mukrainetz wrote:
| Being new to car audio I have a lot of questions which may seem pretty straightforward but hope I get a few answers anyway. |
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Not a problem. That's what we are here for!
mukrainetz wrote:
I purchased two 12" Volfenhag subs (4 Ohm) which are said to be 1000w max - 500w rms
I also purchased one Volfenhag 2000w amp which I will use bridged for both subs (said to provide 600w rms bridged) |
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One thing to remember about brands like Volfenhag, they WAY overrate their products. Figure half the real-world power handling on the woofers, and if you are lucky, half the power production capabilities on the amplifier.
mukrainetz wrote:
| I have a subscription to and been purchasing Performance Auto & Sound magazine for years and read through them religously. One article I found yesterday basically said an amp will draw about 100amps per 1000w (I hope I quoted that right) and continues with information about stock vehicle electrical systems being barely able to cope with larger audio installs if not at all.
My question I guess is will my stock battery and alt. be able to power my system or will I be left with a dead battery or burnt out alternator / fuses? I dont know exactly what the efficiency is of the amp or the draw when the subs are connected bridged at 4 ohms.
The head unit I bought is the new Sony CDX-F605X which I believe is 52wx4 if I need to consider that as well.
None of this setup is installed as yet because I cant find a dealer that sells a harness to install my new H/U into my car (2006 Yaris) but the car is wired and ready for it all to go in.
Thanks for any help |
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The way I figure efficiency and current requirements is this: Stated Power output, times 1.5, divided by 14.4. This'll get you close, most of the time, for ANALOG amplifiers. For digital, multiply by 1.25, then divide by 14.4. Generally speaking, I ignore the speaker load spec, as the efficiency will not change dramatically, and the numbers I use often are a bit high... but they average pretty well, from load to load.
600w (out) X 1.5 = 900w (in) / 14.4v = 62.5A (analog figure)
600w (out) x 1.25 = 750w (in) / 14.4v = 52.1A (digital figure)
The head unit will ONLY be figured in if you are planning on using the internal amplifier to power your highs or component sets. 52w (head-unit watts) X 4 really translates to 20 watts or so, so add 2-3A continuous for the HU.
With most smaller cars being provided with 50-70A alternators, you are (close to) doubling what the manufacturer is assuming the OEM alternator will ever run, so I would say an alternator is your first step. Adding a second battery will only exacerbate the problem. Your first step with ANY high output amplifier or sereo system will be your alternator.
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."
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