Info on Car Audio

[RtN]

Hey I wasn't sure to post this here or noobs forum but yeh! Umm does anyone know a site or info on car Audio. Like what capacitors are for.. and info on uses for mono, 2channel, 4 channel, 6 channels amps? etc Thanks. And also bridging the amps etc.

[arverson]

mobileelectronics.com.au

formerly caraudioaustralia.com

[tron07]

First, let's define what a capacitor is, how it works, and what it does. This is best done by the following webpage, provided by our friend and colleague Perry Babin of BCAE1.com:
http://www.bcae1.com/capacitr.htm

Now with that out of the way, this is what a capacitor will and will not do for you.
A capacitor WILL:
-Act as a filter for AC ripple effectcaused by the imperfect rectification of the AC current produced by an alternator, and rectified by a DC voltage regulator.
-Smooth the demand curve for current on the alternator, thus extending (theoretically at least) the alternator's lifespan, and, on a not so good note, this can also help to mask the symptoms of an insufficient alternator by smoothing these spikes that also cause the more obvious signs of a weak charging system, like dimming headlights when the bass hits.
-Reduce propagation delays in current supply for brief, spiked demands by the amplifier from the amplifier, and response to this by the electrical system. Amplifiers have to provide a very dynamic and quick response many times. A capacitor can assist in this if the rest of the charging system is up to par.

A capacitor will NOT:
-make your system magically sound 10 times better.Many people believe that a capacitor adds NO real benefit to an audio system, and this is why you never see before and after demonstrations, or factory capacitor company vehicles at car shows.
-Replace the need for a larger, high-output alternator and/or a deep-cycle battery or batteries.
If your electrical system is inadequate, the ONLY way to fix this, and again I repeat, the ONLY WAY to fix this, is to replace the alternator if your voltage rails are sagging to below 12 volts while the car is running. This is the SOLE source of electrical current for your car when the motor is running. The car's battery is in parallel with the alternator, and while the battery will help to stablize voltage at 12VDC, the alternator puts out a higher voltage, and if your voltage rails are dropping to 12 volts, you're already overdrawing the alternator's capacities, and if your voltage rails sag to below 12 volts then you're also going beyond the abilities of the battery or batteries to stablize your voltages. Both of these symptoms will result in battery and alternator damage.
A capacitor only masks these symptoms, in much the same way as regulating voltage to your headlights so they won't dim as bass hits, when voltages can fluctuate between 14.4VDC and 12VDC.

When the motor is turned off, the battery then becomes your source of electricity.
When the battery is run down, and when the capacitor(s) is/are depleted, the alternator has to work even harder in order to supply current to the car, the audio system, and also to recharge the capacitor(s) (which deplete more quickly) than they recharge) as well as recharge the car's battery(ies).

If you plan to use the audio system for prolonged periods at high volumes with the car turned off (such as for SPL events) you'll want to use isolated deep cycle batteries dedicated to the audio system to avoid damage to the batteries, and damage to the speakers and equipment from clipping.

So by adding a capacitor to try taking the place of a high-output alternator, you are actually causing more work for your alternator, and causing even more damage to that stock alternator.


A capacitor does have it's uses, but it is not a magical fix for a lacking electrical system.



Another item I'd like to touch on is the more recent advent of the high capacity capacitors (25, 50, 100+ Farad capacitors) and so-called "BattCaps."

These types of capacitors have extremely high ESR values which makes them very bad choices for the uses mentioned above. They are usually carbon-film based capacitors in order to get such high values, as opposed to the much lower ESR electrolytic capacitors you tend to find in teh 20 volt 1Fd type cylinder style units.
End result is avoid anything like the 100Fd capacitors like a plague.



revised 01-August-2005
(c) GlassWolf, WolfWare, Ltd.

[arverson]

in a more brief summary: best not to spend your money on a cap cus they're next to useless, you're much better off investing that dough into upgrading your wiring and/or battery.

[tron07]

in a more brief summary: best not to spend your money on a cap cus they're next to useless, you're much better off investing that dough into upgrading your wiring and/or battery.

Useless or not, its depends on you application and how well you use it. I know people using 0.5 farad caps on the HU to get better SQ.

[RtN]

oh thanks guys.. i wasjust scared of how some guy i read in these forums said hes ECU fried coz he had 2 subs + 2amps w/o a capacitor ROFL.. OK .. so now. someone help me of choosing amps =] do I need 2 or 1? and how many channels?.. I see people have like an amp dedicated to just a sub and.. how do they synchronise that with the amp for speakers..... GG im LOST LOL Thanks guys!

[arverson]

in a perfect world you'd like to have each driver to have its own dedicated channel, eg. 5 channels in a system that has 2 fronts, 2 rears & 1 sub.

the majority of people, including me, wouldnt bother amping their rears, so thats minus 2 channels.

so lets say you want 3 channels to power a basic system consisting of fronts + sub, you could:

1. get a 2 channel + a monobloc
2. get a 4 channel and use channels 1+2 for the speakers, and bridge (combine) channels 3+4 for your sub.
3. get a single 5 or 6 or 100 channel amp to run everything, but i wouldnt do this. plus theres no 100 channel amps out there.

if people have a monobloc id assume they have another amp for their speakers too. no magical synchronization goin on

u dont NEED 1 or 2 amps. just depends on your budget i guess. depends on the voice coils of your sub too..

[RtN]

ooO thanks!! that was informative! Oh umm so why cant you be bothered amping up the rears? How about this scenario.. 4 channel amp.... 1 for each speaker.. and a monobloc for sub =]


BTW when they say 1000w 4channel amp.. they mean 1000w @ each channel yep?

[arverson]

lol.. all that info is really basic stuff

bout the rears.. its simply cus i sit in the front seats and i fade the music all the way to the front anyway. when i DO fade back i barely hear em, theyre more than loud enough for my rear passengers unamped so spending more on rears is unneccesary. besides, the money used could be used to improve my frontstage thru better installation/better 2chan for the fronts/better front splits/etc. rears drag your sound stage back too if youre worried bout that...

oh yer how could i forget bout 4chan + mono !! yes u could do that, most people do

i doubt that amp is 1000w RMS per chan... probly nowhere even close to half that

[RtN]

oh i mean how the companies advertise their amps as 1000w etc.

hmm thanks!

[arverson]

they're taking advantage of marketing gimmicks

[tron07]

yup.... usually lot of marketing gimmicks....

usually when they say 1000w 4channel amp, its usually 250w per channel at the lowest ohm it can go... if the amp is able to run at 1 ohm, its 250w at 1 ohm.... but in real world, few amps can run at 1 ohm (there are amps that can run at 0.25 ohm, but thats another story)

I would assume the amp (highly rated, qood guality amp here) is 125w X 4 @ 4ohm, measured at 14.4v.

But then again, good and branded amps usually dont advertise their product as 1000w 4 channel amp.