We anxiously awaited its delivery because we had a major sporting event coming up where we could give it a "baptism of fire" evaluation against equipment we knew and trusted.

As Murphy’s law always has it, the amplifier (Altronics told us it was the first one off the production line) didn’t quite make it in time (it arrived just two days after the event – of course!) so, while we were able to give it a preliminary check-out, we couldn’t easily give it a real-life run until recently.

Power output into a 4W load. It didn't quite make the 250W mark but the difference is too small to be noticed.

Claimed frequency response is 50Hz-12kHz (-3dB) and this test shows that's just about spot on!

Testing a high power PA amplifier is normally not quite as simple as testing a stereo amplifier or similar. Amplifiers are normally tested in two parts – on-bench testing using dummy loads to see if they meet manufacturer’s specifications, then evaluation by ear using high performance, known speakers to see how they sound.

True PA amplifiers have an extra "wrinkle"– they’re normally designed to work into 100V (or 70V) lines. This is to minimise I²R losses over long speaker lines.

Our dummy load setup was never really intended to cater for 100V-line amplifier measurement.