Audio and IR Questions


I am in the midst of wiring my 'old' house. I'm running 2 pair of Cat5e and two pair of coax to each room from a wiring enclosure in the basement. I'm using snapstream to record TV on my computer in one room and showing the video in other rooms using Hauppauge's mediamvp. All works well in that department.

In addition, I want to connect my computer's audio output in one room to the audio receiver in the living room Mediamvp can do audio files in this manner but it doesn't support all the types of audio files I want to play (itunes for example). The computer and receiver are about about 70 feet apart. I've tried using several methods. First, I used a custom made balun that I bought from ebay. It supposedly split the audio output (miniplug) into 4 unbalanced cat5e outputs. I connected one such output over cat 5e to the receiver. It worked but the volume is low and the hum is very bad. I then tried directly connecting the computer to the receiver using a 75 foot miniplug extension cord just to see if that worked. Again, a lot of hum and low volume. I then connected the speaker output of my cheap amplified PC speakers to my receiver using both methods described above. Each method produced significant hum again although the volume was slightly louder. Besides the hum using all methods there seemed to be significant degradation of the audio quality making it more am radio like then mp3 quality.

So my question is - what have you tried and what should work? I'm using onboard audio from the motherboard which apparently has provision for SP/DIF connector altho I haven't been able to locate the correct cable for this. Would coax digital work without the hum? Would I use a balun to convert the coax digital to Cat 5e or could I use an existing (extra) coax RG6U cable? Any other thoughts on how to do this that is relatively inexpensive?

Next question. I want to control the computer from the living room using IR and I want to control the living room receiver from the computer room using IR. I will use either a USB-UIRT or Firefox min at the computer end. I also want to be able to control the computer from other rooms using IR. I've been reading about IR and understand one zone going into multiple emitters (i.e computer room controlling receiver etc in living room) but I'm really have a tough time figuring out multi zone IR (receiving and transmitting from and to multiple rooms). Again, I'm looking for something inexpensive. I'm sure many on this board are doing the exact same thing. What are you using for this purpose? All thoughts and suggestions appreciated.
Welcome to CocoonTech!

70 ft is pretty far for a low-level audio signal to travel without some noise and sound degradation. You can try to make your own cable with some shielded wire (that's what I'm doing, but it's only 10-15 feet). Using a digital signal should work better, but I've never used one that long to know for sure... again you should be able to make your own cable for it.

As for IR - I'm using Xantech hardware, but using my HVPro to manage everything (so it knows what room wants the music/video, etc).
I use cat5 to distribute line-level audio over a couple of 50-foot runs. I'm not doing anything fancy - left on one twisted pair, right on another. No baluns, no impedence matching. It works pretty well.

If you are getting a hum, it sounds like you might have a ground loop. If you can't fix the loop itself (make sure everything has the same ground) you need to isolate the two ends of the cable. The easiest thing to do is to get a ground loop isolator from some place like Radio Shack (Radio Shack 270-054). These are handy things to have around when you are trying to debug hums.

I also use a 30-foot optical connection between my PC and receiver. This works fine, too, of course. A coax digital connection should be ok.

There have been some discussions about ground loops here, but I can't find the threads I think I remember.

If possible I'd go with a digital connection. You should be able to get better quality audio and not need to worry as much about the distance. With optical, you won't have to worry about ground at all.

I only have one problem with my optical connection. The receiver that my computer connects to has optical inputs and it will play whatever my computer sends it. But, it will not output the analog audio through the line level outputs on the receiver - it will only do it through the speakers. This means that I can't distribute the audio from that receiver to other locations when I am using a digital source.
for your audio try a FM transmitter . . .

I have one like this . . .

but there are better ones out there . . .

I do this so I can listen to my mp3s on a boombox on the patio and walkman while doing yard work . . .

as far as the IR goes . . . I think most are simple repeater type setups . . . anything from any IR reciever goes out to all IR xmitters . . . I use a Niles IRZ6+ (I got off eBay cheap) that lets me pick which recievers go to which xmitters . . .

Pete C

I love my country, but fear my government.
Thanks all for the great information.

Pete is it possible to use cat5e cable instead of shielded cable with the Niles product?
I've already run much of the Cat5e.

Smee thanks for the tip on the ground loop isolator. If I go with the digital coax connection can the run be as long as 70 feet? Can I use baluns on the Cat5e or should I just suck it up and run some digital coax (I guess I should have run fiber optic)? If I have an extra RG6U coax running to that location, can I run digital audio through it? In other words is digital coax cable different from TV coax cable "swept to 3 ghz"?

nadler1ny said:
Pete is it possible to use cat5e cable instead of shielded cable with the Niles product?
I've already run much of the Cat5e.
yes, I use one cat5 run for IR and temp sensors (3 wires each) as I have them co-located in a double gang j-box just above the light switch in most rooms . . .

. . . and from what I've garnerd from a quick look around the net your RG6 should do fine . . . seems 75ohm cable is needed and RG6 is 75ohm. . .