what size / brand capacitor?

[autobahnsho]

I just got a wiring harness for my van from Crutchfield.com and read their "how to install a stereo" guide for fun. (It's free with most orders.) Here is a small excerpt I scanned in. I trust them, they sell a lot of stuff for a reason. (Page 21)

Demands of a multi-amp system
Can your vehicle handle several amps?
Your vehicle's electrical system is designed to supply the car's components with enough power to operate properly and keep the battery charged.
Some systems are built for additional loads (towing packages, for example), but most arenot. Manufacturers do design their electrical systems with a reserve capacity to power a sound system.
Check the tag on the side of your car's alternator. It shows your alternator's amp rating (how much current in amps it produces). Most produce 55-65 amps. This is adequate for sound systems up ic 350 watts RMS.
Most German automobiles have charging sys¬tems, rated up to about 90 amps. This will work for systems up to 500 watts. Some Hondas, on the other hand, are rated for 35 amps. This will support system- up to 125 watts.
If you want more power than your alternator supplies. Yon can have it rebuilt for higher out¬put, or invest in a high-output aftermarket model. Unfortunately, we can't help you with this.
Installing a second battery only helps you play your stereo with the engine off.

How you use your system helps determine current draw
A system at one-third volume draws considerably less current than it does at three-quarter volume, and may not need a charging system upgrade if the volume level is kept reasonable.
On the other hand, you may be asking for trouble if you keep it cranked. If your amp needs more power than the alternator supplies, it can get some from the battery, but only up to a point.

Estimate your electrical current demands
To calculate the current draw of your amp, multi¬ply the number of channels by the RMS watts per channel (for multiple amps, add the current draw figures to arrive at a grand total). Double it. Finally, divide by 13.8 (the average number of volts an alternator produces). The result is your system's approximate current draw in amperes.

Estimate your reserve current capacity
Take your alternator's amp rating and multiply it by 40% (0.4). This will give you an idea of your electrical system's reserve capacity. Say your alternator's rated at 90 amps; 90 x 40% = 36 amps left to power your sound system. If this is higher than your estimated current draw, you're in good shape.

Power line capacitors for big bass
If your dash lights dim every time your sub hits a strong bass beat, the stereo is demanding too much current from your electrical system.
The best remedy for this is to install a capaci¬tor on the power lead of your sub amp. A capaci¬tor stores current for release when the amp needs short bursts of energy for loud, deep bass notes.
The capacitor does a better job of supplying short bursts of current than your alternator can. The current doesn't have to overcome the inter¬nal resistance of the alternator and the battery or travel through 20 feet of wire to get to your amp.

 

[yamahaSHO]

1 farad will support 1000 watts RMS.... Use 1.5 farad at a minimum.

 

[blk\blk90]

It doesn't matter if you put on in though; it's just for peak's in the music. It doesn't supply a steady stream of power. Think of it as N2O for your amp. When you need it it will be there, but it's very limited till it refills.(bad analogy I know)

 

[autobahnsho]

It doesn't matter if you put on in though; it's just for peak's in the music. It doesn't supply a steady stream of power. Think of it as N2O for your amp. When you need it it will be there, but it's very limited till it refills.(bad analogy I know)

Actually, the analogy is a good one. Just as N2O doesn't make your engine more powerful, it allows the fuel to burn better.

A capacitor doesn't make your stereo any more powerful, just allows the current to burn better.

And like you said, the Cap isn't a power source, but has to refill. It won't add juice to the system, just store a little for when it's needed.

ps- at work we use some 5000 volt capacitors for highpowered satellite and microwave radio systems...

 

[K-Dawg]

Power line capacitors for big bass
If your dash lights dim every time your sub hits a strong bass beat, the stereo is demanding too much current from your electrical system.
The best remedy for this is to install a capaci¬tor on the power lead of your sub amp. A capaci¬tor stores current for release when the amp needs short bursts of energy for loud, deep bass notes.
The capacitor does a better job of supplying short bursts of current than your alternator can. The current doesn't have to overcome the inter¬nal resistance of the alternator and the battery or travel through 20 feet of wire to get to your amp.

You trust a company that's trying to sell you something to be objective?

 

[autobahnsho]

You trust a company that's trying to sell you something to be objective?

Sometimes. They want you to install it yourself and order from them, rather than go pay a shop to do it.
OF COURSE they want you to buy more stuff from them, but the whole booklet does a very good job of explaining what each component does and whether you need it or not.

 

[yamahaSHO]

It doesn't matter if you put on in though; it's just for peak's in the music. It doesn't supply a steady stream of power. Think of it as N2O for your amp. When you need it it will be there, but it's very limited till it refills.(bad analogy I know)

Uh, actually, if you look in all the good amps, they already have many large capacitors in them. Musical peaks are when most really start to lose power. Yes, caps to help. If you have had bad luck, it was not big enough.

