TrevorMilburn wrote on Sun, 16 January 2011 05:14 |
Quote: | The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000.
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I haven't used SMAART myself, so I am not conversant with the displays shown (I saw the 0dB in the display), but were the measurements taken at full power on the IT4000 or at 1w or some other power? I say this because the speakers IIRC are rated at 1600w program which means that if they were being given the full 2000w the IT4000 is capable of at 4ohms and had a 4db HF eq boost applied, the HF would be pushed well beyond it's comfort zone. I would expect most lesser speakers to be screaming for mercy or completely giving up the fight. Also, is it possible that the coaxial MF/HF was mounted in the centre position (it is a sealed unit so can be moved quite easily from what I have read elsewhere) and the measurements were inadvertently not taken on axis at all? Just curious.
Regards, Trevor
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Evan stated:
"I measured the horn on axis @ 1m, and ground plane at 1 & 2m. The measurements were all consistent. It's not the mic, as it showed the EV and Mackie boxes flatter out to 16k."
The posted photo clearly shows the coaxial speaker in the top position.
Unless one is specifically testing for distortion or power compression, speaker testing normally is done at a level that will be 20 dB or so above ambient noise.
With speakers like the ones tested, pink noise with peaks of a watt or two is usually plenty of level to be well above ambient noise. You learn to avoid taking screen captures when dogs start barking, vehicles drive by or fly over, or the wind gusts.
If any of those things happen, they will show up as a reduction in the red coherency trace shown on the top of the screen. Evan's coherency traces all look good within the range under test.
That said, it does not take much wind to make the phase change 180 degrees at 16K, even though the frequency response will stay pretty consistent.
Frequency response testing at high SPL levels just makes the neighbors complain, and gives you no better information.
Art Welter