Capacitor for Amp

[notaverage]

Hi Guys,

I have a small 0.5 farad cap at home that I want to add to my amp. The instructions say that I need to ground the cap and amp separately, is this necessary? Can I just have the positive and ground going to the cap, and then have the postive going to the amp from the cap, and the ground going to the amp from the cap?

Any help would be greatly appreciated

[AppleBonker]

In a worst case scenario you could do this. It would be better for current flow to have both grounded to the chassis somewhere (even if they're grounded to the same point). If you decide to ground the amp to the top of the cap, you will want to run thicker gauge cable from the cap to the ground than from the amp to the cap (on the negative terminal). However, I would recommend grounding separately as the instructions state (this will keep a bottleneck from forming).

[notaverage]

Thanks for the reply, I'll try to see if I can ground it myself this weekend. I finally got a chance to dynamat the trunk lid, it took a long time for me, cuz I'm a noob. But what I noticed was, that the trunk lid has basically two panels that need sound insulation, the inner panel and the outer panel, the inner panel was hard to get your hands on, but I found a way to insulate both. When I do the rest of the trunk, I'll try to find a spot for the ground for the cap.

[AppleBonker]

The bolts for the seat belts are usually pretty strong. If you do use them, though, make sure you don't do anything that would damage their operation. Last thing you want is someone to get hurt because of your stereo.

[notaverage]

On a side note, how should I fill my box with polyfill? Should I pack it in, or lightly drop it in. If I just drop it in, barely any polyfill gets in there, and I am supposed to be using like a pound of it, but I can't fit anywhere close to that amount in my enclosure without trying to tightly pack it in

[shortys408]

iv read on car audio forums that capacitors actually put more strain on your battery. before resorting to the capacitor you should upgrade the wiring under your hood to 1 awg wiring. Look on any car audio forum and they will have more information on this.

[rjdmmfl1]

before resorting to the capacitor you should upgrade the wiring under your hood to 1 awg wiring. Look on any car audio forum and they will have more information on this.

What he's referring to is the big three upgrade, which is a HELL of a lot easier to do on the 2.5 than it is on the 3.5 (the alternator location in the 3.5 is VERY hard to get to)In any ase, applebonker has info on the Big 3 upgrade in his Q and A write up at the top of the page!

iv read on car audio forums that capacitors actually put more strain on your battery. .

I think that depends a lot on what type of battery you have... if you've3 got the crappy factory battery, then yes, this is true. But if you got a nice deep discharge high capacity battery like one of the Kinetics HC power cells, or an Optima yellow Top, Or Stinger or schoshe red top, then these batteries are designed to withstand the drain that a system (and capacitor) puts on the battery, and it doesn't decrease the life of the battery the way it would a wet cell battery

IMO, for the best out of your system, you should do

1. Big 3 upgrade2. Replace factory battery with a Deep discharge battery3. Place another deep discharge battery in the trunk (smaller Kinetik, BATCAP, etc)4. Get one of Sentient's Grounding kits.. (hey, if done properly, it can only help, not hurt)

the 2.5 and 3.5 Altimas have 115 mp and 130 Amp alternators, so replacing this is not necessary IMO, unless you're running a 5000 watt system, which I don;t think anyone on this forum is (applebonker is close)

[notaverage]

Thanks for the details rob, I appreciate it! I have a fairly small system running 400 watts RMS. I only wanted a little more kick to the bass. Unfortunately I ended up getting 8AWG wire because my amp said 8AWG is recommended. I had it installed at a shop, cuz I'd never wired an amp before, and I didnt want to mess up my new car because of my lack of experience. Unfortunately, unless I get help, I doubt I will replace the 8awg power wire with 4awg or 2awg. I will however consider getting a better battery.

Do you think you could also answer my other question above regarding the polyfill? I just took out my subbox and removed the sub, and took out all the polyfill I had in there before, to see if there is a difference in sound. Any help there would be also appreciated! Thanks in advace

[shortys408]

a capacitor isnt going to give you any extra bass. if your head lights are dimming then it will reduce this. I dont think a 400 watt system should cause your headlights to dim, i have a 400 watt system in my a/c and its wired with 8 awg and I have no dimming problems.

[notaverage]

a capacitor isnt going to give you any extra bass. if your head lights are dimming then it will reduce this. I dont think a 400 watt system should cause your headlights to dim, i have a 400 watt system in my a/c and its wired with 8 awg and I have no dimming problems.

