capacitor instal quick Q

1933 Views 17 Replies 7 Participants Last post by Stealth, Feb 9, 2005

Hamsterman

Discussion Starter · Jun 23, 2004

I installed an SPL 1.2 farad cap a little while ago- i am pushing 1 12" kicker compvr and just wanted the assurance of the cap- also makes my system look better and what not...

the question i have is about the power wire that leads from the cap to the amp... I think i remember reading somewhere that the wire should not be more than 18 inches, but i wanted to use a longer wire so i could instal my cap on the back deck of my cam inbetween the 6x9's... right now it is just on the back of the rear seats like the amp... does anyone know if the cap wire should truly not exceed 18 inches- or if that was bogus info- i read lots o' crap on the web :thumbup:

thanks
nate

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Pineapple

· #2 · Jun 23, 2004

Cap should be as close to the amp as possible to be effictive. If its too far away, it'll like no cap at all. Don't know how far is far but I have mine right beside the amp.

Hamsterman

Discussion Starter · #3 · Jun 24, 2004

yeah, i have mine next to the amp right now too, but it took all 18 inches of wire just to get it to be that close!

eddiem67

· #4 · Jun 24, 2004

Why are you putting in a cap to begin with, did you upgrade the big 3 first? If you haven't you haven't fixed anything, your just causing more strain on the battery and alt.

JaJay721

· #5 · Jun 24, 2004 (Edited)

The closer the cap is to your amp the better off you are. I don't know if there is a general rule, but I think 18 inches is too far. As said before upgrade your battery ground, alt ground and battery - alt wires first. See what you need from there. I'd take a new alternator before a cap and if I did do a cap it wouldn't be a little 1 farad pos. But, since you're only running one 12" Compvr I'd say the money spent on even the 1farad cap was a waste. You shouldn't need a cap to run a few hundred watts.

With the $100 you wasted on the cap you could have gotten an L5 or a better driver. But, I guess your system looks better with an SPL cap. I would have gone with a better sounding system personally.

david in germany

· #6 · Jun 24, 2004 (Edited)

eddiem67 said:
Why are you putting in a cap to begin with, did you upgrade the big 3 first? If you haven't you haven't fixed anything, your just causing more strain on the battery and alt.

???????

where did you Hear that? with the addition of a cap generaly there is no need for any other power upgrade...
the cap will not assist when the car is off but when running there is nothing that would be better.
larger batteries add more of a strain to the system than any other upgrade but extend the vehical off listening times a larger alternator would help a little but the cap is 10 x faster energy than the pulses created by an alternator. under 18" from the battery is the IASCA text book perfect install for a fuse between the battery and the amp. the cap should on the other hand be "as close as possable" to the amp
David

Hamsterman

Discussion Starter · #7 · Jun 24, 2004

JaJay721 said:
With the $100 you wasted on the cap you could have gotten an L5 or a better driver. But, I guess your system looks better with an SPL cap. I would have gone with a better sounding system personally.

yeah well that is good and all- but the cap only cost me $50- and my system is fine, my headlights do not dim anymore with the cap and i got a buddy hooking me up with an optima for around $1-120... I appreciate you other info but i didn't "waste" money on the cap- i got a good deal and i would buy the battery now- just gotta wait for my buddy to hook me up, i would like some extra sound equip- but actually the kicker puts out enough bass for me, i wanna save my hearing since i am not doing any comps or anything

thanks everyone for the info though- i am considering

eddiem67

· #8 · Jun 25, 2004 (Edited)

david in germany said:
??????? where did you Hear that? with the addition of a cap generaly there is no need for any other power upgrade...
the cap will not assist when the car is off but when running there is nothing that would be better.
larger batteries add more of a strain to the system than any other upgrade but extend the vehical off listening times a larger alternator would help a little but the cap is 10 x faster energy than the pulses created by an alternator. under 18" from the battery is the IASCA text book perfect install for a fuse between the battery and the amp. the cap should on the other hand be "as close as possable" to the amp
David

So where do you think the cap gets its voltage from, some magic power source built inside it? No from the battery. So now not only are you supplying power to the amp, now you need to for the cap as well. Its a buffer but not a good one. now say he hasn't upgraded the big 3 and has a cap in his car, That is like water flowing through a straw to a cup, now you add another cup (a cap) so now the water needs to fill both cups, that would be very hard to do and put a huge strain on the alt. But if he upgraded his big 3, then the water would flow through a water hose (larger gauge wire), more flow, more current. Now the amp will be happy because it is getting the voltage it needs without a cap. Also you battery theory is bogus, most aftermarket batts, ie Optima, SVR, Odyssey are deep cycle high output batts, and with a magic 3 upgrade, the alt will charge the bat just fine. Alt is the key source, if your alt cant support you system, then nothing can fix it, not even 5 caps.

