20 replies to this topic

[matrix]

Hey all,

i would just like to know if & when i will require a cap. Planning on running LRx2.5 + LRx1.4 mono amps to feed 1xBoston G512/G212 sub & set of Morel Elates/Hertz splits possibly all signalled by a Alpine D310 H/U. Would this setup drain too much power from my batt and would it require a cap?

Cheers

[Wh33lzz]

As far as I can tell, the general consensus around this forum is that you will never never need a cap.

The money spent on a cap is far better invested in upgrading to possibly a 5 point earthing system.

I am in no way an authority in these matters, but it certainly seems that 99% of the serious audio guys around here will scoff at the use of caps.

[mad89]

everything u need to know is in here:
http://www.caraudioaustralia.com/forums/in...showtopic=77816

(including the further links in some of the posts)

- mad89

[Pulse-R]

you would benefit from having a cap when the maximum current draw of your system (whilst driving) exceeds your alternator's output capacity, and/or the wiring is inadequate for peak power levels.

if the engine is off, and the wiring is adequate, then a cap won't help much

[fuddbutter]

you only really need one when you run out of other useless crap to buy

better off putting your money towards upgrading your power supply (cables, battery, alternater etc)

[Pulse-R]

unless you get one real cheap, then use that.

[DG Phil]

Fuddbutter, on Jan 5 2007, 09:04 PM, said:

you only really need one when you run out of other useless crap to buy

Or if you really like it because it is shiny. :)

Phil

Edited by DD Phil, 06 January 2007 - 09:27 AM.

[fuddbutter]

Pulse-R, on Jan 5 2007, 11:16 PM, said:

unless you get one real cheap, then use that.

i got one real cheep, put it in one car for decoration, never was hooked up (had power cables on it etc)

[Selfdestruktor]

Get a voltmeter and glue it to an old baked beans tin?

[spentan]

haha mine was free with my SK0/4CAP Soundstream Amp Wiring Kit, so Ima gonna use it (got kit from usa for like 200US) (RRP=AUD750)

[Juls]

in a Large system, a good cap can help smooth out the voltage spikes, which in turn will help your amps be more dynamically capable.

however for most systems the difference will never be noticeable,
and as said above, money is better spent elsewhere, unless you have nothing left to buy.

I generally go on the rule, 1 farad per 500W. (capacitor headroom I call it)

Juls

[~thematt~]

I read a science-based tut by Richard Clark a LONG time ago that proved (using electrical theory) that you would need around ~500 Farads (or more) to stabilise (within ~0.1 Volts) an amps current draw for musical responses between 20-100Hz (was a while ago so cant quote exact numbers though). It also stated that to stabilise demands above 1kHz required an ESR that cannot be found in today's Caps.

Ive seen a few Power Stations which stabilise voltage, and Rockford Fosgate has an amp that can continously output 5+kW with only a megre current draw. Both work on the same principle though, by a constant oversupply and storage of charge for instant depletion when required. Caps cannot do this on their own.

[kiwi]

My wife works for a company that makes power transformers for Electricity supply companies... maybe you can strap one of those to the roof ?

I have to admit that despite being commonly thought of as a waste of money.. they do look nice and blingy for installs, and do get people who dont know what they are, going ooh-ahh

[matrix]

Wh33lzz, on Jan 5 2007, 01:27 PM, said:

As far as I can tell, the general consensus around this forum is that you will never never need a cap.

The money spent on a cap is far better invested in upgrading to possibly a 5 point earthing system.

I am in no way an authority in these matters, but it certainly seems that 99% of the serious audio guys around here will scoff at the use of caps.

Anyone got one of these 5 point earthing system for sale or know where i can get one? How much do they set u back?

Bake beans can n voltmeter is a great idea, throw in some led's n ill have noobs goin oooh...

[DG Phil]

~thematt~, on Jan 8 2007, 04:03 PM, said:

I read a science-based tut by Richard Clark a LONG time ago that proved (using electrical theory) that you would need around ~500 Farads (or more) to stabilise (within ~0.1 Volts) an amps current draw for musical responses between 20-100Hz (was a while ago so cant quote exact numbers though). It also stated that to stabilise demands above 1kHz required an ESR that cannot be found in today's Caps.

Ive seen a few Power Stations which stabilise voltage, and Rockford Fosgate has an amp that can continously output 5+kW with only a megre current draw. Both work on the same principle though, by a constant oversupply and storage of charge for instant depletion when required. Caps cannot do this on their own.

Isn't it more to do with the square waving that you get down the DC line feeding PWM power supply, and the subsequent loss that occurs? Adding a large cap has benefits, making an LCR circuit........

Anyhow, the gains are minimal to say the least.

Phil