capacitor do or dont

Systems · March 2005

ive gotten a couple replies to system woes thank you very much!!! i dont quite understand why ditch the capacitor???

MacLeod · March 2005

Unless youre running 4000 watts and you have a 30 amp alternator, you dont need one. A stock charging system will generaly have enough juice to run most systems. You would be better served just getting a better battery like an Optima.

neomagus00 · March 2005

well, that is true to a point, but a cap helps protect the battery you have... a battery is meant to provide a steady, powerful stream of current, but to feed a subwoofer amp, you need huge, short bursts of power... the cap acts as a buffer between the amp and the battery, giving the amp the power it needs whilst allowing the battery to produce a more-constant stream of current.

MacLeod · March 2005

But ya dont need it. It wont hurt anything to have one but if you dont want to spend the extra money or take the extra time to install it you dont have to and youll be fine.

TrappedUnder Ice · March 2005

Ok..lets look at it another way>
+ for cap: looks cool, looks cool, looks cool.
- fpr cap: dont do a dang thing.

ok there...

actually... a cap would be good on your fronts of a very high end system. since it filters a/c ...it could improve your head room. Caps on subs...lol.. just a joke IMO

MacLeod · March 2005

Originally posted by TrappedUnder Ice
Ok..lets look at it another way>
+ for cap: looks cool, looks cool, looks cool.
- fpr cap: dont do a dang thing.

ok there...

'Nuff said!

exalted512 · March 2005

lol. i love how thomas doesnt come on for months, makes one posts about how caps suck and leaves.:)
As far as caps go, I have 2, one in my truck and 1 in my room that I'm too lazy to install. If you have slight headlight dimming, they can be for you. What a capacitor does is store enery. Its kind of like a battery but with much less internal resistance so it can discharge power much faster than your battery can. I will never own another cap now that new, better technology has emerged in the form of batcaps. They're the price of 2 1F capacitors but have a much larger storage capacity. When I redo the system in the truck again I'll be selling the caps and buying a couple batcaps
-Cody

TrappedUnder Ice · March 2005

capcitor is not a battery- nor is that its intended use! ...capcitor is an A/C filter!
BTW....I on ly pipe in when the conversation warrants and I have something too say.

next!

TrappedUnder Ice · March 2005

oh yeah...now when Vinnie was in here...convo was good

exalted512 · March 2005

Originally posted by TrappedUnder Ice
oh yeah...now when Vinnie was in here...convo was good

sorry were not good enough for you:(
j/k
-Cody

TrappedUnder Ice · March 2005

vinnie was too the point and funny too listen too!

neomagus00 · March 2005

ah, the grammar ****... how like high school this is...

Systems · March 2005

Originally posted by TrappedUnder Ice
Ok..lets look at it another way>
+ for cap: looks cool, looks cool, looks cool.
- fpr cap: dont do a dang thing.

ok there...

actually... a cap would be good on your fronts of a very high end system. since it filters a/c ...it could improve your head room. Caps on subs...lol.. just a joke IMO

hey man...i reccomend u take a physics class before u open ur mouth again...ur an idiot

thats all i gotta say

RuSsMaN · March 2005

The only power-supply caps you need, all already built into your amp. If they aren't doing the job, get a properly designed amp.

Cheers,
Russ

exalted512 · March 2005

Originally posted by RuSsMaN
The only power-supply caps you need, all already built into your amp. If they aren't doing the job, get a properly designed amp.

Cheers,
Russ

huh?
that doesnt make sense, but i know you know your stuff so what am i reading wrong?
im reading "if your car's electrical system cant handle the amp, get a better designed amp"
youve got to remember in car audio theres not an endless amount of current available;)
-Cody

RuSsMaN · March 2005

Well, I'll never proclaim to be a car audio guru, but in the 110/120 volt world, amps are built with all the PS capacitance they need.

Maybe car amps aren't, due to size (or inherent 12v) constraints, I don't know. I've never had to add 'extra' capacitance in a home rig. When those caps empty out (headroom exhausted), you either A. Turn it down. B. Buy a better amp.

Is an extra cap in the auto doing anything more than storing current?

