# Best way to connect two amps and a cap?



## electrons (Jul 25, 2010)

Hello everyone.

Okay, so after watching a friend hook up my previous system, I decided to try it myself. That was a while ago..and it wasn't exactly neat and proper.
Now, I'm upgrading everything else except the amp and sub, which is a Kenwood KAC-9105D mono, and Polk DB1222. I'm adding a 4-channel amp (alpine mrp-f300).

What would be the best way to connect the two amps and the stiffening cap together?

The Kenwood is supposedly 900 watts RMS..but I read some where that amps generally put out about 70% of what they're rated. Is that true? 
The Alpine is 200 watts RMS. I'm using 4 gauge wire right now, would I need to use a lower gauge?

I was thinking this: 4 gauge from battery to a distribution block split near the amps block (KNF-23) , 8 gauge wire from the block to mono amp + capacitor, 8 gauge from the block directly to the 4-channel amp, 8 gauge connecting amps to ground block (KND-23), and 4 gauge for the ground point.

Thanks for any help!


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## kyheng (Jan 31, 2007)

First of all, why you need a cap? It is a junk that have no added value on real life usage anyway. If just for bling bling purpose, then go with it.


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## electrons (Jul 25, 2010)

Yeah, I've read that caps don't really do much..but I already bought it and hooked it up.


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## Candisa (Sep 15, 2007)

Use a fused distro block, run the 4ch directly to it and the mono trough the cap to it.
A cap is only useful (if it's already useful) if it's connected as directly as possible to the amp that needs it. 
This is only possible if there are no fuses between that amp and the capacitor, but since every power wire needs its own fuse, there is no way to connect 2 amps to 1 cap in a secure way.

A 200W RMS 4ch amp driving speakers will never need a cap. A 900W RMS mono, well, actually it doesn't need it either if everything is alright, but it'll have more use of it...

Isabelle


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## BigAl205 (May 20, 2009)

Candisa said:


> Use a fused distro block, run the 4ch directly to it and the mono trough the cap to it.
> A cap is only useful (if it's already useful) if it's connected as directly as possible to the amp that needs it.
> *This is only possible if there are no fuses between that amp and the capacitor,* but since every power wire needs its own fuse, there is no way to connect 2 amps to 1 cap in a secure way.
> 
> ...


Wait...what? I don't want to go into the effectiveness of a cap, but I would put a fuse on anything that stores/produces power. What would happen if the power lead came loose from the amp and touched metal?


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## Candisa (Sep 15, 2007)

The cap would unload in less than a second and then the fuse that's before the cap will blow.

I totally agree on you if you're talking about an alternator or a battery that's able to produce a high current for a reasonably long time when shorted.
A cap is very fast and can deliver high peaks of current, but it won't do this for a long time.

Off course the best thing you can do is:
- make sure the cables can't come loose
- make sure, if a power cable can come loose, it won't touch metal or some other grounding point.

Isabelle


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## electrons (Jul 25, 2010)

What gauge wire should I run from the battery to the block, and block to amps?
My lights still dim even with the cap hooked up.. Battery upgrade is part of the "big three", right? Is there a certain kind/brand of battery people use?


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## gijoe (Mar 25, 2008)

4 gauge from the battery to the block and 8 gauge to the amps will work without any issues. The big 3 typically refers to upgrading your wires, chassis and engine ground and the alternator to battery wire. I'm a supporter of upgrading grounds, but honestly believe the alternator to battery wire is a waste. Upgrading your grounds may help, but you aren't running a lot of power, I think that a good battery is a must. Upgrade the grounds and see how things go. The next step would be a new battery.


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## TREETOP (Feb 11, 2009)

Candisa said:


> I totally agree on you if you're talking about an alternator or a battery that's able to produce a high current for a reasonably long time when shorted.
> A cap is very fast and can deliver high peaks of current, but it won't do this for a long time.


A cap can also EXPLODE when shorted.


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## MarkZ (Dec 5, 2005)

If I were to add a cap (I won't because (a) I'm too cheap, and (b) I have no room in the engine compartment for one), I would hook it directly to the constant 12v junction box under the hood. This is generally the closest (electrically) to the headlights you can get it, and therefore the most effective at reducing dimming.


