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General Asylum General audio topics that don't fit into specific categories. |
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General Asylum General audio topics that don't fit into specific categories. |
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In Reply to: Also not correct posted by Richard BassNut Greene on November 18, 2004 at 10:52:19:
RG: Floor bounce would cause a 1/4 wavelength cancellation at a narrow band of frequencies in the 125-400Hz. range, however it would not cause weak bass from 125Hz. all the way to 400Hz., which is what I believe the original poster wrote and something I said was very unusual.Sean: There was no mention of the speakers used, nor could i find a system listed in AA's inmate system listing. The use of multiple woofers or mid-woofers at staggered heights can provide the aforementioned problem. On top of that, it is not uncommon for the dip to spread almost one octave in bandwidth with a single woofer / mid-woofer, let alone multiple woofers / mid-woofers. While multiple woofers / mid-woofers mounted at various heights would tend to fill in the depression somewhat and lessen the severity of the dip, it is still quite possible to have a depression of very measurable amount over a wide frequency range. A dip of 6 - 10 dB's in the warmth region is not that uncommon with a single woofer / mid-woofer.
RG: It's also unusual for audiophiles to complain about a floor bounce cancellation because we live with this effect throughout our lives in every room where there is live or reproduced sound.
Sean: While the effect of this is quite audible, most people don't know what they are listening to or for. As i've mentioned many times before, hearing and listening are different things.
As far as this taking place in every room, this is true. The difference is that radiation patterns differ quite drastically when comparing acoustic instruments to amplified reproduction through "coffin" type speakers.
On top of that, it is quite possible that this person and others may have taken measurements on their system and found the hole that was mentioned. Once one is aware of the problem, takes steps to correct it and hears the difference that it makes, the lack of output in that region becomes even more noticeable when one encounters it. This is kind of like looking for the picture hidden within the picture. Once you find the hidden item, it is hard to look at anything else. Such is the case with specific problem regions when working with the speaker / room interphase.
For further information directly dealing with the room / speaker interphase, i would suggest studying the information that Acoustic Research published in 1978. As far as i know, this is the most advanced and thorough research available on the subject. Stereophile made note of this a few months back. We can thank such folks as Edgar Villchur, Henry Kloss, Roy Allison, etc.. for providing us with this info as it was accumulated over a period of appr 20 years. Sean
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Follow Ups
- Re: Also not correct - Sean 19:38:23 11/18/04 (1)
- Our problem is not enough information about the speakers and their location to understand the problem - Richard BassNut Greene 08:03:45 11/20/04 (0)
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