Maybe it's time to ask the question again. I'm wondering if anyone is working on a non-oversampling DAC project which will handle high sampling rates?
The Metrum Octave DAC is getting rave reviews. I guess they are using some industrial DAC chips(whatever those are) which work up to 15 mhz. Judging by the pictures of the inside, it would appear to be a relatively simple circuit. Of course it's probably harder than it looks. Very interesting concept though. Just when you think you've heard it all, something comes along that's better.
http://www.nosminidac.nl/Octave_English.html
http://www.6moons.com/audioreviews/metrum/1.html
The Metrum Octave DAC is getting rave reviews. I guess they are using some industrial DAC chips(whatever those are) which work up to 15 mhz. Judging by the pictures of the inside, it would appear to be a relatively simple circuit. Of course it's probably harder than it looks. Very interesting concept though. Just when you think you've heard it all, something comes along that's better.
http://www.nosminidac.nl/Octave_English.html
http://www.6moons.com/audioreviews/metrum/1.html
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Well who listens to CD anymore? I listen to as much hi-rez material as I can find.
My guess, FWIW : Digital to Analog Converter - Precision DAC (=<10MSPS) - DAC8581 - TI.com
From looking at the datasheet (don't know for sure its this part of course, I'm not the designer) if its this chip then it has glitch problems. So low-level performance would tend to suck rather.
They say they've paralleled 4 per channel, so nothing too fancy happening.
Better than what though? Than a DAC designed for audio with low glitch energy at the zero crossings?
dsd, in which case it would be played from 1bit. actually i'd have to check what the bit depth is at that rate, but the dac usually runs internally at 1.5mhz, normally it is upsampled and oversampled asynchronously, but you can run it without the OS filter ie NON OS in which case it will simply play at the speed of the incoming signal up to 1.5mhz. you need to then either slave it to the incoming clock, or run both transport and the dac from the same master clock
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i havent used it in this mode with any commitment, so i'm not clear on the detail, but afaik RayCtech runs his sabre design in this mode. i will revisit it when i start working on my own masterclock setup, as without a realy good clocking scheme you are opening the jitter floodgates using a clock piped in on the signal
i think there is a half speed and double speed DXD as well. i have seen rates from 1.4 up to 5.6mhz. i only mentioned it as the question was asked what chips can use this mode 24bit NOS and as you mentioned, i would much rather run a part designed for audio. the reviewed unit looks interesting enough, but in trying to shun the usual audiophile scenario, they have created their own. i mean do you really need that much smoothing in a dac with decent regulators?
i think there is a half speed and double speed DXD as well. i have seen rates from 1.4 up to 5.6mhz. i only mentioned it as the question was asked what chips can use this mode 24bit NOS and as you mentioned, i would much rather run a part designed for audio. the reviewed unit looks interesting enough, but in trying to shun the usual audiophile scenario, they have created their own. i mean do you really need that much smoothing in a dac with decent regulators?
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There is a new chip coming soon AT1401 from ARDA Arda Technologies - Home
Looks very promising
Looks very promising
I for one am not holding my breath on that part http://www.diyaudio.com/forums/digital-line-level/182166-new-multibit-dac-chip-arda-technologies-at1401.html
Summer'll be over in a couple of days and not a peep
I get the impression the original 'NOS' was referring to replay of multi-bit rather than single bit audio. DSD is already heavily oversampled at the recording stage.
What gives me the heebiejeebies in their blurb is talking about their heavily filtered dual toroidal PSU. From the pics I can't see any filtering, let alone of the heavy kind. Two paralleled toroidals is double trouble when it comes to mains noise ingress.
Summer'll be over in a couple of days and not a peep
qusp said:
I get the impression the original 'NOS' was referring to replay of multi-bit rather than single bit audio. DSD is already heavily oversampled at the recording stage.
qusp said:
What gives me the heebiejeebies in their blurb is talking about their heavily filtered dual toroidal PSU. From the pics I can't see any filtering, let alone of the heavy kind. Two paralleled toroidals is double trouble when it comes to mains noise ingress.
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yeah the arta thing never came to anything, i pop my head in there myself from time to time. so you didnt see the 2 box build with a massive bank of parallel caps? massive for a dac anyway and from my understanding of modern IC regs, they dont even really like too much capacitance at the input, or output.
again, I only made reference to DXD as you asked me directly what might need speed that high. the sabre NOS mode can be used for any speed and applies just as well to 24 or 32/384+ if you like. i personally do use realtime 384khz sampling for playing my own analogue modelled synth and piano plugins for logic, not in NOS mode though, as its just on the boundary of still being able to use OS. this is generated on the fly at that speed with models, no upsampling
again, I only made reference to DXD as you asked me directly what might need speed that high. the sabre NOS mode can be used for any speed and applies just as well to 24 or 32/384+ if you like. i personally do use realtime 384khz sampling for playing my own analogue modelled synth and piano plugins for logic, not in NOS mode though, as its just on the boundary of still being able to use OS. this is generated on the fly at that speed with models, no upsampling
Yes I did see that - I kinda filtered it out because its so common to see massive oversupply of electrolytics.
I have no experience with the Sabre so please correct me if I've got the wrong end of the stick here, but I figured the whole architecture is a noise-shaped, low-bit one (I have read some datasheets but they're hardly gospel). So kind of anathema to the NOS crowd who are looking for purist digital - no noise shaping and no digital filtering whatsoever.
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