Ga22ar

Bit of advice please..

Doing my first amp install, which is going on a board mounted vertically behind rear seat..

Some questions.

1. What are the cable lengths generally from headunit to amp, battery to amp and amp to front speakers.. Just need a rough idea
2. What is the consensus about routing of cables, power one side of the trans tunnel, everything else the other.. Or completly opposite sides by using the gap between seats and door.
3. Best place to mount earthing from amp ?? Seat belt anchor?
4. Best routing point for power cable thru bulkhead into engine bay ?
5. General idea on length of time required to do the cabling, assuming speakers/amp/headunit are already in place. ?

Thanks for any answers

cheerio

[Edited by Ga22ar - 1/29/2002 9:32:09 AM]

chiark

1 - dunno. Be sure to get too much
2 - Routing cables. I've gone for power in the passenger "running board" trim thing, rcas up the middle, sundry bits down the drivers side and speaker cable down the appropriate side.
3 - Earth - take your pick. I made another hole. Just check where the fuel tank is
4 - Try the aircon grommet. It's huge. Should be a picture on the faq.
5 - Allow yourself a full day, or at least four hours. DO NOT take shortcuts, and remove the bits that you need to remove rather than try to work around them...

HTH

Nick.

Ga22ar

Thanx for the reply

So can I assume that..

1. 3 meters or 5 meters - this seems to be the standard off the shelf size..
2. Speaker cables down the appropraite side - so speaker cable next to power cable is ok on the passenger side ?
3. What did you do about rusting etc.. Did you hole penetrate the outerbody (underneath that is)

cheerio

Luke

Dont drill holes... No need and could regret it.

TBMeech

I would suggest that by obtaining too much cable is the best solution, you will probably require at least 3 meters of decent power cable, speaker cable I would NOT run near the power cable as it will pick up interferance, I have run my passenger speaker cable across the car and over to the right to run with the driver cable, my rca's up the middle, and my power down the left, it doesnt pick up any interferance and i am running 3 amps, I have an air con car, took a while to put the power cable from the battery thru, used the same grommet and made the hole slightly bigger, as Luke has said there is no need to drill extra holes....

nom

5m power cable definately.

Power can run next to the speaker run, but not next to signal. It shouldn't cause interference & it's better to run them seperately, but it depends how much effort you want to put in... I have heard as well that it's quite possible to pick up interference from the transmission tunnel as well!

Ga22ar

OK, so we have have..

1. 5 meter power cable, RCAs OK at 3 meters ? Speaker cable 5 meters each ?
2. Power cable down passengers running board side, RCAs down drivers trans tunnel, speakers down drivers running board side.
3.Best to find pre-existing hole/bolt - so rear lower seat belting mounting point sounds best
4.Aircon gromment - but requires opening up.
5.A day to do the job

Any other input ??

Glen Stenhouse

Installing Your Own Car Amplifier

Installing an amplifier calls for a little more skill and creativity than installing a receiver or a pair of speakers in the factory locations. But it's not necessarily all that difficult. If you know what to look out for before you start, you'll save a lot of troubleshooting time after you're finished.

Carefully plan each step and allow plenty of time. If you run into a little engine noise, don't be discouraged. It's usually not that hard to get rid of. Remember, if you bought your amp from Crutchfield, you can get toll-free technical advice seven days a week.

Whatever it takes, we're sure you'll be thrilled with the end result. With the extra power, you'll get more volume and much cleaner, more dynamic sound, even at low volume.

Finding the right spot

An amp can be securely installed with just a few screws. But since amps can be sensitive to electrical and motor noise and because interference from the amp may affect your radio reception, try to mount it at least 3 feet away from the receiver. Good locations include:

»Under a seat

Pros: Closer to the receiver, so you can use shorter patch cords and signal cables. Closer to the front speakers, so running wire to them will be easier. No cargo space sacrificed.
Cons: You may have to remove the seat to do the installation. Larger amps won't fit.

»On the firewall (passenger side)

Pros: Short wires and patch cords may be used. You won't have to remove a seat or climb into the trunk.
Cons: Only very small amps fit here. Closer to some common noise sources.

»In the trunk or hatch area

Pros: Lots of room for large amps. Near the rear speakers.
Cons: You sacrifice some cargo space. Longer wires and patch cords required

When working inside the trunk, tape over the latch, so you won't become trapped inside accidentally.

