HiFi World have a review in their August edition. The claim is that the DAC basically reduces high treble, which would then explain the pleasant sound.
NHL said:
this statement is both true and untrue at the same time. it's true that Metrum DAC will reduce high treble (I never seen any measurements but since it's a NOS DAC it will have attenuated highest frequencies, read on). but it's untrue that it's the reason for pleasant sound.
with every DAC you get aliasing artefacts - essentially lotsa noise at half of sampling frequency, which in case of Red Book standard falls at around 22K Hz. but this noise has to be removed because it pollutes the original signal. so, with upsampling DACs you get the benefit of digitally filtering out of those unwanted frequencies and maintaining ruler flat freq response all at the same time. however, the drawback is that digital filtering adds ringing to the original signal. depending on the filter type you'll get pre and post ringing or only post ringing.
in case of NOS DACs there's no digital filtering involved so the signal comes out intact. but in order to get rid of aliasing artefacts passive analog filtering is most commonly used (telling frankly, I don't know how it's like with Metrum, but I suspect it's the way I describe). analog filtering is not as efficient as digital filtering, especially when you use shallow filter slopes to keep the filter as simple as possible. so the side effect is that you get slightly attenuated highest frequencies because you can't really set the cut off frequency at 20K Hz. it has to be slightly lower in order for the filter to do its job. but this attenuation should not really be audible as it affects the frequencies where there's little musical energy anyway. for instance; in case of AMR DP-7 DAC in NOS mode freq response starts rolling off quite soon at 3K Hz (obviously very shallow filter was used, possibly only 6dB slope). but at 10K Hz attenuation is only -0.5dB (it should be noted here that what we perceive as high treble resides around 10K - 12K Hz, higher are mainly harmonics), -3dB point resides at around 19K Hz. I bet you couldn't hear 20K Hz tone at normal listening volume levels anyway - up to some 80dB loud. in case of Peachtree iDAC, another NOS DAC, the situation looks very similar. rolling off starts at around 3K Hz. but at 10K Hz you get only -0.3dB attenuation and at 20K Hz only -1dB attenuation.
so all in all, those figures clearly show that it's not rolling off of high frequencies responsible for smoother sound of NOS DACs, because this attenuation, within audio band, is really meaningless with relation to human hearing acuteness. I tend to believe that it's the fact that there's no ringing artefact present in case of NOS DACs responsible for more analog sound of those type of DACs.
For anyone interested, I've just had the Metrum Octave DAC delivered and, though it's still early days, I think it sounds great. Even makes my laptop sound good, something my DAC XP never could!
metrum is about to release a new dac. this time it's hex (and one chassis only, thank god)
http://www.nosminidac.nl/Hex_English.html
http://www.nosminidac.nl/Hex_English.html
DocG said:
apparently the number of DAC chips matters in case of a non sigma-delta DAC. I believe others better informed could elaborate more on the topic.
DocG said:Who-ever buys one without listening or refund option is my hero!
well, I do. deck, phono pre, CDP and amp all bought totally blind. only based on reviews and my little knowledge. cart and speakers were bought blind without an option to returning. and never thought I made a wrong decision.
For anyone interested, and repeated on a different thread on the same topic, I've just had the Metrum Octave Dac delivered and I've had a couple of evenings of listening to it. Comparing it to my very lovely Cyrus CD6 SE2 + Cyrus Dac XP (not +) set up, I would say that Macbook Air + Metrum Octave Dac (using the DAC XP as preamp only) equels it without surpassing it. At this point I can hear B-all difference between the two set ups. The Cyrus CD6 SE2 + Cyrus Dac XP might just have a tad more warmth and rhythm, but there really isn't much in it. Of course this might change over time. So, to give you something to compare it to, it's at least equel to a Cyrus DAC XP, without the pre amp of course. And considerably cheaper too!
Over a month in, and I have to say that the Macbook Air (WAV + Bit Perfect) + Metrum Octave Dac (using the DAC XP as preamp only) combination is constantly making my face break out in an innane grin , and has rendered my very nice CD6SE2 redundant. The space, the depth and the detail are all, frankly, breath-taking. As others have said, this DAC is very sensitive to file quality (and therefore quite unforgiving), and as a result I'm mostly using WAV files, even rather than Apple Lossless, as there is a difference. It's one of those pieces of kit that makes you want to rediscover all your favourite recordings again. In fact I like it so much that I've just ordered another one for my second system that I'm in the process of building - can't bear to be without it. Pity about only having two inputs though...........
, and has rendered my very nice CD6SE2 redundant. The space, the depth and the detail are all, frankly, breath-taking. As others have said, this DAC is very sensitive to file quality (and therefore quite unforgiving), and as a result I'm mostly using WAV files, even rather than Apple Lossless, as there is a difference. It's one of those pieces of kit that makes you want to rediscover all your favourite recordings again. In fact I like it so much that I've just ordered another one for my second system that I'm in the process of building - can't bear to be without it. Pity about only having two inputs though...........
paradiziac said:
I was enjoying reading the extrenal links until I read "chromium brightness" and "fine grain sheen" an oxymoron if ever there was. I used to respect MC as a reviewer but that's OTT and puts me off. By the time I got to placing both the DAC and the PSU on spikes it's enetered Beltworld for me. I've got an opne mind, but if anyone can seriously hear the difference between spiked and unspiked PSUs? If so, then it would come with them fitted, and we'd all be charged even more for it.
I'm going to investigate this DAC, but not if it contains any more alloying elements or requires a special H&S certificate to locate it. :roll:
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