Capacitor and fuses

[Colby]

If i have a capacitor and i hook it to my bass amp do i need a fuse between the two?

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[Gauntlet 5,000+ posts]

Not really.

 

[Brock 5,000+ posts]

Originally posted by Colby If i have a capacitor and i hook it to my bass amp do i need a fuse between the two?

y do you have a cap in the first place?

but to answer your question...no...

 

[AudioNutz 10+ year member]

YES 4-sure

 

[jlaine 10+ year member]

Originally posted by Colby If i have a capacitor and i hook it to my bass amp do i need a fuse between the two?

Absolutely do NOT fuse between the capacitor and the amp itself. A fuse creates a voltage drop across its lead, something you are trying to avoid in the first place.

Fuse before the capacitor, never afterward. And put it as close in line to the amp in question as you can.

 

[n2audio 5,000+ posts]

Originally posted by evo2k3 what about the caps that have built in distrobution blocks? that goes into smaller wiring. Not to mention if he is within 12 inches like i know you say it should be.....a 4 guage wire over 12 inches will handle as much current as the 0 guage feedline over 15-20 feet.....seems to be some faults in your logic.

My thoughts exactly. Plus, resistance and voltage drop are one in the same.

 

[maylar 10+ year member]

Originally posted by n2audio Jlaine - I know nothing at all about caps, but I do know something about wiring and fusing.

 

What if the wire changes guage? Wouldn't it be appropriate to fuse at that point? And do you know the voltage drop across , say a 60A fuse? As a wild guess - maybe 0.01V - tops?

Fuse, fuseholder, terminals, crimps... all have restance. As jlaine has been trying to get across, even milliohms of resistance defeats the purpose of using a cap.
A 1000 watt system with a 60 amp fuse could easily hit 200 amp peaks for short transients. During that time the voltage at the amp's terminals drops by (200 X R) volts. Just 25 milliohms of total resistance relates to 5 volts drop at that current.

A capacitor is supposed to help compensate for voltage drop in the feed wiring and alternator when the amp hits those high current peaks, by providing a localized source capable of supplying huge currents for short periods. If the wiring between the cap and amp has even ~milliohms~ of resistance, you'll lose the effectiveness of its ability to keep the amps terminal voltage up.

Wiring should be fused at the battery end. Period. If the load shorts out, the main fuse will blow. The cap will discharge... like it was designed to do.

 

[jlaine 10+ year member]

Originally posted by evo2k3 what about the caps that have built in distrobution blocks? that goes into smaller wiring. Not to mention if he is within 12 inches like i know you say it should be.....a 4 guage wire over 12 inches will handle as much current as the 0 guage feedline over 15-20 feet.....seems to be some faults in your logic.

You mean the caps with added goodies, that make them even more worthless than they are?

Do you even GET the idea of a capacitor?

The POINT is to NEVER, I repeat, NEVER!!! Restrict it in any way or form. This includes FUSES, JUNCTIONS, TERMINALS, and ANY OTHER RESISTIVE SOURCE, INCLUDING digital displays!!!!!!! Pop quiz, open your amplifier case, check out the capacitors feeding the power supply, you see ANYTHING in their path source to the voltage rails for the amp? NO!!!!!!!!!

The fault is in YOUR logic, and I am getting tired of repeating myself for you! The REASON the 4ga will handle that amount of current is based upon current draw and average voltage drop. Drop voltage, create heat. Now tell me, why the HELL would you feed a cap with 0 gauge, then drop it to 4 to feed your amplifier, how bloody STUPID can you get? The highest current surge will happen AFTER the capacitor, for the feed to the amplifier, to put a smaller cable on it is about the same as running your head into a wall for an hour straight figuring you can walk through walls -- POINTLESS!!!!!

Read maylar's VERY EXCELLENT (thank you maylar!) response for added information, I'm really sick and tired of butting heads with you on subject matter that is common law to most educated car audio installers and techs.

 

[tex 10+ year member]

How are you supposed to cram the 0 guage wire into the amp without ever reducing it?

 

[jlaine 10+ year member]

Originally posted by tex How are you supposed to cram the 0 guage wire into the amp without ever reducing it?

Why would you be feeding the amp a 0 gauge primary lead in the first place.

It should be reduced at a fused distro block long before it ever makes it to the amp primary.

 

[tex 10+ year member]

If I'm reading you're theory correctly, you shouldn't reduce after the cap. And now, you said it should be reduced before the cap. Okay, if this holds true, you would have to run a 4 or 8 guage wire to amp from cap and something even smaller from the distribution block to the cap.