Don't mount an amp or other car stereo components such as electronic crossovers or equalizers directly on steel — you will invite noise problems. Instead, mount the amp on a non-conductive board and mount the board to the car body (or use rubber grommets under the screws to isolate the amp).

Before you drill the screw holes to mount your amp, hook it up and give it a test run. If the amp is operating correctly, with no engine noise, then proceed with the installation. There is also a safety issue here: Components that aren't securely mounted could break loose during an accident and injure someone as they fly through the passenger compartment. Use bolts and nuts to secure amplifiers and other components to their mounting locations.

Keeping your amp cool

Something else to consider when choosing a mounting spot: Amplifiers produce heat, and the heat must be efficiently dissipated. The amp's cooling fins absorb heat and radiate it into the surrounding air. For the cooling fins to operate efficiently, they need a few inches of air space around them. When mounting the amp on a side wall, try to position it so that the slots in the cooling fins are vertical.

Amps should not be mounted on the bottom of a rear deck with the fins facing down because the heat will radiate back up into the amp. Leave yourself enough room on either side of the amp to make all the wire connections and adjust the controls. If you have a subwoofer box in your vehicle, you can mount the amp on the outside of the box.

If you are mounting the amp to the floor, check beneath the car to be sure your screws won't puncture a brake or gas line.

Wiring for safety and good sound

Most amps do not come with power and ground leads or patch cords to carry the signal from your receiver. For most single-amplifier installations, the best way to buy these is in an amp wiring kit that also supplies a thin piece of wire for the turn-on lead, a fuse or circuit breaker, and all the connectors you need.

The main power lead should be thick — nothing thinner than 12 gauge will do. It draws power directly from the positive battery terminal. An in-line fuse or circuit breaker installed near the battery is a must. Without one, an accidental short circuit could pose a fire hazard and damage your amp.

Thicker wire — 10, 8, 4 or 2 gauge — might be called for, depending on the length of wire you want to use, the power of your amplifiers and how you plan to use them.

For amps that put out up to 50 watts x 2 channels or 25 watts x 4 channels, 10 gauge power cable will usually suffice. Step up to 8 gauge or 4 gauge cable if you're running the wire all the way to the trunk and you like loud music with a lot of bass.

Thicker wire delivers more current

If you're planning to use your amp to power a subwoofer, install thicker wire. Amps require a lot of current to handle loud, low bass notes, and the thicker the wire, the more current it can deliver. To attach the power lead to the battery, crimp a ring terminal onto the end of the wire (most wiring kits come with the ring terminal already attached).

Unscrew the nut that secures the positive (+) battery terminal to the battery post, slip the power lead terminal over the bolt that secures the battery terminal to the battery post and replace the nut. Do not attach the power lead terminal directly to the battery post.

How and where to ground your amp

The ground wire should be the same gauge as the power cable and must make direct contact with bare metal of the car.

Look for an existing bolt or screw that makes contact with the car body near the amp. Remove the bolt or screw, and scrape away any paint or grime. A star washer will help your ground wire maintain solid contact with the car body. Crimp or solder a ring terminal onto the end of the ground wire, slip it underneath the washer, and replace the bolt or screw.

If you can't find a convenient ground screw or bolt, drill a hole for one. Again, be careful not to drill into the gas tank or a gas or brake line.

Grounding multiple components

If you're installing several components, try to ground each one separately, with about a half-inch of space between each of the grounding points. If you'd rather use a single bolt, place the ground for the component that draws the most current (probably your biggest amp) closest to the car body. Put the ground for the component that draws the least current (probably the electronic crossover) on top.

Glen Stenhouse

Wiring for automatic turn-on

Most amps turn on when a positive 12 volt signal is applied to the amp's turn-on circuit. Since this is a very small amount of current, you can connect the turn-on lead to the power antenna lead of your receiver. Such a connection will turn the amp on and off when you turn your receiver on and off.

Most amp cable kits come with 15-20 feet of thin blue wire that is meant to be used for the turn-on connection. If your receiver doesn't have a power antenna lead, or if it only works when you actually use the radio, you'll have to find another source of switched 12 volt power (power that flows only when the key is in the "accessory" or "on" position).

Turning on multiple components

If you have more than one amplifier or other components in your system, you can, in most cases, tie the turn on leads together. If you have four or more components in your system, you may need a relay network to protect your receiver. That's because the receiver's power antenna lead can only supply a limited amount of current.

