Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 62 - diyAudio
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Old 4th June 2012, 04:58 PM   #611
zinsula is offline zinsula  Switzerland
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Ian, I somehow missed that:
Are your S/PDIF inputs galvanically isolated? Hooking up a noisy source/ground (eg a PC) to the FIFO without galvanically isolate it isn't really what one would like...
And the optical input will make "only" 96kHz.
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Old 4th June 2012, 09:09 PM   #612
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Hi,

Have you seen Naim audio products? it sounds FIFO is great idea (:-).

Ian, Is it so that output clck frequency is adjust to input clck in order to not run out or full the FIFO ? how can it be done as output clock is at a fixed frequency ?

About galvanical isolation, have you seen AD icoupler ? also there are some advices about PCB design in AN-1109, does it makes senses with FIFO board ?

have a nice evening
anaeroben
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Old 4th June 2012, 09:27 PM   #613
vzs is online now vzs  Europe
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Quote:
Originally Posted by qusp View Post
bad idea, high speed switching is not a simple task and will ruin performance for both devices. you must do this actively, passive switching will ruin impedance termination
I also want to switch between two sources and I was thinking about these options (in this order):
1. use one of Omron's G6Z high-frequency relays with 50ohm impedance
2. Use two Potato semi PO74G125A buffers and switch by their OE pin
3. Use a high frequency bus switch like PO3B3257A

Which of the above or else would you recommend?
Thanks.
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Old 4th June 2012, 11:13 PM   #614
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Quote:
Originally Posted by zinsula View Post
Ian, I somehow missed that:
Are your S/PDIF inputs galvanically isolated? Hooking up a noisy source/ground (eg a PC) to the FIFO without galvanically isolate it isn't really what one would like...
And the optical input will make "only" 96kHz.
Hi zinsula,

For the S/PDIF input, usually I like OPT, it isolate electronic signal natually. The good thing is, with the FIFO, there is no difference between OPT and COX input.

However, to use the COX input, most of the digital source, even the USB sound cards, equiped with digital transformer, which also isolate the ground and most of the EMI noise. Don't use the COX S/PDIF source without transformer.

Regards,

Ian
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Old 4th June 2012, 11:40 PM   #615
zinsula is offline zinsula  Switzerland
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Quote:
Originally Posted by iancanada View Post
...Don't use the COX S/PDIF source without transformer
Hi Ian, exactly, that was my point. I have to check whether my source i was thinking to use has a transformer output.

If its OK, i may need the SPDIF board. I'll not be able to tell WM8804 to accept 176.4....so your TI DX.... receiver comes in handy :-)

Ciao, Tino
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Old 5th June 2012, 01:28 AM   #616
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Quote:
Originally Posted by zinsula View Post
Hi Ian, exactly, that was my point. I have to check whether my source i was thinking to use has a transformer output.

If its OK, i may need the SPDIF board. I'll not be able to tell WM8804 to accept 176.4....so your TI DX.... receiver comes in handy :-)

Ciao, Tino
Actually I did evaluation on both before I made decision. Trust me, DIX9211, very good indeed, especially for higher Fs .

Ian
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Last edited by iancanada; 5th June 2012 at 01:30 AM.
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Old 5th June 2012, 01:43 AM   #617
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Quote:
Originally Posted by anaeroben View Post
Hi,

Have you seen Naim audio products? it sounds FIFO is great idea (:-).

Ian, Is it so that output clck frequency is adjust to input clck in order to not run out or full the FIFO ? how can it be done as output clock is at a fixed frequency ?

About galvanical isolation, have you seen AD icoupler ? also there are some advices about PCB design in AN-1109, does it makes senses with FIFO board ?

have a nice evening
anaeroben
That's true. The FIFO concept really works for eliminating the jitter from digital music. The reason I could use a fixed frequency secondary clock is, there is a big enough memeory equiped on board. So, it a true FIFO .

If you want to make the secondary clock following up the input clock, you will increase jitter.

Regards,

Ian
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Old 5th June 2012, 04:36 AM   #618
qusp is offline qusp  Australia
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Quote:
Originally Posted by zinsula View Post
Ian, I somehow missed that:
Are your S/PDIF inputs galvanically isolated? Hooking up a noisy source/ground (eg a PC) to the FIFO without galvanically isolate it isn't really what one would like...
And the optical input will make "only" 96kHz.
the optical input isnt limited to 96khz, your optical output is, haha I just noticed there is no tx on the input (i've only used optical or i2s) so ya I get your point.

Last edited by qusp; 5th June 2012 at 04:39 AM.
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Old 5th June 2012, 04:43 AM   #619
qusp is offline qusp  Australia
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Quote:
Originally Posted by vzs View Post
I also want to switch between two sources and I was thinking about these options (in this order):
1. use one of Omron's G6Z high-frequency relays with 50ohm impedance
2. Use two Potato semi PO74G125A buffers and switch by their OE pin
3. Use a high frequency bus switch like PO3B3257A

Which of the above or else would you recommend?
Thanks.
2 I think, with termination on the input, well I cant advise on 3 or 1as I have no experience with them, though 1 sounds interesting, I would worry about linearity, but i'm a bit of a 'worry wart'
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Old 5th June 2012, 05:58 AM   #620
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I saw some discussion on another forum, maybe a newsgroup (can't remember), where there was doubt about the Potato IC's being even close to the specs they claim. This is still just hearsay so take it for what it's worth.
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