The SPL guys claim that a capacitor is just a band-aid for a bigger problem - not enough amperage from the electrical system. Going to a high-output alternator should help most, according to that school of thought..
That being said, I've never used either. I haven't seen any signs of excessive current draw.
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, amplifiers are made up a bank 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 and lead plates, as the place of storage. For a more detailed
description of a capacitor, go here:
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 13.5V) 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.
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
A large 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 basically a peashooter. W+e need a Howitzer cannon here, to do the job well.
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 SWEZ says, ・.The cap already shot its wad, an does limp til recharged・ I知 not so certain I will allow him to babysit my kids, but you get the drift. (I never said it quiet like that... and oh...I'm great with kids!)
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痴 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.
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, and I wish my Archie Bunker skills could have said it better myself.
I'm going to have to agree and disagree with some of that post as some points mentioned there are such gross overgeneralizations.
Rather than get into the technical aspects of how a cap works and how it compares to say a 2nd battery in parallel to the starting battery I'll just state the following:
1. A cap will never improve the sound quality of your system.
2. A cap will not fix the problem of an undersized electrical system.
3. The charging and discharging characteristics of a cap is very different from a battery.
4. A system with amps that are rated to draw 200A will never draw 200A while playing music.
5. A cap can help remedy headlight dimming in certain cases.
6. A high output alternator is not always the best solution.
the "old school" dielectric caps aren't the thing to go with. like stated, batteries have a surface charge that can be quantified to capacitance. and there are batteries that charge and discharge super fast these days. putting a battcap or the kinetic, or one of the likes, close to the amps would be a better idea. if you have the space, you can just go ahead and put a good battery close to your amps. a good "dry cell" type is my favorite.
the old idea of 1 farad for 1000w is not good enough. if you want to make a good diff, it needs to be more like 1 farad for every 10 amp draw. which can be in the form of another battery, or a whole trunk of 1 farad dielectric's. but everything needs to be considered on the whole. it's amazing how good a stock alt can do with a good battery and huge + and - wires to feed the amp. and not a simple body ground with a thin ring terminal on a 2kw amp.
sure, a battery has to be charged back up just like a "cap" and caps can charge quickly. but like noted, there are some really good manufacturing techniques of batteries (low esr).
The real benefit to the capacitor is the Electrical Series Resistance which allow for speedy delivery of current. But those big bad many-farad caps are usually made from alternate materials which drive ESR up.
They can't possibly benefit your stereo better than your standard super-low-ESR 1 farad cap models.
IMO, you will get better results by beefing up your alternator, battery, and wiring. Add bigger or extra grounding and charging wires in the engine compartment.
I'm running approximately 2400 watts RMS. Stock 130 amp alternator, Optima battery, upgraded wiring, NO caps, no dimming lights, even when playing bass CDs. My voltage drops a maximum of .2 volts when the bass hits.
i don't think it was mentioned clear enough in that link (or maybe i read a little too fast), is that a cap placed any where in the system will discharge to anywhere in the electrical loop in the vechicle. there are going to be some draw backs to the current going back long runs of wire, or wires a little smaller than desired.
think of volts as pressure. where ever there's a point of higher pressure in the system, it's going to equalize over to the area of lower pressure.
That web page is pretty vague and has a non-related explanation for capacitors.
The diagrams have no relevance to reality, and the order on that page of electrical "upgrades" is pretty illogical.
There are no good pages describing capacitors and their influence on the electrical system that I've ever seen.
A capacitor may influence the electrical discharge and load rates, but for any modern alternator (80+ amps) someone is going to need a massive capacitor with ultra low equivalent resistance at a low duty- 50-100hz (and practical equivalent impedance) to have any real effect on the electrical system. Good luck finding one of those.
The capacitors in amplifiers are implemented for very low current relative to voltage. It's very different than stiffening capacitors, which deal with very high current relative to voltage.
Just by glancing over the page these are 2 major problems, I'm sure there are more:
Quote:
Originally Posted by BETTERAUDIO
A capacitor is added because batteries are slow to give up charge, relatively speaking, and are slow to recharge, where capacitors are nearly instantanious.
Think of it like eliminating a speed bump in the road.
A typical car battery has a reaction rate under a millisecond. Human visual/audible perception is limited to about 1/20 of a second. External resistances (wiring/grounding/amplifiers/etc) are what regulate the discharge rate of a source. So speed of the sources really has nothing to do with this.
Quote:
Originally Posted by BETTERAUDIO
In addition, it puts a higher drag on your engine, which reduces your horsepower at the wheels and accelleration, it is expensive, and it might not even be avaliable for your car, depending on what car you have obviously.
They are also tricky to shop for, because you don't want to end up with a "200 amp" alternator that in reality produces the same or lower output current at idle.
