FAQ- Why a cap is useless!

Member02

Audio GOD
After studying a little history on large 1 Farad capacitors in car audio, you'd be amazed that they even sell at all. How useful are they? What do they really do? Will a Cap 'improve' my sound quality? Will it Prevent my lights from dimming? Will it audibly affect my audio system in any way?

Before you get the truth to any of the above questions, chances are, you've probably spent $100 or more on one of these devices. However, let's study a little history regarding this issue.

A long time ago, in a land far away, 2 elves...Ok, Richard Clark & Wayne Harris (Carsound magazine and the inventor of DB Drag, respectively) separately came up with a solution to preventing their lights from dimming.

WHO WERE THESE GUYZ?

As you may know, Richard Clark is one of the founders of autosound2000 Tech Briefs, Carsound magazine, and a published author of the industry of mobile electronics. In SQ competitions, he posted a record of 1234 1st place finishes, and only ended up NOT 1st in his first event. I've heard that he had minor system problems, but judging by his record, he must have corrected it. (evidently, he needed a Capacitor )

Wayne Harris was previously a leader at Rockford Fosgate in their development. Later, in his free time, he created the organization we call DB DRAG. Wayne was the first SQ World Champion from the organization we know as IASCA (International AutoSound Challenge Association).

Both of these gurus are both legends, and considered the leading experts in the field. During their competition days, both guyz came up with a way to assist in the prevention of voltage drops. In SQ competitions, the look of your system is actually more important than the sound, and having your lights NOT dim under high playing levels is a competitive advantage.

As you may know, an amplifiers is made up a battery of little capacitors, resistors, etc. What has been common engineering knowledge is that capacitors store energy, and more or bigger ones assist in balancing the power supply.

Wayne came up with the idea of putting several dozen 'little' (approx 100uF) capacitors on a circuit board to 'extend' the power supplies storage. At about the same time, or shortly afterward, Richard came up with the idea of one huge mondo capacitor (I believe it was 800,000uF or 0.8F) to do the job.

Eventually, Richard won. The large cylindrical tubes won over the complicated 48 caps strapped to a circuit board. However, what did this really accomplish? Let's start here:

WHAT IS A CAPACITOR?

Basically, capacitors are an energy storage device. Large, 1 Farad or more
capacitors store energy (electrons) between their plates. Capacitors differ
from batteries because batteries store energy in the form of chemical
energy--and rely on acid as the place of storage. For a more detailed
description of a capacitor, go here:

www.eatel.net/~amptech/el...raudio.htm

Then on the right hand side, scroll down to CAPACITOR. Keep in mind the use
of capacitors in an audio system.

WHY DO PEOPLE BUY CAPACITORS?

The number 1 reason would have to be because their lights dim when their
system is playing HARD. In car audio, we are told that a capacitor is
designed to prevent the voltage drop associated with your lights dimming.
The number2 reason is that it is rumored to 'improve' sound quality or
'stiffen' the power supply/source.

WHY DO MY LIGHTS DIM?

Headlights brightness is in direct proportion to the source voltage. For
instance, if your car is running, system voltage is ~12.5 -14.4 VOLTS. Your
lights will be much brighter than when your car is turned off--where battery
voltage is ~12V. Most car alternators put out between 75 to 120 amps of
current. When this current draw threshold of the charging system is
exceeded, system voltage will drop as power demands are now shared by the
alternator and the storage devices (battery & cap). We are using battery
reserves beyond this point until the demand lessens

When playing your system really hard. Your lights dim because your
alternator can't keep up it's charging voltage (around 13.8V) and therefore,
demand exceeds output. When this happens, your electronic devices are
dipping into the power storage of the battery. Since the battery stores
power at ~ 12-12.5V, there is a 1.3 to 1.8V drop in voltage available. This
in turn is why your lights dim down.

HOW MUCH POWER DOES A CAPACITOR STORE?

