You must check signal integrity of coaxial output. Coaxial output stage of DVD/CD player should use RS-422 line driver which has high sink & source current capability. But, many DVD players simply use general logic gate series and low quality pulse transformer due to cost. If you have a oscilloscope, you can see the signal integrity of coaxail output signal. (You should terminate 75 ohm) Many players show severe overshooting at rising edge or distorted square wave. This could cause jitter related problems. The extrem case is that the optical output line in front of TOTX module share above distorted coaxial line. In this cases you needs tweak. Consult a competent DIYer.
Originally posted by Soycrema The question says it all. I have a Sony NS 700P DVD player and I want to get the best possible sound with my digital connection, which one is better?
Conventional wisdom has it that plastic TOSLINK connections have lower bandwidth than coax. High frequency rolloff in the bitstream can introduce jitter into the receiver because these type of connections carry the clock as part of the data. Therefore, coax is likely to give better results.
However...whether this is a problem or not depends entirely on the sophistication of the receiver's clock recovery circuit, so there is no simple, pat answer--it depends on the receiver, and it's quite difficult to measure the results. (It requires a spectrum analyzer with very good selectivity and dynamic range, or else a dedicated jitter analyzer.)
One thing that is incontrovertible is that the optical connection will not introduce ground loops, nor is it subject to EM interference. From this point of view, optical is clearly superior.
Robert is right. Optical should be better, except toslink is fundamentally flawed. Anyone who knows the details about the SPDIF interface format and the various digital audio connection types would tell you the same. Toslink has a narrow bandwidth (6 MHz) which causes the digital pulses to ring, rather than be square. This introduces jitter in the signal (the timing between each bit is not the same, but varies). Not only that, the jitter with toslink is not random. For a PCM digital signal, this causes distortion that is easily detected with test equipment, and can be heard with good quality equipment. This is because the SPDIF format assumes that the timing between samples is exactly 1/44,100 seconds and remains constant. If the timing varies, the samples are used to reconstruct the proper amplitude of the wave, but at the wrong time, which distorts the shape of the signal, which is distortion. Unless your DAC reclocks the incoming data stream, this will effect the sound. All this has NO effect on DTS and Dolby Digital signals, because those formats are not sensitive to the timing between samples.
All this means that for DD and DTS, it probably doesn't matter which you use. For PCM data from CDs, fed to an external DAC, coax is better unless your dac reclocks the incoming signal.
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