S/PDIF Pops

xb2003

New member
I'm using a 50' "Digital Coax" cable to hook my audio interface to my home theater receiver. The cable is a brand new Monoprice 75 ohm cable. I'm just kind of wondering how (for lack of a better word) robust S/PDIF over coax at 50' would be. if I mess with the cable some of the receiver side, the audio will momentarily drop out and come right back. But I'm not seeing a pattern. It almost seems like the jack on the receiver might be bad, not the cable. It does the same thing on both of my coax inputs. I do not hear the pops on my studio monitors, just the home theater speakers over the S/PDIF connection.

Thanks!
 

Chili

Site Moderator
10m is the specified limit based on Wikipedia. That's a little over 60ft, so you're pushing up to the limit. Then it probably becomes a matter of cable quality, rfi noise in the area, your receiver, etc. Have you ensured you are running at the proper sample rate and bit depth. Your home theatre might be expecting 48khz and you're sending 44.1khz. Probably not because they would never sync, but just worth asking if you checked all the stupid stuff first.

Is it possible you can send a signal from another spdif source to your receiver? Or move your interface and use a shorter cable.
 

Armistice

Son of Yoda
10m is the specified limit based on Wikipedia. That's a little over 60ft, so you're pushing up to the limit. Then it probably becomes a matter of cable quality, rfi noise in the area, your receiver, etc. Have you ensured you are running at the proper sample rate and bit depth. Your home theatre might be expecting 48khz and you're sending 44.1khz. Probably not because they would never sync, but just worth asking if you checked all the stupid stuff first.

Is it possible you can send a signal from another spdif source to your receiver? Or move your interface and use a shorter cable.

They're big metres you have in Texas.... :laughings: Down here in Orstralia, where we have the smaller metres, 10m = 32 ft, so at 50ft, the OP is well over the spec (based on that Wiki entry...)
 

Chili

Site Moderator
Meters? Fathoms? What's the difference? Arrrrgh!!

Yeah, what Armistice said. you coax is too long.
 

ecc83

Well-known member
A few years ago I experimented with long S/PDIF runs using high quality "Low Loss" TV downlead.
IIRC I got it to go way more than 50ft. However, use BIG Mother RCA Plugs and make sure they are properly SOLDERED! Crimp conns' work fine at UHF, not so good way down the band.

If push come to...You can get S/PDIF to CAT5 baluns. These will allow use up to 90mtrs.

I have also sent MIDI down CAT 5 directly. 44mtrs, no sweat!

Dave.
 

xb2003

New member
Ok so it's probably too long, makes sense. That is kind of what I figured.

After messing with it for a few days, playing music rarely drops out anymore. Sometimes it takes a second for it to recognize that there is signal, which could just be my receiver. Such as if I am using my piano to play a virtual instrument in logic, it cuts in and out somewhat frequently and if I hold a hold a note too long. I may just send the cable back. I'm running an hdmi cable also, I wish I could just shoot the S/PDIF over that. I'm sure somebody makes an adapter of some sort for that.
 

ecc83

Well-known member
Ok so it's probably too long, makes sense. That is kind of what I figured.

After messing with it for a few days, playing music rarely drops out anymore. Sometimes it takes a second for it to recognize that there is signal, which could just be my receiver. Such as if I am using my piano to play a virtual instrument in logic, it cuts in and out somewhat frequently and if I hold a hold a note too long. I may just send the cable back. I'm running an hdmi cable also, I wish I could just shoot the S/PDIF over that. I'm sure somebody makes an adapter of some sort for that.

CYP - PU-304-KIT - AUDIO OVER CAT5/6 EXTENDER TXRX | Premier Farnell CPC UK

Bit pricey but I bet a search will find cheaper. A bit of CAT5e cable is peanuts. Farnell also do a S/PDIF converter that takes Video and IR pass thru.

Dave.
 
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