Subwoofers, Why The Low Impedance

[Kapetol T]

I have always been wondering this and just thought of asking.

Why is it that sub woofers for cars are rated at like 1 or 2 ohms and PA subs for just about everything else are rates 4 and up?

What about the High/Low impedance makes them more suited for each of their tasks?

[BigPimpin91]

Car audio amps can handle 1 ohm loads.

House amps due to power conversion and what-not can only handle so much.

[Guest MegaloManiac]

cheap power....

[Kapetol T]

cheap power....

So its just that they can make those cheaper?

And the power issue with in the wall socket.

They also don't sound QUITE as good though would they?

[Guest MegaloManiac]

lower impedance levels will increase distortion on paper, but its nothing super audible at all. higher impedance is friendlier on your electrical

[BigPimpin91]

So its just that they can make those cheaper?

And the power issue with in the wall socket.

They also don't sound QUITE as good though would they?

It's easier to convert DC to AC than AC to DC.

Which I don't quite understand.

Something to do with oscillators.

[MickyMcD]

Parrallel two 1 ohm woofers, and what do you get? A (theoretical) load of half an ohm. Parrallel two 8 ohm woofers and you get a four ohm impedance, which can be paralleled again with another two 8 ohm woofers to give you (around) 2 ohm. That's four bins off one channel. PA Amplification is designed to run multiple cabs off a single channel or amplifier to maximise usage from minimal power.

Also, a true high-power amplifier such as the Crown MA5000Vz is absolutely MASSIVE in power supply size and in terms of the number of transistors per channel. My largest amplifier personally is a Peavey PV Series PV3800. It delivers 1300watts continously per channel at 4 ohms. To do so, it has 13 power transistors each side, with a power supply drawing 2980w (240v, 12.41A). Drive it at 2 ohm a side, it complains. Drive it at 1 ohm a side, BANG BANG BANG x 26. Understandable as the amplifier tries to draw a good 20A plus off a 240v feed. Not good.

Car audio woofers are designed at a low impedance to get a metric dickton of power. You can happily throw 3k+ to some woofers, individually. And it is not rare to see people throwing 2k+ a coil on these drivers. The only drivers that I have ever come across in my field that can remotely and briefely handle that sort of insane power are the Peavey LowRider, ProRider (to some extent), the higher end JBL array drivers, the EV Array Drivers and the P.Audio woofers. I am sure that there are more, but still a few out of thousands.

All in all, it boils down to cleaner power that is easier to supply and more useful in terms of multiple driver arrays. It's great when we can run 8 NeXO Geo-s cabs a side off one Lab.Gruppen IP6400. And yes, you CAN here the difference between an amplifier run at 8 ohm and at 2 ohm. To many it's not audible, to some it's ear splitting.

And Bigpimpin, it is much easier to convert AC to DC. Four diodes and a capacitor will get you a smooth DC feed from a dirty or inconsistent AC feed.

Cheers,

Mick

[Kapetol T]

Parrallel two 1 ohm woofers, and what do you get? A (theoretical) load of half an ohm. Parrallel two 8 ohm woofers and you get a four ohm impedance, which can be paralleled again with another two 8 ohm woofers to give you (around) 2 ohm. That's four bins off one channel. PA Amplification is designed to run multiple cabs off a single channel or amplifier to maximise usage from minimal power.

Also, a true high-power amplifier such as the Crown MA5000Vz is absolutely MASSIVE in power supply size and in terms of the number of transistors per channel. My largest amplifier personally is a Peavey PV Series PV3800. It delivers 1300watts continously per channel at 4 ohms. To do so, it has 13 power transistors each side, with a power supply drawing 2980w (240v, 12.41A). Drive it at 2 ohm a side, it complains. Drive it at 1 ohm a side, BANG BANG BANG x 26. Understandable as the amplifier tries to draw a good 20A plus off a 240v feed. Not good.

Car audio woofers are designed at a low impedance to get a metric dickton of power. You can happily throw 3k+ to some woofers, individually. And it is not rare to see people throwing 2k+ a coil on these drivers. The only drivers that I have ever come across in my field that can remotely and briefely handle that sort of insane power are the Peavey LowRider, ProRider (to some extent), the higher end JBL array drivers, the EV Array Drivers and the P.Audio woofers. I am sure that there are more, but still a few out of thousands.

All in all, it boils down to cleaner power that is easier to supply and more useful in terms of multiple driver arrays. It's great when we can run 8 NeXO Geo-s cabs a side off one Lab.Gruppen IP6400. And yes, you CAN here the difference between an amplifier run at 8 ohm and at 2 ohm. To many it's not audible, to some it's ear splitting.

And Bigpimpin, it is much easier to convert AC to DC. Four diodes and a capacitor will get you a smooth DC feed from a dirty or inconsistent AC feed.

Cheers,

Mick

So are the drivers that run at the higher impedances more efficient so they can get louder off lower wattage but great ohms?

[Guest MegaloManiac]

So are the drivers that run at the higher impedances more efficient so they can get louder off lower wattage but great ohms?

yes. i am looking for the thread on diyma that shows how it works. give me some time to find it.

btw in a car you are really converting twice. from AC(inside the alty) to DC(to battery and then to amp) back to AC(out your amp)

Edited May 6, 2008 by MegaloManiac

[Kapetol T]

yes. i am looking for the thread on diyma that shows how it works. give me some time to find it.

btw in a car you are really converting twice. from AC(inside the alty) to DC(to battery and then to amp) back to AC(out your amp)

Thanks, thats what I thought but I wasn't 100% sure.