Hi,

I've got 1 JL Audio amp wired into a 12-speaker Boston speaker system (all 6.5 or smaller) and I'm adding another JL Audio amp Monday and 2 10-inch JL subs

I HAVE noticed a slight loss of instrument lighting when the bass hits from time to time. Is adding the new amp and subs gonna make this worse?

They said they would add the cap for another 200-300 bucks but I want to save my money for another project if its not really needed. The last thing I want to do is cause an electrical problem or harm my speakers, though.

Thanks!

200-300 dollars, WOW, for that just get a high output alt.




2002 Cav.
2.2
5 speed yellow
Yea it's stock,
Yea I know Stock sux.

1 farad cap will do ya just fine. I think the rule of thumb goes...

1 farad for every 1000W. You can get a pretty good 1 Farad cap for under 90 bucks. Cheaper still, on ebay.

RandomGuy 171 wrote:1 farad cap will do ya just fine. I think the rule of thumb goes...

1 farad for every 1000W. You can get a pretty good 1 Farad cap for under 90 bucks. Cheaper still, on ebay.

He is correct. Or .5 Farad for every 500W, but same damn thing.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

I hope this doesn't turn into anouther cap debate from people that don't understand how they work. But, as long as your alt can support the average current draw, then a cap will/should help you with bass hits.


._____________________________.
Causa latet vis est notissima

DIY Clear 03+ Headlights

Grimor wrote:I hope this doesn't turn into anouther cap debate from people that don't understand how they work.

you know it will turn in to one big flame war it always does

here is my opinion a couple post down there is a post call the how to: big 3 try that 1st if that doesn't work then get a deep cycle battery (or get something simular) if all else fail get an a ho alt but im will to be if you do the 1st one, it will most likely solve your problem

Yeah I'd really like to try that but I'm not sure if I'm ready for that kind of project. I'm good at hooking up LEDs, switches, etc and I am somewhat handy with the mechanical aspect, but I'd rather let a professional handle that one.

I'm more of a design-minded person. Some of those mechanical projects can go to hell pretty quick if you don't know what you're doing.

^^^^ its really easy to do, about a half an hour.. I just did mine



hmmmm.... I am confused, and the Blonde genius that is me,
does not easily get confused

Hmm...I'll have to print the thread out and read it while looking at the car. maybe I can do it...

if thats all you have now, i would go out on a limb and say you have power/ground issues. i would tweak every connection b4 buying a damn thing. you may not need it.


mecp certified installer#39272

Like andy said, check all connections b4 buying anything, i had a serious problem at nite with the dimming of my head lights and interior lights, was pushing 3 JLw6's and two hifonics 1000 watt d class, the current all drawing from a factory battery, in some cases may not be the case, will cause you lights to dim, get a hoe alternator, which i did, or another battery, red top, and the cap helps out alot also, i have 2 legacy 1.5 farad caps, but one or the other should help out with your problem....... also, who in the hell told you a cap would cost 200 300 dollars, lol, I have never heard of such a cap, is it made of GOLD lol, cause i LOVE GOLD lol peace hope this helped out. Also check you power and ground wires for freying, black or burnt anywhere on wire, could cause a problem




just riding around in the 4 door cav

A cap can help sustain a regular voltage for like....no time at all. You will never (well...probably never) see a cap with low enough ESL/ESR values to actually provide current for a second.

So without further adu, here is the proof that a cap does not work for increasing SPL. Done by Richard Clark....
http://www.welcometotheden.8k.com/caraudio/Captest.pdf#search='richard%20clark%20capacitor'



Dark Blue curve--no cap and engine off

For our first test we played the system with the engine off and no cap. The result
was the purple trace at the bottom. We played the system as loud as we could get it
that seemed to produce no audible distortion. This was track 30 of the IASCA disc. It
starts off with fairly low level sounds for the first 34 seconds. In order to insure the
electrical system was stable we did not start the measurement until we were 20
seconds into the song. This means that our 0 starting point is :20 on the CD counter.
The battery was able to maintain it's voltage just below 12.5 until the loud bass hits
at 34 seconds (14 seconds into our chart) At this time it dropped to about 11.5 and
had a few large variations due to the music. According to the computer calculations
(third chart) the average voltage for this test was 11.7volts. This test was done as a
baseline for the following tests.

Yellow curve--no cap

For this test the volume was left as it was for the baseline test. The engine was
started. Notice that at low volume the alternator was able to maintain about 14
volts. When the loud music hit the voltage dropped to about 12.5 where it remained
except for a few short moments where it actually climbed back to over 13.5 volts.
The computer averaged calculations for the average voltage during the 100 seconds of this test was 12.973 volts.

Red curve—cap added

This test was identical to the previous test except the cap (15 farad type) was added
6 inches from the amp with 4 gauge wire—no relays or fuses. The red curve seems
to overlay the yellow except that the actual peaks don’t rise as fast or as high during
the brief quiet moments. I feel this would be due to the alternator having to recharge
the cap. The voltage on loud passages hovered around 12.5 volts. The computer
averaged calculations for this test show the average voltage to be 12.878 volts. I see
no meaningful differences with or without the cap. I certainly don’t see the voltage
sitting solid at 14 volts.

