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.

[RtN]

http://www.kenwoodaudio.com/australia/prodDetails.asp?Cat=Car%20Entertainment&SubCat=Power%20Amplifiers&Model=KAC-X40

800W @ 4 channel! LOL but yeh i think i get it now.. 200W per channel!

thanks guys

[arverson]

kenwoods own site says its not even half of 200 per chan..

i think something that would help you in car audio is DO NOT LOOK at max/peak power ratings. look at rms/nominal/continuous ratings ;)

and.. for $699 you can get something so much better, but its up to you

[OMG.JAI xD]

lol .. check out ebays brutha.

4 channel 5000 watts!!! (PMPO) LOL

mate .. my soundstream monos only produce 2000watts @ 1 ohm rms .. and tht costed 1 grand ish . .retail.

sif get 5000 watts for a few hundred bux .. psahh!


just be on the look out that most sellers out there try to sell theyre products using PMPO ratings.
which basically, i think, derived from chinese manufacturers thinking they can put the principal of a normal speaker which has an RMS and peak rating.
which CANNOT , be applied to an amp.

an amp is the power source, to be on the general side, and cannot have a constant power output at variable rates. unless diferent ohmages (if thats a word) is applied.

btw.. PMPO is supposedly .. peak music power output.
which some how...is equivalent to 10 times of the rms.

RMS is root mean square.
its the formula used to rate, or give, to a electronical device that produces an always variable output.
in this case, different frequencies will take different amounts of watts to produce.

lol i tried to understand rms ... but it didnt really help LOL.
all i know is, theres a test involved with it, and ends up giving a precise rating. =]

however, with speakers .. you have to look at both RMS and peak.
its basically a minimum and maximum sorta thing.
rms is the recommended .. and anything in between up to peak. should, be safe...or fine..

theres alot to audio.
alot to learn.
but its interesting.



off topic. but to all those that find electrical stuffs interesting.
go look up perepertia generator or prepertiria generator or some shet like that.
its pretty interesting.
apparantly some white dood in americano figured out a way of eliminating the back emf created by an induced motor. and using that emf to turn a rotor that runs to the induced motor.
so .. liek a cycle sorta thing.
so.. basically... its creating energy.. simply by magnets .. =]

pretty coolio i reckons.

have fun =]

[tron07]

http://www.kenwoodaudio.com/australia/prodDetails.asp?Cat=Car%20Entertainment&SubCat=Power%20Amplifiers&Model=KAC-X40

800W @ 4 channel! LOL but yeh i think i get it now.. 200W per channel!

thanks guys

its 200w probably at 2 ohm or 400w X 2 bridged.... you probably wouldnt be using it this way cause the THD is very high.... You can get away by using it for sub as you cant really hear the THD if its just slightly higher then the rated.... then again there are always execptions....

power is not always tell you the whole truth... I would prefer 25w RMS from a good Class A powering my comps then a noisy 200w from a el-cheapo amp.

[tron07]

lol .. check out ebays brutha.

4 channel 5000 watts!!! (PMPO) LOL

mate .. my soundstream monos only produce 2000watts @ 1 ohm rms .. and tht costed 1 grand ish . .retail.

sif get 5000 watts for a few hundred bux .. psahh!


just be on the look out that most sellers out there try to sell theyre products using PMPO ratings.
which basically, i think, derived from chinese manufacturers thinking they can put the principal of a normal speaker which has an RMS and peak rating.
which CANNOT , be applied to an amp.

an amp is the power source, to be on the general side, and cannot have a constant power output at variable rates. unless diferent ohmages (if thats a word) is applied.

btw.. PMPO is supposedly .. peak music power output.
which some how...is equivalent to 10 times of the rms.

RMS is root mean square.
its the formula used to rate, or give, to a electronical device that produces an always variable output.
in this case, different frequencies will take different amounts of watts to produce.

lol i tried to understand rms ... but it didnt really help LOL.
all i know is, theres a test involved with it, and ends up giving a precise rating. =]

however, with speakers .. you have to look at both RMS and peak.
its basically a minimum and maximum sorta thing.
rms is the recommended .. and anything in between up to peak. should, be safe...or fine..

theres alot to audio.
alot to learn.
but its interesting.



off topic. but to all those that find electrical stuffs interesting.
go look up perepertia generator or prepertiria generator or some shet like that.
its pretty interesting.
apparantly some white dood in americano figured out a way of eliminating the back emf created by an induced motor. and using that emf to turn a rotor that runs to the induced motor.
so .. liek a cycle sorta thing.
so.. basically... its creating energy.. simply by magnets .. =]

pretty coolio i reckons.

have fun =]

lol..... I acctually dont understand what you wrote.... :p

[RtN]

Hmm now onto a new topic =]!!