1 Farad = 100 joules or 100W/second
850cca battery = ~2,200,000 farads

For storage purposes, you'd need ~2,200 1 Farad capacitors to equal the energy of your battery.

Due to its impedence (ESR & ESL), a cap's energy is only 50% available. What's worse, is that in order for a 1 Farad cap to discharge, first the alternator output must have maxed out, and the voltage must have dropped around 1.5 volts. But I thought a cap was supposed to prevent that (voltage drop)!!!!!????? Yep, you got the point.


IF A BATTERY = 2,200 CAPS, THEN WHY BUY A (PUNY) CAP?

My question exactly. Marketing is the reason why people buy caps. In many cases, upgrading wiring will help your system get the maximum transfer of current. Once that has been reached, adding a capacitor may have a minor effect on your system. 50W over the course of a second is not a lot of power considering an amplifier may draw 2000W to put out 1400 watts. Let's look at the situation from a resources standpoint.

Alternator 80 amps
Car accessories (minus stereo) 40 amps
Car Audio system (DRAWS ) ~200 amps AT FULL OUTPUT

In this case, you have 240 amps of draw, but only 80 amps of current from the alternator. In your case, you need 160 amps x 12 volts or or let's say 1920 watts of energy. Since a cap stores 50W, how much of a difference do you think it's going to make? A cap is a peashooter, and we need a Howitzer 150 calibre cannon.

Also, Once a cap is discharged, where does it get it's power from? The alternator, which is already overloaded. Once a cap is discharged, it's worthless. Like justin says, “..The cap already shot its wad, an does limp til recharged…” you get the drift.

SO, WHAT IS A CAPACITOR GOOD FOR?

1. Audio Jewelry- impress chicks with large cylindrical shiny thingy
2. Extra weight in winter time
3. A very POOR... BUT expensive distribution block
4. A projectile in the event of a crash
5. Rolling pin--for cooking purposes
6. A neat thing to tell your friend, "..Hey man, lick the top of this..


Please do not try # 6. New hairstyles are always refreshing, but if you are wearing railroad tracks across your teeth, you might have one big filling after it’s over.

HOW CAN CAPACITORS IMPROVE SOUND QUALITY?

They can't. Sound quality is not dependant upon the presence of large bulky 1 Farad capacitors. How many 1 Farad Capacitors do you think the Boston Pops, Aerosmith, or Snoop dog use in the recording studio?

IN A NUTSHELL.......

When Richard, our fearless inventor, became World renown for winning every competition under the sun, people began copying what he did. Soon, every 'serious' competitor had a 'stiffening' capacitor--not to be confused with the 'loosening' capacitor.

WHY?

In the late 80s, people began sticking out their tongue when dunking the basketball because Michael Jordan did. Did sticking out your tongue improve your dunking ability? Same here with adding a capacitor to your electrical system.

STILL A GLUTTON FOR MORE PUNISHMENT?

Here's the Original Cap Debate.

www.carsound.com/ubb/Arch...00307.html

Phoenix Gold's marketing guru had just posted information on how their Powercore (basically the Alumapro CAP15 in a Phoenix shell) had both stabilized their voltage and improved the sound quality. Richard called him on it (all in another post) and the marketing geek was unable to quantify any of the conditions that resulted in the voltage being HELD at 14.2V and the 'improved' sound quality.

Please do not read every stinking post as valid. There are a lot of people that have had the efficacy of capacitors inbred to their minds, and were not (and still not) convinced in the futility of a 1 Farad storage device.

In a final note, Richard relayed a quote regarding battcaps ( www.battcap.net ) as, "..The audio industry is the only place i know of where you can publish specs that show your product is useless and still be able to sell them------and whats worse is that technically ignorant people will argue against the math!!!!!!!..............RC.." when referring to the product. This also relates to most digital readout capacitors.
 