Cheers,
Russ

exalted512 · March 2005

well ac voltage is a lot different from dc voltage.
since in a car you have a battery and not a sub station filling your electrical needs. a battery, to produce voltage, has to have a chemical reaction. chemical reactions take time so when youre playing music and the bass hits, it takes time for the battery to give you the power you need to keep everything flowing "even". this is where capacitors come in. capacitors store a charge(measured in farads...1.0F caps are common in CA) and have much less resistance(than a battery), they can discharge almost instantly. this is why theyre great for solving minor head light dimming. when the bass hits during short bursts, the capacitor picks up the slack.

but obviously everything is limited by a car's 12V system. as you know cars run at 13.8-14.4V which means it goes off the alternator because a 12V battery can only supply 12V. So if you have an amp that draws a lot of power, its necessary to upgrade the cars stock wiring(because its too small and limits the flow of currrent), add batteries, and replace the alternator if necessary.
if a car's voltage goes down for several seconds, a capacitor will not do the trick b/c i can discharge a 1F capacitor back down to 12V in a matter of seconds, this is when batteries are added and alternators are replaced.

something new that has come out is the batcap, which is like a hybrid battery/capacitor. it can hold a much larger amount of energy(like a battery) but can discharge that energy instantly(like a capacitor). there as tall and deep as a battery, but about a 1/4th the length. a lot of imports are starting to use them as well because they have enough power to start and run a car and are smaller and lighter than batteries.

you also have to remember that car audio has to have a lot more watts to get it to be as loud as a HT system(road noise, etc). in HT i believe you have very low current because you have a high voltage source whereas CA is opposite. ohms law, the whole voltage=resistance*current thing.

my next truck will be drawing about 400A or so, well, not at daily driver levels b/c that would be insanely loud, but its capable of running at 400A all day. a single battery and the stock alternator isnt going to cut it. Im going to have 2 batteries, 2 batcaps, and a 235A alternator to power everything correctly. the amps im using are very high quality amps. if you would put them on a scale of 1-10, 10 being super high end, these would be a 9. i dont have to upgrade the electrical system because of crappy amps, i have to upgrade it simply because the current draw is so massive and there are major restraints with the electrical system in car audio.
-Cody

RuSsMaN · March 2005

Dude, you've got to break that **** down into sentences, and better yet, paragraphs before I can even attempt to read it.

Cheers,
Russ

exalted512 · March 2005

its in sentences, just not capitalization. i broke it down into paragraphs, i dont have time to do more than that.
physics sucks ****.
-Cody

AustinKP · March 2005

Originally posted by Trppedunr = ****
hey man...i reccomend u take a physics class before u open ur mouth again...ur an idiot

thats all i gotta say

I love how when someone has beef with another, they just post an anonymous comment so they don't have to step up to what they've said. Gutless wonder.....very mature.
:rolleyes:

neomagus00 · March 2005

i thought thomas was in electronics courses? hum...

i do wonder about the accuracy of that statement, but not in the violent way of the idiot

. as mentioned, amps have powersupply caps, and for highs, which draw very little current compared to subbass, they should be more than enough to provide a perfectly flat DC voltage to the amp, even if the battery is fluctuating a bit. rebuttal?

cody - everyone agrees that caps are worthless over long durations (i'd consider 1 second very long). their potential usefulness is in the milliseconds-long transients in the music. batteries simply cannot respond that fast (you said this yourself), but a capacitor can.

as to what russman said, i completely agree - amps should have enough capacitance to run a standard music program (caps are much less helpful for sine waves, but still better than nothing). but they don't - imagine buying a big sub amp that had 3-4 F of capacitance built-in... it'd leave no room for subs!

thus the need for external caps, to perform the smoothing thomas mentioned - take a fluctuating input signal and smooth it to a constant DC supply for the amp. more capacitance = more severe filtering (if you don't believe me, read up on the use of caps in passive xovers). thus, adding external capacitance allows you to smooth out more extreme fluctuations in the battery's supply voltage.

now, what causes these fluctuations? other than normal car operation, you have the subwoofers themselves. their draw on the cap is roughly (yay bad ASCII art!):

_   _ 
---- _/ \_/ \

say that the horizontal line is what the battery can give up at that particular time (more would be possible if the demands changed more slowly, but because the requirements go up and down so often, the battery's supply can only ramp up to that line before the requirement ceases). the capacitance (internal and external, it's all the same) provides the juice for that very short peak above the line, and recharges during the very short trough below the line (when the battery can provide everything necessary).

problems arise when the cap can't get charged up enough while the demand is below that line, and if that happens, it'll eventually run out of reserve. if you're pushing your music that far above the live, you're simply demanding more of the car's electrical system than it'd ever be able to provide, and that's when the upgrades need to take place, all of which raise that line (well, that line isn't time-invariant, and that's why we get alts AND batteries AND the big 3 AND etc... they all help in different ways).

that should be relatively clear, and makes sense if you read carefully.

