Author Topic: Computer transport interface  (Read 21176 times)

Offline stevenvalve

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Computer transport interface
« on: May 22, 2014, 02:56:24 PM »
 I have 6 terabytes of computer stored music via wave files and I need to play them without turning them back to CDs, So I need a computer transport but unfortunately they still do not quite cut it. I have word from our tech heads that this is the interface to get, its cheap and could be the best around. It has direct Clock, word, Data, Ground. including galvanic isolation. Danny Digital has one on order for evaluation.  What do you guy's think, do we buy one. http://www.ebay.com.au/itm/XMOS-DSD-384-kHz-32bit-multi-format-USB-to-I2S-SPDIF-/251531449671?pt=LH_DefaultDomain_0&hash=item3a90715547
« Last Edit: May 22, 2014, 03:02:39 PM by stevenvalve »

Offline stevenvalve

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« Last Edit: May 22, 2014, 03:02:15 PM by stevenvalve »

Offline Tuyen

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Re: Computer transport interface
« Reply #2 on: May 22, 2014, 03:38:37 PM »
It looks interesting.  Feature rich.

I use an XMOS based USB to I2S interface too powered by dedicated 5V power supply.
http://luckit.biz/

Very happy with it.   

Thing is though, I can't imagine computer audio ever reaching sonic expectations for any KDAC users.  So many (sometimes unavoidable) SMD components in the path.  Potentially be a big waste of valuable time/money.   No??

Offline ozmillsy

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Re: Computer transport interface
« Reply #3 on: May 22, 2014, 04:33:07 PM »
How does the clocking work?
It's all about the music,, not the equipment.

Offline treblid

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Re: Computer transport interface
« Reply #4 on: May 22, 2014, 05:30:44 PM »
What's XMOS?


Offline dannydigital

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Re: Computer transport interface
« Reply #5 on: May 22, 2014, 05:33:07 PM »
I have 6 terabytes of computer stored music via wave files and I need to play them without turning them back to CDs, So I need a computer transport but unfortunately they still do not quite cut it. I have word from our tech heads that this is the interface to get, its cheap and could be the best around. It has direct Clock, word, Data, Ground. including galvanic isolation. Danny Digital has one on order for evaluation.  What do you guy's think, do we buy one. http://www.ebay.com.au/itm/XMOS-DSD-384-kHz-32bit-multi-format-USB-to-I2S-SPDIF-/251531449671?pt=LH_DefaultDomain_0&hash=item3a90715547

When I get it, I will initially be trying it out for DSD audio. I will integrate it in with my Pioneer DV-989AVi which I modified for 2 channels only. I'll use the DAC in it to stream DSD. It has quite a reasonable BB DAC (PCM1738E) with an analogue stage that's been modified with OPA627's and 2SK170/2SJ74 complementary FET output.
Should be quite interesting.

I imagine the USBtoI2S board will have plenty of potential for upgrade tinkering, especially in the clock re-generators.

Hope to get it soon.  :D

p.s. The board is available from this site too: http://jlsounds.com/products.html


« Last Edit: May 22, 2014, 05:44:21 PM by dannydigital »

Offline zenelectro

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Re: Computer transport interface
« Reply #6 on: May 23, 2014, 01:06:17 AM »
When I get it, I will initially be trying it out for DSD audio. I will integrate it in with my Pioneer DV-989AVi which I modified for 2 channels only. I'll use the DAC in it to stream DSD. It has quite a reasonable BB DAC (PCM1738E) with an analogue stage that's been modified with OPA627's and 2SK170/2SJ74 complementary FET output.
Should be quite interesting.

I imagine the USBtoI2S board will have plenty of potential for upgrade tinkering, especially in the clock re-generators.

Hope to get it soon.  :D

p.s. The board is available from this site too: http://jlsounds.com/products.html

Danny,

I'm not sure what you mean by 'regeneration' -  it is just a synchronous re-clocking arrangement.

The big issue with these boards is they require galvanic isolation, but the isolators add jitter.
As such the clock needs to be DAC side of the isolator and a/ be sent back through the isolator
b/ re clock signals coming out of the isolator.

