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Why Do TEF Systems read 3-5 dB high ?
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<blockquote data-quote="Art Welter" data-source="post: 24346" data-attributes="member: 52"><p>Re: Why Do TEF Systems read 3-5 dB high ?</p><p></p><p> </p><p>I don't think that windowing alone, even in a Large room, would cut it for valid LF measurement.</p><p></p><p>My best guess as to how to use a room as a virtual whole space would be to first measure speakers in a real whole space situation, then measure them in the room, and subtract the difference. Considering subs do have different directionality patterns, the room would react differently using a big horn loaded sub compared to a single 15" bass reflex, so LF directionality measurements would have to be done on a variety of subs outdoors, and also included in a room transfer function for it to be valid below the frequency that room absorption works.</p><p></p><p>Although I can conceptualize how all this could be implemented, I have no idea if that is what EAW has done.</p><p>Then again, I have no more than a vague understanding how Gunness Focusing works, but after hearing it and seeing how flat an ordinary appearing speaker's phase and magnitude can be made using it, I think Dave could have pulled off the complex transfer functions needed to turn a semi-anechoic room into a virtual whole space measurement environment.</p><p></p><p>Of course, assuming EAW's measurements are valid still leaves the whole space to half space comparison difference. Seems odd that EAW would not include half space measurements on their subs, I see more of them sitting on the ground than flown. </p><p>Oh well, comparing anything not measured in the same place with the same test gear is difficult.</p></blockquote><p></p>
[QUOTE="Art Welter, post: 24346, member: 52"] Re: Why Do TEF Systems read 3-5 dB high ? I don't think that windowing alone, even in a Large room, would cut it for valid LF measurement. My best guess as to how to use a room as a virtual whole space would be to first measure speakers in a real whole space situation, then measure them in the room, and subtract the difference. Considering subs do have different directionality patterns, the room would react differently using a big horn loaded sub compared to a single 15" bass reflex, so LF directionality measurements would have to be done on a variety of subs outdoors, and also included in a room transfer function for it to be valid below the frequency that room absorption works. Although I can conceptualize how all this could be implemented, I have no idea if that is what EAW has done. Then again, I have no more than a vague understanding how Gunness Focusing works, but after hearing it and seeing how flat an ordinary appearing speaker's phase and magnitude can be made using it, I think Dave could have pulled off the complex transfer functions needed to turn a semi-anechoic room into a virtual whole space measurement environment. Of course, assuming EAW's measurements are valid still leaves the whole space to half space comparison difference. Seems odd that EAW would not include half space measurements on their subs, I see more of them sitting on the ground than flown. Oh well, comparing anything not measured in the same place with the same test gear is difficult. [/QUOTE]
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Why Do TEF Systems read 3-5 dB high ?
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