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Old 18th August 2011, 03:36 PM   #321
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Default I2S only?

All this excitement about the I2S conectivity makes me wonder. Will the new USB board have S/PDIF out at all?

I have an uncompleted BII build with the S/PDIF MUX waiting for the USB module.

Cheers

Thomas

Last edited by thomaspf; 18th August 2011 at 03:54 PM.
 
Old 18th August 2011, 03:41 PM   #322
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It will have both SPDIF and I2S but SPDIF will be limited to 192khz/24bit
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Old 18th August 2011, 03:53 PM   #323
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perfect!
 
Old 18th August 2011, 04:20 PM   #324
labjr is offline labjr  United States
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Originally Posted by barrows View Post
Hi Russ,

Looking at the new B-III DAC board, it appears that TPA is adopting IDC/ribbon cable as the preferred method of hooking things up. Recently I have been investigating the different wiring options for I2S lines, and came across the U.FL approach. It appears to me that U.FL micro BNC style jacks and pre made cable might be very good options for I2S connections. I suggest that you consider the option of U.FL connection for I2S lines between boards-in the US, jacks and premade cables are available from Digikey.
Additionally, the more I find out about I2S isolation, the more I am thinking it may be better to not isolate the I2S lines, as every approach appears to add considerable jitter (GMRs, LAN transformers, etc). Just something to think about... I am sure you have been considering many options.
Looking forward to the product!
If the ESS DAC truly eliminates jitter then I guess it shouldn't matter if the isolation adds a little.

BTW don't the U.FL jacks have a 50 ohm impedance? Is that the correct impedance for I2S lines?

Last edited by labjr; 18th August 2011 at 04:23 PM.
 
Old 18th August 2011, 04:24 PM   #325
labjr is offline labjr  United States
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Originally Posted by Russ White View Post
It will have both SPDIF and I2S but SPDIF will be limited to 192khz/24bit
I was kind of hoping it wouldn't have S/PDIF. May save a little cost. Someone's gotta start getting rid of S/PDIF.
 
Old 18th August 2011, 06:50 PM   #326
4est is offline 4est  United States
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For better or worse, methinks SPDIF will be around for a long time yet elsewhere. In this case it extends their market considerably I would imagine. How many DACs are there that have i2s inputs anyway?
 
Old 18th August 2011, 06:58 PM   #327
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Quote:
Originally Posted by labjr View Post
BTW don't the U.FL jacks have a 50 ohm impedance? Is that the correct impedance for I2S lines?
No, there is not correct impedance for I2S lines, as they were never meant to leave the circuit board. I2S (really IIS, or Inter-IC Sound) was designed for interfacing two nearby chips. If you add a line driver for distance, the correct impedance will depend on the design of the transmitter and receiver.

S/PDIF was designed to transmit digital audio over cables.

http://www.nxp.com/acrobat_download2/various/I2SBUS.pdf
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Last edited by BrianDonegan; 18th August 2011 at 07:00 PM.
 
Old 18th August 2011, 07:03 PM   #328
labjr is offline labjr  United States
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4est, I guess Brian answered 2 questions at once. DACs aren't supposed to have I2S inputs. Looks like we'll have to put the USB board inside the DAC for best performance.
 
Old 18th August 2011, 10:35 PM   #329
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Default Nonsense

Quote:
Originally Posted by labjr View Post
4est, I guess Brian answered 2 questions at once. DACs aren't supposed to have I2S inputs. Looks like we'll have to put the USB board inside the DAC for best performance.
DACs with I2S input (of the top of my head, there are more):

Northstar
Stello
Empirical Audio
PS Audio
Perpetual Technologies
Zanden

I guess all these manufacturers did not get the memo that "DACs aren't supposed to have I2S inputs"!

Yes, SPDIF was designed to have a convenient interface on a single wire for consumer use, it is an interface which does not offer the highest performance possible, as the embedding and stripping out of the clock signals causes additional jitter problems. Too bad that some folks are still chained to SPDIF in their mind. Like any DAC chip, the ESS 9018 sounds much better with a lower jitter feed, contrary to claims, it is not "jitter immune".

Tonight I will be fitting a USB-I2S board (with filtered/regulated battery power supply) to my B-II for testing, should be fun!
 
Old 18th August 2011, 10:46 PM   #330
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Embedding and stripping out of clock hardly matter if the clock is ignored.

ES9018 does not decode SPDIF like any other device I know of, it is very unique in it approach. Dustin actually provides some gems on the way it works but you will have to search for them.
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