Crackling sound when using a DAC

Hmmm. So to summarize, these are the two scenarios:

A)
-The DAC is configured to use the coaxial digital input
-You then put in a CD
-The CD player reads the TOC and outputs a signal
-The DAC recognizes the signal; CLock engages
-You get a sharp "crackle" from your speaker

B)
-The DAC is configured to use the optical digital input
-You then put in a CD
-The CD player reads the TOC and outputs a signal (the DAC doesn't receive the signal because it's not hooked up via the Toslink connection)
-You switch the DAC to the coaxial input
-The DAC recognizes the signal; CLock engages
-You get no "crackle"

It sounds strange because I would think that since the ouput relay and servo are engaged when the DAC receives the signal, then if they are the cause of the problem (i.e. they are faulty) it shouldn't make a difference whether you use method "A" or "B". One possibility is that there is a brief initial "burst" discharge from the NAD's digital output when it sends a signal, which goes away after it has a second or two to settle. Perhaps this is upsetting the DAC's receiver, and by switching the DAC's input off and then on a bit later, you are effectively giving the transport's digital output enough time to settle before engaging the DAC. Have you tried using the DAC with another transport? Have you used different DACs with the NAD? Again, I would encourage you to email John Wright for his thoughts.

It was the NAD, I've since used another Transport and I didn't get the problem.

I have no idea why this happens with the NAD. I can avoid the problem by switching it to optical and then back to coax once it's loaded.

Im not sure I could buy a DAC that would beat the NAD handsdown for under $500 as a simple transport, so I might keep the NAD for awhile, I've seen a Theta and CAL audio Lab transports for sub $500 but I have no way of telling if they would be a sonic improvement to the NAD, so I might just live with it for awhile.

The NAD doesn't send a continuous digital signal all the time. As such, what you are hearing is the DAC locking and unlocking. This is what i described in my first response. This is a common problem with some specific CD and / or DVD players when used as transports. Before buying something else, you should contact the manufacturer to find out if the transport constantly sends a signal out of the coaxial jack or if it engages as needed. Sean
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Hey Sean, thx. Do you know of any used CDP's that I could buy and use as a dedicated Transport, which would have a digital signal sent out at all times? Ideally I'd like to sell my NAD 541i and use that money to buy an equally as good transport. Perhaps an older ROTEL, ARCAM, or something? The idea of a detachable power cord for future upgrades would be also nice.

This is a more common problem with newer CD players and most DVD players. From what i can recall, there's "probably" a very simple modification that can be done to your DAC to correct this problem. I had to perform a similar mod to some 24 bit CAL dac's that i had several years ago due to the same problem. Whether or not you want to send your DAC in to do something like this is another matter.

As far as selecting a good transport that will negate this problem, i don't know what to suggest to you. You might want to look through the archives to see what has been suggested as being a cost effective transport. Once you narrow your search down, i would suggest calling the manufacturer to find out if that specific model outputs a constant signal or makes / breaks as needed. Given that your specific DAC "probably" ( i think that it does ) re-clocks the incoming signal that is sent to it, it might not be as sensitive to transports as some other less well designed DAC's. That's because the higher than average jitter that a lower grade transport produces is no longer a factor. That doesn't mean that "anything" will work optimally as a transport, only that you might have more options open to you. Sean
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