MacLeod · March 2005

Its not so much that the amp has enough capacitance but that its being fed enough juice and as Cody has so elequently put it, a car's stock charging system aint exactly a sub station.

Personally I dont think you need caps unless youre running insane amounts of wattage, but one thing is for sure, they cant hurt.

Oh, and Russ, hang out here long enough and youll eventually be able to read Cody's typing!

Actually he used to be a lot worse. He would hit return after each sentence.

exalted512 · March 2005

Originally posted by MacLeod

Oh, and Russ, hang out here long enough and youll eventuall be able to read Cody's typing!
Actually he used to be a lot worse. He would hit return after each sentence.

im trying, at least theyre in sentences now, someday i might progress to capitalization too...
-Cody

Toxis · March 2005

definitely do a cap. The strain on a battery from a decent sized sub amp will hurt it in the long run. Get a cap, save the battery and reduce the noise in your system. I didn't feel like reading the whole thread but figured I'd throw in a few pennies.

neomagus00 · March 2005

Originally posted by exalted512
im trying, at least theyre in sentences now, someday i might progress to capitalization too...
-Cody

yeah, right... i'm a grammar **** myself and i don't even capitalize on the net... it just looks weird...

and toxis brings up an interesting point, namely the strain of varying demand on a battery. i wonder how much it actually hurts it (if at all)?

Toxis · March 2005

back in the day, I killed the "best Die Hard" battery Sears offered with only a 300w Kicker amp. The alternator died before the second battery but still, the damage was done.

TrappedUnder Ice · March 2005

For the person with the Lack of Balls to use thier real name. I do have a degree in Electronics and I have taken many Physics classes.

Where do you get off telling me that my statement is wrong. Instead of rattleing of being beligerent- why dont you prove me wrong.

The idea of putting capacitor on a high end systems front stage is too smooth out any fluctuations in voltage from the mids- this will improve your dynamics or "head room" and give you a better front stage. The "toms" will stand out more be more "real" This can also be heard in a better quality amp...using better capcitors. Of course...there is always a point of limited return.

If you want too use a cap... by all means...go for it. Its your money and your system. However...if you want to recomend a cap to someone or be ignorant to someone....you should have the facts too back it up! I really have no problem going head to head. I normally try to keep it "KISS" keep it simple stupid.

anyway...Y'all have a nice day.

PoweredByDodge · March 2005

Thomas doesn't have an "electronics" degree - he's not a "tech" somewhere.

If you want to know the truth - he's an Engineer for Advanced Micro Designs (Read: AMD Processors - the only competitor to Intel - or these days you could say Intel is the competitor to AMD).

I know not another man who is both as SMART and DOWN TO EARTH (two qualities which normally don't go together) as he is.

So whomever this "Trappedunr=****" guy is - eat **** and die.

As far as capacitors - book is open - we've all hashed this out about 1000 times... there are plusses and minuses.

- it's not going to fix the problem for a guy who's trying to draw 100 amps from an 80 amp alternator... but it is a very good supplement for a person drawing (on bursts) 100 amps from a 95 amp alternator and relying on additional large batteries for backup current.

It will also help stabilize the power system - when your alternator is bouncing between 13.79 and 13.81 volts, and since power is not instantaneous but always has some time factor - a capacitor can help that read more like 13.81 "all the time" or at least 13.80 to 13.81. Is this a BIG DEAL? ... no. Does it help a little - a very little - yes - just enough to keep somebody like me - who's probably a little to messed up in the head than he should be - happy.

I don't think anybody will argue much with me on that.

MacLeod · March 2005

I guess the general consensus to "should I use a cap" is:

Wont hurt

neomagus00 · March 2005

whoa, i'm totally confused now... since when do we have a general consensus on anything like this?! especially one i agree with?!

and pbd, that was what i was trying to get across, only you managed it in about a third of the space

.

TrappedUnder Ice · March 2005

funny thing is...the big "dogs' like Alma Gates and them... have proven that caps can actually "hurt" a system. the caps just are not designed for what a lot of guys are using them for ...period. Most kids use them for thier subs...to give them xtra power...which is poppy ****! The fact is that the caps may not be able to charge and discharge quick enough may actually hurt your performance

so before you can generaly say...eh...it cant hurt....guess a gain.

PBD has the right idea.... to stabalize a couple volts... great! Nothing wrong with that. You have diagnosed an issue with the syestem and implimented a fix. definatly nothing wrong with that!

BTW...If it aint broken ...dont fix it. I have seen cap cause more issues then any other "add on piece" ....

ta ta

capacitor do or dont

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