Capacitor... ANY one?
 

For those who didn't read my audio thread, I have a 800w amp with an alpine type r with stock business CD, no DSP.

I need a capacitor for sure. Lights DIM on base notes, especially when I have the heat or AC on.

Any suggestions on brand, type, Capacitor or Mini-battery, ect...

I found these on ebay:
http://cgi.ebay.com/NEW-POWER-ACOUST...QQcmdZViewItem

http://cgi.ebay.com/NEW-PYLE-6-FARAD...QQcmdZViewItem

http://cgi.ebay.com/POWER-ACOUSTIK-P...QQcmdZViewItem
It would be nice to see what you guys think.

THX

i suggest getting the 3rd one. The 1st one looks fruity, and the 2nd one is gigantic!! As far as capacitors go, u dont need the BEST/MOST EXPENSIVE one just a good quality one, you already have a bmw with a high quality battery. Now if u had a honda or somethin im sure ud need a fatty ass capacitor if not an extra battery depending on how much power your system is drawing. It mostly depends on what kind of car u have, and how old/new ur car battery is.

A good quality capacitor that I can recall I think is made by Rockford Fosgate.

Are you installing the cap or are you having it installed? it is best to take it to a reputable local shop they will be able to properly advise you as to how much reserve power you need...not to mention if you dont know how to properly hook up a cap you can very easily damage the circutry in your amplifier

800W!!!! OH WOW!!

I have been professionally employed in the electronics industry for 35 years and this is the first I heard of this power level in a automoitive application.

OK I realize I'm showing my age but assuming the base frequencies cause the amp to draw near maximum current thats over 80 amps assuming 80% efficiency. Even though it may be for a few milli seconds thats huge current.

What gauge wire feeds the amp? Is there a direct line to the battery?

May I suggest a Honda Generator to supply the audio system and ear protectors.:rofl:

BTW as a saftey margin the capacitor working voltage should be at least 50% higher then the capacitor terminal voltage. The vehicle electrical system voltage is closer to 13.2V with rpms above 1K so the capacitor should have a working voltage of 19V or higher.

Not jacking the thread, but mine is 2200 watts, so why would 800 watts be bad? What does that mean for 2200.

Good question. To answer that the rating standard used for these amplifiers would be needed.

Manufacturers have many creative ways to inflate advertised output power. One is the peak music power rating. There is no industry standard for measuring peak music power. Another is RMS power which is more realistic but worthless by itself.

The accepted rating method for car audio is CEA-2006.

but to deliver the rated power using this method the voltage at the amp terminals must be a constant 14.4 V under full load!

Capacitors act as a buffer and supply some reserve current during peak loads but if the terminal voltage does not remain at 14.4V the the rated power will not be obtained.

With all the electronic stuff in cars these days and the pressure on auto manufacturers to control costs do you think the reserve capacity is sufficient to supply another 80+ amps?

I don't think so. :rofl:

With todays amps ,800 watts RMS is only going to draw 35-40amps.
Also , you will need 1 farad for every 1000 watts of peak power.
So you should be fine with a 1 farad cap.
However the cap will not be any good if you listen to anything with a long extended bass note.(mainly R&B and rap)
What kind of amp do you have and what size power wire are you using?



How old are you v10rick......1000watt+ systems are pretty common.
Check out this nutball http://www.cnn.com/2003/TECH/ptech/0...i.stereo.kill/
BTW home and car audio are night and day difference.
200 watts in a home application would be comparable to 1500 in a car.

That is amazing.

I looked over the online specs of several high power amps and none listed current requirements.

Since we are working with DC current simple ohms law can be used to calculate this. Using I=P/E at 100% efficiency to deliver 800 watts RMS at 14.4V the current needed is 55.5 amps. Assuming a class D amp at 80% efficiency the current needed would be closer to 66 amps.

Of course the actual demand would depend on the audio content and the position of the volume control. Maintaining the amps rated output will depend on the capacitors ability to supply the reserve needed at peak load.

The reason I'm shocked at these power levels... I was employed in the commercial sound industry for a number of years. A paging system that supplied as many as 100+ speakers at once would require two 100 watt amplifiers.

But mega base rap music did not exist back then.:rofl:

Capacitor
 

I would suggest to get a high quality one, to name a few Rockford Fosgate, Phoenix Gold, SoundStream ... I had a Pyle capacitor before on a Honda Accord and the light still got dimmer once in while when I listened to R&B. I later replaced the capacitor with a Phoenix Gold one and it solved the problem. I still use that Phoenix Gold capacitor in my X5 now. I guess the other capacitors did not hold charge as well.

cap is not going to help. get a different alternator.