Thanks for your reply shorty, my head lights dont dim, but I bought a capacitor when i bought my system, and never hooked it up. The point of the capacitor is to store energy and have it readily available incase the amp requires it. I just want to hook it up cuz I already bought it

[AppleBonker]

Do you think you could also answer my other question above regarding the polyfill? I just took out my subbox and removed the sub, and took out all the polyfill I had in there before, to see if there is a difference in sound. Any help there would be also appreciated! Thanks in advace

There are two extremes when doing this. One, just lightly placing some fill in the box. Two, cramming as much in there as you possibly can and then shoving the sub on top to keep it from spilling out. You should try to aim for about right in the middle of these two. You want to pack the fill in a bit, but you don't want it to be so dense that it is reducing the internal volume of your enclosure. I couldn't help you with if there is a difference or not when using polyfill. I've never used it, but I've always designed my enclosures to the exact specifications of the sub. If the enclosure is perfect for the sub, polyfill probably isn't needed, and wont be beneficial. Sorry if this wasn't helpful enough, this is one thing I have very limited experience with.

[AppleBonker]

iv read on car audio forums that capacitors actually put more strain on your battery. before resorting to the capacitor you should upgrade the wiring under your hood to 1 awg wiring. Look on any car audio forum and they will have more information on this.

This is another one of those hotly debated topics. In my opinion, your statement is correct. Adding anything to your electrical system will put a drain on it. You've got more to charge, so the car will have to work harder to do so. Is this a major problem? Probably not. My first two systems had capacitors, and I had no electrical problems at all. I will also agree that the vast majority of high end mobile audio enthusiasts would never recommend a capacitor. They may recommend an extra battery or an upgraded alternator, but the gains with a capacitor do not validate the cost.

[AppleBonker]

Thanks for your reply shorty, my head lights dont dim, but I bought a capacitor when i bought my system, and never hooked it up. The point of the capacitor is to store energy and have it readily available incase the amp requires it. I just want to hook it up cuz I already bought it

I would say go ahead and connect it. If we want to talk in theories, the capacitor should help the system somewhat. It will have the ability to discharge energy at a faster rate than the battery can. However, capacitors do not have the ability to store anywhere near the amount of energy that a battery can. Therefore, you'll be pulling the same current from the battery and dropping the voltage in nearly the same way (the voltage drop is what would cause dimming headlights if that is happening). The capacitor will merely help keep the depression of voltage not quite as severe (this could be measured, but it certainly shouldn't be a significant amount). So, in theory, there will be an improvement. In reality, however, there will almost certainly not be an audible difference (this is the reason I no longer use capacitors). The important thing is, this really shouldn't damage the system in any way.

[notaverage]

There are two extremes when doing this. One, just lightly placing some fill in the box. Two, cramming as much in there as you possibly can and then shoving the sub on top to keep it from spilling out. You should try to aim for about right in the middle of these two. You want to pack the fill in a bit, but you don't want it to be so dense that it is reducing the internal volume of your enclosure. I couldn't help you with if there is a difference or not when using polyfill. I've never used it, but I've always designed my enclosures to the exact specifications of the sub. If the enclosure is perfect for the sub, polyfill probably isn't needed, and wont be beneficial. Sorry if this wasn't helpful enough, this is one thing I have very limited experience with.

Thanks for the advice! Thats the way I had it before, in the middle of the two extremes. But I started noticing that my subwoofer itself was rattling, and decided to open it up and see whats going on. The subwoofer hits hard, but it rattles like crazy (so I don't think its blown)! I heard that adding polyfill will make the subwoofer think its in a bigger enclosure, so thats why I want to add more polyfill to see if it will stop the rattle. (My box is slightly smalled than the minimum required sealer volume).

Is there any other reason why the sub itself rattles?

EDIT: I have a Kicker CompVR 07CVR104 connected to a Kenwood 8103D amp

Kicker is rated at 400 watts rms and kenwood amp is rated at 500 watts rms

[shortys408]

could be a loose dust cap.

[rjdmmfl1]

(My box is slightly smalled than the minimum required sealer volume).

THat's a good way to blow your sub... it doesn't have the air it needs to breathe... they usually give a range for the sealed box volume, going BELOW THE MINIMUM is never a good idea...

It would have been cheaper to have a regular custom box built to the woofer's specs than to use the generic box you're using, and then blow the sub, only to eventually replace both the sub and the box

[domdada]

Doc, AppleBonker.....I wanted to know if adding a alumipro 5 farad or the 15 farad cap would do me any good while running the Mmats 2200.1 and Rockford t-400-4 amp. I am going to be changing the factory battery and adding a second one in the trunk. Also, going to be doing the big 3 upgrade and possibly a grounding kit.

[notaverage]

THat's a good way to blow your sub... it doesn't have the air it needs to breathe... they usually give a range for the sealed box volume, going BELOW THE MINIMUM is never a good idea...

It would have been cheaper to have a regular custom box built to the woofer's specs than to use the generic box you're using, and then blow the sub, only to eventually replace both the sub and the box

Do you think its blown even though it produces a lot of bass? I can hear and see the sub rattle only when i open the trunk, but when I am inside the car, the bass is hard and loud. I mean its obvious the sub is working at near capacity, thats why I didn't think it was blown...

[AppleBonker]

Doc, AppleBonker.....I wanted to know if adding a alumipro 5 farad or the 15 farad cap would do me any good while running the Mmats 2200.1 and Rockford t-400-4 amp. I am going to be changing the factory battery and adding a second one in the trunk. Also, going to be doing the big 3 upgrade and possibly a grounding kit.

