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Discussion Starter #1
not had the money to spend on car audio due to kids, house, wedding etc etc etc but found a load of my old kit (wires a sub and a couple of amps - my old install was no way on the scale of what i am planning) in the attic and i have the makings of about half an install i think.

This is what i have found/aquired so far.

Got a JL audio 12" sub (half decent don't know exact model or rms etc but its at least 250W rms)
some 90W RMS 17cm alpine comps/tweeters for the front
not bought any rear speakers yet, need 13cm, probably go for something in the 60-90w rms range dunno what yet
2x american pro 2 channel amps, each 130w rms per channel
small 2 channel generic piece of crap amp which will probably get replaced at some point but will be running the rear speakers for the time being, prob about 45w rms per channel. (hey it was free ! )
Need to pick up a power cap (probably a cheapie off ebay)

I also have a 6 dvd changer, alpine cva 1003r 6.5" flip out headunit and an 11" flip down screen in the back but these are not going to be run from the amp's power cable.

I know that a lot of this stuff is not top spec or competition level stuff but i want an install of okish quality without spending 3 grand (i am gonna try to stay sub £100 on what remaining stuff i need to buy)

This car is also my work / family car so needs to stay reasonably practical as far as boot space etc goes

I need to know the following 2 things.....


1.) What i am gonna need with regards to power cable and fuses etc.

total rms that i'll be running will not exceed 450w and i will definately not be wanting any more power from the system in future

what fuse size will i need at the battery (amps are already individually fused with spade fuses) and what gauge wire will I need - will 8 gauge cut it for the main feed or is this one definately a 4 gauge job?

2.) As i need the boot space reasonably useful i was going to stick bullet connectors on the sub speaker cables so i can remove the box easily if i want to for lugging stuff - will this cause any major issues?

Also i want to build the amps into compartments in the sides of the boot one in each side, one with an amp and power cap and one with 2 amps in it (MDF frame with perspex windows to see the amps through)

I am a computer techy so can get my hands on 100's of 90cm 12v fans (or bigger) if i stick about 4 fans in each side of the boot will that keep everything cool or is this just a totally dumb ass idea.

Thanks guys and sorry for the stupid questions

Russ
 

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hi
any good store that sells cables will give you an idea of what you need for your power needs
if you do the maths you need 37.5a cable @ 450w so it up to you how much bigger you go and you always fuse more you dont run the fuse at peak amps ,
removing the sub is fine as long as you disconnect the power to the amp that powers it (eg isolate the remote with an independent switch when sub is out)
the fans are good in theory but may cause interference with the amps its been known to happen depending on your fans of course.
 

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hey russ
if it was me with the kit you have i would do the following:

Put your alpine components up front. mounted well with fully deadened doors run off one of the 130wrms x 2 amps.
Put your JL W0 12 (my guess from the power rating) in a small sealed box, 1-1.5cft should be fine and run that off the other amp. If you bridge the 2 channels it should show more than 250wrms @ 4ohm. Is the sub a 4ohm sub?

Wiring, i'd go for 4awg. Its not too big, 8awg is a bit small really. If you get a wiring kit they normally come with a fuse for the under bonnet fuse. i'd guess about 60amp

Dont bother with a power cap, they are using in SQ installs to smooth the power flow but are usless in all other car audio aplications ;)

Your idea for the build seems pretty good and 2 fans each side should be fine imo (they will also be pretty noisy if you have 8 back there lol)
You want the sub box secure but easy to remove so maybe a small section of false floor at the back of the boot by the rear seats,make the box sloped so it can sit against the seats and screw to the false floor so to remove just unscrew it and disconnect the speaker cables (if you just disconnect them at the sub box end cover them up as if the + and - touch bad things will happen lol )

hope this helps
 

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Discussion Starter #4
Cheers

interference should be ok on the fans i think, I've seen them used before I am sure, if not i'll just sod the perspex windows and just recess the amps instead and hide the wires

I wanted to grab some pretty cable off ebay as there will be a power cap on view in the install so could do with knowing whats needed before i go shopping

Anyone?

Edit:

ryan. said:
hey russ
if it was me with the kit you have i would do the following:

Put your alpine components up front. mounted well with fully deadened doors run off one of the 130wrms x 2 amps.
Put your JL W0 12 (my guess from the power rating) in a small sealed box, 1-1.5cft should be fine and run that off the other amp. If you bridge the 2 channels it should show more than 250wrms @ 4ohm. Is the sub a 4ohm sub?

Wiring, i'd go for 4awg. Its not too big, 8awg is a bit small really. If you get a wiring kit they normally come with a fuse for the under bonnet fuse. i'd guess about 60amp

Dont bother with a power cap, they are using in SQ installs to smooth the power flow but are usless in all other car audio aplications ;)

Your idea for the build seems pretty good and 2 fans each side should be fine imo (they will also be pretty noisy if you have 8 back there lol)
You want the sub box secure but easy to remove so maybe a small section of false floor at the back of the boot by the rear seats,make the box sloped so it can sit against the seats and screw to the false floor so to remove just unscrew it and disconnect the speaker cables (if you just disconnect them at the sub box end cover them up as if the + and - touch bad things will happen lol )

hope this helps
lol cheers I'll grab some 4 gauge then

The sub is already in a box, i was gonna stick big strips of industrial velcro on the sub box and the boot floor and lie the box down so it won't topple over

reason i was gonna use bullet connectors for the sub was i can put the female half of the connector on the amp side and it will be sheilded by a rubber cover in case i forgot to turn it off but yeah i was gonna stick a kill switch in for it.

