Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 214 - diyAudio
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Old 17th January 2013, 06:45 AM   #2131
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It is what I have been looking forward .Hope you support includes all components or finished kit.
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Old 17th January 2013, 08:14 AM   #2132
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I would doubt that very much
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Old 17th January 2013, 08:36 AM   #2133
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Isn't much better to isolate the USB port rather than I2S? I mean using a true USB galvanic isolator capable to provide to the output USB port power from a battery pack or from an external power supply and not from PC.
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Old 17th January 2013, 08:41 AM   #2134
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why is it any better? the i2s is isolated then reclocked, certainly it seems as though the ESS prefers the clock domain to be powered/grounded on the dac side. here it makes no difference where it happens as long as its before the reclocking stage.

weve been through all of this. there is a theoretical benefit to isolate the i2s input as well, and then again before the reclocker, but both of these isolate the reclocker from the USB ground, for the same result. isolating the USB is not cheap and does not provide additional benefit as far as can be told.

we cant even prove better, let alone 'much better'
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Old 17th January 2013, 08:45 AM   #2135
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Quote:
Originally Posted by qusp View Post
why is it any better? the i2s is isolated then reclocked, certainly it seems as though the ESS prefers the clock domain to be powered/grounded on the dac side. here it makes no difference where it happens as long as its before the reclocking stage.

weve been through all of this. there is a theoretical benefit to isolate the i2s input as well, and then again before the reclocker, but both of these isolate the reclocker from the USB ground, for the same result. isolating the USB is not cheap and does not provide additional benefit as far as can be told.

we cant even prove better, let alone 'much better'
IMHO, any I2S isolator will add jitter and there is no reclocking stage into Ian's I2S universal isolator board.

Last edited by roender; 17th January 2013 at 08:51 AM.
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Old 17th January 2013, 09:59 AM   #2136
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umm, so what are you talking about? some unnamed random application of the universal isolator unconnected to the subject of this thread?

I presumed since..you are in this thread, you might be talking about some application that had a connection to this thread. the universal isolator, was built as..a universal isolator. a USB isolator, may not be better at isolating i2s at all and is not really very universal as an i2s isolator

its like telling someone who just eaten a really nice chicken dinner that beef might have been more enjoyable

Last edited by qusp; 17th January 2013 at 10:05 AM.
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Old 17th January 2013, 10:04 AM   #2137
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Quote:
Originally Posted by qusp View Post
umm, so what are you talking about? some unnamed random application of the universal isolator unconnected to the subject of this thread?

I presumed since..you are in this thread, you might be talking about some application that had a connection to this thread. the universal isolator, was built as..a universal isolator. a USB isolator, may not be better at isolating i2s at all and is not really very universal as an i2s isolator
Exactly, used as Ian description: an Universal I2S isolator.
As it is designed now, it doesn't have any reclocker circuit in order to attenuate the added isolator jitter

Last edited by roender; 17th January 2013 at 10:12 AM.
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Old 17th January 2013, 10:32 AM   #2138
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Quote:
Originally Posted by roender View Post
Exactly, used as Ian description: an Universal I2S isolator.
As it is designed now, it doesn't have any reclocker circuit in order to attenuate the added isolator jitter
It could be readily assumed that since Ian has a fifo + reclocker and oscillator, he is designing for use with his boards. Reclocking before the fifo makes little sense to me. Ian's design works well for his system. Anyway Acko has designed exactly what you describe and there is a GB for that. Ian's isolator isolates and isn't concerned about output jitter because he already has a solution to that.
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Old 17th January 2013, 10:45 AM   #2139
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Quote:
Originally Posted by hochopeper View Post
It could be readily assumed that since Ian has a fifo + reclocker and oscillator, he is designing for use with his boards. Reclocking before the fifo makes little sense to me. Ian's design works well for his system. Anyway Acko has designed exactly what you describe and there is a GB for that. Ian's isolator isolates and isn't concerned about output jitter because he already has a solution to that.
I totally agree with you.
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Old 17th January 2013, 09:52 PM   #2140
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Default Why I2S/DSD isolator is better than a USB isolator for digital audio interface

Quote:
Originally Posted by roender View Post
Isn't much better to isolate the USB port rather than I2S? I mean using a true USB galvanic isolator capable to provide to the output USB port power from a battery pack or from an external power supply and not from PC.
I can see there are two reasons:

1, Most of the USB isolators we can touch currently are for USB2.0 full speed 12MHz, not for high speed which is 480MHz. In this case, it will degrade the performance of many good USB audio interfaces which were designed optimizing for 480Mhz high speed, especially for higher Fs application as 192KHz and 384Khz.

2, Even when high speed USB isolator becomes popular down the road, I2S/DSD will still be the better solution than the USB isolator. The reason is very clear. Since we have to power the isolated section from DAC side, powering half I2S/DSD isolator comes with much less noise than powering a whole USB interface. The USB interface usually needs a couple of clocks with different frequency running at same time, not only drawing more current, but also introducing much more EMI noise from power supply and ground.

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Last edited by iancanada; 17th January 2013 at 09:54 PM.
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