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capacitors?

Discussion in 'Audio' started by jekbrown, Mar 3, 2002.

  1. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    I know guys with big amps and stuff use caps to reduce strain on their electrical system. I'm not an electronics guru, but I know a cap is basically a dry cell battery, stores a charge so when the amps need juice NOW they can get it from the cap. At any rate, my question is, where in the electrical system is the cap usually placed? Would all your electrical devices (off road lights, winches etc!) benefit from it or just your amp(s)? Are there any downsides to using a cap? How much $$$ is reasonable for a cap? I know 1.0 farad caps in Summit were $70-100. If anyone has any general info, or a link to a www site with "the scoop" on caps...lemme know, it'd be greatly appreciated!

    J
     
  2. rebelk5frk

    rebelk5frk 1/2 ton status

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    Capacitors are pretty much only good for amplifers since they can only provide a short burst of energy. They mainly help in situations where the music produces a really large and short peak in the music.... (like a bass drum hitting etc) It won't really help for anything like lights or winches because they pull a constant current. If you aready don't have enough current from your charging system for the constant needs of an amplifer then a capacitor will do little good. The prices you mentioned from summit are about average. Better deals can be found if you look hard enough. As for the connections of a cap. it should be as close to the amplifier as pratical and wired in parallel with the positive and negative wires to the amp.


    hope that helps a bit...
     
  3. BlueKnight

    BlueKnight 1/2 ton status

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    The caps are found on the power leads just prior to the amps. they are only good for extremely quick burst of energy that bass can need. I run nearly 3 farad on my system and very happy with the results. It wouldnt work well or reallt at all on the entire vehicle.
     
  4. '73 K5

    '73 K5 1/2 ton status

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    The other folks are right. The reason a cap helps out so much with stereos is because music is transient...it changes very quickly. The amplifiers consumption needs change very quickly. That is not a good thing when it comes to your vehicles charging system...its slow to charge and slow to discharge. Its meant to be used for a constant, steady amperage draw...like your lights for example. The capacitor can charge and discharge itself very quickly which is perfect for an amp or two. Its like a reserve tank of power for your amps. Hopefully this better explains why a cap wouldn't do anything for lights, etc.
     
  5. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    yeah, i didn't think they did, just thought I'd throw it out there. I do get the little dim going on my lights when my amp really hits some deep bass. Maybe when I add a second amp for my mids/highs I'll toss a cap in too. Then again, I have always said that once my rig is 100% trail only, I wont even have a stereo in it. /forums/images/icons/wink.gif

    J
     
  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Jek,

    If your headlights dim when the bass hits......that's a sure sign that a capacitor is needed!

    The rule of thumb is 1 Farad for each 1000 watts of power.....so a 500 watt system would need 1/2 Farad.

    You'll be amazed at how much cleaner and "tighter" the bass will be with the cap installed.....your amps will be getting FULL power and will control those subs much better. PLUS, you'll actually be able to listen to music AND see down the road at night!!!! /forums/images/icons/laugh.gif
     
  7. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    yeah, I guess so. Do caps have a problem with heat? If I installed one now, the best place would probably be inside one of my rear side panels... so it wouldnt be getting much in the way of ventilation. Is this a problem for a cap?

    J
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    You can check out my stereo install pics in the link below....I've got two 1 Farad caps in the passenger side panel. They don't generate heat.....so they're fine in enclosed spaces.
     
  9. Strahan

    Strahan 1/2 ton status

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    Well, it's a sure sign that something in your charging system isn't pulling its weight. A cap can help the problems, but your alternator still isn't pulling its weight. The cap bandaids the issue because it'll store the current that the alternator is dropping the ball on then get recharged when the bass isn't hitting. I'd get a cap, but also investigate upgrading the alternator. Even asides from a system, it's a worthwhile investment if you make use of other devices (loads of lights, winch, compressor, etc).
     
  10. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Ken,

    I don't know what you are basing your conclusions on....but stiffening caps are an essential part of a high-end audio installation. The typical automotive electrical system is NOT capable of meeting the transient demands of music....neither the alternator or battery will provide the "instantaneous" source of current that is needed.

    While I agree that the rest of the charging system needs to be in proper working order (and potentially upgraded based on accessories)....I think your comments about the capacitors being a "band aid" for a faulty electrical system are wildly inaccurate.

    In the world of audio, there are plenty of products that are all "hype"......however in this case, stiffening caps are a REAL product, based on solid electrical principles. They work!

    My K5 audio system has a maximum current draw of 240 amps....I don't know of ANY other product that would support that type of instantaneous current requirement....
     
  11. Strahan

    Strahan 1/2 ton status

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    I'm basing my conclusions on experience. What I'm saying is that if your lights are dimming, you're drawing more than the alternator can give. Adding caps doesn't increase current, it just pools it. If you aren't running some monster system and you're dimming when the vehicle is running, you really should check the charging system. A cap may make it go away, but the problem is still there. If a person in that situation put caps in then played a 40hz test tone, the lights would still dim.

    So perhaps I didn't word my previous note properly. I'm not saying caps are not good, I always put caps in my systems to bolster current supply but if you are having problems just adding a cap isn't really a fix. A check of the full charging system would be a prudent move at that point.
     
  12. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Ken,.

    Looks like we do agree after all.... I guess in the simplest terms I would summarize by saying: Be sure to have a properly sized charging system FIRST......then add capacitors to ENHANCE the performance of the audio gear.

    I've heard that some guys will use capacitors to help isolate "engine whine" problems......that for SURE is a "band aid" repair!!! /forums/images/icons/smile.gif
     
  13. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    not trying to butt in on my own thread or anything... /forums/images/icons/wink.gif ...but, I dont really want a "high-end" audio system in my rig. Pretty much just asking some punk to break into it to steal it. That said, with the low-end-but-loud-enough-with-the-top-off-at-hwy-speeds system that I have, maybe a cap would still be a good idea. The alternator upgrade is a given, I plan on doing it, just haven't got to it yet. Its benefits for off-road lighting, winching etc make it well worth the cost of the upgrade. Upgrading my stereo system is always a little bit tricky tho, because as my rig moves more and more towards a trail-only rig, it becomes less and less sane to have a big/nice stereo in it. /forums/images/icons/wink.gif

    J
     
  14. Strahan

    Strahan 1/2 ton status

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    I'll drink to that /forums/images/icons/wink.gif
     

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