 

[ViPER1313]

Side note - don't ever waste money on so called "high quality" interconnects. I've been a member of Hydrogenaudio.org for a long time, and tests have shown there is virtually no difference between $0.10 a foot lamp cord and cables such as these - http://www.harmonictech.com/product_detail_speaker_cables.asp?keyword=34 (take a look at the price.) Just thought I'd let ya know......

 

[qwik huh]

They wanted $600.00 for the subwoofer. I though that was a little high myself.

Thats actually fairly reasonable if its quality glass work....its not easy to do by any means and takes quite a bit of time

 

[blk\blk90]

Uh, actually, if you look in all the good amps, they already have many large capacitors in them. Musical peaks are when most really start to lose power. Yes, caps to help. If you have had bad luck, it was not big enough.

Yeah, they have 'em inside. That's how it was designed. The big caps you buy are worthless though.

 

[yamahaSHO]

You don't know electronics very well, do you?

 

[yamahaSHO]

Yeah, they have 'em inside. That's how it was designed. The big caps you buy are worthless though.

You don't know your electronics very well, do you? Capacitors do to work... In fact, I started my car from a cap before.

I know how amplifiers work, I work at the component level of circuit boards on a daily basis.

 

[autobahnsho]

Heheheh
I saw an older BMW station wagon just yesterday with crazy amounts of stereo mounted to the back seat. They had a cap the size of a Big Gulp mounted next to the amp!!

 

[Dave Ladely]

capacitor ignorance

Here is an example of a little knowledge being worse than none at all!!
Sure, look in hme audio amps and you will see large caps, but they are for filtering the power supply, which is converting AC to DC - not as inferior substitute batteriies as is the case in DC car audio! DC car audio does not need filteringThe part in the home amps that should occupy attention is the size of the Power tansformer, which is the AC version of alternator/battery! So, the larger output the alternator, and the larger tha battery, and low resistance, high current cables are the soul of power.

So a capacitor in series in a DC line is about useless, besides, it really soaks up alternator power to charge it! And when it discharges, it does so in milliseconds. Since you have dimming lights, the problem occupies SECONDS,. literally thousands of times LONGER than the cap can supply!!
Why is it that people will spend hundreds of dollars on what is basically useless and a hype, when they won't spend the money on a high output alternator and larger battery? And the alternator should put out good output at low rpm, which the one wire alternators generally dont. I had a 160 amp alternator, large case, and an 8HD battery, and used 0 marine cables, which have a higher capacity than the auto versions, but are less profit oriented. I also use marine/aircraft DC breakers, not gold plated dinosaur fuses. Talk about gilding the lily, literally!!
Needless to say, my lights never thought of dimming! And my sound was rock hard, no sag. Regarding cables, what a crock and a hype! Using gigahertz theories on mere audio frequencies is fraud! Talk about subjective biased opinions, the shrinks should do a study on that!! Profit sure is an incentive for extolling falsehoods and motive for bias!!
The guy who started the "superamp" rage back in 1966 (by getting Bob Carver to help him build a stereo amp 4 times larger than the largest available then ,the 150 watt McInsosh model 275 and dual Marantz model 9s, and started Phase Linear Company, builder of the first monster amps.

Get a high output alternator and a bigger or second battery!! Second battery should be deep discharge type. Your lights will stop dimming and your sound will improve greatly. That high current is the problem

 

[yamahaSHO]

Here is an example of a little knowledge being worse than none at all!!

Would you like to know what I do for a living?

Sure, look in hme audio amps and you will see large caps, but they are for filtering the power supply, which is converting AC to DC - not as inferior substitute batteriies as is the case in DC car audio!

True, but not all of them.

 

[Dave Ladely]

capacitors

The large capacitors referred to by a post to support by inference, however incorrect the premise, were almost certainly all large electrolytic power supply capacitors, as I said. The exceptions are smaller and unlikely to be the ones referred to.
This idea of using huge capacitors in a typically overcompensatory method of avoiding the real problem and real solution has been encouraged by greedy manufacterers and greedy ignorant, bs' ing salespeople.
Why so many seem desperate for a "band aid" fix that is not a fix is beyond me. Maybe they shy away from having to replace tiheir alternators and batteries, so the avoid reality. I remember in the mid 60's when fools, and I use the term accurately, would insist, without anything but subjectivity and bias, that the Macs and Marantz amplifiers were "more than powerful enough" and ridiculed my express belief that way more power, not just a few percent more, but a tripling or more, was necessary to bring life to music Even the magazines claimed 150 watts rms was more than any hme, however large, whatever interior, whether "live" or "dead", and were adamant about that false and untested claim. They completely ignored the reality of the 3db problem: that every slight increase in loudness was about a 3db increase and every 3db increase demanded a doubling of power, which is a terrible consideration: background music, say 10 watts, then click click click etc to 7 clicks and mroe, goes the volume control to lifelike, not really loud, level, and, doing the math, over a thousand watts is soon demanded but seldom supplied. Then that is assuming 100% efficiency, so with say, 50% efficiency, that doubles the power necessary! Ouch!

