Need advice on alternator setup

[SirPimpsAlot]

Hi guys.
I need some advice or input on my Polo Vivo 2012 concerning the alternator.

The reason for this thread is due to installing a new sound system in the car. The previous installation was a disaster after the car caught fire ( thanks Soundmatch).

I currently have the following to jnstall:

2 x RA Audio Tivo 75x4 amps
Energy Audio 9000w 1200w rms mono
12" Powerbass XL 12D4 sub 1200w rms
Phoenix Gold ZR67 6" Split system 80w rms
Phoenix Gold RX 6" speakers 70w rms
Energy Audio SQ692 6x9 80w rms
Pioneer AVH P4450BT ( old doubke din)
Energy Audio distribution block

Now my question is what size alternator do I need to upgrade to and what size spare battery would I need to run the system optimally?

Thanks guys!

 

[Scrooloose]

I believe that the Vivo (Polo Mk5/6R) has a 120A alternator.

The combination of amplifiers that you are installing have a peak current draw of 150A, which is unlikely to ever be reached by the loads that you're connecting. However you'd be best off measuring the current draw once the system is installed, using a high-output workshop PSU as power source to check out what the true current draw is.

Once you have that down, you can check out the car's manual to see what the electrical system and power plant requires, add the two together, bump by 20% and you have your alternator size.

As for battery, install the biggest you can fit. It's a buffer for when the alternator can't deliver the additional power needed. Capacitors are a farce, a 1 Farad capacitor can hold 1 Amp-second of electrons at 1 Volt - That's 75 Joules of energy at 12V - Less power than a flat AAA flashlight cell. Useless when you need 250A+ delivered each time your sub goes "doof" as you drive down the street with your kak music blaring for everyone to hear at 2AM.

FWIW, your amp needs to deliver at most 50% of the speaker's peak power capacity, so a 600W Monoblock would have been more than sufficient for that 1200W DVC sub of yours. In the pro-audio industry, we use a 1:3 ratio, sometimes even higher. Some guitar amp cabinets have a peak of 400W where the amps deliver 100W RMS max, and the speakers can rarely handle the amp at full tilt. It's more complicated than just the wattage rating, there's voltage and amperage ratings of the speakers to consider in the design.

I drove 2x 1000W 15" subs off a 500W monoblock amp at 2 Ohm (max output was 500W @ 2Ohm), with 2x 3 way splits (silk tweeters) in the front and 2x 2 way splits in the back running off a 600W 4 channel (150W per channel) amp and I pumped 130dB SPL with superb clarity. This was like 20 years ago now.

If you want loud, you don't necessarily need bigger wattage. You need bigger drivers that can move more air.