Member02

Audio GOD
ItWouldAppearSo said:
very sweet FAQ, sadly i dont understand a quarter of what you said. :cry:
it's ok, even tough you don't understand it, you now believe that a cap is worthless because someone smarter than you said so, right? i'm not implying that I am smarter, just that I am more knowledgable in this certain subject.
 

bhamstangguy

New Member
hey bro maybe i read over it or something but where did you get your battery is aprx 2,200,000 farads or whatever you said it was?
 

prored2000

Active Member
Long but I want to clear up confusion:

Having studied electonics I can tell you that caps have alot of uses. Smoothing out current draws are one of them. Your thinking is somewhat flawed, it's current you need to be concerned with more that voltage. Current is the electrical energy and voltage is the force that moves it.

The thinking behind the idea of putting big caps in an audio system is if you have a system that draws just enough current to make the lights flash to the beat of the music. Then a cap would make sense because it would give the quick response current the amp demands and because they charge so fast it keeps the current in your electrical system steady.

This assumes that your amps are not drawing so much current that you've out stripped what your charging system can supply all the time. As you say in your post, in that case a cap is useless. Once it discharged then the battery is making up the difference. As many a person has found out if you want big sound you need big power. You gotta add an extra battery or larger alt. and all the wiring / regulators etc. that you need to go with it.

A cap is still useful once you've done this. As I said it gives instant response to smooth out current flow and give you better quality sound but you gotta have the current to run your stuff.

One of the first things we built in electonics class is a simple power supply using a transformer and diodes. When you scope the output of that it gives you pulsing DC that goes from 0 to the peak voltage and back to 0 very quickly. The next thing we do is add a cap, that gave us much smoother line.

So why are external caps useless now because unlike when people started using caps car audio has come a long way. Any good quality amp has a power supply that takes the cars 12.5 to 14.5 volt system power with it's somewhat variable available current and makes it a rock solid steady voltage with even current flow with reserve for the peaks Part of what they use to do this are caps, correctly sized for the job.

Ok so I agree with you I'm just a stickler for facts sometimes :crazy: :D
 

Aaronck

New Member
hey man that is a very intelegent responce to that issue but i do disagree with what your are saying. on the fact that a cap does nothing to improve sound quality. first of all it it did nothing why would just about every car in competition have one or more in them? in my opinion they do improve sound quailty but i also think the 75% of people that buy them don't really need them. if you have a high current system have you ever notice on a hard rolling bass note. the system will hit then drop off. this is what caps fix. when your voltage drops at the amp, the amp produces less power. ex: when companys test there amps they test at 12v and 14.4v which one shows higher output? 14.4 so if you amp see a volatage drop you get less output. and what do caps do? the help prevent voltage drop by storing up large amouts of power and release it at one time to compensate for what the Battery is limited to. and it is kinda of funny that those guys that invented the caps won so many SQ comp. and they used caps??????? i wonder why they had such an advantage?

not trying to agrue with you but i still will have capicitors in my system. just speaking my mind and opinion
 

Masgrada

New Member
Yup, you're pretty much wrong.

"They can't. Sound quality is not dependant upon the presence of large bulky 1 Farad capacitors. How many 1 Farad Capacitors do you think the Boston Pops, Aerosmith, or Snoop dog use in the recording studio?"
Hahahaahahah, you might want to think this one through unless you're putting in sarcasm.
 

JayLS5

New Member
Aaronck said:
hey man that is a very intelegent responce to that issue but i do disagree with what your are saying. on the fact that a cap does nothing to improve sound quality. first of all it it did nothing why would just about every car in competition have one or more in them? in my opinion they do improve sound quailty but i also think the 75% of people that buy them don't really need them. if you have a high current system have you ever notice on a hard rolling bass note. the system will hit then drop off. this is what caps fix. when your voltage drops at the amp, the amp produces less power. ex: when companys test there amps they test at 12v and 14.4v which one shows higher output? 14.4 so if you amp see a volatage drop you get less output. and what do caps do? the help prevent voltage drop by storing up large amouts of power and release it at one time to compensate for what the Battery is limited to. and it is kinda of funny that those guys that invented the caps won so many SQ comp. and they used caps??????? i wonder why they had such an advantage?

