what size / brand capacitor?

[Venom SHO s7]

Using a HiFonics bx1500d amp, what size capacitor do you recommend running to help with the lights dimming and amp turning off?

It puts out 1500watts RMS at 2ohms, so i was thinking of getting a 1.5 or 2 farad cap for now, then getting thicker battery wires.

Would a 1.5 farad cap be enough? or will even a 1 farad one do the job?

also, does brand really matter in a cap, or more important than brand, are there certain specs i should look for when buying one?

Ive seen Boss, Legacy, and Stingpro caps on Ebay for around 80 bucks ( for the 1.5 and 2 farad caps)

(I know many will say a cap is a p.o.s. or that its only a band aid or the real way to do it is to get a bigger alternator, but many have used a cap with good results and i just dont want to spend that kind of money on an alternator or battery right now)

 

[Slo-Sho]

Depending on the amperage the amp draws...I would say 2 or 0 awg wire with the biggest cap you can afford if not several wired in parallel.

 

[SHO92]

Run big wire and don't use a cap. Go over to the forums on carsound.com and search for "Richard Clark Cap" and read all about why a capacitor is just a way for companies to make money, it doesn't help to any degree that you would be able to hear. Also here is a pdf file that also explains it. If you really want a cap, read as much about them as you can first, then decide for yourself which size you want and how much you want to spend. In the car audio competition world, caps are considered a mostly cosmectic component.

http://www.welcometotheden.8k.com/caraudio/Captest.pdf

 

[mike93lx]

sho92 - i work in a stereo shop and every time we use a capacitor, it makes a difference. have you personally ever used one and not seen a difference?

venom SHO - for the most part, a cap is a cap, so don't worry about brand. as far as size goes, i wouldn't get smaller than a 1.5 farad for that amp. alumapro makes a 5 farad plate capacitor for about $330 that is pretty nice. being a plate cap, its only about an inch thick, so its easier to hide if you so desire.

besides upgrading the power and ground wires for the amp, upgrade the underhood wiring. the ground from the chassis to battery, ground from the block to chassis, and power wire from alternator to battery.

 

[K-Dawg]

I agree with everything that Bill said. Don't throw away your money.

 

[SHO92]

I've used a cap before and then sold it on ebay, it didn't provide anything worth mentioning. My system is also fairly low watts, about 600 total. Look at the PDF file I linked. The difference between using a cap and without one was less then .5 volts, and that was with a Crown 2000 watt amp near clipping! You're never going to notice that >.5 volt difference at anywhere near normal listening levels. Besides that, a cap is supposed to be a fix for an alternator that can't supply what the system needs. Since a cap is pretty much an additional battery, your alt needs to keep that charged along with the stock battery and power the system and anything else that may be on at the time. That cap is an extra load you are placing on an alt that already can't keep up, you're doing your alt a disservice by using a cap. The only time a cap would be of use is on an SPL rig that is trying to "burp" to get the extra DB at a certain level. They don't care about SQ, and its only for short periods of time.

 

[SHOZ123]

I took my ganged 2 Farads of caps and connected it to my brake lights. Gives me a nice fade.........

#2 wire and an Odyssey battery are all you need.

 

[2 4shofast]

I would go with a 2 farad cap. Like said earlier the brand doenst matter too much, but I wouldnt run that much power without one. My opinion....

 

[Venom SHO s7]

First off, thanks for the replies.

Right now im running 4 gauge power and ground wire for the amp.
I was going to use 2 or 0/1 gauge but i found it would be hard to find a way to get it through, and the amp manual recommended 4 gauge.

Ok, I think ill first get thicker/better ground wires from the battery to the chassis of the car.
And maybe get a 2 farad 80 dollar cap off ebay. That way, if it doesnt help, i can at least probably sell it and it would be as big of a waste of money.
Oh btw, I will look at that link you posted.
Again, thanks everyone for their help.

 

[muzik]

Here is a little info to help you out. First a pic of a cap being installed in Rich's personal SHO. http://www.cartunes.com/installs/ford/1990SHO/images/bill_capacitor.jpg Second if you haven't heard of Rich Inferrera or his shop called Rich's Car Tunes check it out here. http://www.cartunes.com/about_us.htm Third the complete install is here. http://www.cartunes.com/installs/ford/1990SHO/90SHO.htm I know it is his personal ride because I tried to buy the subwoofer when he took the stereo out to sell the car.

 

[SHO92]

How does that help with making a decision on if and what cap to buy?? Walk into any stereo shop and there will be caps for sale, that doesn't mean they work effectively. Rich and his shop seem to have done some nice installs by looking through his website and seeing the different articles, but that SHO doesn't seem to reflect the ability of the shop.

 

[muzik]

I was simply trying to give some help. I thought I would share the fact that Rich used a cap in his own car. As for as being for sale in most shops, yes they are but if he was using it as a sales tool why would he hide it behind the seat? Different people have different opinions that what makes life so fun. I doubt I will ever use a cap in any of my installations but that doesn't mean they don't work. Just that I have decided they are not for me. I instead chose to use a second battery in the trunk, which is a whole new story as nobody agrees on that either.

 

[thebigjimsho]

Here is a little info to help you out. First a pic of a cap being installed in Rich's personal SHO. http://www.cartunes.com/installs/ford/1990SHO/images/bill_capacitor.jpg Second if you haven't heard of Rich Inferrera or his shop called Rich's Car Tunes check it out here. http://www.cartunes.com/about_us.htm Third the complete install is here. http://www.cartunes.com/installs/ford/1990SHO/90SHO.htm I know it is his personal ride because I tried to buy the subwoofer when he took the stereo out to sell the car.

