Power Capacitor Distance?

[Spinworkx]

Some questions for the gurus here...

Is there a maximum acceptable distance a Powercap can be from the amp?

Here's my current situation, my amps and power caps are under my seats but the rear passengers are kicking the caps...so i intend to shift the caps to the boot but leave the amps under the seat.

 

Here's my intended setup...

 

 

Will it work because the distance from the distribution block to the power cap is about 3.5M and the amps are under the seats so in theory the power needs to travel from the Cap in the boot, to the dist block in the front, to the amps under the seat, total distance will be about 4.5M the current will have to travel...unless it doesn't work that way?

[Hattee]

My guess is not just the distance your power capacitor from the battery, the per metre resistance (or impedance) of the connecting cable. Too much resistance will only means your power capacitor will not have enough time to get charged up before it can release enough charges in the next sinusoid peak from the power demand to drive the punch of deep bass.

 

Between the distance to battery vs distance to amp, the former might be more critical perhaps.

[Headshok]

cap has to be as near to the amp(or in ur case the dist blk) as possible... this way, the dist "travelled" by the electric charge is shorter and it's able to feed ur amps faster. having ur caps placed so far away is as good as not having them at all.

 

also, btw, u paralled down the caps to get 2.5F rite?

[Spinworkx]

Yea, i parrelled the caps to get 2.5F...

Actually, they're all under the seat next to the amps but because people keeps kicking them, i wanna shift to the boot...

But it seems like my idea would be as good as useless huh...the caps won't do anything like this then...

 

What would you suggest i do? So that i can have the amps under the seat while the caps in the boot? Or is that a definate no no to begin with :)

[Headshok]

hmm..

 

a bit hard leh..

 

cos initially, tot u can just move ur fuse blk to the boot near the power caps, but then once the power cap feeds to the fuse blk, the dist from the fuse blk to amps is still a bit far leh..

 

at most, fabricate something and lay it behind ur back seat so as to prevent people from kickin the caps. cut some wood and make a "drawer" like thing to place the caps and amp inside, so if pple kick it, tehy wil lnot kick the caps directly

[User12343]

i suggest forget about the caps totally. they do nothing to improve SQ.

[Headshok]

tats another option.. hehe..

 

i gave up on caps too..

 

but since u have a pair, see wat u can do lor.. if not sell off lose $$ sian diao lor

[Ae86]

Don't need to worry the distance between the amps and the caps there will not be any significant difference.And the caps are just like extra batteries they will be charging each time you on the system but it will store the current and will only discharge if there is a sudden heavy load, after which it will recharge again in no time and store the current inorder to standby.

[Spinworkx]

I know....

But i'm not using the caps for SQ :)

It's for blasting...and they look nice, that's why i wanted to relocate them to the boot so everyone can see them rahter than being unders the seats, no one can see :)

 

but seing the distance and my setup, i'll have to forgo this plan and leave it under the seats then...oh well...less work for me then.

[Hyun]

i dun have caps but by logic they should do some good. if u see the fluctuation of the voltage in the power lines, and if u reason that the fluctuation should translate to variable power to everything from the HU downwards, and that variable voltage affects output (provided output varies with voltage) then sound output might fluctuate .. unless there are many mechanisms built in, or internal capacitors that ensure output remains steady ...

 

amps, for instance, are meant to output more with higher voltage. at that pre-set gain, u'll end up with variable output. it isn't meant to keep signal output voltage constant, as far as i understand.

 

all this may not be perceptible in SQ (though some say it is, right?) but i guess it all goes to affect SQ? everytime the aircon compressor or something sucks momentary power ...

 

and as far as electricity is concerned, there is no "traveling time", is there? or rather, we assume it's the speed of light? the length of power cable in between only contributes resistance that results in a miniscule potential drop in between, which hardly amounts to anything unless it's a thin power cable - which results in the resistance EATING up the power transfer (electrons, joules, watts), not the transfer speed.

 

btw, mr user12343, how come u still using "corolla" and not "civic" in your avatar, hehe. must put the 1/3 beryllium in also mah. next time i must try to chope front seat in your car liao ...

[Bobcatsysop]

Hi Hyun,

 

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In my opinion, 'devices' like voltage impedance stabilizers and capacitors each does help to play a part to supply or maintain the required voltage to keep your sound system run at 'optimal designed level'. I beg to defer to those that say both voltage impedence stabilizers and capacitors does not help. Plug in a 'digital voltmeter' that gives digital decimal readings, you will see whether such 'devices' are effective or not.