david in germany

· #9 · Jun 25, 2004 (Edited)

the batterie does not power the system, the alternator is the correct power sorce, but You also need to know how a cap works before you say that it is like another cup. think of it more as a valve. the alternator produces pulses (you probably knew that) and the design of a cap is to buffer those pulses and create an open state when the pulse of the alternator is not present. for the cap to do that it's electrical properties need to alow it to be able to dump its "load" about 100 times faster than those pulses that the alternator is producing.
in short terms when the alternator pulses the cap charges, when the pulse dies down the cap releases it'S pulse which inturn creates a more solid power sorce.

most recomend .5 farad for every 500 watts rms I say 1-1.5 farad for every 250watts rms

as for my celica I was running a custom built 140A alternator, 1 optima red top, and 3.5 farads worth of caps (harrison labs)
the MOST noticable difference came from the caps since a High output alternator generaly has a "lower output" at idle than the stock model.
to test some of these pieces of info that I have just given you you can do some experiments (make sure your caps , battery, and alt are all in good shape first though.) (and at your own risk)
I will not be held resonsable for you jacking up your stuff

1. while tha car is running check the voltage at the amp

2. disconnect the battery (with stereo on)
and measure the voltage at the amp

3. same thing but with caps hooked up

4. then the same test with battery hooked up.

by the way I have been installing car audio since 1987...

this post is not to flame but to inform.

David

by the way I looked at your Camry, Looks Nice! Sweet that you didn't get all crazy with modding it!

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eddiem67

· #10 · Jun 25, 2004

Wow, someone who has been doing systems as long as I have. Well I used to use caps at one time, with my honda. My honda had a 60amp alt, so I supplied 2 digital caps to support the alt and bat, was running old ppi 2000watts, well at idle with music at 80 percent I dipped well below 11V, the caps help for like 5 seconds and then they were drained. So amp would get hot due to lack of current. So I upgraded the alt to a 150amp, left the cap on, steady 14.4 dipped to 13.4 at 80% volume, so I figured hey I guess I dont need the caps, so I removed them, and my voltage still read 14.4 and dipped to 13.5 at 80% volume the alt supplied the battery which didn't have to fight witht he caps for power from the alt. So that is why I would rather invest on a battery (a bigger cap if you think about it) than a cap and upgrade the alt to what is necessary to run all your equipment. My alt is set up to put out more amps at idle, dominick can customize your alt to whatever amount of amps you want it to put out at idle.

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Pineapple

· #11 · Jun 25, 2004

Ther was a website with the guy put the whole system on a oscilloscope to see how well a cap work. He recorded voltage change with same piece of music with and without cap. The result, cap does filter and smooth out the curve but doesn't supply the voltage needed during bass hit like most of us believe. It'll block out some high freq noise in the system and that's about it.
As long as the system can't supply enough power, a cap will not save you. In order to keep the system running, the alt need to supply enough amp to run the system and some extra to charge the cap and battery.
A cap will not add much load to the alt. When its full it'll not take any power from the system. Unless its a very bad cap which leak power by itself.

Do I have a cap? Oh yea

:

david in germany

· #12 · Jun 26, 2004

eddiem67 said:
My alt is set up to put out more amps at idle, dominick can customize your alt to whatever amount of amps you want it to put out at idle.

that is the key. But the design of the cap and the battery are completely different. I believe that a high output alternator is a big BIG plus when you are running lots and lots of watts but for the average system (500 watts RMS) the alternator is really not that much of a benefit. you said you were running 2000 watts of PPI correct? in your case the Big 3 you mentioned were a must. ( (I am assuming the big 3 for you are bigger battery, bigger cable, better alt) most people wopuld see the most benefit with upgrading the grounds from the chassy to the engine then running a better alternator.
Have a great day!

JaJay721

· #13 · Jun 26, 2004

The big three is the battery, alt grounds and the alt/battery power wire.

eddiem67

· #14 · Jun 27, 2004

Uh the big 3 is Ground wire from Bat to Chassis, Ground wire from chassis to engine block, and Power wire from alt to Battery. Here is link of a step by step on how to do this. Upgrading the big 3 should take care of majority systems keeping your stock alt and battery.

http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic;f=5;t=007801

whocares04

· #15 · Feb 3, 2005 (Edited)

i'm not taking sides just telling you my experience....

my old system (had for 4mos.) was pushing 400W w/cap and i didn't have dim, but then it got stolen.

my current system (had for 5mos.) is about 500W w/o cap (b/c i'm a poor college student) and i current have a dead battery. i had dim thruout this system and listen to people saying "You don't need a cap." The battery was brand new a little under a year ago.

My experience has been that a cap has helped eliminate dim and allow my batt. enough juice to start.

Edit: Getting ready to get a good deal on a Power Acoustik 5 Farad cap for $100, so i'm gonna buy and install.

eddiem67

· #16 · Feb 3, 2005

I see you have an MTX now, so what amp were you running before?

whocares04

· #17 · Feb 8, 2005

eddiem67 said:
I see you have an MTX now, so what amp were you running before?

assuming ur talking to me...i had a lanzar powering 2 JLs (w0s) i believe

Stealth

· #18 · Feb 9, 2005

5 farad cap... for 500w? that can't be good for the system.

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