RCA Pre outs!
So basically if you have 2 pairs of RCA = more control over your speakers?
and 3 Pairs of RCA = even more control?

But we need to buy an amp to support 2 or 3 rca's respectively right?

[tron07]

+rep me, then I will dig or post some stuffs about RCAs.

[Vinnie]

lol you cant hold info hostage for pq points :p

rca's pre-outs on their own do not enhance the sound or give you more control, they are merely used to connect your amps to the h/u. hence, a h/u with at least a couple of good voltage (eg. 4v) pre-outs is a wise investment.

and i think what jai was trying to say is be wary of the large power ratings printed on some cheaper amps as they are not an accurate indication of how good the amp is :)

[dahon]

rca pre-outs are basically the raw signals that come from you headunit. they arent amplified by your headunit at all, thus the 'pre' term. with these preouts you connect to your power amplifier to boost, process and amplify the signal. thus if you have an awesome amp then you gain a better amplified signal when you compare a speaker level output (signal was processed by headunit) + power amp combo.

ALWAYS look at the RMS rating of amplifiers. DO NOT look at those 1000w figures... these figures are what they get in the laboratory during controlled tests and by the time your speaker/amp combo hits half of that figure it will have cracked. they are a marketing gimmick to try and get your attention.

try to match your amplifiers RMS output with your speakers RMS capacity, as these will get you good enough results. Depending on the amplifier you may be able to drive a higher rated speaker, ie 50w amp driving 80w rms speaker, but mostly these are the good branded ones. for example my home theatre stereo power amp only puts out 100w RMS for each channel and it drives a pair of b&ws rated at 150W RMS.
you also have to look at the inductance? (is that wat its called) of the speakers and amps, ie the 4ohms and so forth. the lower the number, the harder the amplifier has to work to drive the said speaker. normally i would recommend you stick with 4 and 8 ohm systems.

also some h/u's offer a sub preout, and these connect to your monoblock amp, allowing you to buy a dedicated amp without the low pass filter as the h/u does the work. so look around for your options.
-if you want to power subs i would recommend looking for amplifiers with the low pass filter, as these filter out the bass notes.
-for splits (driver + tweeter combo), look for crossovers or inbuilt mid/high filters in the amplifier aswell to seperate the midrange & highs.

tip1: DEFINATELY INVEST IN A GOOD AMP. you can always get a decent speaker/average speaker. its the amp that does most of the work processing the signal.

[tron07]

lol you cant hold info hostage for pq points :p



:p Do you know there are so many configuration you can play with RCAs... even with one RCA preout, you can split it with line driver, external crossovers, etc... and different HU with different specs, etc... then there is signal matching... just too much to write.....



Since the original thread is about amp, here are what some info on what the specifications on the amp means.....

Frequency response refers to the range of frequencies which the amplifier can reproduce within a certain power range, usually +/-3dB.

Continuous power output is the power output of the amplifier into one channel into a certain load (usually four ohms) below a certain distortion level (usually at most 1&#37;THD) at a certain frequency (usually 1kHz). A complete power specification should include all of this information, e.g. "20W/ch into 4 ohms at < 0.03%THD at 1kHz" although this can also be stated as (and be assumed equivalent to) "20W/ch at < 0.03%THD". The amplifier should also be able to sustain this power level for long periods of time without difficulties such as overheating.

Peak power output is the power output of the amplifier into one channel into a certain load (usually four ohms) below a certain distortion level (usually much higher than the continuous rating level) at a certain frequency (usually 1kHz). A complete power specification should include all of this information, e.g. "35W/ch into 4 ohms at < 10.0%THD at 1kHz" although this can also be stated as (and be assumed equivalent to) "35Wch at < 10.0%THD". Consumer warning: some manufacturers will state the "peak power output" rating by including the amount of power which can be drawn from "headroom", which means power supply capacitors. They usually will not tell you this in the specification, however; indeed, they tend to prominently display the figure in big, bold letters on the front of the box, such as "MAXIMUM 200W PER CHANNEL!!!" when the continuous rating is 15W/ch and the unit has a 5A fuse.