But obviously, the benefits are that a good one can produce more current any time the car is running, if you do fall into the category who needs this.
Realistically though, that's not the majority- there are a whole number of interesting factors to consider though, including not just the wattage of your amps, but your listening habits, the "duty cycle" of the bass that you are playing, recording levels, volume levels, and your batteries recharge/discharge rates and the "duty cycle" there, also...
An alternator's reaction rate is around 2-4ms. Bass is defined by it's duty cycle, someone can't call 3,000hz of an output signal bass. Bass is the load causing the major Vdrop. Thee frequencies are around say 40-120hz, which contribute the most. So a properly sized alternator can discharge "fast" enough into the load; wiring, grounding, proper alternator size, and external components are the major factors determining if the discharge matches the load.
- A capacitor could never cover the shown bass load from T1-T3 in the graph.
- Upgrades 1-2-wiring- are great. #3-capacitors isn't needed, but even if someone were to think it was, it should be added for reducing ripple and shouldn't be a number. #4- battery # increase- isn't going to stop voltage drops from 14.2V to around 11.xx volts. Someone should be upgrading alternator before they start adding batteries, and should only add batteries to listen to music w/ the car off or if their load duty is greater than their source duty.
Nothing against whoever wrote this page, but it’s not factual or relying on realistic principles. It’s just his/her opinion on the subject.
A cap can buffer and smooth out the current. They are used in amp to buffer the "noisy" voltage from our car's electrical system.
There are purposes for them, however, it's not really what people think or better yet what marketing tells them.
There just isn't that "I get mad pounding bass yo cause I run a 100F cap."
The idea of induced resistance should be well understood too. At some point as you run larger caps, you start to raise the resistance to a counterproductive level. You actually build a bottleneck into the system.
No lawn darts in the fairway! This is a golf course damn it!
A cap can buffer and smooth out the current. They are used in amp to buffer the "noisy" voltage from our car's electrical system.
There are purposes for them, however, it's not really what people think or better yet what marketing tells them.
There just isn't that "I get mad pounding bass yo cause I run a 100F cap."
The idea of induced resistance should be well understood too. At some point as you run larger caps, you start to raise the resistance to a counterproductive level. You actually build a bottleneck into the system.
Resurrected.....
Here is my question, or answer, or opinion, im not sure yet...
I have 20 farad Powercore, had it for years and in my last 5 systems. When I get out my spl mic on my Audio Control Spectral Analyzer, I am able to achieve 1.5 more DB with the Capacitor installed. I am also allowed to go 2 more clicks up on my volume control with out audible distortion coming through my speakers? I don't know the numbers, but I know that these are my notable changes from having the 20 farad capacitor installed in my system. If I can get the same thing from an extra battery in the car, so be it. Ill Take my power Core.
So tell me again, it really really does not do anything? Ohh and my headlights don't dim any more too. That is fact, not marketing.
That web page is pretty vague and has a non-related explanation for capacitors.
The diagrams have no relevance to reality, and the order on that page of electrical "upgrades" is pretty illogical.
There are no good pages describing capacitors and their influence on the electrical system that I've ever seen.
A capacitor may influence the electrical discharge and load rates, but for any modern alternator (80+ amps) someone is going to need a massive capacitor with ultra low equivalent resistance at a low duty- 50-100hz (and practical equivalent impedance) to have any real effect on the electrical system. Good luck finding one of those.
The capacitors in amplifiers are implemented for very low current relative to voltage. It's very different than stiffening capacitors, which deal with very high current relative to voltage.
Here is my question, or answer, or opinion, im not sure yet...
I have 20 farad Powercore, had it for years and in my last 5 systems. When I get out my spl mic on my Audio Control Spectral Analyzer, I am able to achieve 1.5 more DB with the Capacitor installed. I am also allowed to go 2 more clicks up on my volume control with out audible distortion coming through my speakers? I don't know the numbers, but I know that these are my notable changes from having the 20 farad capacitor installed in my system. If I can get the same thing from an extra battery in the car, so be it. Ill Take my power Core.
So tell me again, it really really does not do anything? Ohh and my headlights don't dim any more too. That is fact, not marketing.
If you do the math, A 1 farad cap help a 1000 watt stereo for about a half a second. You need larger caps to notice a difference, this is why there are so many arguments over it. If implemented properly they do make a difference, but you need 10's of farads at a minimum with a ultra low esr and proper duty cycle. We are just now in an age where this technology is becoming cheaper because of the implementation of ultra-capacitor technology in hybrid vehicles... which is where my cap comes from. A Maxwell Technologies 500 farad ultra capacitor module.
I had my 6-channel amp's opamp and power supply upgraded to better quality parts / grades. The SQ turned out fantastic after some burn-in. Resolution was greatly improved with excellent transparency
100 farad capacitor?
Linear Mode
