confused about power ratings

dylan

Please bear with me, I'm a hair short of dumb **** with electrics... I'm trying to power a 10" MTX 8000 sub (single vc, 4ohms). I see some amps are rated wattage wise at 12v, while sometimes they also rate the output at 14v+.

Unless I'm mistaken, my car is only going to supply it 12v? I have a Subaru Legacy GT sedan with an 85 amp alternator. If the car is running does it supply 14v? I just bought an MTX 8302 closeout from Crutchfield, and the difference goes from 300w bridged at 12v to 425w at 14v.

I'm confused. Thanks.

dylan

Alright, I'm clear on the voltage thing now... but I'm still confused about something. How do mono amps compare to bridged 2 channels as far as output? After some listening it seems their power ratings is far above a 2 channel bridged... ie it seems like a 300w mono amp pushes harder than a 2 channel bridged to 300w. Is there a rule of thumb with this, like maybe a 300w mono is about like a 400w bridged, all other things being equal, like brand, power wire, etc. Just curious. Thanks.

PoweredByDodge

power = voltage x current --- this is not a direct correlation since your battery is not pushing yoru speakers... but for a basic correlation it fits --- so... if voltage increases... power will increase proportionally.

far as MTX's ratings for 12.5 and 14.4 v --- its not all straight.

u have to look at it sideways through a foggy mirror... if u get my drift.

they underrate their 12 volt power by as much as 50% sometimes (at least in the last 5 years... i can't speak for 2003 models they all changed), but their 14.4 volt power is either dead on the money or like 5% overrated.... usually.

ie -- thunder 204: rated 25 x 2 at 12 ... thing does like 48 x 2 on the birth certificate at 12 though... then u turn the car on and get 60 something x 2.

81000d -- rated 1000 x 1 @ 12 / 1500 x 1 @ 14 -- birth sheet comes out around 1200 x 1 at 12 and then it'll do like 1450 - 1500 at 14 v.

as far as the 2 channel bridged versus the mono's --- 2 channel class AB amps wipe the floor with class D amps. for clarity, true power w/ out psuedo DC clipping, and all around quality -- class AB 2 channels are the way to go. But -- they cost more and suck a shitload more pwoer out of your car's alternator / battery. class D's are more efficient, use less power to make more power, are cheaper than compareable power AB's.

but far as power goes -- 300 w is 300 w -- the mtx 8302 u bought is rated at 300 @ 12 / 425 @ 14 --- i've seen some 302's and blue thunder 150x2's do as much as 500+ watts... well beyond their power rating, and its still clean, clear, and solid. i'd put that 8302 up against any 400 - 500 watt mono amp.

it'd prolly beat the piss out of a JBL 600.1 mono.

dylan

Originally posted by PoweredByDodge

u have to look at it sideways through a foggy mirror... if u get my drift.

That's how I was starting to feel. Something I wasn't thinking about was the class of the amp, good to know. Lots to learn. Hey PBD, thanks for your time!