Gday

When I bought my car the guy said "Its got 4ga running to the amp" I thought that was good and didnt question it. Neways it turns out its only 8ga, and I have just bought a distribution block and 4ga wire to put a second amp in. My question is will the 8ga be enough to power a 100wrms amp and a 350wrms amp (not at full gain). The 350 has a 1fd capacitor and is wired with 4ga wire.
I dont really want to have to rewire the entire setup from the battery. Also is there any problem having the wire going from 8ga from the battery to 4ga to the amps from the dist block? (I wouldnt have usually done this but it was a mistake)

Thanx

[Battery]--------(8ga)---------[Dist block]===========(dual 4ga)=======[Amp 1&2]

With 350rms and 100rms I would honestly look at 4 gauge cabling as it would be drawing some serious current.

Yeah I thought as much. Is there any point in trying it out with just the 8ga to see if there are any problems?

Is it ok to run a second 8ga wire to the dist block to save $$$?

With 350rms and 100rms I would honestly look at 4 gauge cabling as it would be drawing some serious current.
As an apprentice sparky, I'm at a loss to explain the common belief that u need huge cables to run the average car stereo... espeacially when useing caps.
Its only around 32amps continuous (450w/14V= 32A) and from memory houseing wire only needs to be around 4-6mm sq for that, so TECHNICALY speaking, 8 Guage (unsure of mm sq) should SAFELY handle it (ie not set ur car on fire).

There would be no advantage to going 4G from the block, if u keep the 8G main cable, and yes, it is quite acceptable to run a SECOND cable in parrallel... NO real disadvantages except for looks, & ease of terminating, both at the battery & distribution block.

BTW in my Lancer i had 4G to distrib. & 8G to each of my 2 amps - 380rms & 400rms & it was fine. You only have about half that so :think:

I put the amps and subs in today with the 4ga wire. Working with 4ga wire to amps is a pain in the ass, Im going to redo all of it with 8ga because the 4ga it way too dodge (the ends wouldnt fit into the amp connectors properly). I'll leave all of the grounds as 4ga because they actually went in easy and Iv heard its better to have the grounds thicker than the input.

BTW I flattened out some 10mm copper tube and drilled holes in either end for the internal connections in the dist block, looks heaps better and was easier than stuffing around with wire.

I forgot to disconnect the battery (hits self in head!) and I need a new fuse, would it be a good idea to go for a switch instead?(the ones that cut off when there is an overload or short...cant remember the proper name...) To save getting new fuses when something goes wrong, and to make disconnecting the power to the amps easier.

would it be a good idea to go for a switch instead?(the ones that cut off when there is an overload or short...cant remember the proper name...)
Circuit breaker? I didn't know you could get those for cars, hmmm....that would be very handy!

Circuit breaker? I didn't know you could get those for cars, hmmm....that would be very handy!

My thoughts exactlly. Also with the parrallel 8ga wiring it will be perfactlly safe, but you may expirience inceased noise (interferance) :)

If you can't find any automotive circuit breakers (if they exist) tell me at what current loading you want them to trip and I'll have a look here at work for ones that might be suitable, we have **** loads laying around :D

yes - you can get these "circuit breakers" for cars - they are basically a re-usable fuse - normally run and set off the same as fuses - get one rated for 80 Amps or so when running your 4 gauge - as thats what you want - anything smaller and you may be tripping it constantly. but then again - thats wht i was running in my car ;)

and the smallest i have seen a fuse on a amp setup is 75amp (only cos it was the biggest we could get at the time)

For memory - i put one of those "circuit breakers" (i am sure they are called something else - but mental blank) in Dan's car - Cypher VR-X when installing his sub / amp combo as pictured below!

Manual

Yep circuit breaker, thats the name. I got one from Jaycar 75amp for $22. Works fine under full load and does trip with a short so it does the job. It makes disconnecting the power to the amps heaps easier...just push a button.

Another thing, how much power should be running to the amps when the engine is about 2000rpm??? Mine gets 14.5V+ with the amps off and about 13.9-14.2 with them at listening level. I know this level is good but I want to know if it is right for a 1990 TP Magna (I want to know if the alternator has been upgraded)? BTW I am taking the readings from the voltmeter on the dist block. Or an alternator part number would also do the trick.

a 8 Ga would be enough
but however a 4 ga would be plenty a stinger 4ga would be pushing 150 amps.
add up to how much amps you have and see.

