What Size Amplifier Do I Need For PA Speakers?

by Andrew Bishop

Getting the Right Amplifier Matters.

I recommend that the amplifier’s RMS power be up to twice the loudspeaker’s RMS power handling. If the amplifier RMS output is higher than 125%, you risk damaging the loudspeaker with too much power in the event of feedback. If the amplifiers continuous power is lower than 80%, you will probably clip the signal in an attempt to get enough volume out of the loudspeaker. Clipping a signal produces strong high frequencies which have been known to burn out tweeters.

Just be sensible with the volume control. You will hear it if the speakers are hitting the buffers, so just ease back slightly.

Impedance matters. If you are joining speakers together of differing values and not sure what the final value will be please call us.

For example, suppose a loudspeaker has 200 watts RMS handling amplifier’s continuous average power should be 400 watts (within 80% to 125%, or 320 watts to 500 watts). 

Remember some speaker companies quote the program power which is twice the RMS. in this case ideally, the power amplifier’s peak power should not exceed the loudspeaker’s peak power rating.

If you’re mainly doing light dance music or voice, I recommend that the amplifier power be 1.6 times the RMS rating per channel.

Under powering a speaker driver can do as much damage at overpowering a speaker so always double-check and contact BishopSound if you are in any doubt.

If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies two to four times the loudspeaker’s RMS rating per channel. This will allow 3 to 6 dB of headroom for peaks in the audio signal. BishopSound loudspeakers are built to handle those short-term peaks.

Impedance often confuses amplifiers and users. We try to avoid going down to 2 ohms impedance as some amplifiers can overheat. We prefer to work the amplifiers with a 4-ohm load. Here are some examples of speaker wiring options.

Speaker Wiring Diagram

Wiring Up Speakers - Please contact us for more help.

If you have any questions on the best amp to use for your speakers go onto my Live Chat and speak with me. I would be happy to help you match the right amplifier to my speakers to get the very best performance.