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View Full Version : 2447J Measurements, help with analysis?



emilime75
02-19-2017, 11:27 AM
I'll start by admitting I am rather inexperienced at taking and analyzing measurements, especially of frequencies above sub bass levels. I've done plenty with sub woofers and used them to even out response with great success, but this is a whole different ball game for me.

The signal chain here consists of a Dell laptop - HDMI - Onkyo PR-SC5508 - MiniDSP 2x4 Balanced - Crown amp w/no dsp built in.

The only processing going on is a high pass of 24dB, LR @500Hz.

All processing in the Onkyo is bypassed.

The driver is a 2447J on a 2382 horn stood vertically. The mic is a UMIK, on axis.

My measurement setup is quite unscientific, I'm just holding the mic at a guesstimated 1 meter away from the horn mouth, no baffle, it's simply sitting on top of a plywood box about 14" from floor to bottom mouth edge. It's also right up against the back wall.

Anyway, I'll post 3 plots. 1st is the sweep, 2nd is the waterfall and 3rd is the distortion plot. I don't know why REW didn't plot distortion beyond 7.2 and 10.8Khz, but this is what I got.

Do these look like accurate measurements? What would some of you more experienced folks make of them?

760797608076081

grumpy
02-19-2017, 11:56 AM
I don't know why REW didn't plot distortion beyond 7.2 and 10.8Khz, but this is what I got.

because you'd have to capture a 40KHz bandwidth to pick up the second harmonic of 20KHz... 60KHz
for the third. What you are seeing is expected.

emilime75
02-19-2017, 07:58 PM
because you'd have to capture a 40KHz bandwidth to pick up the second harmonic of 20KHz... 60KHz
for the third. What you are seeing is expected.

I see, I think. I'll have to research that to understand it. Thanks.

Any thing else here look wrong or right? Is this considered good or poor performance?