tapping into electricals for stereo power

[Lord Warlock]

What is the best circuit to tap into in order to hook up a sound system?  I have a new Head unit and a 200 watt amp to add to the system, I don't want to overload the simple fuse box, I plan on keeping the original AM/FM stereo hooked up to the dash speaker so can't use that circuit.  I was thinking about using the cigar lighter, but don't want to compromise the circuits to any of the tail lights, stop lights, or turn signals.  This leaves the option of using the console/Emergency flasher circuit, something that I doubt would see much use.  I don't have a console in the car, and the emergency flashers I can live without if i have to, should the circuit blow.  The heater and AC circuit is also a possibility as the AC is currently removed from the car, and the heater is bypassed since it was leaking a little 20 years ago, I do expect to fix the heater and ac eventually but I could use it until then. 

The underdash wiring is all original at the current time, probably pretty brittle,  is it best to just hook into one end of the fuse holder from the front? or tap into the wire itself from the rear of the fuse box? Or should i just tap the wires direct from behind the fuse panel?

[myk]

You said it yourself, the wiring's pretty brittle.  With all of the restoration work you've got into this car, don't you feel like installing fresh wiring?  If you put in an aftermarket wiring system you'll have plenty of spots for power hungry accessories like stereos, and you won't have to tap into or otherwise cannibalize any other system...

[b5blue]

What is total Amp draw? You really need a separate wire off Alt. output sized for the draw and fused correctly. You need to know what idle output of your Alt. is to know if it can handle the extra demand. Remember as the Amp/Volts drop lights dim, wipers and blower motors slow and your spark weakens at idle. 

[tan top]

You said it yourself, the wiring's pretty brittle.  With all of the restoration work you've got into this car, don't you feel like installing fresh wiring?  If you put in an aftermarket wiring system you'll have plenty of spots for power hungry accessories like stereos, and you won't have to tap into or otherwise cannibalize any other system...

X2   

What is total Amp draw? You really need a separate wire off Alt. output sized for the draw and fused correctly. You need to know what idle output of your Alt. is to know if it can handle the extra demand. Remember as the Amp/Volts drop lights dim, wipers and blower motors slow and your spark weakens at idle.  

x2   yeah!    

[twodko]

Flog me if you will guys but I tapped right off the stock radio 12v lead. The OEM AM radio never gets used. I get the juice my super efficient SecretAudio head unit needs and enjoy the "switched" power turning the key to "accessories" offers. 

[Lord Warlock]

The draw on the amp will depend on whether I run it at 4 ohms or 2 ohms, most likely it will be 4 but the amp can support a 2 ohm load, whether the car will is another story.  Unfortunately I can't quite start the car and let it run off of the alternator at idle, the motor is dry meaning it has no oil or water in it yet and has no gas in the tank or lines yet either.  Was hoping to wire the stereo system up, and test it using an inverter or an AC powered amp.  Then do the final hookups once i get the car running again.  I'm not averse to putting a new alternator in the car, even a more powerful one if need be, but that will involve getting suggestions since I really don't have much experience with charging systems.

I'm still testing out positions for the exciter (speakers) as to which offer the best sound, best so far was on top of the rear fenders next to the quarter glass, but that makes the whole rear section of the car act like a speaker so anyone outside the car would hear it just as good as inside, which I'm trying to avoid.  The original plan was to mount a pair under the upper door panel but i'm not sure there is going to be clearance there or not, they are only about 1/2 inch thick at most.  Tomorrow is supposed to be mid to high 60s so I'll be playing around with positioning tomorrow, also determining where to mount the Head unit, either under the dash or under the drivers seat, the amp can go under the passenger seat or on the trunk floor under the package tray.  

As to running new wiring, I'd prefer to run new wiring but reading wiring diagrams is not my strong point, nor is checking voltage using a meter, and before I'd attempt to replace the dash wiring harness I'd want to totally remove everything under the dash that isn't wiring, i.e. ac/heater box, hoses, ,etc which only makes a simple wiring job of running wire into a major league wiring exercise I'd hope to avoid.  I'll probably swap out the wiring harness in the future when I decide to upgrade the gauge cluster, and do a heater core rebuild, i'm just hoping to start enjoying the car a little before i start the next phase of dash upgrades.  Have a new dash pad to install that will require taking out the radio and cluster.

Running the wire off of the cigar lighter wire puts it on the same circuit as the stock radio, but also runs the tail lights.  (which i haven't checked out yet after doing the trunk job).  I'd prefer to have it run off of a switched accessory than a full time draw like the headlights are on, good way to drain a battery if there is a short somewhere.

[twodko]

I don't have any more than a marginal knowledge of basic DC circuitry but I can tell you that you def don't want to piggy back power off the HL, cigar lighter etc.

