Need some expert advice on options to finish up new system.

[Databyter 10+ year member]

In order to help me I'd better tell you what I already have and what I'm doing because I know it will be asked.

I have, or have on the way, the following.

On the way my new head-unit a pioneer DEH 7200HD

In the Car I have 2 Front 2 way speakers and 2 rear 2 way speakers (I have a station wagon). All four are Alpine sps-600's (80 RMS 250 Peak), way in the back a single JL Audio 10" PowerWedge W3v3 Sealed Enclosure (100-500 Watts RMS).

I have a JL Audio 4 channel amp (80 watts per @ 4 Ohms), and plan to get another amp to power the sub when I can afford it (although until I do get it I plan to bridge 2 channels on the 4 channel and just leave out the rear speakers for a while).

I plan to eventually get a Large deep cycle batt so I can play music with the engine off and still get home with the starting battery. I'll be using an isolator.

I've ran a fused 4 Ga. cable from the Batt to the rear cargo area (where I plan to make a small component rack).

Ok so here's where I'm unsure of myself, and where I don't want to be nit picky and waste additional money or redo some of my wiring unless it's necesary.

Question 1.)

Both of the Amps I plan to eventually get BOTH say they REQUIRE 4 Ga. supply leads from Batt.

If I add all my max RMS power requirements for 4 speakers and the sub together I'll be at (80 X 4 plus lets say 350) for 670 RMS watts total. So,... is one single 4 Ga. Cable ran through a dist. block adequate for this? I don't plan to have the system cranked up all that much most of the time, but want to have that capability when the time and place is right. I'm hoping the 4 Ga. requirement on both still gives me some overlapping headroom over the very thin 8 Ga. I don't relish the thought of tearing off all the moulding and kickplates to run 2 Ga. toa block if the 4 Ga. is enough for my lil system.

Question 1a.)

If the Ga. is too small I guess the result is less current. Is the result simply loss of performance, or can you damage your amp circuitry if they are starved on one end?

Question 2.) Rather than having the deep cycle in the engine compartment as I first thought, I was thinking of having it back in the cargo compartment with the amps., fed from the alternator by the 4 Ga. wire I've already run, that way I wouldn't have to upgrade the batt. to amp gauge (assuming you guys tell me I need to) Also I figure this would reduce the length from the batt. to the amps making Question number one sort of less important. I wouldn't sweat a 4 Ga. run from an aux batt if it was only a few feet.

Question 2a.)

One problem I thought of as I wrote this though is that if I ran an alternator lead through the whole car to the cargo area, wouldn't I be asking for alternator whine right where I don't want it? Or is alternator whine just from the generator itself, and not so much from the charging leads?

Question 2a.) I like deep cycles because they have a lot of juice, can be ran down and re-charged alot without much damage. But I don't see them much on audio forums, I'm supposing this is because they possibly don't have the instant draw performance of some of the other types, but, for my average needs, which will mostly be at moderate levels ( I'll want to crank it now and then though) isn't it good enough? I saw some recommended batts for audio systems that I think were jell or glass pack types, but they were around 300 bucks. If I run em down alot I'd hate to spend that kind of money a year from now to replace it. I'm not running 3K watts or competing. Isn;t a deep cycle enough for my moderate system?

Thanks in advance. I'll try to edit this to make it shorter and clearer.

Click to read more...

 

[Databyter 10+ year member]

cough..

 

[bugflipper 10+ year member]

4 ga is plenty for the two amps. I run 4 for up to 1000 watts. As for a charging system just realize not as many amps can be delivered to the battery. So it will be slower to charge off the alt. Personally I run 1/0 to batteries in the back. May be overkill but that is a long distance for smaller gauge. If you have the room under the hood it would be better for 1/0 to starting bat then 1/0 iso to system bat. And 4 that you alread run for dist. The bats would benefit from 1/0 over 4.

The positive wires act as antennas they carry the sound of the alt. Shielded rca kept away is best. I generally run power on one side and low level on the other. Every vehicle I have runs a blue top optima boat battery. Never had an issue. Most of them have upgraded alts as well.

 

[Databyter 10+ year member]

Thanks for your response, I was thinking the 4 Ga. would probably be enough for the two amps.

Regarding the batteries, I'm still up in the air on whether to put it under the hood and use the 4Ga. to power the amps from it, or to use the 4Ga. to wire from the battery isolator (alternator load switcher) to the battery in the back cargo area. There won't be much charging required on the starter batt., so I expect I'd be pretty much trickling the aux batt all the time no matter where I put it. The advantage of putting it in the back would be more efficient power to the amps when I need it, and CLEAN efficient power especially when the car is off. I'll take a look at the Blue Top Optima. I hope it's a budget minded device =).

EDIT: Wow, thanks for the info on the battery. I think I'm sold. I didn't realize the lead acid tech had improved so much.

http://www.1st-optima-batteries.com/?gclid=CPr626yVqKECFRFcbQode1CwEA

This is better than a standard gel with it's low resistance, fast charge and discharge and low self discharge.

A win win, and in a pinch I won't have to worry about off gassing in my passenger compartment.

 

[Databyter 10+ year member]

Now I'm wondering about something else.,,

If I am powering my head unit with the starter battery and the amps with the deep cycle in back,.. any noise issues. I realize the common ground will make it all work, but, separate power sources...

In my initial thoughts, I think it's unusual, but I don't see any issues, in fact I could make an argument that it could decrease low level noise. It's too much work to power the HU with the rear cargo batt. so I was assuming I'd just use stock factory power harness to get my signal, and run rear power for the amp section.