Print Page | Close Window

best place to put cap?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=96852
Printed Date: May 24, 2022 at 5:12 PM


Topic: best place to put cap?

Posted By: luckydawg003
Subject: best place to put cap?
Date Posted: September 02, 2007 at 10:20 PM

Where's the best place to put a cap. Before the Distibution box or after going to only the subwoofer amplifier?



Replies:

Posted By: haemphyst
Date Posted: September 02, 2007 at 11:14 PM
In the dumpster. BUT, if you've laready bought one before finding out that they are essentially useless, immediately before the distribution block.

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: speakermakers
Date Posted: September 03, 2007 at 1:56 AM
The benefits of a cap (for the dollar) are debatable. It depends on several variables with the most prominent factors being the type music that you listen to and the type of power supply that your sub amp has. In the event that you have one or do decide to use one the closer you place it to the amp the better of a job it will be able to do. I suggest physically placing it as close as possible to your sub amp. Placing the cap before a resistive connection (distribution block) or other electrical devices (amps) will negate the benefits of its existence.





Posted By: DYohn
Date Posted: September 03, 2007 at 10:52 AM

speakermakers wrote:

The benefits of a cap (for the dollar) are debatable. It depends on several variables with the most prominent factors being the type music that you listen to and the type of power supply that your sub amp has. In the event that you have one or do decide to use one the closer you place it to the amp the better of a job it will be able to do. I suggest physically placing it as close as possible to your sub amp. Placing the cap before a resistive connection (distribution block) or other electrical devices (amps) will negate the benefits of its existence.

The utility of a cap depends far more on the quality of the vehicle's existing power source and the quality of the amp's power supply than on the type of music.  I agree that placing one as close as possible to the amp is the best approach, although I disagree with the last statement about negating benefits.  Care to elaborate on that one?



-------------
Support the12volt.com




Posted By: sarcomax
Date Posted: September 03, 2007 at 11:13 AM
And so begins the next installment of "Good Cap, Bad Cap"...




Posted By: DYohn
Date Posted: September 03, 2007 at 11:16 AM

sarcomax wrote:

And so begins the next installment of "Good Cap, Bad Cap"...

Not at all.  I just want to know what he's talking about.  Maybe I'm missing something.



-------------
Support the12volt.com




Posted By: sarcomax
Date Posted: September 03, 2007 at 3:56 PM
I know, it's just that this topic comes up like once a month and grows to 12 pages in about a week sometimes depending on how many new cap lovers we have. I know that I have never benifited from a cap, my guess as to where he was coming from is that if the cap was there to help just the sub, and the cap is put in a location that allows other sources of power draw to access it, then the performance of the sub amp is lower than it would be if it was directly set up to power the sub amp. Just speculation on my part, but it is really slow at work today, my wedding is in 6 days, and I am trying to do as little actual "work" as possible. Hawaii here I come!!!  




Posted By: DYohn
Date Posted: September 03, 2007 at 4:12 PM

Wedding in six days?  Damn man, congrats!  A word of advice: after the wedding, you must place the cap EXACTLY where the wife wants it, regardless of if it makes any sense or not.  posted_image

A cap anywhere in the power system will be "used" by all amps in the system, and by the car as well.  The idea of placing them as close as possible to the highest power amplifier is to keep the amount of cable between the cap and the amplifier as short as possible to minimize the heating and losses introduced by cable resistance and the large instantaneous current flow when they discharge.



-------------
Support the12volt.com




Posted By: haemphyst
Date Posted: September 03, 2007 at 5:03 PM
sarcomax wrote:

And so begins the next installment of "Good Cap, Bad Cap"...

Good Cap, Bad Cap... Funny.

sarcomax wrote:

but it is really slow at work today, my wedding is in 6 days, and I am trying to do as little actual "work" as possible. Hawaii here I come!!!

1: Damn, gotta WORK on a holiday? That sucks!
2: Don't do it!!!! I don't mean the Hawaii part, but the other part! posted_image

Oh, and sarcomax, I have me a new toy coming for my bike! A smaller front sprocket, and an EFI Controller... oughta add about 14HP at the rear wheel, and the smaller front will make the holeshots even MORE fun! Check out the Bandit 1250 section over at www.holeshot.com

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: speakermakers
Date Posted: September 04, 2007 at 12:32 AM
Well Dyohn as far as your question about negating the benefits due to the caps location, what exactly is it? The very idea of using a cap is to stabilize voltage for a very brief period of time. Any voltage drop caused by a connection or distance of wire will defeat this. The voltage near the cap will be stabilized but the voltage at other points along the parallel circuit will not be as stable. Calculate dynamic voltage drop and use Ohms law to calculate total voltage at various points along the parallel charging system and you will find that the voltage is most stable closest to the cap. I fail to see the confusion here. Yes the other amps in the system and every other electrical component is connected to the cap but not equally.

