Wiring marine Audio / Visual

I have a 12 volt LCD television with a built in DVD player in it which I plan to use on my boat. to improve the sound quality and also allow me to use it to play audio (cd's) I want to hook the output from the tv to an amp and then a couple of speakers.
What I want to know is how to wire the thin up (in terms of power supply, I mean). The amp requires a fused (25 amp) power supply, which is simple enough, but it will be located in a locker, so I don't want to have to dive in there and turn in on every time I want to watch the tv or play a bit of music.
Th tv has its own 12v power supply of course, but I'd be hesitant about connecting it via the same 25 amp circuit breaker, or would that be ok?
Should the amp be turned off when not in use? And will it draw much power when not in use, but turned on?
As a rule, I don't generally turn my circuit breakers on and off every time I want to use things and I'd rather avoid doing so in this case

Any thoughts / suggestions?

 

There are ways around anything, what it really comes down to is how much effort and money you want to go into it. There are AMPs that will turn on when they sence an input. So taking a line from the TV Audio out and straight to the AMP should be suffice.

If you already have an AMP that doesn't do that, you can make/get a device that sits between the AMP and its power, and it taps into the audio line from the tv to the amp and when its sences a signal it will allow power to the amp there by turning it on. But some AMP's when they loose power and then get it back, they only go back to standby mode defeating this device.

In regards to connecting the TV power throught same fuse as the amp is possible, but some what frowned apond it is very dogy and not good practise.

And for those of you's out there that like to pull CCT breakers to turn things off should have their fingers chopped off, they are a safety device not a switch, they do have limited switching life so don't use them as one.

 

Thanks for the quick reply Dave.
The amp is a (new) Fusion FM-402, 2 channel amp, connected to 2 fusion speakers. Unfortunately the tv only has a headphone jack, so input will have to come from that. I know that's not as good as from proper output, but it will have to suffice.
I agree, circuit breakers are not switches - hence my desire to avoid having to use it as such. Similarly, I understand that it's not good practice to connect the tv to a power supply with such a big breaker.
So - what's the solution? Just accept that the amp is going to be powered up ( I don't know if it turnes itself on / off or not), I guess....

 

Ok, when you said AMP, i was thinking of a home stereo AMP. Car/marine have a remote line, normally you connect this line to the head unit of the car stereo and when the stereo turns on, it turns on the AMP, same deal will be here. All you need to do is provide 12 volts to this remote line on the amp and it will turn on, drop the 12 volts on the remote line and amp turns off.

Cheap option is to just have a on/off switch near the TV, when you turn it on, you can turn the amp on as well.

Another option is to get a device like this http://shop.voltelectronics.com.au/vox-relay-kit.html and modify so instead of a mic as in input, it gets it from the TV headphone jack.

You can use this http://www.jaycar.com.au/productView.asp?ID=KC5159&CATID=25&form=CAT&SUBCATID=557 to up your gain from the headphone jack on the tv to the input of the AMP

 

Ok - so I could have a switch that would turn on both tv and amp, with the single wire coming from the switch (in the +ve wire) to the REM connection? That would also eliminate the power drain from the tv when in standby mode.
The other sounds maybe a bit more elegant - but I'm into simplicity. Also, I'm definitely not electronics whiz! (just in case you hadn't already figured that out...)
Do I need to up the gain from the headphone jack? What happens if I don't?

 

No, quite the opposite. The output from the headphone jack will be considerably higher than a line level signal and could quite possibly overload the amp input if you turned the TV volume up high. This wouldn't do any damage but would sound horribly distorted as you max out the pre-amp stage of the amplifier. That amp is very tolerant of high inputs though, so you will probably be okay without any attenuation - just be judicious with the use of the TV volume control.

You may find that you can only use the first third of the TV's volume before making your ears bleed

Tony

 

Accually, there is a gain control on the AMP (well usually there is).

 

The spec states "Input Sensitivity 300mV-8V" so it should be fine.

 

yer, the only thing i'm worried about is the immpedance matching, but most equipment is made robust these days its not really an issue and unless you realy into fideality as most people can't hear the lack of it.

 

Impedance matching in this scenario is irrelevant. It'll be fine.