PA POWER RATING

[MIKE900]

My band have the following PA set up:

Alessis multimix 16 desk

yamaha P3500s amp

Yamaha P5000s amp

Wharefdale 12" tops 8ohm(300W)

JBL 18 passive subs 4ohm(400W)

 

Were using the P3500 for the tops and the P5000 for the subs, running 3 x vocals, bit of Kick and snare. My question? Is it Ok to push the amps at 3/4 to max output or am I in danger of blowing the speakers (particularly the tops I'm concerned about). I was told to push the amps near max and bring main mix level down a bit, I'm now a bit confused as to what each amp power rating is with this setup. Any help much appreciated.

Mike

[timtheenchanteruk]

have a read on gain structure, my thinking is reduce the level at the last point in the system, ie the amps to keep system noise to a minimum.

[TimmyP1955]

Noise should not be a problem with modern equipment.

 

Turning the amp's controls down does not reduce the amp's power rating, it merely changes (increases) the input signal level that is required for the amp to reach a given power.

[MIKE900]

Am I ok pushing the amps to near max without any damage to speakers particularly the tops??

[Simon Lewis]

Am I ok pushing the amps to near max without any damage to speakers particularly the tops??

 

The P3500s delivers 350W per channel into 8 Ohms (20-20kHz, THD+N=0.1%). If the power rating of the loudspeakers is realistic, then you should be able to deliver the amp's full output power into those speakers without damage. You must not let the amp's clip light come on though.

 

However, the amp doesn't 'cap' its output when it reaches 350W, and if a signal voltage higher than the rated input sensivity (+4dB) is applied (when the "volume control is all the way up) it will try and deliver the signal, albeit with increased distortion and harmonic products. It is often these distortion products and the creation of a flat topped waveform that can damage the speaker. Your amp is rated at 390W per channel when delivering a single tone (1kHz) and producing 1% distortion.

 

In many professional rigs, a larger amplifier than is actually needed is used, so that the amp does not clip when driving the speaker at its rated power. Of course, if such an amplifier is allowed to 'clip', then it's likely the speaker will fry, and the larger amp will cost more.

 

Simon