not trying to agrue with you but i still will have capicitors in my system. just speaking my mind and opinion

The battery assists, but when the alternator is drained and the battery is called upon, you lose a good 2V (dimming occurs). Caps do not solve this problem... unless maybe it is a small amount of dimming occuring from sharp sporadic bass notes. That is the only time i could see a cap assist in the power aspect. Not only this, the cap NEEDS a trickle charging system to be useful. I don't think a cap would help at all if it didn't charge slowly from a resistor of some sort. If it didn't have a resistor (or some other slow charging method i may not be aware of), the moment it was called upon to drain power, it would also demand an instantaneous recharge from the struggling alternator... so how would that help?

I have a 1 farad cap (No, i do not use it for my stereo) that can charge from my alternator in less than a second, because it does not have a trickle charge. If the Alternator is struggling already, what good is it to have a thing that demands an instantaneous recharge once it is used? It just adds more problems to the electrical system.

Yes, amps produce less power when there is less voltage. I must ask, why spend so much money on a cap that is likely not to help at all? Get a H/O Alternator and a decent battery, and call it a day.


Masgrada said:
Yup, you're pretty much wrong.

"They can't. Sound quality is not dependant upon the presence of large bulky 1 Farad capacitors. How many 1 Farad Capacitors do you think the Boston Pops, Aerosmith, or Snoop dog use in the recording studio?"
Hahahaahahah, you might want to think this one through unless you're putting in sarcasm.
Who was this directed at? Which person was wrong?
 

Aaronck

New Member
even with a high output alternator you are still rely on the battery to release the power to your amp's what i am saying is that a battery can not realse enough power instantly to acommidate some of todays high output amp. but a cap can realse all of its power instantly hense a cap does have a purpose in car audio . i know there are no porfessional car audio people in here but i am sorry if they are using them then there is a purpose i just think you guys have the wrong idea on what they are for and if you are going to keepo looking at it as a light dimmer preventer then you will always see them as useless.
 

AnotherV6

Alumni
Car audio has come a long way since people started using Caps, for example no one had even come to imagine a class D amp. (totally digital) they thought class AB was great! That's the solution to having problems with current draw. Since class D amps only draw power when they need to produce large amounts of sound very quickly, the efficiancy of them is nearly 80% which is a great increase from the 10-15% from class AB amps you might be using now.
think of it this way. You're listening to the new sweet hit from fitty cent and you're thumpin away with the volume cranked and your top end class AB amp drawing 100 amps just to make 1000 watts. Throw a class D amp with the same output in the system instead and suddenly you're only drawing 30 amps from your car. (loose estimation on numbers to provide an easily understandable example) - No cap needed anyway!
 

Aaronck

New Member
AnotherV6 said:
Car audio has come a long way since people started using Caps, for example no one had even come to imagine a class D amp. (totally digital) they thought class AB was great! That's the solution to having problems with current draw. Since class D amps only draw power when they need to produce large amounts of sound very quickly, the efficiancy of them is nearly 80% which is a great increase from the 10-15% from class AB amps you might be using now.
think of it this way. You're listening to the new sweet hit from fitty cent and you're thumpin away with the volume cranked and your top end class AB amp drawing 100 amps just to make 1000 watts. Throw a class D amp with the same output in the system instead and suddenly you're only drawing 30 amps from your car. (loose estimation on numbers to provide an easily understandable example) - No cap needed anyway!

class ab run about50-60% efficent vs class d 80-85%
 

Member02

Audio GOD
prored2000 said:
Long but I want to clear up confusion:

Having studied electonics I can tell you that caps have alot of uses.
the only uses I've seen in car audio are in the amplifiers themselves. Richard clark once used capacitors before they even existed in car audio, but after a while he needed more power and his gap of power loss to supply from the alt. became too great, so he upgraded his alternator and ditched the caps.