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## 89grand (Nov 23, 2006)

MarkZ said:


> If I were to add a cap (I won't because (a) I'm too cheap, and (b) I have no room in the engine compartment for one), I would hook it directly to the constant 12v junction box under the hood. This is generally the closest (electrically) to the headlights you can get it, and therefore the most effective at reducing dimming.



I never thought about it like that before, but that makes a lot of sense. Not that I ever plan on getting a "cap", but still.


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## electrons (Jul 25, 2010)

What kind of battery should I be looking for? Something like this?

What do you guys think of "cap batteries"?


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## kyheng (Jan 31, 2007)

Try not to turn on your sound system and see does the lights still dimmed or not. Knowing the actual causes of dimming is way more superior than adding this or that.


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## finfinder (Apr 15, 2006)

Uh guys, how bout we go back to the beginning.

How many amps does your alternator put out ?

What kind of battery is in there now. How old is the battery ?


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## electrons (Jul 25, 2010)

My lights only dim when playing music loud enough. I think my amp may have cut off due to insufficient power..not sure. Much to learn, much to learn..


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## kyheng (Jan 31, 2007)

Possible cause :
you wire your sub at lower impedence, have to remember that current act on resistance, your amp's resistance is lower, so current will flow there first before it goes to your lights. Try wiring your sub at higher impedence and see does it helps?


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## electrons (Jul 25, 2010)

finfinder said:


> Uh guys, how bout we go back to the beginning.
> 
> How many amps does your alternator put out ?
> 
> What kind of battery is in there now. How old is the battery ?


My alternator and battery are stock. I believe its 90 amps for alternator (lancer 2006 ES). Battery is probably around 2 years old..


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## kyheng (Jan 31, 2007)

That's strange, I have a 75A alternator running for 7 years with a close to 3 years battery and I have yet to get my lights dimmed. But I wire my sub on 8ohm.


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## electrons (Jul 25, 2010)

kyheng said:


> That's strange, I have a 75A alternator running for 7 years with a close to 3 years battery and I have yet to get my lights dimmed. But I wire my sub on 8ohm.


Yeah. I believe the sub is 2 ohms (polk db 1222). The amp only puts out 500 watts at 4 ohms so I kept it at 2.


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## MarkZ (Dec 5, 2005)

Wiring your sub at a higher impedance is the same as turning your volume down. If your lights are dimming, it means your amp is drawing a lot of current. Amps have to draw a lot of current to produce a lot of power.


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## spmpdr (Nov 5, 2009)

Skip the distro block, wire 4ga directly from battery to cap w/ inline fuse 6-18inches from battery.The cap then becomes your power distribution point . Use ring terminals to connect the power wires of the amp directly to the power side of the cap. ground everything seperately within 12" inches of the component (amp or cap).done. This is assuming that your cap has bolt connectors.


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## kyheng (Jan 31, 2007)

^Not that agree with you on this. Proper driver selections are important. That's why I always choose drivers with high sensitivities of >88dB so that I no need to crank up high to get loud.


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## MarkZ (Dec 5, 2005)

Yup. Efficiency is very important. I'm just saying that rewiring multiple coils isn't usually going to give you much better efficiency.


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## Candisa (Sep 15, 2007)

spmpdr said:


> Skip the distro block, wire 4ga directly from battery to cap w/ inline fuse 6-18inches from battery.The cap then becomes your power distribution point . Use ring terminals to connect the power wires of the amp directly to the power side of the cap. ground everything seperately within 12" inches of the component (amp or cap).done. This is assuming that your cap has bolt connectors.


I actually agree with nothing of the above!

Unless you'll be able to run power wires from the cap to the amps that are as thick as the main power wire, or if you can use a main fuse that's weak enough to protect the thinnest power wire without blowing it, you WILL need a fused distro block to be safe.

About the ground: not only is using multiple grounding points asking for trouble, by putting the cap and the amps seperately to the ground, you are raising the resistance between the ground terminal of the cap and the ground terminal of the amps massively, reducing the effect of a cap!