Very nice place, very expensive work too. When checking out components and labor rates for a system in my '01 Accord, I stopped by. Got to sit and listen in his '90 SHO for a while. He kept trying to get me to let him put a system in the SHO. Great sound without overkill.

 

[muzik]

Very nice place, very expensive work too. When checking out components and labor rates for a system in my '01 Accord, I stopped by. Got to sit and listen in his '90 SHO for a while. He kept trying to get me to let him put a system in the SHO. Great sound without overkill.

They wanted $600.00 for the subwoofer. I though that was a little high myself.

 

[blk\blk90]

Run big wire and don't use a cap. Go over to the forums on carsound.com and search for "Richard Clark Cap" and read all about why a capacitor is just a way for companies to make money, it doesn't help to any degree that you would be able to hear. Also here is a pdf file that also explains it. If you really want a cap, read as much about them as you can first, then decide for yourself which size you want and how much you want to spend. In the car audio competition world, caps are considered a mostly cosmectic component.]

He's not BSing. I work at Sound Systems Ltd doing home installs but THE car guy(can't stress THE enough)say's they're worthless. We don't sell em and never will. We carry JL Audio, Eclipse, and Alpine, so we're not a crappy store either. Also THE car guy has been in the car audio stuff for around 15 years so he's been around the block.

 

[Shoaz]

I just looked at the pdf for the cap test, which is pretty interesting. A cap should help sustain voltage when the current demand gets large, and it didn't appear to be doing that. It did soften the voltage rises, which you would also expect, but not nearly as much as I'd expect from a 15F (that's HUGE) cap.

The test may have been more meaningful if they'd used a 2-3F cap like it appears that most people use in real applications. That huge cap may have been what kept the charge voltage low. If they'd used a smaller cap it might have come up to peak voltage more quickly and then been able to hold that voltage longer during the high current draw instances.

Admittedly, I'm not a car audio person, my SHO has the original factory stereo, unmodified, as does my truck and most vehicles that I've owned through my lifetime. I am, however, an electrical engineer with a lot of experience, so I'm only speaking from the electrical theory perspective, not an audio application perspective.

An important question to ask is how sensitive your system is to drops in the supply voltage. A lot of systems only require some minimum voltage (say, 11V, for example), and as long as the supply is higher than that it'll work fine. The test did show that without the cap, and even without the alternator, the system held over 11V the entire time. If that doesn't bother the audio, then there is absolutely no reason to use a cap. If it needs 12V, then you need the engine running, but still the difference between cap (albeit probably too large of a cap) and no cap is negligible. Caps won't create power, they just help to smooth the voltage out so that sudden drop outs are held longer until the system catches up. I really can't imagine a current draw from a stereo that would require 2-3F, let alone 15F (what were they thinking!), but, again, I'm not that familiar with the details of car audio. These numbers are way larger than would give a typical engineer great pause, though.

The audio market is historically filled with crap that takes money from customers for no benefit (kinda like what I feel is the equivalent of a K&N filter). Monster Cables come to mind, where the supposed benefits of really expensive cables with some sort of special magic will make you system sound better. There are tons of examples, but it is entirely possible that the same is true about these caps, its more marketing than technology.

 

[blk\blk90]

GEEZ! 15F's! Theres no way you could get enough voltage to even charge that. The main reason caps are there is if you have every accessory on, Something pluged into your cigarette lighter, and your 10,000W system hit a 25hz note @ 150db. That's what a 2-3F cap would be for. Using caps would be like putting a ford 9 inch under a pinto. There's no point unless you got something HUGE under the hood.

 

[SHO92]

I agree that 15F is huge, but that seems to be the recent trend. A lot of companies are coming out with huge caps now, I'm pretty sure there is a 20F cap out now. I'm not an EE, or even just an E, but to me it would seem that a big cap wouldn't be any different that having a 2F cap. Though it might take longer to charge a 15F then a 2F, the 15F will also take longer to discharge, and therefore shouldn't need to be fully charged during stereo play, therefore the charging time wouldn't seem an important factor.

The monster cable is a good point about spending money on worthless things. There are people in the competition scene that go both ways on this. Some people are running interconnects that are ~$100/ft, and then there are others that are using 1 RJ45 Cat6 cable with RCAs soldered onto each pair, and using that as their interconnect cables, cost maybe $10 for the entire cable. Both camps are winning competitions, so is there really a benefit to $100/ft cable versus $10 for the entire thing? It's the same with caps, if you can do it without a cap, why bother having one except to say you have it?

BTW, I find car audio competitions somewhat pointless. Its almost completely subjective, with only one piece of the competition judged using a test machine, everything else is done by a judge who judges on what he hears and sees, and is expected to be impartical. I enjoy the craftsmanship and skill that is involved with making a competition install and the finished product in both sound quality and visual appeal.

 

[Fast4SHO]

I ran an 1,000 watt amp in my old 95 MTX and never had any dimage of lights. I don't know a whole lot about this stuff, but maybe a larger battery would help? Mine was a large duralast one.

 

[SHOZ123]

Caps are band aids for insufficient wiring and the wrong type of battery. A 15 F cap is nothing but electron Bling Bling and a money maker for the seller.

And also forget about the output rating when you are concerned about the input power. What does it draw ~50A, 60A, 70A.....? Output ratings are for speaker choices........