Car Audio at Home
Car Audio at home you ask? Why the hell would you want that? Number one reason, bragging rights! Actually it’s not a bad idea if you require a test bench.
Reasons:
A couple of applications for doing this are:
1. Testbench for Parts
2. Cheap Home Stereo (Gets pretty loud)
3. MP3 Stereo (When hooked to Computer)
4. Great for Movies
5. Vast selection of parts.
Running car audio at home is good if you have a few spare parts lying around. It does come with disadvantages. The first is not having all the channels that Dolby Home units boast. I suppose with a digital input, and RF 5.1 car audio system, it can be done. The second is, how do you power the gear, that 12V shaver adapter is not going to cut it for a 50 AMP amplifier.
Ratings:
If you notice I never refer to amplifiers or head units using their Wattage Output. The reason is pretty well known. I don’t call liquid nitro-freezing MOSFETS and driving transistors into over-voltage under one hundred percent laboratory control a fair test. Neither is measuring amplifier output power using a 20Hz single tone signal.
Thus, I use the amp rating. It’s a no-brainer that a 1000W Orion HCCA with 100AMPs worth of fuses is going to push more power than a 1000W Pyramid Amplifier that has a single 25AMP fuse. For car audio, power is generated by the transistors or tubes using DC electricity. Since components are voltage sensitive, the input voltage to 12V electronics has regulators that clip the voltage to certain values. So the other method is to push current like a bat out of hell. What do I mean? Think about it, SPL vehicles have multiple alternators, and stacks of batteries. What’s their system voltage? 130VDC? No, there voltage hovers around 14.4V, with some variance. But they can dish enough current to arc weld I-Beams if you short their supplies.
Home Power Source:
There’s a couple of ways to come up with a stiff 12V power source:
1. Make one (Huge Thyristors, Diodes, Heat Sinks, Transformers, Ripple Filters, Brown Out Caps, voltage regulators)
2. Use a Car Charger and Car Battery.
3. Buy a 14.4VDC wall Supply
I did the latter two choices. I weighed the options, the money to build a 12V high current supply would kill me just buying a massive transformer, and trying to stuff my Home Improvement project into a big box, all this to say, ‘hey guys look what I made.’
So since the price of building a supply died, I pulled out the car trickle charger, and a spare car battery. I think the battery had 600CCA, and was pretty big. At full charge (10 hours plus), it can run two amplifiers, over 7 speakers, including a subwoofer for six hours at a room shaking level. This includes a head unit.
What you need is to build an enclosure that looks like an electronics store display to house a set of components, a battery, amplifiers etc etc, whatever you want to install. Charge, Fuse, Wire, and you’re good to go.
Later I replaced the car battery with a 14.4VDC – 50AMP, 120VAC supply made by Tripplite (They make UPS supplies, ,Part: PR-50). The supply is CSA approved, cost $350 CAD, and pushes alot of power. The specifications say I can start a car with it, and also charge battery banks. To make the power switch more convenient, I purchased a remote outlet from the local hardware store. I can turn the supply on and off using a remote control across the room.
Wiring:
Everything is the same as if it were in a car. The only difference is if you decide to use a different input source other than a head unit, like the TV or computer, you do a wiring mod on the amplifiers. The remote pin should be tied to +12V to trick the amp’s power relay. That’s it. Everything should still be fused, because at 50 AMPs DC from a wall supply, wires will singe.
Using an old Fosgate Parametric Controller, I control the volume via a wired remote. This allows full volume control over the amps.
Test Bench:
The system is great when it’s too hot or cold outside when you need to test equipment. On a regular occurrence I test amplifiers, subwoofers, head-units, and sub enclosures in my basement. it’s hard to rewire your car just to test one sub, or another amp, so maximum access, is two thumbs up.
Testing Subwoofers:
I test these for damage and performance. Having the audio source being a computer I can run tone generators and fully control test wave magnitudes, and frequency. Can’t really do that with a head-unit in your car can you?
I first run a couple songs into the sub (crossed-over for protection) to listen for an obvious problem. I then go to the tone generator, and range a low magnitude wave into the sub from 2 Hz to 100 Hz. At 6 Hz or so, I can watch the sub go into full excursion very slowly, and rhythmically. If the coil is messed up, you can move the sub around like on it’s side to hear if the coil scratches the internals etc, etc.
Testing for blown coils is a pretty simple too, since indoors, you have access to the speaker posts, so for DVC subs, you can switch leads pretty easy, and test for failed coils.
Testing Amplifiers:
Again with the tone generator, I can test the performance of cross-overs in amps, and whether or not the amp has problems. Same goes for head units
Head Units:
You can completely test a head-unit on the power supply. Access to the twelve volts is clean and easy to get at. This is good if you want to map the harness. Power is pretty simple to pick out, but speaker outs, and speaker phasing is a little trickier. It’s much easier to do this with the use of a test bench in a warm indoor environment rather than in the car during the winter, when your hands are crippled, and your sitting on a screwdriver, balancing the deck in your lap, holding ten wires, nursing a leg that fell asleep, and trying to hold two wires together while turning up the volume with your tongue.
Future Improvements:
The lack of channels sucks for DVDs. However, when I muster the cash to go Home Audio, I’ll have an 11 speaker center channel.
The number one reason to do this for home audio purposes is if you wire in a volume controller to you amplifier inputs, you can run any Car Audio Subwoofer you can afford for Sub Bass instead of the limited selection of Home Audio Subwoofers. There is no way a Home Audio sub could out perform Car Audio SPL equipment in your basement. This is also your only chance to run JL/Vega Strokers/Soundstream Subs etc etc for Home Audio Subs.
Date: March 27, 2002
Written By: ectwo
Rev0
