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Speaker Ohms Question


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#1 Syn Holliday

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Posted 25 April 2012 - 11:03 PM

I'm putting together a PA system for a band, have a Mackie board and a Crown XTi 2000 amp.  Just need to choose the speakers now.  Was wondering about the difference if I choose 4 ohm speakers versus 8 ohm speakers.  The XTi 2000 shows 4 ohms @ 800 watts/ch and 8 ohms @ 457 watts/ch.  Does that actually equate to 4 ohm speakers being that much louder than the 8 ohm speakers for my amp, almost 70% louder (800 475)?

The speakers I am leaning toward purchasing are 8 ohms, but if they're that much quieter than 4 ohms then I might try to find a good set of 4 ohms.  The system is just for rehearsal but they'll have a lot of stuff plugged into them (lead vocal, 2 background vocals, guitar via POD, bass, stereo keyboards, stereo electronic drums) so I need all the power I can get from the amp.

#2 dakos

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Posted 26 April 2012 - 12:29 AM

QUOTE(Syn Holliday @ Apr 25 2012, 11:03 PM) View Post
I'm putting together a PA system for a band, have a Mackie board and a Crown XTi 2000 amp.  Just need to choose the speakers now.  Was wondering about the difference if I choose 4 ohm speakers versus 8 ohm speakers.  The XTi 2000 shows 4 ohms @ 800 watts/ch and 8 ohms @ 457 watts/ch.  Does that actually equate to 4 ohm speakers being that much louder than the 8 ohm speakers for my amp, almost 70% louder (800 475)?

The speakers I am leaning toward purchasing are 8 ohms, but if they're that much quieter than 4 ohms then I might try to find a good set of 4 ohms.  The system is just for rehearsal but they'll have a lot of stuff plugged into them (lead vocal, 2 background vocals, guitar via POD, bass, stereo keyboards, stereo electronic drums) so I need all the power I can get from the amp.

Speaker loudness is measured in decibels, not watts!!!
When you compare two speakers you need to compare the maximum SPL (Sound Pressure Level), Max SPL is equal to the sensitivity of the speaker (how much sound the speaker makes with 1 watt of power connected to it measured at 1 meter distance) adding to it a logarithmic description of how many doubling of that 1 watt at 1 meter (equals a 3dB difference) the speaker can handle. So you are looking at the dB difference between the models of the two speakers.

Now you have to make sure the speakers you compare were specced the same way, some were specced at 2 watts at 1 meter, some were specced at 1/2 meter away so pay attention to the small hidden units when comparing.

One more thing, most important!! Don't buy speakers before you listen to them!!!

Good luck smile.gif