1.0 farad Cap.

thedeal7235 · Post by **thedeal7235** » Tue Oct 28, 2008 4:11 pm

Ok, so ive searched all the previous posts about this. And, im gonna share what ive experienced. I have a 02 audi A4, red-top, 1/0 gauge going to a stinger spv680 in the rear, from there 4gauge goes into distribution blocks, then fused, then 4 gauge to a ti 600.2(tweets active), a ti 500.4(active to 2 sets of ti 6.5), then lastly another 4gauge to a rsd 1200.1, and a ti voltage display-rddp. So, my voltage usually ranges from 14.1-13.5(the lower at higher musical peaks, ofcourse), but i went ahead and removed the cap. Heres what I noticed, my volts on the rddp have been @ 14.o( at start up-ofcourse), been mainly staying at 13.8, 13.5, and hard bass notes-musical peaks, 12.9-13.2, and also the subs don't sound as clean-so, in the am, I'm gonna put my cap back in, the subs seem to sound,hit cleaner. This is what Ive tested and found only o nmy audi- for some reason a 1.0 farad cap. seems to help-any comments on how/why this is? also, my audi came stock with a bosch 150amp alt.( i saw where vw337 mentioned that if all ur amps fuse-added together- is 200 percent higher than ur stock alternator, then yes replace alt, ive calculated that my stock alt. ,puts me at 100 percent , just a tad bit shy of that, below that mark-

finkle636 · Post by **finkle636** » Tue Oct 28, 2008 6:43 pm

I would have thought that the reason the sub sounds better with the cap is because the amp can pull what it needs faster from the cap than from the battery.

thedeal7235 · Post by **thedeal7235** » Tue Oct 28, 2008 7:04 pm

hmmmmm, good, valid point

KHPower · Post by **KHPower** » Tue Oct 28, 2008 9:38 pm

It could also be that you cap is cleaning up the power going to your amp allowing them to run a lot better. Thats the reason why I use a cap to filter out the ripple

dedlyjedly · Post by **dedlyjedly** » Tue Oct 28, 2008 10:27 pm

people all too often defer to regurgitated internet claims that capacitors are completely worthless! for most initial charging system upgrades that statement may very well be true, but when you have an adequate supply of current for your electronics a capacitor can certainly be beneficial to accurate audio reproduction.

thedeal7235 · Post by **thedeal7235** » Wed Oct 29, 2008 7:31 am

all i know is it sounds better with it, so , when it warms up a bit here, and yes it got down to 42 degrees this am here, very unusal for florida, but will be back to 78/61 by 2morrow, im gonna put it back in, ive drained off the voltage via the 50 ohm 1/2 watt resistor method, but noticed this am, it went from 0.25volts overnight to 0.80volts????

GX3 · Post by **GX3** » Wed Oct 29, 2008 7:55 am

It sounds better because the cap "acts" like a battery it can store electrons (aka power) and release them quite fast we are talking milliseconds. That is why your subs sound better. The amp you are using on your subs is not getting enough power from the alternator so it will pull power from the cap and recharges its self just as fast. as the Sub amp calms down and is not requiring as much power and the cap recharges and is ready for the next HIT . The general rule of thumb is 1.0F cap per 1k watts. unlike batteries caps DON"T add to the stress on your cars charging system and you can never have too much capacitance I'M using a 40F Hybrid cap in my system.

thedeal7235 · Post by **thedeal7235** » Wed Oct 29, 2008 7:58 am

so, i dont remember when i hooked it up having any/checking voltage, but if ive drained it off to under a volt, do i need to be concerned that once i hook up the power, it may spark? ofcourse the anl fuse before the cap would be disconnected-

Post by **stipud** » Wed Oct 29, 2008 11:36 am

GX3 wrote:It sounds better because the cap "acts" like a battery it can store electrons (aka power) and release them quite fast we are talking milliseconds. That is why your subs sound better. The amp you are using on your subs is not getting enough power from the alternator so it will pull power from the cap and recharges its self just as fast. as the Sub amp calms down and is not requiring as much power and the cap recharges and is ready for the next HIT . The general rule of thumb is 1.0F cap per 1k watts. unlike batteries caps DON"T add to the stress on your cars charging system and you can never have too much capacitance I'M using a 40F Hybrid cap in my system.

*Gulp* oh boy... sounds like typical car audio sales nonsense to me.

Caps aren't useful as an energy storage device. Once they are discharged, caps DO cause stress on the electrical system, because they have to be charged back up. Capacitors are a load on the system! So your amp completely unloads the cap in milliseconds, and now the cap AND amp are both drawing current from your alternator/battery, making the situation WORSE. As such, caps are completely useless for SPL. This is why you never see proper SPL rigs with capacitors: they use BATTERIES, because they are made for energy storage... not caps.