We have some very savvy guys here who know this stuff......Polywideblock is an electrician by profession to name one......in think Tsmithae is also proficient in this area.

If you'd like to just check your stereo system and speaks just hook up the head unit to a stand alone battery. That way you won't fry anything in the car. You'll be able to rough wire your tunes so you'll know how it will go when you do the formal wire later on.  

Somebody here will bring you to the car stereo promised land.

[Carrnutt]

I hooked mine up to the factory radio connector as well, for the switched power and light. I also added a constant 12 volt for the memory.

The amps would require their own large power cables, directly from the alternator / battery or even their own battery, due to the load pulled. Therefore should have no effect on anything at the dash.

The only thing drawn from the radio (dash power), regarding the amp(s), would be the "remote signal", that turns the amps on (very little draw). When the radio tells the amps to turn on, they draw their power from the larger power wires and NOT from the radio.

So basically all you're needing from the dash is:

1. The low draw memory power. It needs to be a constant source, even when the car is off for keeping stations, clock, etc. (dome light for example)
2. The 12 volt switched power for the head unit (radio). Turns on with the ignition switch in the on and / or the accessory position. (for this I used the original radio connector)
3. If desired, wire connected to the light circuit, for dimming the radio when the lights are turned on.  (for this I also used the original radio connector)

The original radio connector is shaped like a T and has a Red (12 volt switched power) and Orange (for the lighting). There was no "memory" required back then since radios weren't digital. LOL

If you're running new wiring, I would connect them to the fuse box at the correct fuse location. Radio for radio power, dome light for memory and you can tap a wire for the light usually orange in our cars. I would also place a fuse inline on all 3 of these wires.

[Lord Warlock]

After playing around with the mini speakers today, found several possible locations to install them, none of which were where I had intended to put them.  The best location I found was on the seat backs of the front buckets, each will have to sit slightly off center to not interfere with a support brace that runs right up the middle of the back of the seat, but it will make the seats feel the bass beat better than using a sub box.  The second location was attached to the dashboard outboard sides, the third location was the cross braces behind the rear seat back, but attached to the front side of the brace about half way up the brace, it actually makes a strong midrange sound with good bass for such a small speaker, however, the rear package tray has two 5x7 coax speakers in it now and there is a 2-8 inch woofer sub box in the shelf directly behind the rear seat, and those sound better than the vibration/exciter speakers do.  So It looks like I'll be putting two under the dash, and 2 or maybe 4 of the exciter speakers in the front seats, wired in parallel to drop the ohm load from 8 to 4.  These will be driven by the internal amp of the Head unit.  The rear shelf speakers and sub box will be hooked up to the external 4 channel amp at 4 ohms. 

I ran the external amp power lead from the battery, thru the firewall, behind the left kick panel, under the door sill wire channel to the back seat area.  It looks like the Head unit needs a constant power source (memory/presets), as well as a switched aux power wire hooked up, I'll probably hook the aux power wire to the circuit for the factory radio. 

Question, for the constant power lead, would it be better to run that wire from the cigar lighter lead?  or can I tap into the main power wire running from the amp to the battery?  The HU has a remote signal turn on wire that i believe runs from the HU to the amp in the back.  I was able to find a kit that allows me to mount the HU under the dash, its a plastic box that mounts the HU inside so you don't see the bare metal sides since the newer stereos don't have an external mount box anymore. It also has a flange so I can use those to screw it to the underside of the dash, may have to drill a couple holes to mount under the ash tray. 

Put the battery in the car, but seems I misplaced the ground lead that mounts to the motor to battery, I'll have to find it or go buy another from the auto parts place.

[b5blue]

By running the 200 watt amp off the battery your feeding that draw through the ALT gauge from the alternator when the car is running.  (With stock wiring.)  Many issues with old B Body cars come from not understanding the factory only considered the battery was used just to start the engine and only allowed for a small margin of discharge.  Just keep this in mind for down the road, the entire car is wired to run off alternator output.   

[Lord Warlock]

so would it be better to run a wire to the alternator instead of the battery?  as far as I know the alternator only has one connection to it, thought the alternator charged any draws against the battery while the engine was running, any draws while not running would drain the battery power.

While answering the power question, it makes me wonder if connecting a postive wire for an electric choke to the alternator would be allowed.  Haven't gotten to the engine electricals yet but they are on the agenda.

[Carrnutt]

Question, for the constant power lead, would it be better to run that wire from the cigar lighter lead?  or can I tap into the main power wire running from the amp to the battery? 

I used the constant power wire from the accessory light connection, pink wires I believe (the ones that power the dome light, etc.). Or straight to the fuse box on the lighting fuse section. It doesn't require a lot of current. But still make sure it is a fused circuit.

so would it be better to run a wire to the alternator instead of the battery?  as far as I know the alternator only has one connection to it, thought the alternator charged any draws against the battery while the engine was running, any draws while not running would drain the battery power.

