USB DAC

I think we all know by now what this section is for.
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#16

Post by ed »

Nick wrote:I worked on this at length last year. The problem is to get above 16/44 you meed USB2 audio. And windows does not have native USB2 drivers at the moment. I gave up.

This will do it

http://www.xmos.com/products/development-kits/usbaudio2

I should have one around here somewhere. Should update the firmware and see how it goes now. Interesting processor, direct descendent of the transputer.
I've been going round in circles on this one........

How do you read paragraph 2 here(if you fancy reading it, that is):
http://thewelltemperedcomputer.com/HW/USB_DAC_Async.htm
??

If I feed the USB with the stream from the server I can use the standard driver, providing the dac can take it...I think......debian/java...as in raspberrypi or this other thing I linked to on another page

http://rhombus-tech.net/

If it works, using 4 line lcd, all parts way less than £100
Attachments
client-block.jpg
There's nowhere you can be that isn't where you're meant to be
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#17

Post by Mike H »

ed wrote:I've been going round in circles on this one........

How do you read paragraph 2 here(if you fancy reading it, that is):
http://thewelltemperedcomputer.com/HW/USB_DAC_Async.htm
??

If I feed the USB with the stream from the server I can use the standard driver, providing the dac can take it...I think......debian/java...as in raspberrypi or this other thing I linked to on another page

http://rhombus-tech.net/

If it works, using 4 line lcd, all parts way less than £100
Right you've got Linux then (or whatever)

If so yes according to that para.

Be aware though that amongst this bumf I read that some board manufacturers may use "cheap" receiver (?) chip(s) to reduce cost, making the board look like a bargain; but this receiver chip (I think it's called) is what does the actual USB interface, from which I gather the more expensive boards are true high speed because of "good" high speed receiver chips. Presumably makes the board more expensive then. Bear in mind memory is getting hazy though but that's the impression I was getting. :D

Or I could be talking out of my bottom ... :lol:
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#18

Post by pre65 »

Mike H wrote:

Or I could be talking out of my bottom ... :lol:
Still windy then ? :lol: :lol: :lol:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#19

Post by Mike H »

You wouldn't believe it....
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#20

Post by Nick »

Yes, OSX and Linux has USB 2 Audio drivers, so if the USB device will accept USB2 audio then it will be fine.

"Be aware though that amongst this bumf I read that some board manufacturers may use "cheap" receiver (?) chip(s) to reduce cost, making the board look like a bargain;"

Well, they are either USB 1,2 or 3 compliant or not. If not they won't get to use the USB tag.

I have forgotten a lot of what I found out, but its simple enough (ish) The limits of speed and bit depth for USB 1 is the amount of data that can be sent in each 1ms frame. and the size of the buffer at the device. USB 2 goes a lot faster so has space to spare.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#21

Post by Mike H »

I may have got the wrong end of the stick but I thought one bit of blurb was trying to say that it may well be USB 2 - 3, but if the interface is the "cost-cutting" variety it still won't do the high kilohertz. :?:

I.e. "buyer beware" ....
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#22

Post by pre65 »

The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#23

Post by ed »

pre65 wrote:What about summat like this ?

http://www.ebay.co.uk/itm/USB-SPDIF-COA ... 3066wt_726
thanks Phil but,

1) there is no mention/provision for spdif in my block diagram
2) it would add more circuitry into the sig chain
3) to quote somebody(I forget where I read it) "spdif is a stoneage protocol"
4) IMO spdif is a breeding ground for jitter
There's nowhere you can be that isn't where you're meant to be
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#24

Post by Mike H »

Found a datasheet, that appears to be a PCM2704, all-in-one chip, USB 1.1, 32, 44.1 & 48 kHz (only).
ed wrote:3) to quote somebody(I forget where I read it) "spdif is a stoneage protocol"
According to Wiki, S/PDIF protocol is 16 bits, 44.1 / 48 kHz.

That chip can also do stereo audio out, but is not implemented there.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#25

Post by Nick »

I may have got the wrong end of the stick but I thought one bit of blurb was trying to say that it may well be USB 2 - 3, but if the interface is the "cost-cutting" variety it still won't do the high kilohertz. Question
Well, if it doesn't do the faster data rate, its not USB 2. Its not optional,

sp/dif doesn't define a max data rate, just the frame format and 20 or 24 bits
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#26

Post by Mike H »

OK wrong end of the stick it is then. :D
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
Post Reply