Car Audio Central - Ultimate Car Audio Forum and Community

I bet you couldn't find any manufacturer who actually would say "ground to a different spot"... in other words "don't ground to the same spot as your amps".

The closest you might find would be a manufacturer who states that you don't NEED to ground the capacitor to the same spot as your amps, but that doesn't make it a bad idea - and no manufacturer would [have any basis to] claim that it is a bad idea. ;)

Not to nitpick - but anytime that anyone says "some manufacturers say... while other manufacturers say..." and in reality, they don't really know [i]any [/i]information from [i]any [/i]manufacturers - that's misleading, and it's the wrong way to start a thread. ;)

[quote="energumeno"]1. Is it possible to place the capacitor before a fused distribution block? (Some manufacturers say yes, some others say never put a fuse between the capacitor and the amp.)[/quote]
can you? yes. Is it as effective? questionable.
you want the capacitor to be as electrically close to the amplifier as possible, so between the fuse block and the amp is ideal. It's also generally advised to use 1 farad of capacitance for every kilowatt of power the amp is rated for, so sharing a cap between amps isn't the best idea. Better to dedicate caps to each amp ideally.

[quote]2. Should I wire the ground of the capacitor to the same grounding point of the amps or should i ground it to a different point in my car's chassis? (Again some manufacturers say to ground at a different point, some others suggest at the same point to avoid grounding loops.)
What do you think?[/quote]
doesn't matter. common ground anyway as long as you use sufficient gauge wire to handle the current draw, and have a solid ground connection. Your car's chassis is equal to 4AWG wire anyway due to spot welds that hold the unibody together, so if you need more than 4AWG wire for the system, you're better off running 0AWG wire directly to the battery negative terminal anyhow, and using a grounding distribution block.

[url]http://www.bcae1.com/capacitr.htm[/url]
[url]http://www.glasswolf.net/caraudio/capacitors.html[/url]
[url]http://www.glasswolf.net/caraudio/charging.html[/url]
[url]http://www.betteraudio.com/geolemon/newmain/battcapalt/[/url]
[url]http://www.bcae1.com/charging.htm[/url]
[url]http://www.bcae1.com/chargin2.htm[/url]
[url]http://www.bcae1.com/battiso.htm[/url]
[url]http://www.glasswolf.net/caraudio/batteries.html[/url]
[url]http://www.the12volt.com/info/recwirsz.asp[/url]
[url]http://www.optimabatteries.com/[/url]

these sites are invaluable information on charging systems. Please take a moment to at least skim over them.
Geolemon, Perry Babin, and I wrote most of these articles and all three of us have backgrounds in electrical engineering and the mobile audio industry.

Well, everything in the electrical system is really tied to two points - usually they happen to be:
1) the power terminal at the battery (or the main fuse box located right near it, if only one wire comes from the battery terminal)
2) the chassis metal of the car, which plays the role as the "ground plane". The battery, engine (and therefore alternator), and everything else are grounded to it.

You would have to connect the amplifier to ANOTHER completely separate electrical system in order to isolate that amplifier - and then if you hooked up a capacitor to THAT electrical system, then sure, it wouldn't be in the circuit defined by those two points above anymore.

But since it is, absolutely any electrical device in the car that is using the battery/alternator, and is grounded to the chassis, will also potentially benefit from the capacitor.

It essentially works like a big shock absorber for the whole electrical system - I just do all I can to make it [i]most [/i]efficient for one or two specific amps - the troublemakers. :D

[quote="geolemon"]Remember, there's no way to hook up a cap "to the subwoofer amp"...
It's simply in your electrical circuit, or it isn't - there's no way to "isolate" a capacitor so that it's connected to the subwoofer amp, and [i]not[/i] to any other amp. ]


i tried explaining this to someone a couple weeks ago and they couldnt get it at all......

[quote="ZeroAccess"]I would hook the cap to just the subwoofer amp and have it as close as you can to the amp. Ground it on the same ground..as long as its a safe and secure ground you won't have any problems.[/quote]
Remember, there's no way to hook up a cap "to the subwoofer amp"...
It's simply in your electrical circuit, or it isn't - there's no way to "isolate" a capacitor so that it's connected to the subwoofer amp, and [i]not[/i] to any other amp. ;)

Depending on your system, you can install it physically closer to one amp than another, or have heavier gauge power wire on one amp and the cap than the other - but all you are really doing in that case is increasing the ESR to the other amp, which is bad news for the performance of that amp. :sad017:

A cap is either installed in your system or it isn't - but electrically speaking, you can't hook it up to just one amp in the system.

