power question

**catchinup99f150** · 09-07-2006, 08:49 PM

so what do you consider to be a nice 10inch sub shadow.

**GoHybrid** · 09-07-2006, 09:20 PM

i think a capacitor isn't such a bad idea... even without the audio system. My take on it is that it excels in the area of voltage regulation. In my car, pre-cap, i measured a drop from 12.2v to 10.7v at the battery during engine cranking. post-cap i measured 12.2 to 11.7v. That tells me that the capacitor's stored energy is helping take the hit from the starter. Could be good on a cold day. Not essential... but good. As far as audio goes... i've never measured my amp drawing much more than 6-10A, so I know i haven't had to tap that reserve at all... but we'll see when i install my sub how that goes.

**Shadow** · 09-08-2006, 08:42 AM

Stiffening caps are useless in car audio, PERIOD.

Good 10" subs:
Infinity Reference 10, RE10, Alpine Type S, Kicker Comp VR (least clean sounding), Alpine Type E and many more

**GoHybrid** · 09-08-2006, 10:47 AM

I've seen you say that alot in various threads shadow... but little in the way of support for that theory. would you enlighten me?

**Shadow** · 09-08-2006, 10:49 AM

I posted a showdown with and without a cap a while back using current and voltage readings that was pretty extensive. I don't feel like digging it up but if you're looking for info, search it.

**GoHybrid** · 09-08-2006, 02:08 PM

i've flipped through thirteen pages of your posts, read everyone ripping on capacitors with hardly a number or a reason to back it up, searched here, searched google, and tested my own system to find that they aren't the pointless tin cans you make them out to be. I'm not convinced.

I'd be glad to read your showdown when you find it though.

**Shadow** · 09-08-2006, 02:25 PM

I guess you didn't search well enough. I searched for "caps" with my username and it's the fourth hit.

http://www.mp3car.com/vbulletin/show...25&postcount=5

**GoHybrid** · 09-08-2006, 03:55 PM

sorry i was searching threads. Anyway, I looked at the pdf, and while i think it's a valid test, i also believe that is testing the capacitor as a bandaid to insufficient supply. On that point, I'll agree with you... it's useless to try and make up for a deficiency in the battery/alternator with a cap. In my setup though, I'm running a very efficient amp (about 85%), no sub at present, and a 1F cap. The only thing i've noticed is a more constant, elevated voltage through the system, and it usually stays around 13.8-14.1V, especially when cooling fans turn on, or spikes from defroster or headlights hit. The manual for the amp notes that figures for peak and RMS power were obtained using a 14.4v bench power supply. That makes me think that voltage is "ideal". Why not try to stay as close to that value as you can? So to agree with you once again, the cap is doing it's job as a voltage stabilizer.

All said, I think we agree on what a capacitor can do and can't do... but i guess we continue to disagree on whether or not it's "useless. PERIOD." There are some benefits to having that kind of cushion in your electrical system.

**Shadow** · 09-09-2006, 01:06 PM

Not for your amps. When your amps ask for 75A of current and your alternator's only got 30 to spare, it'll eat everything in your cap and still attack your battery. After that your cap is just playing catch up. Stiffening caps are useless.

Also, how are you getting that your amp is 85% efficient. I'd like to know that one too.

**GoHybrid** · 09-09-2006, 02:02 PM

Here's my amp:
http://www.eclipse-web.com/amp/xa5000.html

here's the amp within:
http://www.eclipse-web.com/amp/ice.html
http://www.bang-olufsen.com/web2/com...sub=sd&page=sC

ok...again, we're agreeing that caps are not for relieving sustained power deficiencies, but they do stabilize voltage, which is beneficial to the entire system, including sound... especially (digging deeper) when coupled with class D amps which are typically pretty sensitive to power supply fluctuations.