One note I might add is that this was a two thousand watt system driven right to
clipping and the average voltage stayed above 12.8 with a stock 80 amp alternator.
Under these conditions the battery would never discharge!
Green and Light Blue Curves--Fun

The green and light blue curves were done just for kicks while we had the system set
up. In both these tests we turned the volume up until the system was very distorted.
This placed a severe load on the alternator and caused the voltage to dip as low as
12 volts. The curves seem to follow each other so closely that unless you have a
good monitor it is doubtful you can tell there are two curves. The average voltage for
these two curves were both 12.277 and 12.295 volts. If this volume were sustained
for very long periods of time this battery would discharge.



kyle

One point about the test above to call into question its validity in a real installation is the fact that they used a 15 farad capacitor in a 2000 watt system. Far above the 1 farad per thousand watt thumb rule.

The time constant for a capacitor is equal to resistance in ohms times capacitance in farads meaning, since the capacitance is seven and a half times the usual amount then the time constant is seven and a half times longer.

This means if it normally took 1 second to charge a 2 farad capacitor, a 15 farad capacitor in the same circuit would take 7.5 seconds to charge. This is a case where more isn't necessarily better.

Another point is that it doesn't state the location that the voltage readings were taken. I would assume they were taken at the amplifier terminals since they were determining the effects on SPL. During high current draws the voltage at the amp will be significantly lower than at the battery due to the voltage drop along the power line. The original poster inquired about instrument lights dimming and since they aren't hooked up to his amplifier terminals you wouldn't get the same results.

I don't know of anyone here who has stated that a capacitor is a good choice in a SPL application.



Can anyone explain to me why all the signal follow the same shape in the segment between 21 and 22 seconds except the yellow one? What is different during this run? With or without the capacitor the shape of the curves should be essentially the same.

Round 1.......fight!

interesting... keep going



hmmmm.... I am confused, and the Blonde genius that is me,
does not easily get confused

Here is an opinion from someone who knows ZERO about hooking up audio electronics.

I went ahead and got the cap, it's a 5 farad. Specs on my 2 amps are above.

I used to get occasional light loss in my needles when the bass hit, and that was with ONE amp and NO subs.

Now I have TWO amps, TWO subs, ONE cap, NO light loss of any kind.

I get nice solid lighting in all areas even when the bass is threatening to shake the car apart.

So I would say that regardless of everything that has been said that contradicts the usefulness of a capacitor, that it definitely does SOMETHING, at least in my limited experience.

I don't see why companies would design, test, develop and sell a product like this unless it worked. Seems that word would spread pretty quickly and they would all be out of business in no time if it did not.

Just an opinion - I have no beef with anyone who says caps are not needed. I can only go from what I have seen in the last 24 hours in my own car.

Hope this helps.

Round 2- FIGHT!

I still say it's a band-aid.. but hey, if it worked, cool!

Yup...just a big freaking band aid.


Go walk around at some comps and count how many caps you see.

Thats because they're hiding that @#$! in the spare tire well.

hehehe

do the big 3 upgrade. if that doesn't help, replace your stock battery with a yellow top.

it is kinda big band aid. and caps are NOT supposed to raise SPL!! they are supposed to take some load off of your factory power system. anyone/company who tells you that is fullavit. cap helped in my car. it depends what kinda music you listen to, and how loud. if you listen to magic mike all day, it wont help. it has to have some breif pauses to recharge.


mecp certified installer#39272

A yellow top battery isn't going to do anything for you when the car is running


-Chris

Yellow tops do help when the car is on because they are able to give energy at a faster rate than the stock battery. so, if your alt can't keep up, the amps will draw from the battery rather than the alt. In this case, the battery will be acting as a huge cap. I know that when i got my yellow top, my lights finally stopped dimming.

schembo2000 wrote:Yellow tops do help when the car is on because they are able to give energy at a faster rate than the stock battery. so, if your alt can't keep up, the amps will draw from the battery rather than the alt. In this case, the battery will be acting as a huge cap. I know that when i got my yellow top, my lights finally stopped dimming.

I say someone needs to make batteries that run at 14.4, that way there wont be any dimming if the electrical system has to rely on the battery and not the alt. Optima redtops run at 12.8 when fully charged... yellow tops run at 13.1 when fully charged and that is why you don't notice the dimming anymore. They should just have batteries that run at 14.4 and then they would get brighter or more powerful when having to rely on the battery.

The last time i brought something like that up someone went into a big long wailing on me about how the cells are a certain voltage and they can't change them and @!#$, and that's why optima would be the perfect company to do so because their batteries dont use traditional cells and if anyone could do it they could

I guess these are kinda just my own theories, I dont have any way to back them up except for the stats I got from optima's website, but I figure to get rid of voltage sag you need to bring the thing with the least amount of voltage up to the same voltage as everything else.

^^^ wouldn't work. Even if you had a battery with a 14.4V rating you'd have to be able to charge it and that would take an alternator putting out somewhere around 16V. The dimming problem would still be there because of the voltage drop from 16V to some lesser value causing the relative brightness of the lights to change.