Being new to car audio I have a lot of questions which may seem pretty straightforward but hope I get a few answers anyway.
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)
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
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.
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)
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
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.
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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."
Thats excellent news (in most regards). I understand my choice of equipment (less H/U) wasnt the greatest decision in the world but its what I have to work with. I guess according to your figures its probably a good thing until I get a bigger alt. or better equipment that your numbers are higher than actual. At least Im at a maximum if the specs were 'actual'. But even at half of what they are rated for its not too bad, to me anyway.
I will be powering my other speakers through the H/U, its the stock 4 speaker system (they dont sound bad considering its stock in a compact) so I wont be replacing them until later.
Also, would it be a good idea to have a switch for the amp? I dont really intend to have it run ALL of the time (I have a two year old who I would like to not be deaf) plus Im sure there will be times I just dont want them on. Can I hook up a two way switch to the remote turn on lead for the amp?
mukrainetz wrote:
Also, would it be a good idea to have a switch for the amp? I dont really intend to have it run ALL of the time (I have a two year old who I would like to not be deaf) plus Im sure there will be times I just dont want them on. Can I hook up a two way switch to the remote turn on lead for the amp?
You most certainly could. I have a setup like that right now for my amplifier.
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