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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: Is this a room anomaly? posted by Dave Billinge on January 26, 2008 at 02:04:33:
Last weekend several others and I were helping a friend move his speakers around in order to find a better position for them if possible. He was using measurement software to measure results in each location we tried as well as listening tests.
One of the things that we observed was a dip of a couple of dB in the 10-20 kHz region which did change in depth with different locations. In the final position we settled on, this dip was almost removed. Treble oddities are possible, and at higher frequencies than you mention.
Still, a 10 dB rise at 5 kHz is a very big rise. It's not what you expect to see from any speaker and especially not from a firm like ATC. It's also well out of the range where you expect to see the influence of a room mode which is what causes peaks in the bass region. If it is a room response I'd suspect that it comes from a very strong reflection over the range you mention. Alternatively it could result from some problem with the measurement technique. Some information about the room would help in deciding if there are any room influences and some information about the microphone, where it was placed, and measurement technique would help with the second.
One possible cause related to measurement technique could be where the microphone was pointed. Some mics/meters are intended to be pointed at the source and some to the ceiling so that soundwaves have a "grazing incidence" across the top of the microphone. Using the microphone the wrong way may well cause some anomalies in the reading, as could using a different mic than the recommended mic if some software measurement system was involved. Mics don't have uniform responses and measurement systems assume that the recommended mic will be used and make appropriate corrections for that mic's deviation from a flat response.
I would have assumed both measurements were made in the same room except that you also said there were 2 different measuring systems so maybe they're not. That complicates things and it's hard to imagine identical peaks from the room if 2 different rooms were involved as well as 2 different measuring systems.
David Aiken
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- It could be… - David Aiken 12:37:35 01/26/08 (0)
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