sub/amp not working!

[.:O4AGTZ:.]

well its a 1200w sub run by a 1000w amp. i put them in a few hours ago and did all the settings rite on the amp and ran all the cables etc and tested them all to see they had something running thru them. when i tested the voltage on the positive and negative before the amp it was at 12v, but when i put them into the amp and tested the terminals they were put into it only read about 7v! only thing i can think of is that the cable from the battery is too small. i used some 8g cable i had to do it but im pretty sure i shud be using something like a 3g? can anyone back this up? all the fuses are good also btw

cheers

[pjay]

4 gauge cable at the minimum.

make sure your ground is well sanded to bare metal as well. ground cable should be the same size if not larger than your power cable. Also what size fuse do you have between the amp and the battery?

[Alex B]

What do they read with the car going? And i take it this is 1000W peak, what is the amp in RMS?

[themaleman]

8 gauge should b sweet

if the fusses arnt blowen there sweet

check ur battry connection, if u have power at one end of the cable and not the other then id sudgest the cable is the problem (and not the diametre of it)

[.:O4AGTZ:.]

its 2 channel and im bridgin it and th rms is 400. i red some specs that told me i shud use 4g so im pretty sure tht is th problem

[Alex B]

You dont loose half your voltage over 5M. As above has said it sounds like a bad earth, what is it earthed to??

[themaleman]

as an example, i was running my 1200watt amp at capacity on 8gauge wire and it went hard. 2 check if the cable is at fault, unhook it from the amp and test it. (u said before that you tested them when they were hooked up to the amp). if its still reading only 7volts then theres a problem with ya cable, but most likely your connection to the battery.

once you've tested the unhooked cables and u find they give u a normal voltage that leaves the amp 2 be questioned

[.:O4AGTZ:.]

its earthed to one of the bolts in the boot so just attached to th chassis. wen i test the power cables i get 12v on the end, but then i attach them to the terminals on the amp and test the voltage accross the terminals and get like 7ish. oh and the amp has 2 lights on it, once is the power light and th other says PROT (im guessin protection? but it didnt say in the manual either) they kinda go on and off randomly.

[DriftMonkey]

Really sounds like an earthing problem to me. Make sure the area around your earth is sanded to bare metal (once earthed you can spray some rust protectant over it all to seal it) and that the bolt does infact go to the chassis.

Try some other bolts as earths around your boot, and see what happens.

It's also better to have too much than too little when it comes to wiring, so when you get a few spare $$ go and get a 4 Guage wiring kit. Saying an amp "goes hard" on 8 guage doesn't cut it, and in almost every case there will be a dB gain from using 4 guage over 8 guage (especially on a 400wrms amp).

[postfach]

yeah had a similar problem when wiring in an amp with my mate, moved the earth and it was fine, the earth we initially used tested fine with a multimeter but in practice it wasn't good enough

[mr30%jr]

if your gunna bolt it to the chassis (your earth) make sure you rough up the paint so you can see bare metal

[.:O4AGTZ:.]

ok ill give the earthing a try. wen i got the car it had a wire for the earth still in it from the previous owner so im not sure how they managed to run an amp if i cant?

[Dr J]

im going to jump on the band wagon here and disagree. it will be that your power cable is 2 thin there is no way that you could run a 1200w amp on full with 8 gauge cable. if you do manage to get it running as soon as you hit some decent bass it will cut out.

good luck

[Alex B]

It wont be 1200w RMS for one and it wont be down to 7 odd volts at the other end of the cable from using 8G.

[themaleman]

for all you disbelivers out there, i can show u a 1200watt(peak) amp going hard on 8g cable

[Bling]

huge difference between 1200W peak and 1200W continuous (rms) tho

[Alex B]

Yeah about 1150WRMS

[themaleman]

no 1 said nething bout 1200rms.

there is no way that you could run a 1200w amp on full with 8 gauge cable.

u wana put mony on that? thats 1 of the sillyst things ive herd

[Bling]

this thread is about finding the reason for the voltage drop.

1200w rms was mentioned above to explain that the amp is most likely NOT 1200w RMS, so 8g wire WOULD be sufficient, and THEREFORE the problem with losing power lies elsewere.




I'm sure you can show us a 1200w(peak) trademe? amp working off 8g, it would probably run off speaker wire