The only correct way to connect 2 amps and a cap is:

Part 1.: Front battery --> max 12" of cable --> main fuse --> cable to the back --> fused distribution block
Part 2.: Fused distribution block --> positive terminal of the cap --> max. 12" of cable --> positive terminal of Amp1
Part 3.: Fused distribution block --> positive terminal of Amp2.
Part 4.: Create 1 single grounding point, as close as possible to everything
Part 5.: Grounding point --> negative terminal of the cap --> max. 12" of cable --> negative terminal of Amp1
Part 6.: Grounding point (the same one!) --> negative terminal of Amp2

Amp1 being the amp that draws the biggest current-peaks, most likely the monoblock
Amp2 being the amp other amp, in this case the 4ch.

This is the ONLY CORRECT way to do this and this is also the way that is recommended by many sound-quality competition organisations AND car-electronics-specialists!

Isabelle


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## kyheng (Jan 31, 2007)

But thread starter already said that even with a cap, the lights still dimmed?

Anyway my ground got 2 points, where 1 is from distribution block to chasis and 1 to battery direct.


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## MarkZ (Dec 5, 2005)

Candisa and I disagree on something. Shocking! 

Resistance in the power line is usually dominated by the connections. Unless the wire is really long or really thin. So I'd choose the option that minimizes connections, which means bypassing the need for a distro block, if at all possible. My only question is whether or not the quality of the ring terminal connection (which is actually two interfaces) is as good and as stable as the quality of a good distro block connection (again, two interfaces... but more than that if it's a fused distro block).

So, if properly done, I could see both ways being acceptable.


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## kyheng (Jan 31, 2007)

Ring terminal connections on engine compartment are nightmare, atleast for me as I need to clean them every now and then, average 2 months once.


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## Candisa (Sep 15, 2007)

I meant 1 grounding point for all audio-gear.
Most installs have a grounding point in the back for all the gear and one in the front for the battery. This won't cause problems if the body of the vehicle can transfer enough current and you don't pick parts that are dot-welded to the body as a grounding point.

You'll always have a little loss between the batteries grounding point and the install-grounding point, but at least, the loss is the same for every piece of material if you use a common grounding point.
If you put every piece of gear to a different grounding point, chances are Amp1 gets 13.8V, Amp2 gets 13.85V and the radio gets 13.6V.
This is asking for ground loops and other troubles...

Isabelle


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## kyheng (Jan 31, 2007)

But with newer models, it is better to get an extra lenght, because the quality of the metal used are pretty poor sometimes. 
Some cars even cannot eliminate the static charges on cause fires when filling up petrol/gas.


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## spmpdr (Nov 5, 2009)

Candisa said:


> I actually agree with nothing of the above!
> 
> Unless you'll be able to run power wires from the cap to the amps that are as thick as the main power wire, or if you can use a main fuse that's weak enough to protect the thinnest power wire without blowing it, you WILL need a fused distro block to be safe.
> 
> ...



Point taken.... I suggested this from experience, I ran a 2 amp 1 cap set up just the way the OP is describing in the set up i suggested for more than 5 years with not a problem .... not a blown fuse or anything. What i do agree with is that he should ditch the 8awg and get 4 awg for the whole set up. As far as grounds go , if he has a grounding point for everything within 12" of it all then ground it together as you suggested, Im guessing this is not the case so ground them seperately as i stated above


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## MarkZ (Dec 5, 2005)

I believe the Alpine terminals only accept 8ga, so that's probably why he's using 8ga wire for the amps.


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## glassmancanada (Jun 17, 2017)

Candisa said:


> I actually agree with nothing of the above!
> 
> Unless you'll be able to run power wires from the cap to the amps that are as thick as the main power wire, or if you can use a main fuse that's weak enough to protect the thinnest power wire without blowing it, you WILL need a fused distro block to be safe.
> 
> ...


Great explanation however the dist blocks I can find are 4 gauge in and multiple 8 gauge out, meaning in part 2 only runs 8 gauge to the cap. How do I work around this? Is ther a dist block that is 4 gauge in and 4 or 8 gauge out?
Regards,


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## karmajack (May 9, 2017)

glassmancanada said:


> Great explanation however the dist blocks I can find are 4 gauge in and multiple 8 gauge out, meaning in part 2 only runs 8 gauge to the cap. How do I work around this? Is ther a dist block that is 4 gauge in and 4 or 8 gauge out?
> Regards,


JL Audio XD-FDBU-4

One 1/0 - 4 AWG Input
Four 4 - 8 AWG Outputs
MAXI Fuses required, sold separately

Or cheaper, the Orion DBF1434. 