Also not sure which isolators they are using as there are quite a few different technologies
ATM all with various trade offs. Theoretically if the reclocking is done correctly this shouldn't
matter. We will see.

They appear to have done this correctly (I think). Then it's a case of types of clocks, logic
used for reclocking, bypassing, layout etc etc.

The price is pretty amazing for what they do - so I'm getting one.

cheers,

Terry

Offline zenelectro

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Re: Computer transport interface
« Reply #7 on: May 23, 2014, 01:07:51 AM »
It looks interesting.  Feature rich.

I use an XMOS based USB to I2S interface too powered by dedicated 5V power supply.
http://luckit.biz/

Very happy with it.   

Thing is though, I can't imagine computer audio ever reaching sonic expectations for any KDAC users.  So many (sometimes unavoidable) SMD components in the path.  Potentially be a big waste of valuable time/money.   No??

The Luckit is OK, has Galv isolation but no re clocking after the isolators.

T

Offline zenelectro

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Re: Computer transport interface
« Reply #8 on: May 23, 2014, 01:09:57 AM »
It looks interesting.  Feature rich.

I use an XMOS based USB to I2S interface too powered by dedicated 5V power supply.
http://luckit.biz/

Very happy with it.   

Thing is though, I can't imagine computer audio ever reaching sonic expectations for any KDAC users.  So many (sometimes unavoidable) SMD components in the path.  Potentially be a big waste of valuable time/money.   No??

PC audio will surpass the KillerDAC - no question.  It's just a question of who can do it.

My money is on DSD replay being the best solution. 

T

Offline zenelectro

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Re: Computer transport interface
« Reply #9 on: May 23, 2014, 01:11:35 AM »
How does the clocking work?

USB -> I2S asynchronous operation means the clocks are fixed (not pullable) on DAC side and the computer
just feeds data to a small buffer on demand. This is the best way.

Offline ozmillsy

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Re: Computer transport interface
« Reply #10 on: May 23, 2014, 08:44:31 AM »
USB -> I2S asynchronous operation means the clocks are fixed (not pullable) on DAC side and the computer
just feeds data to a small buffer on demand. This is the best way.
It's probably my lack of knowledge.   But what I was thinking,,,,,   how does the Killerdac derive an 11M clocking signal from this board?     Doed it just sync to 22M?
« Last Edit: May 23, 2014, 09:06:42 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline Greg Erskine

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Re: Computer transport interface
« Reply #11 on: May 23, 2014, 09:18:17 AM »
Hi,

Have you guys been following this thread closely?

http://killerdac.com/forum/index.php/topic,842.msg19303.html#msg19303

IMO they have got it right, a small Linux computer in the DAC, i2s out directly to the DAC chip(s). Add an i2s isolator if you must.

I can't see the point of adding the costs of a PC and USB hardware, also no S/PDIF, no audiophile USB cables.

I'd love to see you guys develop a KillerRasPi.

regards

Offline zenelectro

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Re: Computer transport interface
« Reply #12 on: May 23, 2014, 12:14:57 PM »
It's probably my lack of knowledge.   But what I was thinking,,,,,   how does the Killerdac derive an 11M clocking signal from this board?     Doed it just sync to 22M?

Andrew,

The I2S will OP 2.8MHz clock - I think. Haven't looked at data sheet. Do they have one??

I did some research on these USB converters and will probably steer away from them. There are compromises.
 
T



 

Offline zenelectro

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Re: Computer transport interface
« Reply #13 on: May 23, 2014, 12:18:44 PM »
Hi,

Have you guys been following this thread closely?

http://killerdac.com/forum/index.php/topic,842.msg19303.html#msg19303

IMO they have got it right, a small Linux computer in the DAC, i2s out directly to the DAC chip(s). Add an i2s isolator if you must.

I can't see the point of adding the costs of a PC and USB hardware, also no S/PDIF, no audiophile USB cables.