This is just helpful for the fundamentals behind what they are, and what role they play in your electrical system:
[url]http://www.betteraudio.com/geolemon/newmain/battcapalt[/url]
...which should also lend you some insight into where they should be installed. ;)

More directly - ESR (aka. series resistance, or resistance of any type in series with the capacitor) kills a capacitor's effectiveness.
And lots of things can introduce resistance in the circuit path of the capacitor:[list]
[*]Wire gauge
[*]Wire length
[*]Ground quality
[*]Connector quality[/list]
...essentially, the same things that compromise the installation quality of your amplifier - but won't [i]completely[/i] compromise the performance of your amplifier, they can really impact performance of the capacitor.

And since wire and connection quality [i]might[/i] just also be [i]causing[/i] the symptoms that you believe you can solve with a capacitor, there certainly is absolutely no better time to ensure that all your connections, ground locations, and contacts are not compromised in any way - and then make your capacitor connection just as securely.

Personally, my philosophy is to install the capacitors as closely as possible to the devices causing the high-burst/highly-dynamic current draws on the electrical system... that would be your amplifiers- specifically your sub amp. ;)

Install it just like an amp, and that means the positive being on the shortest power wire from your distribution block possible, and the negative grounded with the shortest power wire possible - and grounded to the same location as your amps (which should be true chassis metal - not a seat frame bolted to a seat bracket bolted to a... etc :rolleyes: - and it should be bare, metal on metal contact, since paint IS an insulator ;) ).

As for fusing, use your own judgement.
Personally, I generally don't - and I use the logic for WHY fuses exist where they do in your audio system (my reason for not using them boils down to not creating additional opportunities for introducing series resistance):[list]
[*]Underhood - exists to protect the wiring and vehicle, should the power wiring anywhere get punctured or worn and become shorted to the chassis (ie. ground).
[*]Each amp - exists to protect the amplifier from a fault - generally a low impedence connected to it, which exists on the amplifier side of it's power supply.[/list]

A capacitor does not have a power supply, and is a single, simplistic electronic component that does not have a "load" connected to it - at least not one that can create an overload/overcurrent situation.
Also - because the wiring to the capacitor is absolutely minimalistically short by nature, it should be relatively easy to simply ensure in the installation that the wires will never be compromised.

One exception to this rule - most capacitors don't come with any sort of protective cover for their terminals - and you don't want to see what happens if you say, dropped a screwdriver across the terminals. :eek:
...a fuse might seem like a good idea here, and I'm not going to argue, EXCEPT to state that in that case, the electrical "short circuit" exists only between the two terminals on the capacitor, so a fuse actually wouldn't stop anything, and possibly wouldn't even blow.
AND, if a condition that would blow that fuse existed - the underhood fuse absolutely [i]would[/i] blow.

So that's my logic - but don't let me completely discourage you from installing a fuse if it makes you feel safer. :thumbsup

I would hook the cap to just the subwoofer amp and have it as close as you can to the amp. Ground it on the same ground..as long as its a safe and secure ground you won't have any problems.

No reason to cut a hole in your car when you have plenty of great grounds to choose from. Maybe its just me but I'm lazy and when theres a great way to get the job done and less work I go that route.

Yes, the distribution block is used to feed power to two amps and i wanted both of them to be connected to the capacitor

My current setup uses
- Soundstream PCA 4.400 Running 6 speakers for the mid-highs. 2 installed on the back which are 6*9 alpine coax speakers. The front part has 4 speakers, left and right front channels have connected in parallel one soundstream mid cone and one 3 way db speakers, I don’t remember the exact model now…
- Kenwood KAC/7201 using two bridged channels to run a T7500 MTX sub

My electrical setup is planned to be as follows
1. car's battery
2. 15 cm of 4 awg cable
3. 150 Amps Fuse
4. 150 cm of 4 awg cable
5. capacitor
6. 10 cm of 4 awg cable
7. fused distribution block with two 60a fuses
8. two runs of 40 cm of 8 awg cable to both amps

About grounds: both of the amps are grounded to rear seatbelts (each amp to a different seatbelt) and i think that the cap will be grounded at a hole that I will drill in the middle of both seatbelts connections. The gound wire is 4 awg and with a length of about 50-60 cm.

Why do I want to connect both amps to the capacitor?? Well after reading tons of posts saying that a cap won't help about lights dimming, etc... I decided to use the cap I already had at least to filter the voltage to the amps and provide a little bit more clean voltage supply to the amps.

However I was not sure if installing the capacitor before the fused distribution block was going to cause any problem, that's why I wanted some advice from you guys.

If it's a 1 Farad + capacitor, it shouldn't really matter. Most amp capacitors are 1 Farad these days, which is more than enough. You could stick several amps on one and be fine, unless you're planning on doing a dB competition with massive current demand, then it might be best to invest in two.

What is the dist. block for? Multiple amps? If so, then hell yes, you want all of them in line with the cap.

I've found that if you're installing a cap, best ground location is the same as the amps, so mount it close with a short run of wire.