Pc -> Dac, How ?

[Russ White]

I have used it with my Buffalo DAC. Its very handy to do so because I only need bitclock, wordclock, and data. The ESS Sabre has an asynchronous I2S input.

I have not tried it with anything that needs a 256/128fs master clock.

Cheers!
Russ

[phofman]

Unfortunately the beagle board has its I2S bit clock generated via PLL from the 26MHz crystal. If there was an affordable miniPCI - PCI adapter available (IMO just a PCB layout with a cable), I would love to test an inexpensive low-power linux router with a quality PCI card with separate crystals for 44,1kHz/48kHz, placed in a shielded compartment away from the router board http://www.diyaudio.com/forums/showt...85#post1667185

[Russ White]

Originally posted by phofman
Unfortunately the beagle board has its I2S bit clock generated via PLL from the 26MHz crystal. If there was an affordable miniPCI - PCI adapter available (IMO just a PCB layout with a cable), I would love to test an inexpensive low-power linux router with a quality PCI card with separate crystals for 44,1kHz/48kHz, placed in a shielded compartment away from the router board http://www.diyaudio.com/forums/showt...85#post1667185

With the DAC(ES9008) I am using this is not a problem in the least.

I can see how it might be with other DACs.

You actually can make the I2S output(clock) a slave. But it is not as simple. And I have no good reason to do it.

[Russ White]

The really cool thing is I can tranfer stuff on to the SD card via USB, then listen to the thing headless. Well it is the head.

I can also play files via a USB hard drive.

[soundcheck]

Some alternatives - potentially not really DIY - pretty much with multichannel in mind:

1. HDMI
HDMI wasn't even put on peufeus list. I think this needs to be considered.
8 channel LPCM. One of the few interfaces if not the only one able to cope with
the demands out there. Licensing might be an issue.
The Sabre is multichannel. The DAC board needs just a HDMI receiver.
2. External PCIe solutions
E.G. Something like Magma via Expresscard. The external PCI card could be
powered by batteries. Magma is even working on a fibre connection.
3. Asus HDAV 1.3 deluxe
Can be full powered by battery. AFAIK 6 channel I2S can be taken of the connector
which connects the DAC daughter-board.



Cheers

[phofman]

Soundcheck, all the presented solutions certainly bring quality sound, but none has the PLL-free crystal-provided clock for 44.1kHz-family audio. Currently I know just about some PCI cards and the asynchronous USB cards from E-MU, poorely supported in linux. Though I slowly start accepting that 44.1kHz audio is history now...

[Pjotr]

Hi Phofman,

(Maybe a bit OT but for reference)

I know of this one http://www.cambridgeaudio.com/summary.php?PID=320

It is available in the US for under $300. Have listened to it recently, sounds very good. I don’t know if it streams audio iso-synchronous or a-synchronous, it doesn’t need special drivers and works fine under Linux as well with Amarok. I couldn’t discriminate any difference in sound between S/PDIF (from my ZIOVA MC) and USB from PC.

Have compared it to the E-MU 0202. The Cambridge sounds slightly better IMO, but we are talking of differences of a few mm over a 10 m length then

However it is 2 channel only.

[soundcheck]

Originally posted by phofman
Soundcheck, all the presented solutions certainly bring quality sound, but none has the PLL-free crystal-provided clock for 44.1kHz-family audio. Currently I know just about some PCI cards and the asynchronous USB cards from E-MU, poorely supported in linux. Though I slowly start accepting that 44.1kHz audio is history now...

How about your ideas?

I think you're looking for an Altmann DAC, the only DAC (maybe also Empirical reclocker?!?!?) I know with switchable PLL-free crystals. But since Sabre there doesn't seem to be a need for it any longer.

When it comes to poor support of EMU, Alsa is still looking for somebody taking care
on the driver. Skilled people shouldn't waste their time in these kind of forums.
As you might know EMU opened up the MAC drivers to the public.

Cheers

[Telstar]

Originally posted by soundcheck

I think you're looking for an Altmann DAC, the only DAC (maybe also Empirical reclocker?!?!?) I know with switchable PLL-free crystals. But since Sabre there doesn't seem to be a need for it any longer.

Only if you dont want to use a different DAC...

[Wavelength]

Originally posted by Russ White

With the DAC(ES9008) I am using this is not a problem in the least.

I can see how it might be with other DACs.

You actually can make the I2S output(clock) a slave. But it is not as simple. And I have no good reason to do it.

Russ,

Actually phofman is correct. It may not seem so but there is allot of jitter generated by the PLL and this will cause a problem before it even get's to the ESS.

For many years it was thought that upsamplers and reclockers could fix jitter already induced into the system. But now we know allot more about jitter and how it effects devices.

For instance, Benchmark and BelCanto both make very good products and say that their upsamplers remove the variable of jitter induced into the system because of thier implementation. If this was correct then any input would merly have the same jitter as seen by the output as the intrinsic jitter of the dac itself and nothing else. But in tests both of these products had significantly higher jitter under USB than their SPDIF counterparts. There was even variations in the output jitter with different inputs on their SPDIF ports.

You can search these finding on Stereophile. Do note the BelCanto 24 bit JTEST was thrown out as the device was 16 bit only USB at the time and the downsampling would have killed the JTEST data before it reached the dac. BelCanto now is using the Centrance code like the Benchmark, Empirical and PS Audio.

To futher prove this I have been working with some of the magazines and Charlie Hansend and the rest of the guys at Ayre. I bought a Wavecrest DTS jitter analyzer. This is the unit that any oscillator company in the world uses to measure jitter. You can basically measure jitter on any oscillator including the Bit Clock (SCLK), Master Clock (MCLK) and Word Clock (WCLK). We tested all the SPDIF ports of several dacs using the Prism dScope as the source which has an extremly low output jitter. We also used MAC's, Linux x86 and Vista and XP to stream data USB. We then took measurements at the output of the SPDIF receiver and the input to the DAC. The results were eye opening... but truely did result in the understanding that yes the implementation of the interface into an upsampler, reclocker and such has a HUGE effect on the resulting jitter of the system.

Therefore we can conclude that the damage was done BEFORE it reached the upsampler in the same way it would with your setup on the ESS.

Now remember jitter is based on clocked audio output. So Peufeu's concept of using the Cypress part which outputs data (non jitter induced) into an FPGA and deriving the I2S output as a function of the dac's MCLK will result in better preformance.

This is why when looking for suitable USB 24/192 devices you must look for ones that have the capability to run what is called Master Clock IN (MCLKin). This is how I use the TAS1020B USB Audio controller in async mode on my products.

Very few devices have this kind of capability. Running say MCLK into a MCU as the system clock will only saturate that clock with phase noise which will result in more jitter. It has to have some way of getting a clean low jitter clock into the section that converts DATA in bytes, words what ever into I2S. That is the true key here...

So far the new Atmel AVR32 is the only complete chip capable of this. The Cyan eCog is but it's I2S output is interrupt driven and may cause problems at 24/192.

Thanks
Gordon