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Re: Not that an anechoic response is very enjoyable

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Ethan Winer

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In Reply to: Not that an anechoic response is very enjoyable posted by Norm on March 27, 2005 at 11:17:52:

Norm,
> absorption reduces the energy and converts it into heat, so the bass is lower in level in the frequencies where it is being absorbed. <
This is a common misconception. In most cases, adding bass traps actually increases the level of perceived bass. Adding traps always makes the response flatter (and clearer), so at frequencies and locations where there had been a peak the level is reduced, and likewise nulls are increased in level.
--Ethan

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For the subwoofer frequencies under 80Hz. adding bass traps usually REDUCES bass output at the seating position - Richard BassNut Greene 08:42:26 03/30/05 (2)
... unless the seating position is in the middle of the room where there are several important nulls (then bass would sound louder.)
Two-channel audiophiles rarely sit in the middle of their room, however, so what they usually report if they use enough bass traps (few do) is less bass output at the standing wave peak frequencies that bothered them in the first place. They often don't notice any changes to any standing wave null that they happen to sit in or near.
A typical audiophile has his speakers in the front 1/3 of the room and sits in the back third, half way between the side walls.

He will typically hear bass peaks caused by the first and second order front to back wall room modes, a peak caused by the floor to ceiling room mode (and a null caused by the side to side room mode if there is one mono subwoofer located off center -- but with left-right subwoofers or full-range speakers this mode would not exist).
The typical audiophile is bothered by up to three room mode peaks
under 80Hz.
Anything done to reduce bass reflections using bass traps will REDUCE bass output by reducing these bass peaks.
1/4 wavelength comb-filter cancellations are typically not audible under 80Hz. because they are overwhelmed by bass peaks caused by standing waves.
- Re: For the subwoofer frequencies under 80Hz. adding bass traps usually REDUCES bass output at the seating position - Ethan Winer 12:14:41 03/30/05 (1)
  Richard,
  > Two-channel audiophiles rarely sit in the middle of their room <
  Nor should anyone sit in the exact center of a room.
  > They often don't notice any changes to any standing wave null that they happen to sit in or near. <
  What can I say? This has not been my experience at all. Most people report more bass, and tighter bass, and all of the room's I've personally treated have responded the same.
  > 1/4 wavelength comb-filter cancellations are typically not audible under 80Hz. because they are overwhelmed by bass peaks caused by standing waves. <
  Again, this is simply not the case in the majority of rooms I've treated. If it's been your experience, well, then, there you go.
  --Ethan
  - Re: For the subwoofer frequencies under 80Hz. adding bass traps usually REDUCES bass output at the seating position - sonicninja 22:38:51 03/30/05 (0)
    Yep,
    I agree...When I started to bass trap it was as if the bass was increased in volume. And I could hear more individual notes instead of a blurry mix.... it sounds more detailed and honest.
    Regards,
    Craig

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