more RFI.
I prefer synchronous oversampling at the DAC. I like the 1990s DAC designs because in my opinion, they're truest to the music prior to A/D digitization.
Edits: 06/12/12
> Synchronous conversion is often known as 4x or 8x or 16x oversampling <
Thanks I wondered about that.
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Our lunacies have been indulged up till now..
By usampling, I take you to mean rate multiplying, synchronous or asynchronous, interpolation filter. In theory, it makes no difference where the upsampling is done. (Well, I suppose one could argue that upsampling on the DAC chip could enable a higher upsampling ratio than with an external upsampling chip by virtue of there not being an speed limited inter-chip communication path involved.) In practice, however, upsampling in software can provide a more accurate result than is often had via the DAC's on-chip hardware interpolation filter. By more accurate I mean, with greater stop-band rejection and with a sharper transistion-band. A hardware interpolation filter could be just as accurate as a software filter, but most (not all) on-chip DAC filter implementations are much less than what they might be.Regarding whether to upsample or not, the answer has both objective and subjective dimensions. Objectively, brickwall upsampling fully recovers the amplitude versus frequency content of the original signal, and moves the undesired ultrasonic image replications (which might otherwise provoke intermodulation distortion) way up in frequency, where they can be much more easily filtered out by the analog stage. Subjectively, many audiophiles prefer no upsampling/digital filtering of any kind. Exactly why is currently the subject of much speculation. Personally, I agree with those who believe that the human perceptual benefit of the perfect impulse response realised from having no digital filter is often preferable to the (near) perfect amplitude versus frequency reconstruction of an brickwall upsampling interpolation digital filter.
As far as what to do as an audio consumer, I suggest keeping an open mind. Ignore conventional wisdom, whatever it may currently be, and trust your own ears. Whenever I've made an equipment purchase by rationalizing the engineering reasons why some component SHOULD sound the best, I've often been sorry that I didn't simply let my ears make the judgement.
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Ken Newton
Edits: 06/12/12 06/12/12 06/12/12 06/12/12 06/12/12
My now ancient 14bit Philips player, possibly the 1st player sold in this country was a 4x oversampler and provided jaw dropping performance for its time. It was also the basis for several modified players which sold for huge markups.
This player, if I could find a laser for it, would be nice in a vintage system. I'd love to A/B it against a 'modern' player which you'd hope would simply smoke it....but I'm not so sure.
Compared to the Sony player of the same era......well, there WAS no comparison.
Too much is never enough
I am still trying to get this. We may not need up sampling at all. But if we do, synchronous should introduce fewer impurities than asynchronous. If it is going to occur there is no reason why it cannot be done on a computer player, and pass through the Dac intact. This would reduce the Dac too one function.
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Our lunacies have been indulged up till now..
Sure, you can upsample in software at your computer if you are using a computer for a music source. I suspect that the majority of audiophiles are not primarily using a computer for a music source.Take what Todd said about asynchronous upsampling with a large handful of salt. Todd says that he doesn't subjectively like the sound of asynchronous upsampling, which is his prerogative as an audiophile. Where he then goes wrong is in ascribing technical rational for his subjective opinion. In fact, most asynchronous upsampling implementations (software or hardware based) have superior accuracy compare to most hardware based synchronous oversampling implementations. By the way, as a general convention, audiophiles refer to asynchronous interpolation as upsampling while refering to synchronous interpolation as oversampling, although I'm aware of no written rule about that. In addition, asynchronous upsampling solutions also feature highly effective jitter suppression. Such strong jitter suppression, while not of much use in a CD player, is extremely useful in an external DAC box, but that is a different discussion.
As always, let your own ears be the judge, never rationalize what SHOULD sound better based on technical explanations.
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Ken Newton
Edits: 06/15/12
Thanks, I was concerned with the external DAC box. I have been computer music based for over ten years. When I get a hold of a Cd I just rip in with Itunes and never open the plastic case again. I was trying to separate all the various functions they are trying to sell us in line Dacs. I was reading about audioquests Dragonfly and Halide design DAC HD. Asynchronous upsampling, synchronous oversampling. Are either necessary?
> I suspect that the majority of audiophiles are not primarily using a computer for a music source. <
You do realize that increasing use of computers as a music source is the trend. Anything viewers learn here saves time and money if we make a trip to the big city and waste some salespersons time before we come home and order it on the net (Think of the Beverly Hillbillies going to town for a stereo listen). Even when I go to the Apple store, I order from home.
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Our lunacies have been indulged up till now..
Ah, the Beverly Hillbillies - among my all time favorite sitcoms.
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Ken Newton
Thanks that is a great help.
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Our lunacies have been indulged up to now..
You are very welcome.
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Ken Newton
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