I'd love to see you guys develop a KillerRasPi.

regards

Greg,

It's not that simple, as stated before, if you add the isolator you need to add reclocking to
remove (attenuate) jitter that isolator adds.

Terry

Offline Tuyen

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Re: Computer transport interface
« Reply #14 on: May 23, 2014, 01:29:15 PM »
As an avid computer audio user, very keen to follow how Terry and Danny get along with the usb boards and what you guys find are worthwhile modifications/power supply/clocking/computer setups.

Hope you guys get a good result and have a chance to share your experiments and results on the forum.  ;D

Offline ozmillsy

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Re: Computer transport interface
« Reply #15 on: May 23, 2014, 01:46:30 PM »
The I2S will OP 2.8MHz clock - I think. Haven't looked at data sheet. Do they have one??

It outputs DSD over PCM.

Quote
5)   DSD Audio over PCM frames. DSD64(2.822400MHz) and DSD128(5.644800MHz) by method DoP with 0x05/0xFA markers.

Steven opened the thread by suggesting this USB interface ticks a lot of boxes (as a potential solution for the Killerdac?).
Which it potentially is, given it is a multi format interface.

My concern is the output clock timings may not be suitable for the TDA1541A ? (not sure)   Here they are......



The specs were on the ebay listing,,,,,
http://www.ebay.com.au/itm/XMOS-DSD-384-kHz-32bit-multi-format-USB-to-I2S-SPDIF-/251531449671?pt=LH_DefaultDomain_0&hash=item3a90715547
« Last Edit: May 23, 2014, 02:04:05 PM by ozmillsy »
It's all about the music,, not the equipment.

Offline Greg Erskine

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Re: Computer transport interface
« Reply #16 on: May 23, 2014, 02:19:41 PM »
Greg,

It's not that simple, as stated before, if you add the isolator you need to add reclocking to
remove (attenuate) jitter that isolator adds.

Terry

Hi Terry,

I am not sure I follow 100%. The picture I linked to has a Raspberry Pi connected to the DDDAC directly via i2s, no isolation.

I thought I had seen pictures of a isolation board using i2s but can't find the picture (it may have been just a USB to is2 board?).

Are you referring specifically to the KillerDAC and using an isolation board?

My lack of knowledge tends to make me view things in a simplistic manner. :o

regards




Offline omodo

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Re: Computer transport interface
« Reply #17 on: May 23, 2014, 02:25:45 PM »

It outputs DSD over PCM.

Steven opened the thread by suggesting this USB interface ticks a lot of boxes (as a potential solution for the Killerdac?).
Which it potentially is, given it is a multi format interface.

My concern is the output clock timings may not be suitable for the TDA1541A ? (not sure)   Here they are......



The specs were on the ebay listing,,,,,
http://www.ebay.com.au/itm/XMOS-DSD-384-kHz-32bit-multi-format-USB-to-I2S-SPDIF-/251531449671?pt=LH_DefaultDomain_0&hash=item3a90715547

the top row on that chart is suitable for 1541a, i.e. 44.1kHz Fs, BCK 64* Fs = 2.8Mhz

and should play up to 96khz fine, i think bck is limited to 6.4mhz on 1541a

Offline ozmillsy

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Re: Computer transport interface
« Reply #18 on: May 23, 2014, 03:04:16 PM »
the top row on that chart is suitable for 1541a, i.e. 44.1kHz Fs, BCK 64* Fs = 2.8Mhz
Ok, cool.     For some reason I thought there was a restriction to an 11M master clock speed,  but you're saying it's less than 11M so it's fine.   
« Last Edit: May 23, 2014, 04:12:52 PM by ozmillsy »
It's all about the music,, not the equipment.

Offline kajak12

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Re: Computer transport interface
« Reply #19 on: May 23, 2014, 05:59:50 PM »
PC audio will surpass the KillerDAC - no question.  It's just a question of who can do it.

My money is on DSD replay being the best solution. 

T
Now your talking but yet to hear it......................
still discovering the link between electronics and audio reproduction.so much to learn and so little time