Thread: Amps????????

basics of electronics 101 (really really basic)
an ohm is the measure of the resistance over wire.
when 2 resistors are in parrallel the resulting resistance is 1/(1/(R1) + 1/(R2)))
when you have 2 resistors in series the resulting resistance is R1+ R2

in car audio your subs are, your resistors, when you have 2 identical subs wired together (in series or parrallel) the resulting power is ~equally distributed between the 2 subs.

so 400W through 4 subs in parrallel that each have a resistance of 2 ohms would give you a 0.5 ohm resistance at the amp and 100W in each sub.


Edit:fixed my maths
1/(1/2+1/2)=1/(1/1)=1
1/(1/1+1/1)=1/(1+1)=1/2
400/4=100

feel free to correct if anyone sees errors on this. im tired and am a little light headed from fibreglassing.

Those are 4ohm single voice coil subs. Wired in parallel, it's a 2ohm load. 380w RMS for 2 subs is 760w. You should probably be looking for an amp that will do about 750-800w RMS at 2ohms into one channel (mono or bridged). Without looking too hard, I'm not seeing a Sony amp (Sony isn't so great anyway) which will produce the power you need for those subs.

Your calculations aren't quite right Virac. 4 2ohm subs in parallel would actually be .5ohms. Without going into details about the formula, the easy way to check is by using this link:
http://www.the12volt.com/caraudio/boxcalcs.asp

Originally Posted by nalav

Those are 4ohm single voice coil subs. Wired in parallel, it's a 2ohm load. 380w RMS for 2 subs is 760w. You should probably be looking for an amp that will do about 750-800w RMS at 2ohms into one channel (mono or bridged). Without looking too hard, I'm not seeing a Sony amp (Sony isn't so great anyway) which will produce the power you need for those subs.

Your calculations aren't quite right Virac. 4 2ohm subs in parallel would actually be .5ohms. Without going into details about the formula, the easy way to check is by using this link:
http://www.the12volt.com/caraudio/boxcalcs.asp

Holy cow thats handy... if only they would have let me use the internets for engineering school tests... (and its been a few years)

anyways ya i fixed my maths.

but you are gonna be spending alota money on an amp to power those, not really that great of, subs. like 400 for an amp to put out 750W http://www.crutchfield.com/p_2068ZX7...owAll=N&tp=115 but if its what ya got an what ya want by all means

would this amp be better??

would this amp be better???

http://www.sonystyle.ca/commerce/ser...h=n32150n46280

see my post 18
http://www.mp3car.com/vbulletin/1311672-post18.html

what will happen if the are under powered?

i dont mind if i dont get the full sound if thats all that will happen if they are underpowered.

Look around, you can find an amp for that price range that will properly power those speakers. The reason not to under power subs is that often they won't sound their best until they reach their optimum power levels. Though, I guess you wouldn't notice much difference with those subs. Any particular reason you're going with Sony and not something better? You can definitely find something better for the same price range if you look around more.