 

[evo2k3 10+ year member]

Originally posted by jlaine You mean the caps with added goodies, that make them even more worthless than they are?

 

Do you even GET the idea of a capacitor?

 

The POINT is to NEVER, I repeat, NEVER!!! Restrict it in any way or form. This includes FUSES, JUNCTIONS, TERMINALS, and ANY OTHER RESISTIVE SOURCE, INCLUDING digital displays!!!!!!! Pop quiz, open your amplifier case, check out the capacitors feeding the power supply, you see ANYTHING in their path source to the voltage rails for the amp? NO!!!!!!!!!

 

The fault is in YOUR logic, and I am getting tired of repeating myself for you! The REASON the 4ga will handle that amount of current is based upon current draw and average voltage drop. Drop voltage, create heat. Now tell me, why the HELL would you feed a cap with 0 gauge, then drop it to 4 to feed your amplifier, how bloody STUPID can you get? The highest current surge will happen AFTER the capacitor, for the feed to the amplifier, to put a smaller cable on it is about the same as running your head into a wall for an hour straight figuring you can walk through walls -- POINTLESS!!!!!

 

Read maylar's VERY EXCELLENT (thank you maylar!) response for added information, I'm really sick and tired of butting heads with you on subject matter that is common law to most educated car audio installers and techs.

Hey, your sick of repeating yourself so stop!!(and the "I am god, **** me off" aditude is not apreciated) as i said before we had both stated out points....you brought in completly pointless observation that the goodies reduce the effectivness. Although i do not diagree, it has nothing to do with reducing wire size. I will ask how you propose to put your 0 gauge wire into the 4 gauge terminal on the amp? it obviously has to be reduced somehow, and if your with in 12" why does it matter if you reduce at the cap or in a sperate distrobution block? Dont make the agrument that the disto distributes better because there is no difference in the distribution wheather you run a 0 or 4 gauge out of the cap. Although the technical idea that maylar stated is completley correct, I will also disagree because I do no believe the milli-ohm resistance will have a noticable effect the output of your amplfiers (with in reason of cource, puting 12 million 1 milli-ohm resisters in the line will obviously have an effect).

 

[evo2k3 10+ year member]

Originally posted by jlaine Why would you be feeding the amp a 0 gauge primary lead in the first place.

 

It should be reduced at a fused distro block long before it ever makes it to the amp primary.

long before....really....but resitance increases with distance, so again you have contradicted yourself because "The POINT is to NEVER, I repeat, NEVER!!! Restrict it in any way or form. This includes FUSES, JUNCTIONS, TERMINALS, and ANY OTHER RESISTIVE SOURCE"

please take the time to format another long response, I enjoy reading them //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[tex 10+ year member]

My question about stuffing 0 awg into the amp was a rhetorical question. "Now tell me, why the HELL would you feed a cap with 0 gauge, then drop it to 4 to feed your amplifier, how bloody STUPID can you get?" Hmmmm, maybe because the 0 guage won't fit into the amp! Even if you cut some copper to make it fit, this would still be considered reducing. Because the cap should be close to the amp the cap should be fed with a bigger wire because it is usually long. Because there is a short distance from the cap to the amp, there is less resistance and a "reduced," smaller wire could be used to plug into the amp.

 

[jlaine 10+ year member]

Originally posted by evo2k3 long before....really....but resitance increases with distance, so again you have contradicted yourself because "The POINT is to NEVER, I repeat, NEVER!!! Restrict it in any way or form. This includes FUSES, JUNCTIONS, TERMINALS, and ANY OTHER RESISTIVE SOURCE"

 

please take the time to format another long response, I enjoy reading them //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

If you are going to quote me, at least understand what you are quoting in the first place.

The entire point of the capacitor is to keep the resistance from the CAP, to the AMP, as LOW AS POSSIBLE. Again, since you are missing the point, is the REASONING BEHIND NO JUNCTIONS!

NOBODY CARES BEFORE THE CAP!!!!!!!!!!!

Whether or not you have 20 feet of 4 gauge, 20 feet of 2 gauge, or 20 feet of 0 gauge, it doesn't MATTER provided current demand is low enough to not create heat and voltage drop. What MATTERS is that the feed from the CAP to the AMP has the LEAST amount of resistance possible. The only thing you did by adding this cute little fuse was waste your time, created resistance by the fuse and added junctions, and do nothing at all for safety. What the hell is the point of adding a fuse AFTER the line has already been fused?

Is that so bloody hard for you to comprehend? Do I need to use pictures? Smaller words?