Ed Littman wrote on Fri, 29 July 2005 19:06 |
The wiring on the adapter is done very cleanly. why would a spdif to aes conversion loose the clock for higher sample rates? |
bblackwood wrote on Fri, 29 July 2005 20:13 | ||
It's not converting the impedance - AES is 110 Ohms, SPDIF is 75 Ohms - this alone can cause issues with more sensitive receivers... |
Ronny wrote on Fri, 29 July 2005 20:46 | ||||
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bblackwood wrote on Fri, 29 July 2005 22:00 | ||||||
Errr, the 'impedance' does have an impact when the data is transmitted at 2x or greater speeds... What else do you suspect it could be aside from "ohms"? |
Ronny wrote on Fri, 29 July 2005 21:30 |
Not sure, Brad, it just doesn't feel like ohms to me, |
Quote: |
it feels more like a clock thing. |
bblackwood wrote on Fri, 29 July 2005 22:00 |
Errr, the 'impedance' does have an impact when the data is transmitted at 2x or greater speeds... What else do you suspect it could be aside from "ohms"? |
Ed Littman wrote on Fri, 29 July 2005 21:43 | ||
Ronny may be onto something, but I don't know what. The input of my pst card has the same type of adapter/connector as the output. I was able to send the program through my adc set to 88.2/96k respectfully into the pst & capture with no problem. If it was strictly an impedance issue wouldn't there be a problem going in not just coming out? |
bblackwood wrote on Fri, 29 July 2005 22:38 | ||||
Let's call it 'impedance'...
OK, then explain why it works when he swaps cards (same clock) or when he switches to an active format converter (same clock)... |
Ronny wrote on Sat, 30 July 2005 00:05 |
You snipped my question and answered it with another question, but I'll answer yours. Because the ohms aren't changing from 44.1k, but the sample rate on the clock is. Same clock, different sample rates. That's where I'd look for the problem, not impedance. |
bblackwood wrote on Sat, 30 July 2005 07:01 | ||
Then how does a simple active format converter fix the issue? The reason the impedance matters as at higher fs, you're dealing with a 'faster' signal - if the impedance is incorrect, the receiver in the card may still be receiving enough data at the 'slower' rate of 44.1kHz to read it, but be unable to at higher fs... |
Ronny wrote on Sat, 30 July 2005 07:04 |
Higher fs does not mean that the signal travels twice as fast as the halved sample rate, only that it's being sampled twice "as much", all frequencies travel at the same rate, although not the same energy. If freq's traveled at different speeds all your ears would hear would be beat frequencies and harmonic structure would be nigh impossilbe to capture and reproduce. I guess we'll just have to disagree on this one, Brad. |
Ed Littman wrote on Fri, 29 July 2005 21:43 |
If it was strictly an impedance issue wouldn't there be a problem going in not just coming out? |
bblackwood wrote on Sat, 30 July 2005 08:21 | ||
No, you simply don't understand what I'm saying. It's a fact that higher fs means that data is crossing the zero point at a faster rate in any given period of time. That's what sampling frequency means, Ronny - that in one second period of time, you have 96k sampled versus 44.1k samples. The greater number of samples means that you have more instances of zero crossings in any given time period - hence the term 'faster'. No one is suggesting that the actual signal travels faster through the wire, but higher sampling frequencies means that the signal appears 'faster' to the receiver chip (not faster from point to point, but the number of zero crossings/given time period), and the impedance can definitely have an impact on higher freqs... |
Chris Cavell wrote on Sun, 31 July 2005 16:38 |
The clocking signal has twice the zero crossings...not the data transmitted along that clocking signal. |
Chris Cavell wrote on Sun, 31 July 2005 15:38 |
The clocking signal has twice the zero crossings...not the data transmitted along that clocking signal. |
bblackwood wrote on Sat, 30 July 2005 04:01 |
The reason the impedance matters as at higher fs, you're dealing with a 'faster' signal - if the impedance is incorrect, the receiver in the card may still be receiving enough data at the 'slower' rate of 44.1kHz to read it, but be unable to at higher fs... |
dcollins wrote on Sun, 31 July 2005 22:28 |
Aka, "where's the clock?" |
bblackwood wrote on Mon, 01 August 2005 04:59 | ||
You have no idea how many times I've almost typed that exact question in this thread already... |