Hi Ipanema,
I have output basic I2S over maybe 10 inches of cat5 twisted pair (one core signal, the other ground) and it worked well.
Since then, I have moved on to using DS9638 and DS9637 RS-423 recievers and transmitters, and I am running happily over about a metre long cable (and could probably go a lot further).
As long as there is no degradation, especially with regard to jitter, I think either this or coax is the way to go (as opposed to just standard I2S).
However, this is basic I2S (which is under 3Mhz) so its fairly straightforward, upon which the affects of jitter are less.
I do also send the 11Mhz MCLK up a spare channel on my cable, but I don't use it yet, and I haven't put a scope on the receiver output to see if its any good. So I can't comment if it will be good enough for that.
If you search the thread about the 'ultimate TDA1541A DAC' started by ecdesigns, you'll see he's done similar, and he's actually analysed the jitter, and it doesn't seem too bad doing things this way.
Personally, I wouldn't use SPDIF. Not only is it more prone to jitter (it is a single channel, self clocking signal), it also requires further electronics to encode and decode it, which is unnecessary if you're happy to use three signal cables (i.e. I2S).
Hope this helps your decision making.
Phil
I have output basic I2S over maybe 10 inches of cat5 twisted pair (one core signal, the other ground) and it worked well.
Since then, I have moved on to using DS9638 and DS9637 RS-423 recievers and transmitters, and I am running happily over about a metre long cable (and could probably go a lot further).
As long as there is no degradation, especially with regard to jitter, I think either this or coax is the way to go (as opposed to just standard I2S).
However, this is basic I2S (which is under 3Mhz) so its fairly straightforward, upon which the affects of jitter are less.
I do also send the 11Mhz MCLK up a spare channel on my cable, but I don't use it yet, and I haven't put a scope on the receiver output to see if its any good. So I can't comment if it will be good enough for that.
If you search the thread about the 'ultimate TDA1541A DAC' started by ecdesigns, you'll see he's done similar, and he's actually analysed the jitter, and it doesn't seem too bad doing things this way.
Personally, I wouldn't use SPDIF. Not only is it more prone to jitter (it is a single channel, self clocking signal), it also requires further electronics to encode and decode it, which is unnecessary if you're happy to use three signal cables (i.e. I2S).
Hope this helps your decision making.
Phil
Hi Ipanema,
Fair enough.
It might be easier to deal with I2S because it is lower frequency (~2.5MHz).
However, it might be better for you to start with a single channel for SPDIF, and then expand to three channels for I2S when happier with the method.
Its fairly straightforward to use these chips, although, be sure to put a 100ohm termination resistor across each pair of input pins of the recevier being used. (100ohms for cat 5 cable - other twisted pairs may work better with a different value, maybe someone else can comment on it - but 100ohms is probablya good starting point).
That termination resistor isn't completely clear in the datasheet.
Good luck.
Phil
Fair enough.
It might be easier to deal with I2S because it is lower frequency (~2.5MHz).
However, it might be better for you to start with a single channel for SPDIF, and then expand to three channels for I2S when happier with the method.
Its fairly straightforward to use these chips, although, be sure to put a 100ohm termination resistor across each pair of input pins of the recevier being used. (100ohms for cat 5 cable - other twisted pairs may work better with a different value, maybe someone else can comment on it - but 100ohms is probablya good starting point).
That termination resistor isn't completely clear in the datasheet.
Good luck.
Phil
Hi,
Not entirely sure I understand the question.
I know that these transmitters and receivers work well with I2S. I assume they'd be okay for SPDIF, but there may well someone with better experience with SPDIF who would be more qualified to comment on that.
Note that the transmitter has a TTL input, and an RS423 output, the receiver converts the RS423 back into TTL at the othe end of the cable run.
If there is already Jitter in your system, you can't really improve on it (except, it may be possible to reclock signals to remove jitter, but that's a different story).
Like with noise, you have to keep the addition of jitter to a minimum. So, you could argue that, taking I2S, converting it to SPDIF then back to I2S has an extra conversion stage that has the potential to add jitter.
I haven't investigated the jitter in my system yet (I need to fit a decent clock module first), but ecdesigns used a quad version of my chips (mine are dual) and, if I recall, his observations were that the jitter added by these devices are quite low.
Hope that helps.
Cheers,
Phil
Not entirely sure I understand the question.
I know that these transmitters and receivers work well with I2S. I assume they'd be okay for SPDIF, but there may well someone with better experience with SPDIF who would be more qualified to comment on that.
Note that the transmitter has a TTL input, and an RS423 output, the receiver converts the RS423 back into TTL at the othe end of the cable run.
If there is already Jitter in your system, you can't really improve on it (except, it may be possible to reclock signals to remove jitter, but that's a different story).
Like with noise, you have to keep the addition of jitter to a minimum. So, you could argue that, taking I2S, converting it to SPDIF then back to I2S has an extra conversion stage that has the potential to add jitter.
I haven't investigated the jitter in my system yet (I need to fit a decent clock module first), but ecdesigns used a quad version of my chips (mine are dual) and, if I recall, his observations were that the jitter added by these devices are quite low.
Hope that helps.
Cheers,
Phil
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