First post here:
I have a car Sirius system in my home, running on a 12v adapter. I have it wired so that the audio goes about 25 feet to a Mac Mini, where I record Howard Stern using Audio Hijack Pro.
I notice a lot of audio dropouts, maybe 10 an hour. I was futzing with this the other day, and I think the problem may be that the receiver is on one AC circuit while the Mac is on another, and there seems to be a different ground potential between them.It seems that this causes the 3-4 second dropouts; maybe the difference in ground potential bleeds off in time, but every time I connect the cable it mutes for a few seconds. It also does this intermittently through the broadcast.
I would like to construct a cable or ground-lift adapter (stereo unbalanced circuit) to see if this helps.
Would the way to do this be to add a small capacitor to the shield connection at the connector going into the destination (Mac)?
Or should I connect the cap in the + circuit?
I am trying to block DC while letting the AC audio signal through, so I also am not sure which value to use. Fc = 1/(2*pi*r*c), right?
Any suggestions are most welcome. I am a Broadcast Engineer, but I have not done something like this for a long time, so you probably do not need to talk to me like I'm a 3rd-grader, but that might actually help 😱!
Thanks in advance,
Tom
I have a car Sirius system in my home, running on a 12v adapter. I have it wired so that the audio goes about 25 feet to a Mac Mini, where I record Howard Stern using Audio Hijack Pro.
I notice a lot of audio dropouts, maybe 10 an hour. I was futzing with this the other day, and I think the problem may be that the receiver is on one AC circuit while the Mac is on another, and there seems to be a different ground potential between them.It seems that this causes the 3-4 second dropouts; maybe the difference in ground potential bleeds off in time, but every time I connect the cable it mutes for a few seconds. It also does this intermittently through the broadcast.
I would like to construct a cable or ground-lift adapter (stereo unbalanced circuit) to see if this helps.
Would the way to do this be to add a small capacitor to the shield connection at the connector going into the destination (Mac)?
Or should I connect the cap in the + circuit?
I am trying to block DC while letting the AC audio signal through, so I also am not sure which value to use. Fc = 1/(2*pi*r*c), right?
Any suggestions are most welcome. I am a Broadcast Engineer, but I have not done something like this for a long time, so you probably do not need to talk to me like I'm a 3rd-grader, but that might actually help 😱!
Thanks in advance,
Tom
You know, I did the same thing, setting my Sirius system up with a separate adapter to use indoors. And all the times I got audio dropouts it was due to antenna placement. Once I got that right there were no more dropouts. Of course, once I learned how easy it was to get endless 'trial' subscriptions on my computer, I no longer needed to bring the Sirius radio inside, but I digress! (You'll have to msg me privately if that interests you).
The more important thing is that what you are describing doesn't sound like a grounding or DC blocking issue at all. The Sirius outputs are almost surely AC coupled already, so with only one cross connection (one ground to another), there should be no DC to block, unless an internal capacitor is shorted (in which case you have bigger problems). Such a situation would not cause intermittent dropouts... it would never work. If the short was intermittent, it would also make some horrendous POPs.
If you really want to isolate though, since you asked, you could try going through a pair (Left and right) audio matching transformers. This is what musicians do when they need to couple audio signals between systems plugged into different AC circuits, to prevent ground loops. then, they'll add a switch between the grounds on either side of the transformers, for the gound/ground-lift option, so they have all bases covered.
Ground loop isolation just doesn't work well with capacitors. They may block DC, but they actually favor AC ground noise, and AC is after all, what make noise. But again, I don't think this is your problem.
The more important thing is that what you are describing doesn't sound like a grounding or DC blocking issue at all. The Sirius outputs are almost surely AC coupled already, so with only one cross connection (one ground to another), there should be no DC to block, unless an internal capacitor is shorted (in which case you have bigger problems). Such a situation would not cause intermittent dropouts... it would never work. If the short was intermittent, it would also make some horrendous POPs.
If you really want to isolate though, since you asked, you could try going through a pair (Left and right) audio matching transformers. This is what musicians do when they need to couple audio signals between systems plugged into different AC circuits, to prevent ground loops. then, they'll add a switch between the grounds on either side of the transformers, for the gound/ground-lift option, so they have all bases covered.
Ground loop isolation just doesn't work well with capacitors. They may block DC, but they actually favor AC ground noise, and AC is after all, what make noise. But again, I don't think this is your problem.
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