The PHase Linear 700A turned all that on its head, having over 700 watts rms, and now even some car stereos have that much power!! And the power supply had large caps, but for filtering AC!
I believe in power to have even a hope to reproduce the energy of an orchestra. My home system is 6000 watts, which is still not enough to accrately reproduce the energy of an orchestra, and I have caused protective circuits to engage,so now I am upping it to biamped 8000 watts and that will be about it as far as I am concerned. I spoke to Arnie Nudell, founder of Infinity and cofounder of Genesis, about the problem and he agreed the biamping with another amp should do the trick. So did Bob Carver, owner of Sunfire.
So, again, I consider the caps to be an ineffective band aid desperately grasped to avoid the horrendous thought of having to spend money replace non-sexy, compared to the hyped gold plated caps,etc, an anemic alternator with one with sufficient power,and replace a battery with insufficient capacity with one that has, such as an 8HD, or a separate deep cycle battery. Start with those basic, fundamental power producers, not avoid them and tack on a cap with only hopes substituted for reality! :****:

 

[Dave Ladely]

capacitor

This will impress then: ten capacitors, each two times the size of the battery, 100 mf, platinum plated: that is the American way of dealing with even imaginary improvements. Like $100/fppt cab;es. etc' after all, the motive is to outdo and impress with glitz, isnt it, like the sound drags? Pure ego? Show offs? Crassness over sophistication. Immaturity over reason. Subjective over objective. The American way.

 

[Dave Ladely]

capacitors

oops, I meant 100 farads, why be pikers!

 

[blk\blk90]

You don't know your electronics very well, do you? Capacitors do to work... In fact, I started my car from a cap before.

I know how amplifiers work, I work at the component level of circuit boards on a daily basis.

I was an electronic technician in the navy for 6 years; I worked at the component level to. But, are you going to jump start your amp w/ a car battery? That cap you used was probably drained all the way. I'm not denying the fact that they put out power; just the fact that you won't ever need that power in your stereo. I had a guy come in today with 4(yes, four) 1000/1 watt amps and 2 300/4 watt amps w/no caps on his system and it runs just fine. bass hits and it dims the radio lights(nothing else) a little. Loudest system I've ever heard, prbably around 155 dB. No caps used. Never have never will.

 

[Shoaz]

My home system is 6000 watts, which is still not enough to accrately reproduce the energy of an orchestra, and I have caused protective circuits to engage,so now I am upping it to biamped 8000 watts and that will be about it as far as I am concerned.

Uh, okay, so big caps and expensive cables don't make sense but an 8kW audio amp to reproduce orchestras does.

BTW,

Sure, look in hme audio amps and you will see large caps, but they are for filtering the power supply, which is converting AC to DC - not as inferior substitute batteriies as is the case in DC car audio! DC car audio does not need filteringThe part in the home amps that should occupy attention is the size of the Power tansformer, which is the AC version of alternator/battery! So, the larger output the alternator, and the larger tha battery, and low resistance, high current cables are the soul of power.

The caps in the car audios, silly as they may be at the sizes people are looking at, are also to filter the supply. No cable is perfect, and the alternator, regulator, and battery all have output resistances that limit the ability to supply transient currents. If the bass is up loud the transient current demands could conceivably outrun the system's ability to supply current. That's all the caps are for, just like in a home stereo, to provide a low-impedance local current supply when the demand dictates.

And most home consumer electronics equipment these days don't have transformers. They're quite a rarity anymore.

So a capacitor in series in a DC line is about useless, besides, it really soaks up alternator power to charge it!

That's why they're put in parallel on the supply line. If you put it in series it'd block the power altogether, but that's the sort of mistake you'd detect quickly.

And when it discharges, it does so in milliseconds. Since you have dimming lights, the problem occupies SECONDS,. literally thousands of times LONGER than the cap can supply!!

The charge/discharge rate will depend on the loading. And the purpose, as I understand it, is to prevent droop on the DC supply during the peaks of the bass cycles, and those don't last very long.

Why is it that people will spend hundreds of dollars on what is basically useless and a hype, when they won't spend the money on a high output alternator and larger battery? And the alternator should put out good output at low rpm, which the one wire alternators generally dont. I had a 160 amp alternator, large case, and an 8HD battery, and used 0 marine cables, which have a higher capacity than the auto versions, but are less profit oriented. I also use marine/aircraft DC breakers, not gold plated dinosaur fuses. Talk about gilding the lily, literally!!

Sounds like maybe you just like a different flavor of hype, which is fine. To each their own.