If the components in your stereo system ask for more current than the receiver can supply, you can burn out that circuit in your receiver. Call our technical department if you need advice on building a relay network (have your invoice handy). A relay network connected to the power antenna lead draws a small amount of current from the receiver, but supplies enough current to simultaneously turn on all your other components.

Feeding the music to your amp

Most receivers provide preamp output from RCA jacks. If both your receiver and amplifier use RCA jacks, they plug right together. Preamp output signals vary in strength, depending on the manufacturer. If you bought both your amp and your receiver from Crutchfield, you can be sure their signals are compatible. If one of your components was purchased elsewhere, make sure the amp's input requirements match the receiver's preamp output level.

Some receivers and amps use DIN plugs (a plug about the size of your thumb with between five and nine pins in the middle). They aren't as common as they used to be, but if you're adding a component to an older system you might find a DIN connection. If you do, first check to see if there are also RCA jacks. If there aren't, you'll need a DIN-to-RCA adapter to connect your receiver to your amp.

Some amps can also take their input signal from the receiver's speaker leads. But if your receiver has preamp outputs, use those instead. You'll get a cleaner signal. If you want to feed your amp a preamp-level signal, but your receiver does not have preamp outputs, one of our effective and inexpensive line output converters will help you step the speaker-level signal down to preamp level. Then run an RCA patch cord from the converter to the amplifier.

Make sure the patch cords supplying the musical signal to the amplifier are kept well away from potential sources of noise, such as brake light wires or rear window defroster wires.
If the amp is in the trunk, run the input signal leads down the same side of the car as any speaker wires you've installed. Run the power and turn-on leads down the other side of the car to avoid interference.

Can your vehicle handle the current demands of a multi-amp system?
Your vehicle's electrical system is designed to do one thing very well: supply the car's different components (headlights, air conditioner, etc.) with the needed current and voltage to operate properly.

Some cars' systems are designed for additional current loads (trailer towing packages, for example), but most of them are not. Luckily, most manufacturers design their cars' electrical systems with a reserve capacity that is well-suited to supplying power for a sound system. Look at the tag that is riveted or screwed to the side of the alternator. This tag tells you how much current (expressed in amperes or amps, for short) the alternator is capable of producing.

Most alternators are capable of producing 55-65 amps. This is adequate for sound systems packing up to 350 watts RMS. Most German automobiles have charging systems rated up to about 90 amps. This will be sufficient for systems of up to about 500 watts. Some Hondas, on the other hand, have alternators only rated for 35 amps. This will only support about 125 watts in amplifier power.

If you want more power than your alternator can service, you will have to consider having your alternator rebuilt for higher output. Or you can invest in a high-output aftermarket alternator. Sorry, we can't help you with this. Installing a second battery won't help. The only reason to do that is to play your stereo for long periods with the engine off. How you use your system can make a big difference in current draw.

The above discussion assumes that you will not be listening to your sound system at three-quarter volume all day long. Any system playing at one-third volume is drawing considerably less current than the same system at three-quarter volume, and may not need a charging system upgrade if the volume levels are kept reasonable.
On the other hand, you could be asking for trouble if you do keep the volume cranked up. If your system needs more current than the alternator can supply, it can grab current from the battery up to a point. Here are a couple of warning signs to look for:

your headlights dim in time to the music when you crank it up loud at night;

your bass sounds great when you first turn it on, but gets mushy and less powerful within a minute or so.

One easy, effective solution is installing a capacitor. Heavy-duty capacitors connect to the power cable (just before it reaches your amplifier) and act as a buffer zone between your amp and your car's electrical system. They store up a reservoir of power which can supply the amplifier's peak demands (like a kick drum beat) without having to get current from the battery.

Estimate amplifier current demands

It's tricky to relate amplifier wattage directly to current consumption. To see how you can figure out what you have, see the FAQ for amplifiers.

How to estimate your electrical system's reserve current capacity
Take your alternator's amp rating and multiply it by 40%. This rough figure will give you a baseline for about how much reserve capacity your car's electrical system has.

If, for instance, your alternator is rated for 90 amps, 90 amps x 40% = 36 amps left to power your sound system. A hypothetical sound system drawing 33 amps would just work with this car's electrical system (system draw = 33 amps, car's reserve = 36 amps). The car's battery would supply the reserve current necessary for the program peaks that are capable of drawing 60-70 amps. Remember, these figures are not scientific estimates.

Ga22ar

Chiark..

Just looked at you site and seen your install in the boot, question - how did you mount/connect the bottom of the amp board to the base of the boot. ??

cheerio