Yes, I would:

1.   Run a piece of the amp wiring from the alternator to the starter relay, this helps pull some current from running through the ammeter for charging the battery, in addition to powering your amp.

2.  Then run my amp power wire from the relay. PUT A FUSE here, near the relay.

3. Run another piece from the relay to the battery (for powering the amp when the engine isn't running) PUT A FUSE here near the battery.

The only time the battery would be powering the amp is if the alternator isn't putting out current. Either the engine not running or there is a problem with the alternator.

While answering the power question, it makes me wonder if connecting a postive wire for an electric choke to the alternator would be allowed.  Haven't gotten to the engine electricals yet but they are on the agenda.

Yes, I used the ignition terminal on the alternator to power my electric choke, this is not the same terminal to put the amp power wire on. It's only "hot" when the ignition switch is in the run or on position it is a spade type connection, if memory serves, and comes from the voltage regulator.

[b5blue]

so would it be better to run a wire to the alternator instead of the battery?  as far as I know the alternator only has one connection to it, thought the alternator charged any draws against the battery while the engine was running, any draws while not running would drain the battery power.

Yes to Alt. output. The battery just starts the engine, there should be no draws off the battery after starting. GM one wire Alt. systems draw everything from battery, they are wired to be this way ours are wired to run off Alt output.

[Lord Warlock]

What connects to the spade connector on the alternator?  Mine has a post with a nut that the main harness fits on, but the spade connector is too wide to fit any plug that comes off the wiring harness that reaches to that point.  I'm thinking about starting a thread asking a similar question as I was looking at the alternator today.

I had replaced the engine harness with a new piece that goes to the voltage regulator, ballast resistor, coil,  alternator, washer resevoir, and horns.  At the juncture where the coil wire comes out (a blue wire to the coil) there is a continuation of the harness, a blue wire to the coil, and a green wire with a plastic plug on one end that looks like it would reach the alternator connector, or the AC female plug but nothing else.  There is also a brown wire near the washer pump I'm not sure where it goes to.  the harness plug for the washer pump fits, but the two green wires off of that end are supposed to be for the horns, but only one reaches the connector to the horn, the other horn the wire won't reach.  

I did hook up two of the exciter speakers to the back of the front seats today, and tested them with a 20w amp and my ipod, was very impressed, thought the music was filling the entire back seat area and you can tell it comes from behind similar to rear shelf speakers, only difference is that you can feel every bass beat, every thump etc without having a subwoofer hooked up.  Its got me thinking of skipping the external amp altogether and just running the exciters to the seats and kick panels or under the dash on two channels running in parallel which would put impedance at 4ohms, and the other two leads to the rear shelf speakers.    

[2Gunz]

To properly do this you need to know the AMP draw of your power amplifier.

IF you intend to have an accurate AMP gauge reading then the amplifier should be connected to the battery.

If you have a serious power amp you will need upgrade your Alternator.

Connecting any power amp other than a little baby one to the fuse panel is just asking for trouble.

Most importantly..... protect your investment .... when connecting "Addons" to the battery or alternator they should be fused,
and as close as possible to the battery or alternator.

[Lord Warlock]

The amp has a built in fuse on the chassis of the amp,  the HU has a built in fuse for the memory wire.  The amp I would consider to be a fairly small one, compared to most of the amps you'd find in anyone elses cars (my challenger has a larger 280watt amp in it).  If I was pushing multiple amps and huge speakers I'd think i'd need a better alternator,  the stock alternator should easily feed the power needs of this one small amp, but the HU has a 200 watt amp built into it already (50w x 4ch) which is really like 18 x 4 in real life.  The external amp says 50w x 4, but it says it will push 100w x 4ch if running at 2ohms, so i think its probably stronger than the internal amp of the HU, which is only designed to push a 4 ohm impedance. 

[el dub]

I tapped into the line side of the brake light switch when I put my stereo in but didn't have an external amp in the circuit.

[2Gunz]

Even if the AMP has a fuse, if you attach it a non fused location (Battery, alternator) it should have a fuse as close to the power source as possible.

The Fuse on the Amp protects protects the amplifier.

To be safe you need to protect the new wire.

[Lord Warlock]

good to know, will have to make another run to the electronic store...lol. 

Installed two more exciters into the footwells this morning.  These dinky little wonders are amazing.  They make the whole area sound like a speaker.  I can feel the music in the doors while leaning on the car, and that is with only a 20wpc amp on 8 ohm speakers.  Now i'm figuring out how to wire the package tray speakers and 8 inch sub box, think I may hook those up to the external amp, i'll also wire the deck speakers to the factory am/fm. 

[b5blue]

This may help you sort out what/how to do....
http://www.bcae1.com

It's a fun site to poke around!