Volume vs air movement

[Sparty]

Can someone shed some light on these subjects for me...? Please..

I have a stereo amp 500w a side at 4ohms or 300w at 8ohms. If I was to run the rig at 2 x 8ohm(2 x 600w 2x12) (1 x speaker either side) would I get better headroom and performance out of the amp than I would running them in parallel giving me one side at 500w.

Also the more speakers you have what effect does this have on volume?? Would I need less volume because I'm moving more air with a 2x12 than say a single 15" and would the stress on the amp be lesser / more running more speakers??
Just need to understand the physics behind it more so I can get the best out of my gear.. Unfortunately flunked all my sciences at school.. Too busy learning the bass..
Many thanks for any replys

[Downunderwonder]

Originally Posted by Sparty

Can someone shed some light on these subjects for me...? Please..

I have a stereo amp 500w a side at 4ohms or 300w at 8ohms. If I was to run the rig at 2 x 8ohm(2 x 600w 2x12) (1 x speaker either side) would I get better headroom and performance out of the amp than I would running them in parallel giving me one side at 500w.

Also the more speakers you have what effect does this have on volume?? Would I need less volume because I'm moving more air with a 2x12 than say a single 15" and would the stress on the amp be lesser / more running more speakers??
Just need to understand the physics behind it more so I can get the best out of my gear.. Unfortunately flunked all my sciences at school.. Too busy learning the bass..
Many thanks for any replys

You have to get your head around "all else being equal" or compare apples and apples every time.

All else being equal:
More speakers = more air moved for the same power output = louder, ie more efficient.
More speakers allow solid state amp to make more power, more volume until you add two many speakers and cook the amp.

What was your question?
I think you have a couple of 2x12 cabs?
Run one on each channel and listen for farting, even 300W could be enough.

If you run them both on the one channel you'll have one hot channel and one channel doing nothing and only 250W of clean power per cab.

[B-string]

Keep in mind the amp "produces" the power (watts), the speaker cabs only accept the power sent to them.

[RickenBoogie]

+1 amp "generates" power, speakers "handle" power. Also be aware- amps can generate more than their rated power, and most speakers will actually handle less than their rated power, so care should always be used, including common sense. Use your ears, a distressed (farting) spkr is telling you it's about to die. One cab per side makes most sense. Always strive for "balance".

[BassmanPaul]

If you are looking for more volume, more speakers trump more power every time.

[Sparty]

Both 2x12 are 600w so if I ran them in stereo (use both channels)at 8ohms I should get a full 300w per side and the speakers should handle that quite comfortably..
Will this in turn be louder than just running one side at 8ohms as I will be running 4 speakers at 8ohms rather than just 2 speakers..(moving more air)
i.e1 .. 300w into 212 at 8ohms using channel 1
i.e2 .. 300w into 2x212 at 8ohms using channel 1+2 would this be louder & more efficient than ie1???

Theory being for smaller gigs I could just use 1 x 212 and for larger gigs the both cabs but off separate channels for more volume without worrying about pushing amps or speakers to the max..

[B-string]

The two 8 ohm 212's into one side or both channels bridged (I don't recommend) will present a 4 ohm load to the amp.
Running the cabs from separate amp sides will be much louder and safest for the cabs.

[JHAz]

It's always been my understanding that, assuming all the speakers can handle the power without compressing, doubling power yields 3 dB SPL increase. Doubling speakers without increasing power also yields a theoretical 3 dB SPL increase. Because we seldom use full power and probably never test these things with amps at max, when you connect additional speakers in parallel, you cut impedance in half and increase power by a factor of 2, so until you get to the bleeding edge of amp power doubling speakers adds 6 dB. Another way to say that is, to keep the power the same when you double speakers requires you to turn down the volume control by an amount that you are not likely to know without connecting measurement equipment.

and the difference between 500 and 600 watts is going to be barely noticeable at less than 1 dB.

[Downunderwonder]

Failed English too?

1 cab 1 channel >> Y dB, loud 300W
2 cabs 2 channels >> Y+6 dB, very ******* loud, 600W

2 cabs 1 channel >> Y + ^5dB, one hot 500W amp channel, one cold channel.

[Sparty]

Originally Posted by Downunderwonder

Failed English too?

1 cab 1 channel >> Y dB, loud 300W
2 cabs 2 channels >> Y+6 dB, very ******* loud, 600W

2 cabs 1 channel >> Y + ^5dB, one hot 500W amp channel, one cold channel.

Pretty much..

So 2 cabs ( 1 in each channel) will give me 600w.. I take it that it is 300watts per channel ( 300w going through each 600 watt speaker) resulting in 600w total output. So if I went down to 4ohms each channel then this would give me 500w each side or 1000w in total and i would be running 4 cabs as opposed to two.
Also what does bridging do?? Is it putting all 1000w into one channel at 4 ohms?? Somebody said it is not wise to do this, but I wouldn't know how anyways..
So in summary reading all replys it would be better to run the 2 channels each at 8 ohms as opposed to 1 channel at 4ohms

I'm used to using a single channel amp down into 4 ohms off 2 cabs but have just aquired a ashdown little giant 1000 but it has two 500w amps at 4ohms. Needed to know best way to use it..

[B-string]

Originally Posted by Sparty

Pretty much..

So 2 cabs ( 1 in each channel) will give me 600w.. I take it that it is 300watts per channel ( 300w going through each 600 watt speaker) resulting in 600w total output. So if I went down to 4ohms each channel then this would give me 500w each side or 1000w in total and i would be running 4 cabs as opposed to two.
Also what does bridging do?? Is it putting all 1000w into one channel at 4 ohms?? Somebody said it is not wise to do this, but I wouldn't know how anyways..
So in summary reading all replys it would be better to run the 2 channels each at 8 ohms as opposed to 1 channel at 4ohms

I'm used to using a single channel amp down into 4 ohms off 2 cabs but have just aquired a ashdown little giant 1000 but it has two 500w amps at 4ohms. Needed to know best way to use it..

Yes.

[Sparty]

Originally Posted by B-string

Yes.

You da man.. Thank you

[B-string]

Rock the house!