The choice of music has a profound effect on the total demand that the audio system puts on the charging system. Due to a large difference in crest factors amongst popular recordings available to the general public (MP3 bass music with 5db crest factor vs. country music with 19.5 db crest factor) the amperage requirements may vary by a factor of 20! I am sure that you are aware that the RMS power out put and consequently power input requirements of an amplifier vary with RMS of the signal at the signal inputs of an amp. And I am sure that you are aware that the RMS of the signal is determined by the music recording.
No Good cap – bad cap. Always good. Not always good for the pocket.
Never herd of an audio system suffering from to much capacitance.




Posted By: DYohn
Date Posted: September 04, 2007 at 10:59 AM

Basic electricity.  Voltage is common at all nodes in a parallel circuit.  Yes, if you add series resistance between the nodes you can drop the voltage.  This is one reason why adding a cap as close to the load as possible is preferred to minimize the voltage drop due to cable resistance, but more to reduce the effects of heating due to current flow.  A capacitor discharges current into the system whenever the voltage changes and this current will go to ground through the lowest resistance path, no matter if that's through the amplifier or through insulation resistance.

Perhaps we are saying the same thing but we don't speak the same language.  :)



-------------
Support the12volt.com




Posted By: sarcomax
Date Posted: September 04, 2007 at 11:16 AM

Oh yeah, but the sales guy said that my lights would stop dimming, my system would gain 300db, I would grow facial hair, and my stock 14 inch rims would turn into 26's if I bought a cap... I want my 20 bucks back!!! JK

These are my favorite threads. Not the cap ones, but the ones with motorcycle references!posted_image

Seriously this time...I have learned more from these friendly debates than my senior year of high school.

Thanks for the wedding well wishing/advice/warnings!!!!! And in my retail life labor day is known as a helloday... I just hid out in the bay away from the crazies trying to get the limited time deals.



-------------




Posted By: DYohn
Date Posted: September 04, 2007 at 11:46 AM
sarcomax wrote:

Oh yeah, but the sales guy said that my lights would stop dimming, my system would gain 300db, I would grow facial hair, and my stock 14 inch rims would turn into 26's if I bought a cap... I want my 20 bucks back!!! JK


That only works with SONY caps.

sarcomax wrote:

Thanks for the wedding well wishing/advice/warnings!!!!! And in my retail life labor day is known as a helloday... I just hid out in the bay away from the crazies trying to get the limited time deals.


That kind of craziness is good craziness.  Enjoy married life!



-------------
Support the12volt.com




Posted By: haemphyst
Date Posted: September 04, 2007 at 2:01 PM
And my recommendation to put it before the distribution block was to provide votage stabilization for all of the amplifiers in the system. ALL amplifiers will "benefit" from the additional current capacity, rumored to be provided by a capacitor.

Any resistance provided in a distro block will be present in all of the outputs of that distro block, each of the fused points, correct? If the cap is ONLY present in the subwoofer lead AFTER the distro block, only the bass amplifier will "benefit", while at the same time causing an even more severe voltage drop on the input side of the distribution (due to the additional current demands of the caps own recharging, after it has "done it's job"). With the cap installed on the input side, the voltage sag, for all devices involved, will be identical.

AFAIAC, the distortion present or created by a low voltage power supply condition will be FAR more noticeable on a mid/high amplifier than it could EVER be on a subwoofer amplifier. I still recommend placing the cap before the distribution block... That, or use the cap's actual terminal for distribution purposes (like I did), that way you don't have to worry about it.

:::::::EDIT:::::::
In order to put the cap in the lead, anywhere, you have to cut the lead, introducing, at a minimum, 4 more connection points. Look at it in your mind, you'll see them all... Everyplace there is a metal to metal contact, there is additional resistance - a connection point. And soldering DOESN'T help... Solder is a relatively POOR conductor of electricity, (in fact, it's quite crappy...) being lead and tin (See here for conductivity, relative to silver, copper, and gold); a proper crimp connection i.e. a "cold weld" is the best option. Solder will make you feel better, but it's only REAL benefit is that it is a vibration PROOF connection. Lead is 12.4 times more resistive than copper, and tin is 6.5 times more resistive than copper. That's a SIGNIFICANT addition, I'd say... and you're worried about the voltage drop in the fuse contact points within the distribution block...

By creating a distribution block, that is actually INSTALLED ON THE CAP, you end up with a grand total of 3 connection points. Input to distro, cap connection point, and output to amplifier. Seems to me this is the VERY BEST way to do it, if TRULY worried about the miniscule additional resistances introduced by connection points...

Oh, wait, that's EXACTLY what I did! posted_image posted_image ...and SHARED the cap "benefits" with all of the amplifiers!

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: luckydawg003
Date Posted: September 04, 2007 at 3:30 PM
Ok I'm going to just put the cap before my distribution block. Thanks for all the weird reply's. You guys sure know how to dig deep into a simple ?




Posted By: haemphyst
Date Posted: September 04, 2007 at 3:53 PM
luckydawg003 wrote:

You guys sure know how to dig deep into a simple ?

That's what we do! posted_image Hope it wasn't TOO confusing for you!

-------------
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."





Print Page | Close Window