system install & questions

[mikeybonez1]

i've been looking into adding a system to my astro and had a few questions along the way. now i'm not a complete noob when it comes to working on cars but i haven't dived into the electronics too much so it's unfamiliar waters and I could use a little guidance.

My current head unit is a Dual XHD6420 that has one set of preamp inputs and is rated for 17w x 4 RMS and 50w x 4 max. with the number of pre-amp inputs I can only run a dual channel amp for either subs or L/R speakers correct? Or should i lay down some extra $$ and buy a head with three sets to run a 4 channel speaker amp & a sub amp?

Second question is, will a stock alternator (105amp) keep up with a 240w max 2 channel amp pushing dual 8" subs?

Third and final question of this post is, when running the amp cable from the battery to the amp, is it possible to wire in a cut off switch so that I can disable the amp when the ignition is in the accessory position to avoid battery drain?

I know i'm asking alot in one post but any help would be greatly appreciated

[JaxSPL]

First question answer: The RCA outputs (not inputs), if I remember correctly, if for rear speakers or subs. You can run more by using a crossover that has bass, mid, and highs on the output side, but only one set of RCA inputs. They are usually pretty cheap. Hell, I might have one laying around that has never been installed. I'll check.

Second question answer: Your stock alternator will keep up with the 240watt max amp without any problems at all, if the alternator is in good shape. I ran 1000 watts on my stock alternator for a year or two without any problems. And just for fyi, MAX wattage doesn't mean anything as the amp will probably never output that. That 240w MAX is probably more like 100 to 120 watts continous (or RMS). That will give you 50 to 60 watts per channel.

Third question answer: The headunit "should" have a wire on it to turn the amp on and off with the headunit. Now, if you want to have the headunit turned on, but not the amp, you can do that with just a normal switch. One side of the switch to the wire coming from the headunit, the other side of the switch to the amplifier remote turn on lead. Very simple, very quick.

I hope this helps you out some. If you have any more questions, please ask them. I, or somebody else into the audio electronics will be glad to help you out.

[Jasen]

A electronic cross over will do the trick of only one set of RCA's or a EQ but theres not much to choose from out there.
I got my Kenwood deck with 3 RCA outputs and built in X overs and sub level control from www.sonicelectronix.com for 1/2 price, $140
As far as a power cut off. Do you want to kill all the power to the amps or just the sub.
You could wire in a toggle on a push on/off switch to the amp remote lead, but turning the deck off will turn off the amps.
I'm pushing about 900 watts off my 105 Alt. and a Diehard Gold batt.

[mikeybonez1]

the ideas given for the amp cut-off switch would work fine if i just run a sub-amp but if i run the speakers through the amp, that would cut power to them as well. is there a way to dual run the speakers? meaning have a set of wires from the head unit to the speakers and a set of wires from the amp to the speakers or would that wreck it? i forgot to ask last time around, should i run a capacitor or will an exide platinum hold enough juice to even out some spikes?

p.s: jasen, hows that die-soft gold holding up lol. i'm an auto tech at sears and we see a lot of dead gold's daily. usually from guys that run systems with the engine off

[93 astro]

I dont believe there is a way to run two sets of wires without running into Ohm issuse, and that could cuz problems. You shouldnt need a farad cap for 250w, your battery and altt. should b enough. Im pushing just under 3000w thro with a yellow top battery, and a 10 farad cap, all to a cut off switch and the smaller subs are just ran off the deck.

[Leeann_93]

p.s: jasen, hows that die-soft gold holding up lol. i'm an auto tech at sears and we see a lot of dead gold's daily. usually from guys that run systems with the engine off

I have a DieHard Gold in my Bravada and HATE it (the bf bought it 2 years ago). I'll be replacing it with a real battery soon...

[JaxSPL]

Never ever, ever, ever, run a crapacitor. They are nothing but hype and are mostly junk. They are useless pieces of junk. I could go on and on about these sales hypes that don't do crap.

I looked to see if I had a crossover laying around and I do. It is a Boss REV40x 3 way crossover. Here is a pic and specs for it. I put in bold the needed feature for your setup. If you want it, shoot me a pm. I do not have the remote level control (bass boost for sub output) at this time.



# Inputs: front, rear and subwoofer
# Outputs: front, rear and subwoofer
# Frequency multiplier: x1 or x20
# Selectable crossover frequencies :
# Low pass: 32Hz-250Hz
# High pass: 40Hz-400Hz
# Variable bass boost, 0-+12dB
# Bass boost frequency selector: 25-250Hz
# Selectable crossover slope 6dB/octave or 12dB/octave
# Parallel input switch (feeding multiple channels from one input)
# Phase shift, stereo/mono
# Signal-to-noise ratio:>110dB
# Out put voltage: 8 volts (max)
# Remote subwoofer level control
# Low pass input selector: Direct or front/rear mix
# Gold plated connectors
# Remote on/off power control
# LED power indicator
# Subwoofer phase switch

[Jasen]

Leeann, really? I've never had one fail on me. I had one in my Toyota for 10 years and it was fine when I sold the truck. Had another for 8-9 years that followed me through 4 cars.
I always get the biggest one I can get under the hood and 800-900 CCA
Maybe it's just the temperate climate here on the left coast

[Leeann_93]

Leeann, really? I've never had one fail on me. I had one in my Toyota for 10 years and it was fine when I sold the truck. Had another for 8-9 years that followed me through 4 cars.
I always get the biggest one I can get under the hood and 800-900 CCA
Maybe it's just the temperate climate here on the left coast

Yup, it's garbage. He even got the truck/SUV one to get the highest cranking amps. I had one in my grandmother's 82 celebrity - failed in 4 months. I'll never buy another.

[93 astro]

Never ever, ever, ever, run a crapacitor. They are nothing but hype and are mostly junk. They are useless pieces of junk. I could go on and on about these sales hypes that don't do crap.

I used to have headlight dimming before I got my cap... I have a 10 farad PG cap handleing 3000 w and no longer have a problem. There not all junk

[JaxSPL]

A capacitor is nothing but a band-aid for a weak electrical system. I'm not going to go into full explanation in this topic due to not wanting to hijack it. I will be posting some information from Richard Clark. For those that do not know, Richard Clark was one of the first people to ever use a capacitor in a vehicle. I would trust his advice on this more than I would anyone else.