itai;322442 Wrote: > > I lowered the digital volume to 85, and the poping stoped! >
This further supports my initial diagnosis that the problem is an electrical issue with the s/pdif receiver. Here's what is happening: There are some jokes among audiophiles with respect to digital signals, in that the slender "ones" have an easier time getting down the wire than the fatter "zeroes". Sometimes the zeroes get stuck in the wire, which is why you have to use large diameter cables. Ones can also be a problem sometimes because they get wedged sideways, etc. It's funny, but not far from the truth here. Seriously, the reason it works in one case and not the other has to do with the s/pdif electrical waveform of a one as compared to a zero. When you have more ones in the signal, it creates kind of a stronger carrier signal for the s/pdif receiver to lock on to. So when you have a marginal connection that sometimes works and sometimes doesn't, the population of ones versus zeroes is probably what makes the difference. When the volume control is being used, SB3 will take advantage of its 24-bit audio path to output the signal as accurately as possible, but when the volume control is at maximum, there is nothing to put in those additional bits because the 16 bit signal is being passed through unchanged. In other words, at max volume the s/pdif interface will transmit the following for each sample: 16 bits, could be ones or zeroes 8 bits always zero 8 bits ancillary data, could be ones or zeroes but when the volume control is in use, you have 24 bits, could be ones or zeroes 8 bits ancillary data, could be ones or zeroes The second signal has a higher distribution of ones. Electrically, a one is represented as two level transitions (matching the signals carrier frequency) wheres a zero has only one transition, corresponding to half the carrier frequency. A receiver needs to figure out what the carrier frequency is in order to decipher the data. A poorly implemented receiver may have trouble receiving the signal if it has a low distribution of "ones". I am glossing over many details here - it would probably help to read this excellent explanation of s/pdif: http://www.epanorama.net/documents/audio/spdif.html What I've described is a pretty obscure phenomenon but it really is the best explanation. Here's a question: does the DAC have any indicator LED to show when it is receiving a valid s/pdif signal? If you pause the SB3 it will output an s/pdif signal containing digital silence. I would expect this DAC to lose lock completely on digital silence, but you'd only be able to tell if it has an indicator. > > And is'nt it said that digital volume should'nt be used?, as opposed to > analog volume? > It degrades the signal, they say. That's a totally separate issue having nothing to do with s/pdif. It has been covered extensively in this forum. -- seanadams ------------------------------------------------------------------------ seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=50151 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