If you haven't purchased a cap already, I would say no. I'm not running one on my setup, and I'm drawing a ton of juice from the alt and batteries. No lights dimming here either. My sundown is rated at 3000 watts rms and my two alpines will pull 900 rms total. I would say big three and upgraded battery in the stock position may cover your needs (depending on where your gain is set on the 2200.1). If the gain is up and you're pulling a ton from the 2200, I would definitely think about adding an extra battery (which you can find for probably just a bit more than a cap). I would steer clear of a cap on this one.

[AppleBonker]

Do you think its blown even though it produces a lot of bass? I can hear and see the sub rattle only when i open the trunk, but when I am inside the car, the bass is hard and loud. I mean its obvious the sub is working at near capacity, thats why I didn't think it was blown...

I'm going to say I doubt it. I've blown a few subs in my day (yeah, I wasn't always smart about my car audio usage), and when they go, they stop functioning altogether. What part of the sub is rattling? You say you can see it rattle, so I'm assuming you're sure it's not just body panels vibrating or something like that? If you're that close to running it at capacity, you might want to double check your gains at max listening volume. Check the FAQ sticky in my sig for a gain setting tutorial (if you haven't seen this before).

[notaverage]

I'm going to say I doubt it. I've blown a few subs in my day (yeah, I wasn't always smart about my car audio usage), and when they go, they stop functioning altogether. What part of the sub is rattling? You say you can see it rattle, so I'm assuming you're sure it's not just body panels vibrating or something like that? If you're that close to running it at capacity, you might want to double check your gains at max listening volume. Check the FAQ sticky in my sig for a gain setting tutorial (if you haven't seen this before).

You are correct, the body panels are not vibrating, the actual rattle is coming from the subwoofer. Honestly, I really dont know what part of the sub is rattling, the cone, the plastic surrounding or what. But the sub is screwed all the way in and my best guess is that the cone is rattling. I read your FAQ for the gain setting, and will adjust my gain with the multimeter as you suggested. Can you recommend anything for the abss boost?

[AppleBonker]

You are correct, the body panels are not vibrating, the actual rattle is coming from the subwoofer. Honestly, I really dont know what part of the sub is rattling, the cone, the plastic surrounding or what. But the sub is screwed all the way in and my best guess is that the cone is rattling. I read your FAQ for the gain setting, and will adjust my gain with the multimeter as you suggested. Can you recommend anything for the abss boost?

Hmm, any chance you can take a video of it? It is possible that the dust cap is becoming separated from the cone and rattling. I guess the cone could also be coming loose, although this is all speculation and hard to determine without seeing in person.

Recommendations for the bass boost? Not sure what you are looking for here. Are you talking about the bass boost dial on the amp? If so, I'd leave it turned down since it generally boosts a specific frequency (and remember from the tutorial that ideally we want a flat frequency response curve, not one with spikes). Setting the gain with the multimeter will set the sub at an appropriate level so it will sound more natural across its operating frequencies. Let me know if I just answered the wrong question.

[notaverage]

Hmm, any chance you can take a video of it? It is possible that the dust cap is becoming separated from the cone and rattling. I guess the cone could also be coming loose, although this is all speculation and hard to determine without seeing in person.

Recommendations for the bass boost? Not sure what you are looking for here. Are you talking about the bass boost dial on the amp? If so, I'd leave it turned down since it generally boosts a specific frequency (and remember from the tutorial that ideally we want a flat frequency response curve, not one with spikes). Setting the gain with the multimeter will set the sub at an appropriate level so it will sound more natural across its operating frequencies. Let me know if I just answered the wrong question.

Sounds good, I'll post a video by this friday to show you. The bass boost thing, you were right on the money, it only boosts certain frequencies, i was just wondering if turning the bass boost dial up on my amp will increase the amount of power going to the subwoofer even though my gain is set to deliver only 400 watts. Basically, will the bass boost make the amount going to the sub more, which can cause it to blow? I know I wasn't very clear in my question. But, I'm just gonna turn it down, like you said!

[AppleBonker]

Sounds good, I'll post a video by this friday to show you. The bass boost thing, you were right on the money, it only boosts certain frequencies, i was just wondering if turning the bass boost dial up on my amp will increase the amount of power going to the subwoofer even though my gain is set to deliver only 400 watts. Basically, will the bass boost make the amount going to the sub more, which can cause it to blow? I know I wasn't very clear in my question. But, I'm just gonna turn it down, like you said!

It will increase power being fed to the sub. If you set the gain with the bass boost all the way down, and then increase the bass boost, you will be feeding more power than you originally set it up for. Like I said, set the gains with the bass boost down, and leave the bb down when you're done. If you're going to be tuning anything like that, I would do it with the head unit or an external EQ. It will probably give you a bunch more flexibility than the selections on the amp.