Smoothing out current draws are one of them. Your thinking is somewhat flawed, it's current you need to be concerned with more that voltage. Current is the electrical energy and voltage is the force that moves it.
voltage loss is what causes the dimming, fool. the current will ALWAYS be drawn, but as the voltage drops the current draw increases, the ONLY limit to current draw is the wire and its size. The only limit to current OUTPUT is the battery and the alternator.

The thinking behind the idea of putting big caps in an audio system is if you have a system that draws just enough current to make the lights flash to the beat of the music. Then a cap would make sense because it would give the quick response current the amp demands and because they charge so fast it keeps the current in your electrical system steady.
Unless your "beats" that dim your lights last for a split second and only occur once every 3-5 seconds, not the common blaring bass everyone plays, a cap will most likely be useless. unfortunately I know ... ZERO songs like this.

This assumes that your amps are not drawing so much current that you've out stripped what your charging system can supply all the time. As you say in your post, in that case a cap is useless.
**** near every person seeking a capacitor is doing so because they have a struggling electrical system. except richard clark. who now doesn't use them. Its a thing of the past. but their new voltage displays look cool (too bad they drain the capacitor ever so slowly)

A cap is still useful once you've done this. As I said it gives instant response to smooth out current flow and give you better quality sound but you gotta have the current to run your stuff.

One of the first things we built in electonics class is a simple power supply using a transformer and diodes. When you scope the output of that it gives you pulsing DC that goes from 0 to the peak voltage and back to 0 very quickly. The next thing we do is add a cap, that gave us much smoother line.
truly amazing. JAYLS5 and I made a capacitor driven car for his physics class because we had no use for it in car audio. it worked great we got an A.

So why are external caps useless now because unlike when people started using caps car audio has come a long way. Any good quality amp has a power supply that takes the cars 12.5 to 14.5 volt system power with it's somewhat variable available current and makes it a rock solid steady voltage with even current flow with reserve for the peaks Part of what they use to do this are caps, correctly sized for the job.

Ok so I agree with you I'm just a stickler for facts sometimes :crazy: :D
what facts? you didn't present any.

read:

http://www.bcae1.com/capacitr.htm

!!!
 

94sexystang

That's what she said
IM not going to get all mathematical on you all since i probably couldnt argue much with it, but.....

When i got my capacitor, it DID stop the lights from dimming in my car, obviously i noticed my car whining louder and harder when the musics up sometimes, because like you said "once the cap blows its load, it needs to suck more juice to recharge"
I dont know how fast the cap recharges but i noticed my music was alot louder once i got the Capacitor in my car, how do you explain that?
I have a 1200 watt amp and i think a 2.0 farad cap, i THINK, i could be wrong, i cant remember at the moment. The 12's didnt kick hard at all untill i installed the cAp.

Not sure here BUT.......

YOu charge the Capacitor ok before installation.
The Alternator takes most of the load, THEN the battery, then the cap?
So if the Cap already has a charge before its used, its ahead of the game right? So in theory as the Battery and Alternator are taking most of the blow like you said, the Capacitor would be draining some, but recharging at the same time, since its already got a charge before hand?
 

94sexystang

That's what she said
Or is that little light bulb that charges the Cap before installation NOT do ****, just get some electricity stored up.

So overall i realize what you all are saying but i still say tell my friends to get a CAPACITOR, because my friends Cavalier only have a 400 watt amp, and 2 10" subs, and they dont kick that hard, but when the cars in motion the lights dont flash as much as they do when standing still, isnt that because the alternator doesnt start charging the batter untill 2k rpm or somthing?
Id rather have a Cap because it kicks harder afterwards and doesnt pop right off after bass hits.
 

Member02

Audio GOD
94sexystang said:
Or is that little light bulb that charges the Cap before installation NOT do ****, just get some electricity stored up.

