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Cambridge DACMagic, anyone? - Page 6  

post #76 of 920
^x2
post #77 of 920
Quote:
Originally Posted by StanleyB1 View Post
...the side effects of upsampling. The padding of the waveform with data that was not present in the original digitally converted audio signal...
This statement reflects a common misconception on Head-Fi about upsampling. :confused_face_2 : Maybe it's just distorted uses of that word though.

Upsampling - by definition - does NOT add INFORMATION. It merely recreates the samples that the original sampling process would have observed had it been running at a different sampling rate. This is a mathematically exact process (implementation correctness, quantization/clocking issues aside). It can be achieved because an accurate sample of an appropriately band-limited signal uniquely and precisely defines the analog waveform that was sampled.

Or to come from another angle, upsampling can't recreate any information that was lost during the sampling process. It's important to realize that any claims to the contrary, or any deviation from the mathematically exact upsampling algorithm referred to above means the "upsampling" process is (a) no longer purely upsampling, and (b) is making stuff up.

For example, "upsampling" can't determine the samples that would have been made with a different band-limiting filter (e.g. one rolling of at a higher frequency, as you might prefer to use if you sampled at a higher frequency in the first place). The information (if any) that resides in the frequencies that now get past the band limiting filter was removed by the original sample's band-limiting filter and cannot be "reconstructed", "retrieved" or "inferred".

What you MIGHT see in practice is that some so-called "upsampling" processes take shortcuts to simplify the problem, and marketers are more than happy to claim this is "upsampling" when it is not. This situation is implied in the DACmagic marketing material which (IIRC) talks about "upsampling" via "straight line interpolation" and shows how their upsampling process is better. There's only one problem with this - straight line interpolation is NOT upsampling, because the points created by this process do NOT lie on the analog waveform that is defined by the samples that make up the original signal. By definition, using "samples" that don't lie on the waveform introduces errors - i.e. distortion. Whether or not you like the end result (and the interaction of that process with the D/A hardware which may respond better to higher sample rates in some respects) is hard to predict - but this may be the reason some people think upsampling introduces artifacts - because shortcut "upsampling" methods do.
post #78 of 920
Quote:
Originally Posted by Mazz View Post
This situation is implied in the DACmagic marketing material which (IIRC) talks about "upsampling" via "straight line interpolation" and shows how their upsampling process is better. There's only one problem with this - straight line interpolation is NOT upsampling, because the points created by this process do NOT lie on the analog waveform that is defined by the samples that make up the original signal. By definition, using "samples" that don't lie on the waveform introduces errors - i.e. distortion. Whether or not you like the end result (and the interaction of that process with the D/A hardware which may respond better to higher sample rates in some respects) is hard to predict
I agree 100% with you on this, and find the Cambridge marketing material quite 'close to the wind'. At least they do mention that the DacMagic is more likely to improve older CD players instead of modern ones.

I have had a few people email or send me PM that they got hold of a test sample of the DacMagic and that they would give a quick review. But so far everyone seems dead quiet .
post #79 of 920
all we need to get the noise down is to see a dozen reviews saying the headroom and pico dac beats it in the sound quality department
post #80 of 920
If the DacMagic is as good as Pico DAC, I'm happy
post #81 of 920
I found one seller who has sample for consideration. But he say he won't sell it. He say that he can not test with his balanced amplifier since he can not find male to female balanced cable to test with his amplifier. He also say that DacMagic is very small and looks too cheap with plug in power adapter for U$400. The selector can only switch between signals between the two banks of inputs. So if you have coax and optical on same bank you can only use one of them if the other one is not on. He says his Zhaolu 3 sounds better and looks more attractive for about same price. He also think no volume control and variable output means it is poor value for money. Maybe at U$250 max it can compete but U$400 has far better products to pick from. Name alone is not good enough in DAC market since people buy DAC to improve sound quality not impress friends. That is for source amps and speakers.
post #82 of 920
volume control? hehehe that will only add garbage to the sound of a dac. an extra preamp section for the same price will lower the quality of the other stuff
post #83 of 920
Benchmark DAC1 and Bel Canto have volume control but nothing wrong with their sound. With volume control you can use DAC as preamp. No reason to have just variable output. Many DAC with volume control also have fixed output.
post #84 of 920
If there is one way to screw up a good signal, its a crappy volume control implementation. In particular, many DAC's and/or CD players with variable output use digital volume control which is generally not ideal and can cause much harm.
post #85 of 920
Quote:
Originally Posted by DC Lee View Post
Benchmark DAC1 and Bel Canto have volume control but nothing wrong with their sound. With volume control you can use DAC as preamp. No reason to have just variable output. Many DAC with volume control also have fixed output.
ya but those are $1000 for the dac1 and much more for the bel canto. They can afford good quality stuff inside
post #86 of 920
I might be interested in buying one of these myself, need a decent dac. Was looking for mostly good deals on used units, but this ones looks well priced for the sound its said to produce. Awaiting impressions, someone buy this thing!
post #87 of 920
i'll buy them next month
post #88 of 920
I must buy it because there's no balanced DAC <400$
post #89 of 920
Quote:
Originally Posted by DC Lee View Post
He also say that DacMagic is very small and looks too cheap with plug in power adapter for U$400
Quote:
Originally Posted by DC Lee View Post
He also think no volume control and variable output means it is poor value for money
Quote:
Originally Posted by DC Lee View Post
Name alone is not good enough in DAC market since people buy DAC to improve sound quality not impress friends.
So basically, two of his criticisms which you so eagerly care to share with us are totally irrelevant?

If you're going to attack based on hearsay, at least do it with some coherence.
post #90 of 920
Here's a thread with some UK owners' impressions
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