One 4-8 in
Four 4-8 out
Mini ANL fuses required, sold separately


Last one. Middle of the road. 
Xscorpion AGU3234P 

Three 2/4 Gauge Inputs (only need to use 1)
Three 4/8 Gauge Outputs
AGU fuses required, sold separately

google fu


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## glassmancanada (Jun 17, 2017)

Thanks bro ^^,
One more question. I have 2 old school Harman Kardon CA 260 amps I will be using. 1 bridged mono for 12" sub and 1 for 6 x 9's. Amps are internally fused with 1 30A fuse, what fuse size should I run in the dist block? Will be following Candisa's recommendation with sub amp coming off the cap and 6 x 9 amp direct from dist block. Both amps will be fed with 8 gauge and common ground for all.
Appreciate the help
Regards,


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## glassmancanada (Jun 17, 2017)

Forgot, also would like recommended main battery fuse amperage.
Thanks


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## Darkghost223 (9 mo ago)

electrons said:


> Yeah, I've read that caps don't really do much..but I already bought it and hooked it up.


They stop the power surge from your system hitting so hard and draining your battery fact is they do some purpose


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## Mike-G (Dec 25, 2008)

Darkghost223 said:


> They stop the power surge from your system hitting so hard and draining your battery fact is they do some purpose


You signed up just to comment on a 5 year old thread?


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## blazeaglory420 (2 mo ago)

Mike-G said:


> You signed up just to comment on a 5 year old thread?


And you commented on a comment on a5 year old thread? What difference does time make? As if relevant information has an expiration date?

Ppl like you who make these kind of senseless comments can't even explain why moderators don't want comments on older threads... can you?


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## ItsonlyaHONDA (Sep 9, 2021)

It's actually 12 years old and caps for car audio are useless. Unless we are talking bout super cap banks. Those old school caps do not help at all. Money is better spent on a good AGM battery.


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## Speedhunter (Feb 21, 2020)

ItsonlyaHONDA said:


> It's actually 12 years old and caps for car audio are useless. Unless we are talking bout super cap banks. Those old school caps do not help at all. *Money is better spent on a good AGM battery.*


Why?


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## ItsonlyaHONDA (Sep 9, 2021)

Speedhunter said:


> Why?


Because they have less internal resistance, they recharge faster, than regular lead acid batteries and are maintenance free. They also store alot more reserve electricity than caps. So it's best to have a good AGM when running higher powered sound systems. Caps are band aids and not a very good one.

Why, do you have a cap in your system?


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## Speedhunter (Feb 21, 2020)

Nahh...I was just curious why.


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## ItsonlyaHONDA (Sep 9, 2021)

Speedhunter said:


> Nahh...I was just curious why.


🤡


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## Speedhunter (Feb 21, 2020)

ItsonlyaHONDA said:


> 🤡


?


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## ItsonlyaHONDA (Sep 9, 2021)

Speedhunter said:


> ?


It was a jk


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## ItsonlyaHONDA (Sep 9, 2021)

Speedhunter said:


> ?


My bad I was making clown 🤡 jokes with some one else lol I thought it was you.


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## Speedhunter (Feb 21, 2020)

For someone who seeks internet concerning AGM shure it fits you 🤣.


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## ItsonlyaHONDA (Sep 9, 2021)

Speedhunter said:


> For someone who seeks internet concerning AGM shure it fits you 🤣.


🙃


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## Mike-G (Dec 25, 2008)

blazeaglory420 said:


> And you commented on a comment on a5 year old thread? What difference does time make? As if relevant information has an expiration date?
> 
> Ppl like you who make these kind of senseless comments can't even explain why moderators don't want comments on older threads... can you?


Because after 5 years, if the person does not have his/her answer, they have long moved on. The only senseless comment was the one made I responded to. If a thread has not been commented on after 1 year, it should be closed permanently.


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