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Running Audio Cable Over Long Distance


Richard Hamilton

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For one of my projects this year I need to run the output of the Show Director Controller audio over a substantial distance. I've got to get it from the controller to a PA system that is almost 300 feet away.

I'm not an expert in the audio area, but my general engineering gut feeling tells me that I'm not going to be able to run the output over that distance. A low level signal is probably not going to be driven that far and still have any decent audio quality without noise... assuming the signal even gets there at all !

Does anyone have suggestions for a wireless audio transmitter/receiver that isn't going to cost me an arm and a leg? Other ideas?

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maybe have a radio close to the house (in the garage per se) that receives the signal from your transmitter and run speaker wire out to the PA after first going through an amplifier?

just a thought...never had the problem of distance since my front door is 15 feet to the curb

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johnny christmas wrote:

maybe have a radio close to the house (in the garage per se) that receives the signal from your transmitter and run speaker wire out to the PA after first going through an amplifier?

just a thought...never had the problem of distance since my front door is 15 feet to the curb


Thanks for the reply. This is for a commercial installation and the client does not want to use FM Radio transmittion. I need to get the audio from the outside Show Director controller to an internal control room where the PA system amplifiers are located.

Bascially, I have been looking for a decent RF transmitter/receiver pair. My home experience with those types of audio/video transmitters is that the range and clarity is not good, so that is why I was wondering if anyone has had experience with a decent wireless audio setup.
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Richard,

You might get away with this if you use shielded audio cable and a audio DA (distribution amplifier).

here are a few links that might point you in the right direction.

http://www.bhphotovideo.com/c/shop/5193/Distribution_Amplifiers_Audio_Distribution_Amplifiers_DA_S_.html#

http://www.extron.com/product/listbytype.aspx?subtype=109

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Guest wbottomley

Richard... I'm in agreement with Greg.

Take the low-level output from the director card, connect it to a DA, then run it to the pa system's line in port.

Sending line-level audio that huge of a distance is a plus compared to a mic level audio.

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I was going to suggest using cat5 and baluns ... but you already found them.

I think those would work great. I've heard from other members that they even used the cat5 + baluns to run the pc sound up to the attic via cat5, then the final balun with to 1/8" headphone jack and they put the transmitter up in the attic to keep the antenna cable short and makes for a way better signal that way for the transmitter, vs. running 100' of RG8 from the transmitter, plus many homes have cat5 in it already.

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Greg wrote:

Richard,

You might get away with this if you use shielded audio cable and a audio DA (distribution amplifier).

here are a few links that might point you in the right direction.

http://www.bhphotovideo.com/c/shop/5193/Distribution_Amplifiers_Audio_Distribution_Amplifiers_DA_S_.html#

http://www.extron.com/product/listbytype.aspx?subtype=109




Greg, Mountain, Donald. This all makes great sense, and is something I did not think about. Thanks for the suggestions. I'm going to check that out. This is probably the right way to go.
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An easy wireless solution is to adapt a wireless lavaliere system. I do this frequently when I need to run sound that would be difficult to hard wire. 300' is going to be tuff without a high end unit. You could also use good ol XLR cable.

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taybrynn wrote:

I was going to suggest using cat5 and baluns ... but you already found them.

I think those would work great. I've heard from other members that they even used the cat5 + baluns to run the pc sound up to the attic via cat5, then the final balun with to 1/8" headphone jack and they put the transmitter up in the attic to keep the antenna cable short and makes for a way better signal that way for the transmitter, vs. running 100' of RG8 from the transmitter, plus many homes have cat5 in it already.

Folks, there are a lot of fabulous suggestions you are making. I knew I could depend on you guys for some smart solutions. That's one of the great things about this boardl... lots of smart, helpful people on here.

I'm really nervous about wireless issues, so these wired solutions look good. I'm going to experiment with Donald's suggestion because it is a LOT less expensive. For $90, it appears to be a good solution and I'm seeing other audio boards recommend similar cat 5 products. I can probably also get away without needing a balun because I don't think there will be any impedance matching issues or similar conversion problems.

I'm familiar with the independent distribution amps from the music industry. I ruled that out because they are much more expensive, but where the cost really jumps is by using xlr or shielded cable over that long a distance. Cat5 is much cheaper. In the music business the solutions are greatly different (and much more expensive), so I couldn't go that route. Nice idea though.

I'll come back in a couple weeks and let you know if this cat5 thing works or if I am still in audio hell ;-) Again, thanks for the clues. I never thought about that solution. And Taybrynn... that is a great solution for running audio up to a transmitter. You got me thinking about using this solution for my own home where I can put the transmitter, antenna, and a short cable up in the attic.
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What if you removed the MP3 Director module from the 1602 and placed it near the PA system? Looking at the data sheet, it looks like it is easily removed. Assuming it has the same capabilities as the USB485 for transmitting the RS485 signals the 300 feet should not be a problem. Then all you need to do is get a wall wart power supply for the MP3 Director card and run a Cat-5 cable from the MP3 Director/PA location to your first controller.



edit: spelling

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I'm right in the middle of a test, from which I plan to write an article. Here's what I've done so far:

I bought a 3W audio amplifier.

I attached the outputs (4Ω) to the 4Ω side of two transformers I got from eBay.

I connected the 600Ω sides to unused pairs in the CAT5 cable used for my LOR network.

Out in the yard, near the LOR controllers, I put another two transformers in boxes to shield them from rain, connected the 600Ω side of each to the CAT5 pair, and the 8Ω side to an outdoor speaker: alarmshoppe.com/p709.htm

I haven't tested this yet. I'll let you know.

Another test I'm doing is to use the TDA7052 low-power audio amplifier chip, which I will power from the accessory power output from a LOR controller! Preliminary tests with the outdoor speaker mentioned above have been very successful. Again, I will let you know more later.

My plan here is to have several speakers outside, without running any additional cables, other than the existing CAT5 cables used for the LOR network. The volume will be enough for pedestrians to easily hear, but not too loud that it bothers the neighbors.

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I was thinking of possibly doing something simple ... like putting a small (cheap) radio out under my sidewalk (have a diamond plate grate with concrete drain to curb under ... and 1/2" rebar to safety fasten to. Then attach a cheap pair of PC speakers (from the computer junkyard I have) to the portable radio ... and then turn it on/off with an X10 channel. I'd probably need to waterproof the radio into something ... but the speaker could fit under the sidewalk and aim out into the street. I'd keep it really low.

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Bob VandenBoom wrote:

What if you removed the MP3 Director module from the 1602 and placed it near the PA system? .......

Bob, that sounds like another clever solution, but in this case, it is a commercial installation and the equipment belongs to someone else. I wouldn't want to run a risk of voiding the warranty by modifying the equipment in any any. If it were my own equipment, I might consider something like that. Adding on other goodies will be simpler for them.
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Might be worth a call or e-mail to Dan to see if it would void the warranty. I have the stand alone Showtime MP3 Director card and it looks identical to the one in the 1602. I'm guessing the only thing connecting the two is a few bolts and the Cat-5 cable. The only cost involved is for a power source for the stand alone MP3 Director since it will be more than 50' from the controller. You are going to run a cable from the PA to the controller no matter what you do.



edit: spelling - I am not a good keyboarder....is that a word?

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