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In Reply to: RE: Why do you say that ? posted by hahax@verizon.net on February 26, 2025 at 18:51:26:
The bass hump is defiantly not anomaly of Johns testing method that's for sure. John Atkinson uses a B&K 4006 microphone with DRA Labs MLSSA system for all his measurements they will be 100% accurate.
I have heard people say his measurements cannot be accurate due to the fact he measures nearfield. Funny thing is everybody measures nearfield when I say everybody, I mean all manufacturers today's standards are @1 watt 2.83 volts at one meter. So, a microphone is placed 3'3" from the speaker and measured with one watt 2.83 volts of input power.
Some of the speakers he has measured also have a manufacturers measurement to compare johns to and in these cases Johns measurements are almost spot on except in the bass region where you can have some differences due to room size. Smaller rooms will increase SPL sound pressure levels and cause an increase in bass larger rooms will decrease the SPL and can cause dips in the bass response.
But to be honest when measuring a speaker like John does room's really do not make a difference like people think they do. Example if you're measuring a speaker in a room that is 20' by 30', and you have the speaker in the middle of the room how close are the walls? closest will be 10 feet away. So, if your microphone is 3'3" from the front of your speaker sound takes 0.001 seconds to travel 3'3" but it would take sound 0.018 seconds to travel 10 feet to the wall and then reflect another 10 feet of the wall back to the microphone so a difference of 0.017 seconds making it impossible to affect the measurements.
But move those speakers into listening position say 3 feet from the walls and place that microphone where your head would be in your normal listening position say 8 feet from the speakers and all bets are off now rooms will greatly affect the measurements.
John Atkinson knows what he is doing he has had the luxury of being able to talk to all the world's top speaker designers over the course of decades so yea he knows what he is doing. And no speaker designer or manufacturer has ever criticized his equipment or his technic and that says it all.
Audiophiles need to be thankful someone like john Atkinson is taking accurate measurements and publishing them for the audiophile community to see. The man is such a perfectionist he even has an accelerometer he places on the speakers' cabinets to measure cabinet vibrations he can tell you how well braced or how poorly braced a speaker cabinet is without even looking in the cabinet.
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- RE: Why do you say that ? - seancuster71@gmail.com 23:13:29 03/02/25 (0)
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