Help with audio cable/installation

ric_sull

Hi all, i am currently installing 26 inch TV'S on a wall facing patients in a 3 bed ward in new hospital. We have been asked to provide the TV sound at the bedside using headphones/headsets.

As I see it we would plug in a 3.5mm jack/jumper cable into the TV headphone outlet and plug the other end into a 3.5mm jack socket on the tv aerial cable outlet box. In conduit run a ?????????? cable, length approx 8 mtrs to an outlet plate with a 3.5mm jack at the patients bedside. To listen to the TV audio turn on TV with the RCM and plug in headset/headphones at bedside.

My queries are as follows:

1.What spec should I use for audio cable from tv to bedside?

2. If this is a screened cable where should I ground the screen?

3. How would I adjust the audio level without using the tv remote ? in other words if the nurse turns on the tv with a certain sound level and then for the patient to adjust the sound level themselves...there are headsets with a vol control on the lead but have you ever seen outlet plates with a 3.5mm jack socket c/w a volume control knob? maybe one could be made? but i would not know what value of resistors/ potentiometer to use?

Mods if this isnt in the correct forum feel free to move it

madtheory

You need two core screened cable. The screen is connected to the barrel of the jack plug, that's the tallest tag in the plug. The same tag usually has a clamp that you squeeze onto the cable for strain relief.

You could supply headphones with built in level controls. Take a look at the Canford catalogue, I would imagine they'd have them. They're usually expensive, but reliable. They might even have a wallbox to do exactly what you need. They're a good source for audio installation cable, as are Studiospares.

If you're going DIY: I don't know of any TV set that allows remote control of headphone level. So you'll need stereo "log" a.ka. "audio taper" pots built into the box by the bed. 2kohm is a typical value for this application, but that depends on what power the TV's headphone amp is putting out. So you'd have to run some tests.

PaulBrewer

PMed !