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Old 9th December 2011, 12:03 PM   #201
marce is offline marce  United Kingdom
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Join Date: Jun 2007
Location: Blackburn, Lancs
Barrows, they are used because of cost not quality or for signal integrity, I spend all day designing PCBs putting together systems and we would not dreem of using a ribbon cable.
I cant see why you wanna argue the fact, why not go do some reseach, have a look at what connectors etc are being used.
To properly control the impedance of the interconnect you either use a FFC cable or design a bespoke flexible PCB or cable assembly.
Again if you are DIYing why not try and use the BEST methods available...
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Old 9th December 2011, 03:10 PM   #202
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Default Hi

Quote:
Originally Posted by marce View Post
Barrows, they are used because of cost not quality or for signal integrity, I spend all day designing PCBs putting together systems and we would not dreem of using a ribbon cable.
I cant see why you wanna argue the fact, why not go do some reseach, have a look at what connectors etc are being used.
To properly control the impedance of the interconnect you either use a FFC cable or design a bespoke flexible PCB or cable assembly.
Again if you are DIYing why not try and use the BEST methods available...
Marce: I am not trying to argue anything, just pointing out that you were wrong to suggest that ribbon cables are not used for this purpose, and in very well respected , very expensive, high end products as well. Considering that some dCS products are pretty much built to cost no object standards, I truly wonder how much real world difference there would be between 5 cm of ribbon cable, and something else when well implemented. My understanding is that there is no impedance spec for I2S, becuse it is designed for very short distances where reflections will not be an issue: is this understanding incorrect?
What is FFC? Are you talking about coax like u.fl, or?
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Old 9th December 2011, 04:50 PM   #203
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by marce View Post
Barrows, they are used because of cost not quality or for signal integrity, I spend all day designing PCBs putting together systems and we would not dreem of using a ribbon cable.
At AMR we use ribbon cables in a number of places. They provide as good or better signal integrity as PCB's if used and specified correctly.

Our ribbon cable cable for signal use is solid core copper with silver plating and PTFE insulation and have at least as precise impedances as you can practically get with strip lines.

Ciao T
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Old 12th December 2011, 11:20 AM   #204
marce is offline marce  United Kingdom
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Location: Blackburn, Lancs
There is better, which is why a lot of mil areo and medical use FFC FPC
Hell just suggesting a better alternative that you may wanna look at, but wot the hell, if you wanna argue without research do so, BYE
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Old 5th January 2012, 09:32 PM   #205
greggp is offline greggp  United States
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hmmm... did something happen to the last 3-4 weeks of this thread?
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Old 29th January 2012, 05:35 PM   #206
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Quote:
Originally Posted by Lorien View Post
Hello guys,
after a while, I must say that I'm close to finish my USB to I2S application based purely on XMOS reference design... with a few changes to accomodate to my PCB needs. The schematic is almost identical to that posted on XMOS site, no facy stuff here, no multichannel support, only stereo.
The board will provide one I2S output (since main reason for developing was for playback only) and one S/PDIP output.
Perhaps there could be few things to notice:
1. The board is 4 layers
2. 2 oz copper thickness for all layers OR 1oz for outer layers and 2 oz for GND planes (I'm still in debate)
3. Ultra low phase noise oscillators (22.5792 Mhz and 24.576 Mhz).
4. OsCONs are present, heavy decoupling for every IC, NP0 most of them.
5. Seven low noise voltage regulators. Every oscillator will have a dedicated voltage regulator mounted under it (keep trace lengths to minimum). The Logic ICs in clock signal's path also have a dedicated PSU.
6. Board provide two USB inputs: one is USB-B mounted on the PCB while the other could be like this
7. The board could be powered using USB 5V or from an 5V external source (still debatable)
8. 24 bit/ up to 192 khz sample rate support. It's far from "ultimate" sollution but it's a start.

My PCB is not ready yet, and I could make few changes to the I2S/SPDIF outputs so any help in this matter would be apreciated.
Kind regards,
L
Hello Lorien, i wonder what happened to your Board?
have you got it finished yet?
cheers
Yurgs
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Old 30th January 2012, 03:45 PM   #207
ENSen is offline ENSen  Sweden
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Quote:
Originally Posted by yurgs View Post
Hello Lorien, i wonder what happened to your Board?
have you got it finished yet?
cheers
Yurgs
You can find information about Loriens board here;

XMOS-based Asynchronous USB to I2S interface
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