Capacitors Aren't Useless

[snoopdan 5,000+ posts]

Ive considered trying it for the fun of it though....Ive got a bunch of caps that have been left in my garage after I removed them from other peoples systems. Next time someone comes to me with a vehicle thats got headlights dimming, i'll probably try it //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

....then actually fix the problem.

 

[scoob8000 10+ year member]

I dunno, I bought a cap years ago when I first started playing with car audio. I mainly bought it because I thought it was a cool idea (in a geeky way).

I've used it in some systems since then and never really noticed a difference.

I forget who told me this some years ago, but they way it was explained to me about the only use for a cap is to tie it directly into your B+ distro block feeding the amps for your highs.

Mainly to help keep a constant voltage to the high amps whenever the sub hits.

Don't know how much truth there is to that. That's just what I've been told.

I suppose it would be easy enough to test with a quality DVOM. Watch the input voltage at the amp while playing a tuen with wide dynamic range, test with and without the cap and see what happens.

 

[audioholic 5,000+ posts]

I dunno, I bought a cap years ago when I first started playing with car audio. I mainly bought it because I thought it was a cool idea (in a geeky way).
I've used it in some systems since then and never really noticed a difference.

I forget who told me this some years ago, but they way it was explained to me about the only use for a cap is to tie it directly into your B+ distro block feeding the amps for your highs.

Mainly to help keep a constant voltage to the high amps whenever the sub hits.

Don't know how much truth there is to that. That's just what I've been told.

I suppose it would be easy enough to test with a quality DVOM. Watch the input voltage at the amp while playing a tuen with wide dynamic range, test with and without the cap and see what happens.

So basically what you are saying is, you didn't read the thread.

 

[natisfynest 10+ year member]

stupidity is bliss

 

[guting 10+ year member]

omg

 

[joetama 5,000+ posts]

From my experience working with power supplies in A/C amplifiers you can have the right amount of capacitance and you can have a better amount of capacitance.

In a car your main filter for ripple voltage is the battery. However, smaller value capacitors are going to have a much faster charge and discharge rate therefor adding them to the system lowers the ripple current even more. They also are going to have a higher V/S or rise time. In an amplifier design these secondary capacitors are known as bypass capacitors.

But, honestly adding a 5F Capacitor doesn't really do any good as it is acting more as a power source than a bypass capacitor. You can't think of a capacitor as a second tank of gas, nor should you really think of your battery this way. Your Alt should always be the primary source of power, unless the motor isn't running.

 

[audioholic 5,000+ posts]

If the engine is running, the alt IS the primary power source. Even if system voltage drops to battery voltage and the batts end up providing current, the alt is still putting out its maximum potential (assuming sufficient RPM's).

 

[joetama 5,000+ posts]

If the engine is running, the alt IS the primary power source. Even if system voltage drops to battery voltage and the batts end up providing current, the alt is still putting out its maximum potential (assuming sufficient RPM's).

You are correct. But the battery isn't the power source, it is a place to store electrical energy until you need it later. It spaces current usage from the alternator over time. You have to think of the time factor. Remember you aren't using current constantly so you can space the 100% alternator usage over time storing power to be used later. This is what gives you the constant voltage when the alternator isn't producing 100% power. Another filter capacitor (stiffening, bypass, etc etc) just gives you another place to store power. If you go with a good quality capacitor the voltage charge and discharge rates are faster than the battery for spikes in current usage. This gives you a much more constant voltage.

 

[mrogowski 5,000+ posts]

Many times when people hear or see caps/capacitors mentioned, they say "get rid of it" or "it's just a waste of money and it's useless", etc.
Well, I picked up a cheap 1.2 farad Tsunami cap and installed it in my system and I liked it. First of all, I didn't get it to "fix" headlight dimming or to "beef up" my electrical system. I got it for power conditioning and the AC ripple filtering that I read about.

I already had a 170A HO alt, Kinetik HC1800, Kinetik HC600, and 1/0 gauge Big 3 before ever getting the cap and never had power issues.

But after installing the cap, I could hear a noticeable difference in sound quality. If I could describe it, I'd say that before I was listening to nice sounds, but now I can hear nice music. It makes sense I guess that if a cap cleans or conditions your power line of noise and AC ripple, then at the end of the link you end up with purer sound. Clean power in = clean audio out.

So I Google'd and looked around to see what other people thought, and found this post from a guy named Larry Frederick:

I'm not the first to say it, but after having my own experience with caps, I can say that they do have a place in car audio and they're not just pieces of junk.

For the SPL fanatic, it looks like they do more harm than good, but for SQ purists, I think they cam be beneficial.

If you believe what the guy says about your capacitor actually filtering out ripple, here's a small test you can do.

A 1.2F cap is *most definitely* not needed to filter the ripple from an alternator. You can smooth it nicely with a couple of 100uF 20 volt Electrolytics. Run to Radio Shack and snag a couple. Then sit down and listen to your system with the 1.2F cap and then replace it with the smaller ones. See if you can notice a difference.

Then let us know...

 

[snoopdan 5,000+ posts]

If you believe what the guy says about your capacitor actually filtering out ripple, here's a small test you can do.
A 1.2F cap is *most definitely* not needed to filter the ripple from an alternator. You can smooth it nicely with a couple of 100uF 20 volt Electrolytics. Run to Radio Shack and snag a couple. Then sit down and listen to your system with the 1.2F cap and then replace it with the smaller ones. See if you can notice a difference.

Then let us know...

Instigator! //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[audioholic 5,000+ posts]

You are correct. But the battery isn't the power source, it is a place to store electrical energy until you need it later. It spaces current usage from the alternator over time. You have to think of the time factor.

I dont believe anything I said contradicts that.
But to play devil's advocate, the term 'source' could be applied to a battery when it is being used to supply current. Such as engine-off sessions, or times when the alternator is insufficient to supply current needs. But that's a simple argument of word definitions. You are correct that all electrical power originates from the alternator.

 

[mrogowski 5,000+ posts]

Instigator! //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Actually this suggestion is legitimate. It would be interesting to see if he hears a difference when switching components out.

 

[jer_stud56 10+ year member]

I totally respect helotaxi and audioholic.

Idk what either of them do or who they are, but they sure make me understand what they're saying and know what they're talking about.

That being said, I think caps do not do much for anything useful. Money can be better spent elsewhere.

 

[joetama 5,000+ posts]

I dont believe anything I said contradicts that.
But to play devil's advocate, the term 'source' could be applied to a battery when it is being used to supply current. Such as engine-off sessions, or times when the alternator is insufficient to supply current needs. But that's a simple argument of word definitions. You are correct that all electrical power originates from the alternator.

Sorry I didn't mean to be argumentative or anything.

I just read your post quickly and am used to dealing with knuckle heads here.

 

[helotaxi 5,000+ posts]

I just read your post quickly and am used to dealing with knuckle heads here.

I can't imagine why that would be the case...