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Old 24th August 2011, 03:41 AM   #191
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Hi all,

The Sabre DAC's can run in two modes: asynchronous and synchronous (these modes are internal to the DAC and not to be confused with USB asynchronous ISOCHRONOUS transfer).

In the AW, we are running the ES9023 in "synchronous" mode as the MCLK supplied to the DAC is at a "correct" integer multiple (eg 192fs) of the incoming I2S data rate.

To run the ES9023 in "asynchronous" mode, the MCLK supplied must be > 192fs. If fs is 192khz, 192fs is 36.864Mhz.

AFAIK, the Buffalo DAC's has clocks at 40/80/100 Mhz, thus > 36.864Mhz, and therefore it is running the DAC in "asynchronous" mode.

The following is my conjecture based on reading the datasheets and "Technical Details of the Sabre Audio DAC" by Martin Mallinson and Dustin Forman, ESS Technology Technical Staff

So to interface the USB-I2S module with the Buffalo DAC, you might just have to add a small daughter board with the low jitter XO's (exactly like the AB1.1) divided down to the 11.2896/12.288Mhz to supply the USB-I2S.

So the USB-I2S module uses the 11.2896/12.288Mhz to throttle the USB data stream from the host. The I2s data is streamed to the Buffalo DAC's I2s input header. The Buffalo DAC then uses its internal DSP to filter, upsample, and jitter eliminate (not that there is any !!!) the samples to the internal high speed clock rate of 40/80/100Mhz.

Alex
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Old 24th August 2011, 11:05 AM   #192
UnixMan is offline UnixMan  Europe
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Quote:
Originally Posted by alexlee188 View Post
AFAIK, the Buffalo DAC's has clocks at 40/80/100 Mhz, thus > 36.864Mhz, and therefore it is running the DAC in "asynchronous" mode.
yes, I think so. It does use only one and the same clock freq. for any stream...

Quote:
Originally Posted by alexlee188 View Post
So to interface the USB-I2S module with the Buffalo DAC, you might just have to add a small daughter board with the low jitter XO's (exactly like the AB1.1) divided down to the 11.2896/12.288Mhz to supply the USB-I2S.
ok, this sounds reasonably easy. Maybe he can even use some prebuilt "clock upgrade" module for that?

BTW: isn't asynchronous (ASRC) operation "wasting" quite some of the benefits of the AW?
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Old 24th August 2011, 11:24 AM   #193
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Indeed it is a "waste" to operate the Sabre in async mode. In fact if I were to design something similar I would clock the ES9018 synchronously exactly like the AB1.1.

However, I was responding to the question about interfacing to existing buffalo DAC's, which are already fixed with async clocks :-)

Alex
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Old 24th August 2011, 01:39 PM   #194
UnixMan is offline UnixMan  Europe
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Quote:
Originally Posted by alexlee188 View Post
In fact if I were to design something similar I would clock the ES9018 synchronously exactly like the AB1.1.
...I'd love to see an AB2.0 designed with two ES9018 wired in mono mode (one per channel), optocouplers on I2S, independent mains PSUs with schottky rectifiers, inductive input filter (gyrators...), dedicated discrete CCS+Salas shunt reg on each supply line of every load, ...

(that would be a huge and heavy thing, definitely NOT intended for portable use ).

Quote:
Originally Posted by alexlee188 View Post
However, I was responding to the question about interfacing to existing buffalo DAC's, which are already fixed with async clocks :-)
sure (and many tnx for that!).

I was just wondering wether it would be possibile (how hard would it be) to modify the Buffalo so that it may be operated synchronously as in the AB1.x...
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Last edited by UnixMan; 24th August 2011 at 01:46 PM.
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Old 24th August 2011, 02:03 PM   #195
2A3SET is offline 2A3SET  Canada
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Default KS under foobar

Has anyone tried AW with KS mode under foobar, sounds better than WASAPI, is there anyway to change the device name, any other speical setting?
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Old 24th August 2011, 04:27 PM   #196
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Oh, BTW:

Quote:
Originally Posted by alexlee188 View Post
So the USB-I2S module uses the 11.2896/12.288Mhz to throttle the USB data stream from the host. The I2s data is streamed to the Buffalo DAC's I2s input header.
with 100MHz clock, the Buffalo is able to handle DXD streams (PCM 384 or 352.8 KHz / 24 or 32 bit). Would it be possible for the AW USB/I2S interface to handle that too, somehow?
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Old 24th August 2011, 05:11 PM   #197
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384khz cannot be done with the current uController - a limitation of the I2S bus. You will have to wait for the next version - a different uC, and/or FPGA, and/or custom interface chip :-). We are looking more at 7.1 channel than 384.

But let us not try to run before we can walk - we really need to get the AW to more testers and do more tweaking of the analog side to get the best stereo sound out first :-)

Most high quality music are currently at 88.2/24, 96/24 and 192/24. You will need a top end system to be able to hear the difference between 192 and 384, I would think. (personally no experience with 384/24 music)

Alex
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Old 24th August 2011, 05:31 PM   #198
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Quote:
Originally Posted by alexlee188 View Post
(personally no experience with 384/24 music)
Me neither, just curiosity.

At the moment, I've seen some DXD files (including free samples) available only from 2L...

Completely agree about maxing out 2ch audio quality (see my previous post about my whishlist design for AB2.0... ). Couldn't care less about multichannel.
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Old 24th August 2011, 06:20 PM   #199
2A3SET is offline 2A3SET  Canada
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Default Pureplayer with WASAPI

Anyway, latest Pureplay(2.7.1) works with AW in WASAPI mode now(W7 with thesycon 1.18), the best player I've tried (prefer over stealthplayer now).

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Has anyone tried AW with KS mode under foobar, sounds better than WASAPI, is there anyway to change the device name, any other speical setting?
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Old 25th August 2011, 11:18 AM   #200
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Quote:
Originally Posted by UnixMan View Post
Oh, BTW:


with 100MHz clock, the Buffalo is able to handle DXD streams (PCM 384 or 352.8 KHz / 24 or 32 bit). Would it be possible for the AW USB/I2S interface to handle that too, somehow?
You know, I see people talk about these super-high-res formats like DXD, WDSD, double DSD and whatnot, but are there actually recordings available in those formats? (Outside of experimental studio setups).
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