 

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Most amps are designed and rated to provide xx RMS at xx ohms based on 14.4vDC. Now, how does a standard factory supplied 12v small little battery gives you that kind of 'constant' 14.4v to your sound system?.. For a amp to operate 'decently', I understand a mininum of 13.8v is required and this is what we should shoot for. 12vDC is way too low. For some HU, like Pioneer P80, they do incorporate a voltage meter that shows real time voltage reading which is what we need most to know our current voltage supply to see the drop and how quickly it goes back up to 13.8v.

 

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Yup very true. If you do not have 'devices' like voltage impedence stabilizer and capacitor, the 'pick-up' to go back to 13.8v comes digitally point by point slower then one that is equipped with such 'devices' that goes back up to 13.8v instantly to continue the power supply to your amps to provide the required amps for your sound system. Again, without a digital voltmeter installed, you will not be able to see how this work, especially when driving at night on a rainy day with all your lights on, front heater and rear dimister on, sport light on, sound system on, etc..

 

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Oh yeah.. last Saturday I was very privilege to be able to have the driver seat of his new Civic for user12343. His system is really 'tok kong'. His a-pillar cost something like $500 I understand. whew!!!... and the sound is 'heavenly', the bass from his IDMAX sub gives you the sensation all the way from the trunk to the driver's seat.

[User12343]

thanks uncle bob for the compliments, but must give a bit of a discount la, still long way from sounding heavenly....still not tuned properly .... tune here tune there tune until give up liao.... listen long liao oso feeling sianz and no-big-deal liao.... now semi-retired from ice liao

Edited November 6, 2006 by User12343

[Hyun]

but not quite accurate to say amps "work best at 14.4V" .. i bet they function just as beautifully whether it's 12V or 14.4V. it's just that with a higher input voltage to start with, all that transformer action inside translating speaker level output to 50V or so can manage even higher outputs. the difference is just output amplitude. the "beauty" of the sound should be similar whether it's 12V or 14.4V.

 

however, some manufacturers quote different THD-ratings for their 12V and 14.4V outputs! for e.g. i've seen like say 100W RMS @ 12V 0.03% THD, and then when they quote 14.4V it's 1% THD @ 125W for example! totally different benchmark.

 

i also wanna give up tuning liao. i just got my brother to go thru my tuning method and make simple judgments like where he feels the sound comes from, based on his hearing. and because of my slight deafness our interpretations can be quite different. i.e. if i tune accurately to what normal-undeaf-people hear, it won't sound right to me. and vice versa.

 

so i'll just do it my way and everyone else can say it sounds way off hehehehe.

[Bobcatsysop]

Hi Hyun,

 

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Nope.. It's that amps RMS output are generally rated at 14.4vDC for their RMS output when published in catalogue. Take for example:

 

Audison LRx2.4 2-ch amp

Nominal output power RMS NP @ 12vDC THD 0.3% gets: 120w x 2 @ 4 ohms

but Output Power RMS @ 14.4vDC THD 1% gets.... 2-ch 130w x 2 @ 4 ohms

so how you are going to rate this amp?.. 120w? RMS or 130w RMS? 8% difference at different voltage!

I would say 130w RMS @14.4vDC is not a realistic figure regardless of different benchmark coz you can never attain the 14.4v constant supply so this higher figure of 130w RMS is therefore, not relevant to me..

Edited November 6, 2006 by Bobcatsysop

[Bobcatsysop]

Hi Bro Kermit,

I am giving an honest opinion of what I heard in your car. Amazed me.. imaging, tonality and spectral balance great man!!.. Need not tune again liao... just ENJOY your music.. and forget about tuning again..

 

Thank you for letting me audit your setup. It was great.

Edited November 6, 2006 by Bobcatsysop

[User12343]

eh, better dun mix up my nick with another same nick here....not nice....my nick is only known in delphi and not in MCF....hehehe

Edited November 6, 2006 by User12343

[Bobcatsysop]

Ok... noted..

[DEREKJJ]

Bro,

 

What is you total power rating of the setup at present?

 

Capacitor are only useful for instantaneous power burst. Once depleted, it will start to charge up by draining from the same power path supplying to ur amps.

 

Capcitors are only useful when you have a setup with true RMS rating in excess of 2kw. Anything less, a good deep cycle battery would probably be more logical as it is a larger reserve to draw from.

Edited November 6, 2006 by DEREKJJ