Car Stereos: audio system, watts rms, inch woofer

Question
hi!! i have just brought a new car its a hatchback...zen estilo...
i wish to put some nice audio system in it..i have installed a sony expload headunit and also sony round speakers in all four doors.but i thinkin of expanding it,,i enquired about woofers of jbl and sony...the vendor told me that a 1100W box type woofer can be installed with 2chn amp of 300W..is it ok??? is it ok to go with this??
and also i need to ask u whether i should go for jbl woofer or sony woofer i need a 12 inch woofer..and around 1200W...and which amp is good sony o jbl?? so please suggest me some good combinations and options...i live in india so please let me know the products available here....

Answer
Hi,

I'm sorry, but I don't really have much knowledge of the car audio equipment available in your area.  Because I live and work in the US, car audio equipment in India is well outside my expertise.

In general, I think JBL is probably a better-regarded car audio brand than Sony; but it's certainly possible to put together a good-sounding system with either.  

You'll have an easier time matching a sub and amplifier combination if you ignore the "peak" power rating, and look only at "RMS" ratings.  For example, a Sony subwoofer that's listed as 1200 watts peak may be rated for about 340 watts RMS.  There's no accepted standard for peak power ratings, so most manufacturers just use them for marketing.  When you're matching the sub to the amp, you'll want to look at RMS ratings in both cases.

Usually, a mono amplifier is your best option for use with subwoofers.  You'll also have to look at the impedance rating of the sub to properly match the subwoofer and the amp.  For example, an amplifier will often be given two different power ratings, depending on the load impedance: the same amp may be rated for 300 watts with a 4-ohm load, and 500 watts with a 2-ohm load.  If you pick a 4-ohm, single voice coil subwoofer, then you'll need to look at the amp's 4-ohm rating; but if you pick a 4-ohm, dual voice coil sub, then the two voice coils will usually be wired in parallel for a 2-ohm load.  Most mono amplifiers work well with either 2-ohm or 4-ohm loads, but most 2-channel amps are limited to a 4-ohm load when they're used with subwoofers.  Ideally, you'll want the amplifier's RMS power output to come as close as possible to the sub's RMS power rating without going over.

I took a look at JBL's web site and found a couple products that you may be able to find in your area.  I'd suggest looking for a JBL P1224 subwoofer, and match it with a JBL GTO3501 mono amplifier.  The sub is a dual 4-ohm design, rated for 400 watts RMS, and the amplifier can produce 360 watts RMS at 2 ohms, so they'd match up pretty well.  You might be able to find the subwoofer pre-loaded in a matched enclosure; JBL's model number for this combination is PB1220.  

Hope this helps!

Brian