Yep circuit breaker, thats the name. I got one from Jaycar 75amp for $22. Works fine under full load and does trip with a short so it does the job. It makes disconnecting the power to the amps heaps easier...just push a button.

Another thing, how much power should be running to the amps when the engine is about 2000rpm??? Mine gets 14.5V+ with the amps off and about 13.9-14.2 with them at listening level. I know this level is good but I want to know if it is right for a 1990 TP Magna (I want to know if the alternator has been upgraded)? BTW I am taking the readings from the voltmeter on the dist block. Or an alternator part number would also do the trick.

As I think I said earlier u should be drawing around 32A? 75A breaker is a bit of OVERKILL... the whole idea of it being there is to break the circuit in the event of OVER CURRENT.. not just short-circuit.

Useing a huge breaker on a smaller rated cable is false security.. if the cable is rated at say 50A, the breaker at 75A & the stezza is drawing 65A then ur likely to end up with either melted/damaged insulation or FIRE.

The fuse/breaker is there purely to protect the CABLE from getting too hot, so it is not wise to just go grab the biggest one you can find, cause it's really not a case of "If it don't blow/trip it's good!"... it may operate in a short-circuit situation, but in the case of overcurrent, it won't protect diddly-squat.. that is of course, until the insultion melts off completely & the wire BURNS it's way down to bare metal until makes a short & finally blows the fuse. :redface:

In your case espeacially.. you don't know if your cableing is up the job in the first place, it seems pretty silly.. if you're worried about haveing to replace fuses all the time just think.. fuses a pretty damned CHEAP when you compare them to replaceing the power cable, or even the hole CAR in the event of a fire. :shock:

BTW I'm not exagerating.. well much anyways. :)

As for the voltage.. sounds about right. The battery may be 12V, but the alternator should put out 14-14.5V? An upgraded alternator will have a higher CURRENT output, not higher Voltage.

K sorry for the babling... :confused:

Iv tested the system on high volume on a heap of Bass tests (45mins) and SkitzMix (1hr) and the power wire was only slightly warm (nowhere near dangerous), everything else was normal. I dont usually have all of the subs going at once for longer than a few minutes so I think Im pretty right with the whole wires heating up and car bursting into flames thing.

As for the alternator question...yeah I feel a bit dumb now, DUH CURRENT GOES UP DUH (hits self in head). Sorry about that stupid question, wont happen again...

Oh yeah both the amps have twin Overload and Overheat protection circuits so I feel a little safer.

I'll have to check the amp rating of the wire and see if its under 75...I'll make a trip down to Jaycar to let the guy know if it is.

Thanx for the help!

how do you connect 2 amps up do you just wire a power cable from the main amp and a ground and a remote all from the main amp and rca out cause im thinking of plugging my old amp in to power the back speakers 60wrms each and i have an mtx amp for my sub so is it just a short length of power ground and remote from the main amp to the second one

Iv tested the system on high volume on a heap of Bass tests (45mins) and SkitzMix (1hr) and the power wire was only slightly warm (nowhere near dangerous), everything else was normal. I dont usually have all of the subs going at once for longer than a few minutes so I think Im pretty right with the whole wires heating up and car bursting into flames thing.

Yeah I wasn't saying it WOULD be hot,or that it will even be a problem in YOUR car. But in the case that it did draw more current then the cable can handle, but not enuff to trip the breaker, it WILL get very hot. For that reason it is safest to go as close as possible, or even less then the cable is rated at. Good idea to go see what the cable is rated at though! :D


how do you connect 2 amps up do you just wire a power cable from the main amp and a ground and a remote all from the main amp and rca out cause im thinking of plugging my old amp in to power the back speakers 60wrms each and i have an mtx amp for my sub so is it just a short length of power ground and remote from the main amp to the second one
Yeah, it's pretty simple.
Just grab a distribution block (metal block with 1 big wire in & 2 out) for the main power, splitting it before the amps.

With the neutral, just have a seperate wire going direct to the body.

For the HU remote turn on, just loop from the 1st amp.

For the RCA inputs, just buy a pair of splitters, & brach out to each amp.
IT's easy as..