[kdbrink]

I'm trying to connect my DirecTV satellite box to a Moon Audio 750D DAC/Transport via either the optical or coax outputs. The DAC locks onto the signal at 48k and I get sound, but it is intermittent...more off than on. It sounds like some kind of digital clocking noise.

Does anyone have any ideas on a remedy?

[jlafrenz]

Does this happen with other sources using the same connection?

[srb]

I assume the DirecTV is set to output 2 channel PCM?  Most stand alone stereo DACs cannot decode Dolby Digital or DTS, so if they were being sent either one of those formats, I would think you would either get no sound at all or only digital noise.
 
Steve

[Mr Peabody]

Yeah, 2-channel opposed to 5.1 was my thought as well.  If you are using 2-channel and just a cheap cable you might try a higher quality cable to see if it resolves the issue.

Some years ago my Dishnet receiver would not work with a Primare processor.  Primare was aware of the problem and I had to send the processor in for a mod.  I'm not sure what the problem was but according to Primare the inputs digital standard was too high and the signal from the receiver was poor.  So if all else fails you may have one of these similar imcompatibility issues.

[kdbrink]

Some years ago my Dishnet receiver would not work with a Primare processor.  Primare was aware of the problem and I had to send the processor in for a mod.  I'm not sure what the problem was but according to Primare the inputs digital standard was too high and the signal from the receiver was poor.  So if all else fails you may have one of these similar imcompatibility issues.

You may be onto something. I had the same problem with the DirecTV box with an EMM Labs DAC, but it worked fine with a lower quality PS Audio or Musical Fidelity V-DAC.

[srb]

kdbrink,
 
I just looked up the Moon 750D and see that it has the ESS Sabre32 DAC chip.  Although the chip has a "Time Domain Jitter Eliminator", if the source's jitter is too high, it will behave as you experienced.
 
It was enough of a problem that Peachtree Audio subsequently modified two of the S/PDIF inputs on their units with a reduced jitter aperature setting (and slightly reduced performance) to acommodate high jitter sources.  Although the problem was mostly reported with the use of the higher jitter Airport Express A1264 (wireless N), any extremely high jitter source has this potential problem with the ESS Sabre32 chips.
 
Steve

[kdbrink]

kdbrink,
 
I just looked up the Moon 750D and see that it has the ESS Sabre32 DAC chip.  Although the chip has a "Time Domain Jitter Eliminator", if the source's jitter is too high, it will behave as you experienced.
 
It was enough of a problem than Peachtree Audio subsequently modified two of the S/PDIF inputs on their units with a reduced jitter aperature setting (and slightly reduced performance) to acommodate high jitter sources.  Although the problem was mostly reported with the use of the higher jitter Airport Express A1264 (wireless N), any extremely high jitter source has this potential problem with the ESS Sabre32 chips.
 
Steve

Thank you, Steve

That would explain why it worked just fine on lower quality DACs. It looks like I'm stuck with using the analog outputs.

Ken

[kdbrink]

Would using something like the Monarch DIP Upsampler between the DirecTV box and the DAC help with the jitter?

[srb]

Would using something like the Monarch DIP Upsampler between the DirecTV box and the DAC help with the jitter?

Great question.  I don't know, but if they do perform the jitter reduction they're supposed to, you would think it might work.  I see the two used units listed on Audiogon sold in under 6 and 10 days.  If you decide to try it and manage to snag one, let us know if it does!
 
Steve

[kdbrink]

I just sent an email inquiry to Monarchy. I'll let you know what they say.

Ken

[kdbrink]

I just tried the Monarchy 24/96 processor. It didn't solve my problem. The digital output on the DirecTV box must be of really poor quality.

[kdbrink]

Tried the DirecTV optical ouput into a MF V-DAC and it works just fine. The satellite output must be too sloppy for the Moon as suggested earlier in this thread.

[kdbrink]

I've done some more experimentation with the DirecTV optical output. Using a EMM Labs DCC2 DAC gave me the same bad result as the Simaudio...erratic, stop/start signal.

I then tried a Berkeley Audio Alpha DAC and it works great! I wonder if the EMM labs uses a ESS Sabre32 DAC chip.

Since I don't play that many physical disks, I think I'll be selling the Simaudio and keeping the Berkeley!

[srb]

Using a EMM Labs DCC2 DAC gave me the same bad result as the Simaudio...erratic, stop/start signal. ..... I wonder if the EMM labs uses a ESS Sabre32 DAC chip.

The DCC2 uses a proprietary discrete dual differential D/A conversion circuit.
 
"Rather than depend on mass-market off-the-shelf converter chips (with all their inherent compromises and limitations) we developed our own proprietary conversion circuitry that's utterly free from the differential non linearities present in every D/A chip created to date".
 
Interesting.
 
Steve