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 79camper
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 posted on May 16th, 2003 at 11:59 AM |
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stereo - 400 watt amp.. can i just wack it in..
hows it going.. i'm not very electrically or mechanically minded but i was given an oldish 400 watt amp and was wondering weather it will be ok
just to wack in or how much juice is it going to drain... can the alternator handle that.... i've heard that there is some kind of invertor (sp?)
or something like that...
..anyways... if you have some advice that would be great.. thanks very much...
..oh.. and with amps.. do you have to run a seperate power line to the battery or can you just supply power from any power line...
..thanks.. and sorry if i come accross a bit stupid with this stuff.. i'm trying to learn.. reading this forum is like the bible of undiscovered
knowledge..
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Purple Martin
A.k.a.: Martin
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| posted on May 16th, 2003 at 01:20 PM |
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Well, with amps... a big current (lots of amps) can very quickly melt a small wire and make it catch fire, and then your camper burns to the ground.
Not very nice.
Most stereos have two power supplies: a supply that needs a big fat wire coming straight from the battery (with a heavy duty in-line fuse in it: the
fuse is essential to prevent fires in the case of an accidental short-circuit), and a small supply that comes from the ignition circuit.
The way it works is that the small supply from the ignition supplies the on/off switch on the stereo. Whe the stereo is on, it draws a big current
through the big fat wire from the battery.
If you want to know what size wire you need for a given current, just go to your nearest electical store (Jaycar or Dick Smith are good) and ask the
assisstant to pick the right wire for you.
The formula for working out how many amps are being used is:
V x A = W.
Your battery is 12V, your amplifier is 400W, so the formula looks like this:
12 x ? = 400.
Therefore your amplifier will draw 33 amps.
It's sensible to use a slightly bigger fuse and an even bigger wire, so use a 40A fuse and big fat wire that will cope with 50A.
[Edited on 16-5-2003 by Purple Martin]
1959 red & white Beetle
1975 Kombi camper
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blownKombi
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| posted on May 16th, 2003 at 05:39 PM |
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i'll be fine
i run a 300 watt amp. I use it all the time and it hides under my back seat. close to starter just one hole and a short fat wire. I take my kombi to
the drive ins alot and leave the sterio running and with a good battery i've never had an issue. Mind you i only bought the battery a year ago
and it cost $90, but its never let me down, any other sterio q's just msg me
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70AutoStik
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| posted on May 16th, 2003 at 10:49 PM |
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Actually, the 400W is the output - if you were to use it at it's rated output, you will draw more like 40-50 amps. Fortunately, the sound
pressures inside would quickly destroy your ears, so you probably wouldn't run it long enough to flatten the battery.  At less damaging levels, you could probably use it for a while, but it
might cause distortion on tough pieces like the 1812 Overture...
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jboy82
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| posted on May 17th, 2003 at 10:33 AM |
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fTQ9n8tR
Just use the fat 6mm wires(cant remember the gauge) u can find at any electro store. They should be sufficient from the battery to the amp and dont
cost very much, stay away from amp hookup kits in car stereo shops, they cost shyteloads and they use the same materials.
Cheers.
Josh
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Quickbug
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| posted on May 17th, 2003 at 12:15 PM |
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Jezuz dont run a wire from your ignition for the on off power!!
You can put the amp straight in just fine.
I have a 1200w amp running off the gnerator in my bug.
You basically have 3 power wires.
One is the positive power.
This will need to be 4G or 8G pwer cable. Place an inline fuse as close as possible to the connection to the positive side of your battery. This runs
the the positive terminal on your amp.
Then you need a ground wire - make sure it is the same size as your positive wire!!
This goes from the negative or ground terminal on your amp.
Affix the other end with a ring terminal or similar to a good clean ground point, a metal part of the car that you can bolt or screw the terminal down
nice and secure.
Then there is the on off wire.
This can be a smaller wire, and needs to go from your stereo head units 'amp on off wire'. If yours does not have this wire then you need to
either wire it to the battery with a switch in your dash - so you can turn it on when you are going to turn your stereo on, or buy a new head unit! Do
not hook it directly to power as your amp will stay on all the time and youll come out to a flat battery in the morning!!
Then you need RCA cables to run from the RCA outs on your head unit to the RCA ins on your amp.
If there are no RCAs on one or the other, then you will have a small clip with some speaker wires. Basically you run speaker wires off the speaker
outs on your headunit to this clip which clips into your amp. A very old and not very good way to hook up an amp. Very few amps around these days dont
have RCA outs - same for headunits.
Make sure you try to run the power cables and RCAs or speaker wires down oppisite sides of the car so as to minimise static and background noise.
The hook up your speakers from the speaker terminals on your amp, paying attn to connect + to + and - to - .
Then turn the gain on the amp down lowish, turn your stereo on, and adjust the gain and any treble or bass settings to the sound and volume you
like.
Its not as bad as that sounds, but if your arent sure then get someone else that knows what they are doing to do it for you.
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 kombi_kid
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Good Kid too many projects
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| posted on May 17th, 2003 at 02:56 PM |
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hey
just dont sit somewhere with ur fluro's on ur cooker going and ur stereo otherwise u will get a flat or theres an alternative of just having a
dual battery setup
cheers
rhys
it aint just cool its aircool'd
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KOM123
Custom Title Time!
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| posted on May 17th, 2003 at 03:13 PM |
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I posted what I had done in an olld thread ( http://www.aussieveedubbers.com/forum/viewthread.php?tid=1378 ) which may give you some pointers or tips.
Hope it all goes well, feel free to contact me with any questions 
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