In Reply to: Stack a' la Mode posted by Peter Gunn on March 31, 2004 at 06:35:26:
i don't enjoy the math either. what drives me crazy is the things you can't see. sometimes math helps me understand what i'm after at least, and sometimes the solution is more evedent. when you plug the dimmensions into the room mode calculator look first for frquencies under 100hz that match pretty close (within 3hz) in the axial mode. these are thre most powerful modes and are the frequency that resonate on the height, width, and length of the room. for example if your room is 8 feet tall take the speed of sound (1130 feet per second) / height (8 feet)= frequency of resonant wave (141.25hz).if you have two axial modes very close to the same resonant frequncy (stacked) the resonance will be reinforced. since we can't move the walls around we move the point of origin of the wave (speaker) and the point of reception (chair) to get an "inbetween" spot that is acceptable. with 2 or 3 stacked axial modes it is almost impossible. cancellation or equalization are about the only two options. running a sub out of phase and positioning it so that the offending mode is out of phase at the listening position. this can be accomplished with time delay and actual placement. here's a graph of a measurement taken in my listening room that used to have serious bass issues. notice the quick decay and even response. i used a combination of all these tricks - parametric eq, cancellation with sub, active bass absorbers and foam corner treatments - to obtain these results.
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Topic - TWEAK REPORT with pics and other maggie news - Peter Gunn 09:11:24 03/30/04 (11)
- Re: "PV-8... threw a slightly forward, but very 2 dimensional soundstage... width and height,but no depth." - Mart 14:26:13 03/30/04 (10)
- Polarity - Peter Gunn 16:37:00 03/30/04 (9)
- Re: Polarity - hemholtz 20:20:12 03/30/04 (7)
- Stack a' la Mode - Peter Gunn 06:35:26 03/31/04 (6)
- aw shucks, couldn't have done it without you - Mart 16:41:42 03/30/04 (0)
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