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Thread: Room Gain and Predicted Response

  1. #1
    Administrator Robh3606's Avatar
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    Room Gain and Predicted Response

    I have a couple of questions for you. With room gain can you predict how much and at what frequencies??

    The reason for the question is I seem to getting more low end out of my E-145's than the box programs would predict. Especially at 40Hz where I should be about 10db down. Its a pleasant but rather unexpected surprise. I tried pink noise for 1/3 octave averages and sine sweeps while monitoring the levels on the RTA. They all read about the same are consistant, and confirm what I was hearing which had me scratching my head.

    If you know your room gain vs. frequency do any of you take it into account when tuning boxes for your room?? Looks like a way to avoid the boom with a flat box. Any thoughts?? I am wondering if that is what I am seeing.

    Rob

  2. #2
    Senior Member GordonW's Avatar
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    Oh heck yeah, I take that into account!

    Most of my box designs, I tend to tune for an initial rolloff starting around 35-40 Hz, but VERY SHALLOW, down to the mid-20s or so, where they roll off steeply below port resonance... usually by tuning the port lower than normal. This tends to alleviate the 40-70 Hz "room boom" found in many places, and has yet to bite me in the @$$...

    Sometimes, I'll also slightly oversize or heavily stuff a box as well, to lower the bass output at 50 Hz, at the benefit of more output at 25-30 Hzm (lower Q, effectively). Same results as above, generally... works for me!

    Regards,
    Gordon.

  3. #3
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    Room Gain

    Hi RobH

    I get similar real world results from my le14a in their original S99 boxes. The 42 hz Fb, in an effective volume of @ 1.9 cu ft gives a curve with a bump around the 60 the 70 hz region . In my room , in my normal listening position, I get great response at 40 hz. This stopped me cold in my tracks , as far as building up the planned "test boxes" for my vertical twin / MTM - thingy .
    Now I think I understand why the orient prefers the smaller box sizes of the K2 -S9500 to the M9500 .

    Do you have any of Dr. Floyd Tooles pdf papers that he has at the Harman Website ? One called "Loudspeakers and Rooms - Working"(???) is particularly good in that it deals with room axial modes and such along with their gain .
    I'd post a link to it , if I could find it . I just looked for it. I have 4 of his pdfs , all aimed at the home user . I can post parts of these files if we can't find the original links .

    regards <. Earl K

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