Power cap was to stop from killing the alternator / battery when running the system at full chat - i'd rather have it in there as a safe guard. was only gonna spend about 25 quid on one from ebay anyway

thanks for the help

Russ
 

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Discussion Starter #6
paul20v said:
you will stuff the amp if you leave it running without a speaker so make sure you put a switch on and use it :D

ah didn't know that.

i think the best thing to do is use a kettle lead style mains adaptor from work and use what would be the live and neutral mains for the speaker wires and then run a remote wire for the amp through what would be the earth pin normally so soon as i unplug the sub the amp is instantly killed off

like one of these style connectors



i can cut it in half and it will all look nicely moulded as well then :)
 

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sonic_vi said:
Power cap was to stop from killing the alternator / battery when running the system at full chat - i'd rather have it in there as a safe guard. was only gonna spend about 25 quid on one from eBay anyway

thanks for the help

Russ
a power cap wont do that. It sits there stealing current and then dumps it all when lots of power is needed then carries on stealing it.
The power you have you shouldnt need to worry about power caps etc My alternator is fine and i dont run one, my system is 3300wrms

Running the amp for long periods of time with out a load on it could damage the amp so maybe put a switch in or just unplug the remote cable when you take the sub out
 

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ryan. said:
[quote="sonic_vi":1kbfva4q]Power cap was to stop from killing the alternator / battery when running the system at full chat - i'd rather have it in there as a safe guard. was only gonna spend about 25 quid on one from eBay anyway

thanks for the help

Russ
a power cap wont do that. It sits there stealing current and then dumps it all when lots of power is needed then carries on stealing it.
The power you have you shouldnt need to worry about power caps etc My alternator is fine and i dont run one, my system is 3300wrms[/quote:1kbfva4q]a power cap reinforces the bass lines by storing power for heavy notes that require high bursts of power,
they charge nearly instantly they dont steal that much power for long ,
but i must be honest i also have never used any but my mate swears by them and his system sounds really good too .
 

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but if your system is low on power by having a small bettery how is taking power and storing it going to help the already restricted power supply?

for the power the op says he will use a power cap will have no affect at all, i very much doubt the voltage will drop much below 12.5v when boming with the engine running
 

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Discussion Starter #11
ok cool i'll see how it runs without one then, it'll save me a bit of £££

as for the breakaway i'll need to either use 2 of those connectors or find something in 4 pin

If i don't i'll need to run the remote wire from the sub side of the break point and that will stop if being able to be taken out of the boot as it will be attached by the remote wire

Simple diagram below for what i am thinking

I have tons of these cables at work so i'll just use 2 of them while its gonna be an install on a shoe string

 

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why not just get a switch and put it in the remote for the sub amp so at the flick of a switch the amp turns off?
 

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Discussion Starter #13
ryan. said:
why not just get a switch and put it in the remote for the sub amp so at the flick of a switch the amp turns off?

Because i am stupid and forgetful lol

this way it physically stops me walking away with the amp leaving the amp switched on

Edit:

might need to stick them opposite ways round though i.e. have the pins exposed for the amp + & - and the pins isolated on the remote wire amp side

othewise with me being so stupid i could inadvertantly hook up the remote wires to the amp + & - and the other way around although i guess that would not actually do any damage unless i am wrong? could always run the live part of the remote circuit throug the earth pin at the top and not use it for anything else :idea:
 

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ryan. said:
but if your system is low on power by having a small bettery how is taking power and storing it going to help the already restricted power supply?

for the power the op says he will use a power cap will have no affect at all, i very much doubt the voltage will drop much below 12.5v when boming with the engine running
if your system is that low on power you shouldnt be doing it ,and the cap doesnt take that much power .
at the end of the day if the engines running the battery has nothing todo with it the alternator does all the work ,thats what there for the battery is only for starting a car .
 

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sonic_vi said:
othewise with me being so stupid i could inadvertantly hook up the remote wires to the amp + & - and the other way around although i guess that would not actually do any damage unless i am wrong? could always run the live part of the remote circuit throug the earth pin at the top and not use it for anything else :idea:
if you did connect them the wrong way round you would be very lucky not to see lots of smoke and a dead amp
 

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Discussion Starter #16
lol BOOM !

yeah don't wanna do that

i think what i will do is have what would be the earth set as - on the speaker wire and the amp side of the remote wire and have the left pin as the + speaker wire on one and the right pin as headunit + side of the remote wire on the other

that way no circuit can possibly complete if plugged in the wrong way and i'll be safe (ish)

Cheers for your help on this one guys really appreciate it.

Also was wondering what minimum RMS means?

i take it that you can have the speakers operating at a whisper if you want and you don't need to run at the minimum RMS value (i.e. 35w RMS for the ones i am looking at) as i don't like to have my ears bleeding all the time !
 

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minimum and max rms confuses so many people, i dont see why companies can put just 1 rms rating.
Basically you can put 1wrms on the speaker is you like, it wont hurt it but it wont be loud. The only time people damage speaker when under powering them is because they try to compensate for it by using the gain as a volume controll and turning it up. This sends a bad signal to the speakers and they die.
your 130wrms amp is fine for the 90wrms speakers
 

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Discussion Starter #19
ryan. said:
minimum and max rms confuses so many people, i dont see why companies can put just 1 rms rating.
Basically you can put 1wrms on the speaker is you like, it wont hurt it but it wont be loud. The only time people damage speaker when under powering them is because they try to compensate for it by using the gain as a volume controll and turning it up. This sends a bad signal to the speakers and they die.
your 130wrms amp is fine for the 90wrms speakers
Cheers Ryan

Found that out by a mixture of googling and one of the guys over on talkaudio

Nice one for all your help guys

I'll post pics when its in :)
 
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