basic electronic questions

[dajoebomb]

HI there again,

I was just wondering about fuses and wires. I have a 400 watt amp being delievered and i just need to buy the wiring kit. What Rating for the wires would you suggest?? Ive found some on ebay that say that a 10awg power wire is good enough, is this right?? also i was wondering what rating fuse to use.

Using my phyiscs A level knowledge, P = VI, so I = P/V = 400/12 = 33.3

So would it be ok to use a 30 amp fuse or would i need a 35 amp fuse?? (if there is such a thing??)

Thanks very much for any help!

Joe

 

[chaos]

Is 400W RMS or peak? I would use 8 gauge cable.

 

[The Negotiator]

Aslong as you did the maths correctly above and it seems you did do, (also depending on RMW or peak, I assume you need to use peak for this), you always need to chose the next fuse rating up. If you chose lower it will blow constantly. If 35 doesn't exist, go for 40 etc.

 

[dajoebomb]

yer its 400 watt peak. 2 x 100 rms at 2 ohms

Whats the difference between 10 gauge and 8 gauge?? what does it actaully mean?? thanks again!

 

[The Negotiator]

Probably good to have a read of Luke's excellent guide on this matter;

https://www.fiatforum.com/showthread.php?t=26935

 

[dajoebomb]

thanks very much, a real big help!!!! thank you!!!

 

[dajoebomb]

actually i have one more question on this issue, if the Amplifier has a 30Amp fuse in, would it be ok to use a 30 amp fuse in the wire from the battery???

 

[poggy]

I think you may be getting confused with the wattage, the 400W I presume is the amp output. This doesn't mean the input is 400W at 12V, you don't normally feed speakers at 12V line level.

What you need to find out is the power consumption of the amp at max output and rate the fuse for that. It should be on the amp somewhere.

If you using it over 10ft you will probably need 4 gauge wire for the power.

 

[Neo-The Matrix]

Yes, if the amp has an internal 30amp fuse you still MUST put a 30amp fuse at the battery (cause if u have a short between the batt and the amp the fuse at the batt will save your amp). Remember, the fuse must be as close to the batt as possible.

If it blows the batt fuse get a 40 AMP, what brand is your amp anyway?

 

[arseofbox]

Branding isnt the issue....a good name wont necessarily protect it from melting due to over-current! But most amps have overload (and often reverse polarity) protection anyway...

Id try 35A over 40A tbh...5A is a lot of additional current to handle

Can I ask a silly question?..

What level is an amp pre- out..eg:RCA lead low level connection. I think my manual says 1v (peak to peak), but I cant measure anything from it! (It works fine on the amp!)

Cos if its 1A, I'll put in a preamp stage and make it variable to 4v....

 

[dajoebomb]

its a legacy la360, its a very low model, but i cant afford anything else at this point, i paid 1,500 for my punto, been saving for over a year for it (9 hours a week in safeways), so i didnt have much/any money left over.

http://www.legacycaraudio.com/itempage.asp?model=LA360

Amp hasnt actually arrived yet, should get it on tuesday hopefully, ill find out what u wanted then, although i have been on the web site and downloaded the .pdf cant find anything about that on it, but might not be looking at the sam thing im supposed to be.

Thanks again!

 

[poggy]

The maximum current draw on the LA360 is 15A, so you should use a 15A fuse which should be plenty.

 

[dajoebomb]

oh cool, thank you.

So using the table

https://www.fiatforum.com/gallery/data/581/7848guagechart.jpg

I should be alright with a 10 gauge wire, using about 4 meteres (13 feet).

Just doing a check before i buy a wiring kit off ebay!

Thank you again!