Damping factor represents the ratio of the load being driven (that is, the speaker - usually four ohms) to the output impedance of the amplifier (that is, the output impedance of the transistors which drive the speakers). The lower the output impedance, the higher the damping factor. Higher damping factors indicate a greater ability to help control the motion of the cone of the speaker which is being driven. When this motion is tightly controlled, a greater transient response is evident in the system, which most people refer to as a "tight" or "crisp" sound. Damping factors above 100 are generally regarded as good.

Signal to Noise Ratio or S/N Ratio is the ratio, usually expressed in decibels, of the amount of true amplified output of the amplifier to the amount of extraneous noise injected into the signal. S/N ratios above 90 to 95dB are generally regarded as good.


As my personal experience...... I do believe different amp has different characteristic.

Specification is one thing, the sound of the amplifier is another thing. @ different brand of amps with similar specs usually sounds different. Good brands usually under spec their product on paper, so you will get better sound/power then what is stated, while el-cheapo stuffs usually overstate/overspec to lure in unsuspecting buyers. However if you do a Richard Clarke test, then the amp will sounds the same, as you strip away all the stuffs that make them sound different.

Then there is also amplifier class, but that another thing for another day.....

[arverson]

lolz are we all helping you rtn or are we confusing u even more?? :P

if its within your budget, try and get a head unit with 3 preouts. and dont worry if its 2, 4 or 8v preouts.. a 2v should be more than sufficient for you.

[RtN]

Thanks arverson ahaha im kinda lost.. but yeh..

Umm I am going to have 2x 12"subs i believe and 220w fronts and pioneer tweeters and dunno about the 6x9" at the back.. ( All Pioneer )

So this set up would require 2 amps right? a 2 channel for the Subs and a 2 or 4 channel for speakers.. Or I could get a 4 channel.. 1 for each sub. and 4 speakers to the 2 remaining channels right?

[arverson]

get:

a 2 chan for fronts OR a 4chan for all 4 speakers.

AND

get a monoboc for your sub duties, not two 2/4chans for each sub. :)


now that you want 2 subs i dunno what voice coil subs to suggest for you cus i dunno what amp you're actually gonna use and what its stable down to...

wouldnt you rather 1 better & higher quality sub than 2 cheaper, lower spec subs??

[RtN]

nah I dont mean a 2/4 chan for each sub.. but get a 2 chan and put a channel for each sub.. but hmm a monobloc... I just need one right?

But you understad what mean right.. how i bridge 2 speakers per channel.. and the remaining two can go into each sub..

But ok so basically a monblock is for subs..

Im being given these subs from a family member of 2x pioneer subs.. so guess its pretty decent

And whats voice voil?

[arverson]

but hmm a monobloc... I just need one right?



yes.


But you understad what mean right.. how i bridge 2 speakers per channel.. and the remaining two can go into each sub..



i wouldnt bridge speakers, you'd change their thermal characteristics.

i wouldnt use a single channel from a multi-chan amp to power subs. you're probably gonna be pushing it into "clipping"


But ok so basically a monblock is for subs..


if it had suitable HPF xo's u could use it for speakers too, but i think i might confuse u more... so lets just say yes its only for subs.


Im being given these subs from a family member of 2x pioneer subs.. so guess its pretty decent

And whats voice voil?



dont worry bout what it is. just give us details on the 2 pioneer subs.

[RtN]

Oh ok.. its the car is not here with me atm so I cant check.. but what the problem that arised was that the MP3 only has 1 pair of RCA Outputs however the AMP has holes for 2 pairs.. so the amp only puts out 2 channels atm.. not four! Is this supposed to happen or is there a way to make 4 channels work with only 1 RCA Pair?

[Dray_Templar]

RCA Splitters should do the job from jaycar/ dicksmith, or your local car audio place should have them..

[teh_mechanic]

watch out when using rca splitters,they can induce some crazy alternator whine into the system if the splitter is close to your amps power cable or any other power wires.i used one ones and everytime i hit the brake the sub would pop loudly.rca cables are shielded to prevent this,the splitter isnt properly shielded

[RtN]

Oh okay thanks will try this! Ahaha why didn't i think of this =]!! You guys need those Positive points! So theres no way we can shield these RCA splitters? Or can i just wrap the wires in aluminium? Ahaha just a thought!