So overall i realize what you all are saying but i still say tell my friends to get a CAPACITOR, because my friends Cavalier only have a 400 watt amp, and 2 10" subs, and they dont kick that hard, but when the cars in motion the lights dont flash as much as they do when standing still, isnt that because the alternator doesnt start charging the batter untill 2k rpm or somthing?
Id rather have a Cap because it kicks harder afterwards and doesnt pop right off after bass hits.

I understand what you might be thinking... but you see, a capacitor won't slowly drain, they don't have that abilty like a battery. they drain instantaneously all at once when the power is needed, they don't drain bit by bit because they cannot. if you have the chance, find a small electric motor, a tiny one, that operates at say... 6-12 volts, connect it to the charged capacitor and you'll find it will last only a few seconds before dramatically slowing down due to loss of voltage/charge. and as I've said unless you are on that very 'fringe where you just need a tiny bit more power to the amp it won't help. you however have a small amount of power I can see it possibly helping... but the thing is... you paid prolly $150 for that 2 farad cap, in fact I could bet you paid more. and for $150 you can get a more powerful alternator that will also stop dimming and allow you to put an even more powerful amp in your vehicle.
 

Member02

Audio GOD
also, another thing, caps work like the placebo effect with pills, you place one in your vehicle, it seems louder, only because that is what you want and expect for all the money you paid. I also thought that once with my old 12" and 1500 watts I had. but I had access to a professional audio control microphone and tested with a cap and without, I scored the exact same dB, but yet I thought it was louder with the cap. placebo.
 

JayLS5

New Member
Member02 said:
I understand what you might be thinking... but you see, a capacitor won't slowly drain, they don't have that abilty like a battery. they drain instantaneously all at once when the power is needed, they don't drain bit by bit because they cannot. if you have the chance, find a small electric motor, a tiny one, that operates at say... 6-12 volts, connect it to the charged capacitor and you'll find it will last only a few seconds before dramatically slowing down due to loss of voltage/charge. and as I've said unless you are on that very 'fringe where you just need a tiny bit more power to the amp it won't help. you however have a small amount of power I can see it possibly helping... but the thing is... you paid prolly $150 for that 2 farad cap, in fact I could bet you paid more. and for $150 you can get a more powerful alternator that will also stop dimming and allow you to put an even more powerful amp in your vehicle.
The voltage of the motor doesn't matter. It matters how much current it draws at that voltage. For example... the 12V motors you gave me ran a very long time on that crappy cap of mine. On the other hand, a 6V motor that ran the hand vac drained the cap in a few secs...

In either case, you are right about the car audio.
 

AnotherV6

Alumni
Aaronck said:
class ab run about50-60% efficent vs class d 80-85%
Eh, whatever, I wasn't sure on numbers. When I looked them up I found about 60% for ABs and since class D varies it's drawn voltage to accomodate necessary amplification, it's efficiency is closer to 90-95% as far as Drawn voltage compared to used voltage goes.

The online Car audio Mathematics Expert

http://www.bcae1.com/
 

Aaronck

New Member
AnotherV6 said:
Eh, whatever, I wasn't sure on numbers. When I looked them up I found about 60% for ABs and since class D varies it's drawn voltage to accomodate necessary amplification, it's efficiency is closer to 90-95% as far as Drawn voltage compared to used voltage goes.

The online Car audio Mathematics Expert

http://www.bcae1.com/
all the power an amp draws gets used it just doesn't all turn into music alot goes to heat. that is why class d's run cooler since less of the power they draw turns to heat waste.
 

poh22

New Member
Actually, caps aren't useless. With all the converting from AC to DC and back from the battery <-> alternator, you get pulses in the DC power that powers the amp. Caps do help for a steady flow of power, but they filter a lot. They get rid of the pulses in the power flow to the amp.. They may not be completely neccisary, but if you want more SQ, a cap would help that
 
Top