Capacitors are used to filter AC ripple. If you hook an oscilloscope to your B+ and B-, you'll see your DC current is not completely DC; there's actually quite a bit of noise on the line, due to how alternators work. A capacitor with low ESR (electronic series resistance) will offer a lot of AC ripple rejection. If you hook up an oscilloscope after the cap, you will see that the DC signal is much cleaner. This makes your amp happier, as the power supply doesn't have to struggle with the fluctuations input current. As such, your stereo will sound a lot better.

This is why they put capacitors in amps... without them, the AC ripple would cause the powersupply to stumble, and your amp would be forced to shut off all the time. For the same reason, they also add filtering caps to the high voltage rails in the amp, so that the output section has minimal ripple after the powersupply. More capacitance = more ripple filtering = better sound quality. Of course the law of diminishing returns applies here, so anything more than 1-2 farads is probably useless... especially when you consider the big aerogel 10+ farad capacitors have much lower ESR and thus do a worse job at ripple filtering.

So, caps can be extremely beneficial, assuming the rest of your system is up to par already. They are certainly NOT a bandaid for insufficient power.

maka78 · Post by **maka78** » Thu Oct 30, 2008 11:51 am

staying with this point... I have a TI 15 Powercore distributing to an X200.4 (among others). The x200.4 has two input +/- locations...

I have a 1 Farad RF cap sitting around somewhere... would it benefit me if I put the cap on one end of the x200.4 and the TI15 Powercore (where the power comes from) on the other side?

Post by **stipud** » Thu Oct 30, 2008 12:18 pm

You could also hook the 1 farad up to a set of + and - terminals on your powercore... I'm assuming you don't have 4 amps to hook up there already. Probably total overkill however...

maka78 · Post by **maka78** » Thu Oct 30, 2008 12:21 pm

Unfortunately I have to use all 4 +/- terminals of the powercore (2 TI400.2s, X200.4, Cadence CDA2500). So you think it's overkill to hook it up to the other side of the 200.4 then?

I could just sell the 1FA cap.

Post by **stipud** » Thu Oct 30, 2008 12:36 pm

You can hook it up there, but I doubt very highly that you will notice a difference.

deathcloud · Post by **deathcloud** » Thu Oct 30, 2008 11:02 pm

Ya i am planning on running a x200.4 (power rsd65cs front.rear) and x1200.1 (2 rsdc124 subs) in the near future and I hope that I do not need a cap because I hope that my wiring and such will be sufficent enough so I don't need a cap that will put more stress on my electrical system. Or I could just wait and save up for a Powercore 15... my dad has his lucky guy cuz i found it and got it for him... But yea after reading what stipud has been saying from the past and again... i feel like you don't really need a cap. especially for what I have hooked up. Correct me if my thinking is wrong. could be.

Post by **stipud** » Fri Oct 31, 2008 6:48 am

Caps are a very good thing. I think every proper system should have one. I would install one in mine if I wasn't so lazy! All of that ripple filtering will make your whole stereo sound much better. 2 farads should be more than enough to do that... low ESR is much more important than the amount of capacitance (farads) beyond this.

BUT people always use them wrong. If your lights are dimming, you should NOT be installing a capacitor as a bandaid. Instead, you need to get your power situation worked out first and foremost.

There's too many threads I see, where people are running a single run of 8 gauge to their 1000w amp, with a shoddy ground, and all factory wiring under the hood. And the first thing they want to do to solve their lights flashing is adding a cap!!! This would make this situation way worse by adding another draw, since that amp is going to be unloading it instantly. In this case, the guy needs to run at LEAST 4 gauge all around, and do the big 3 under his hood before he can even start THINKING about adding a cap. And even then, he needs to make sure his battery and alternator are good enough.

Once your whole power system is sorted out properly, a capacitor is a HUGE asset for taking noise out of the system.

PaulD · Post by **PaulD** » Sat Nov 15, 2008 10:29 pm

ESR is called Equvalent Series Resistance, all electronic devices have an associated resistance and it's modeled by putting a resistor in series with the device.

Why ESR is important: Volts = I(amps) X R(resistance)

If the ESR of a cap is say .040 ohms and you are drawing 150 amps on a peak, the voltage drop wll be 6 volts, making it useless. If your alt is set for 14 volts and your battery floats at 12.5 volts (typical) then you have 1.5 volts to play with ..... the cap will only discharge to a lower voltage. In this example, the max useful ESR would be about .01 ohms.