Knowledge Question Bout Sub Volume

[maxkhor]

Just wonder 2 set of systems below will give any different output?

1st set

an amp that deliver 200RMS power to a 2ohm 12" sub

2nd set

an amp that deliver 200RMS power to a 4ohm 12"sub

will this give any different outcome?

thankx

[trism]

no, it wont. voice coil impedance has no affect on volume, if the subs are running at the same power.

[mikel]

agreed

it completely depends on efficiency of the drivers

an 83db driver will be twice as loud (in sound pressure level - SPL) as an 80dB driver at the same power. Your ear may not "perceive" the SPL increase as twice the volume however - psycho-acoustics being what it is

[bloodsword27]

mikel spot on. power is still power, only that some subs are 2 and other sare 4ohm, but amps are designed differently. more than often, 2ohm rating will produce more power than 4ohm.

[DD Phil]

agreed

it completely depends on efficiency of the drivers

an 83db driver will be twice as loud (in sound pressure level - SPL) as an 80dB driver at the same power. Your ear may not "perceive" the SPL increase as twice the volume however - psycho-acoustics being what it is

Not true unfortunately.

Sensitivity of a driver is measured at 1W, what the driver does with 100W or say 1000W in the real world is an entirely different matter.

It's easy to build a driver with a light coil and suspension, that has an efficiency of 105+dB with 1W, but it would most likely explode when you put even 100W into it.

Also "efficiency" specs never take into account enclosure etc.

The bottom line is, don't buy a woofer based on it's efficiency spec.

Phil

[mikel]

yes, but assuming both drivers have the same wattage rating, the one with the higher efficiency will produce more SPL at a given rms output of the amp.

I completely agree that you shouldn't choose a driver on efficiency alone.

Efficiency is just one of the valid specs to look at when choosing a driver, as is size, rms wattage, Vas, Fs, Q, Xmax, etc.

Efficiency is important if electronically assisting rolloff (eg using a Linkwitz Transform) as otherwise massive gain is required to achieve the desired response shape.

If two drivers met my needs but one was more efficient, I would choose the more effcient driver (assuming similar cost), otherwise you may need bigger amps, with more power drain etc to get the SPL you're looking for.

Not true unfortunately.

Sensitivity of a driver is measured at 1W, what the driver does with 100W or say 1000W in the real world is an entirely different matter.

It's easy to build a driver with a light coil and suspension, that has an efficiency of 105+dB with 1W, but it would most likely explode when you put even 100W into it.

Also "efficiency" specs never take into account enclosure etc.

The bottom line is, don't buy a woofer based on it's efficiency spec.

Phil