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- Nov 10, 2023
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I am new to room measurements, and I am not quite sure how to interpret this.
I have compared 3 sets of speakers, positioned at approx the same place (all three are placed and not moved between measurements, so there is ca 20 cm between them):
Details regarding the setup:
At first I thought this was an error, it seemed consistent across different positions, and being at exactly 50Hz I guessed this might be some mains filtering in the AD-converter of my soundcard. So I changed from using a RadioShack SPL-meter as input to a new UMIK-1 with calibration file. But the well is still there. Measuring just one channel makes this a lot less deep. I see something similar in the REW room-simulator, but at a higher frequency.
Questions:
Then there is the roll-off after 10K, this seems to fall a lot more than other REW-plots I have seen. Questions:
Other than this, the measurements seem reasonably flat above 300Hz, is there a need for any treatment except the bass-issues?
Measurements:
Room sim: this is as exact I can get different distances, but of course the actual room is more complicated than the simulation.
Moving the simulated speakers a few centimeters adds a deep well:
I have compared 3 sets of speakers, positioned at approx the same place (all three are placed and not moved between measurements, so there is ca 20 cm between them):
- Red: Dynaudio Emit 20
- Blue: System Audio SA510, The Dynaudio and the SA are connected to a Marantz NR1603.
- Green: Neumann KH80DSP
Details regarding the setup:
- This is a stereo-measurement.
- Before each test I adjusted the volume to 80dB SPL using pink noise at -15 dBFS.
- The graph has 1/12 smoothing.
- The room is practically square (approx 4,4 meters, height 2,4) and there is no treatment other than some furniture. There are wooden panels on walls and ceiling and a thick carpet on the floor.
At first I thought this was an error, it seemed consistent across different positions, and being at exactly 50Hz I guessed this might be some mains filtering in the AD-converter of my soundcard. So I changed from using a RadioShack SPL-meter as input to a new UMIK-1 with calibration file. But the well is still there. Measuring just one channel makes this a lot less deep. I see something similar in the REW room-simulator, but at a higher frequency.
Questions:
- is there really a cancellation at 50Hz, or does it just look like that because of peaks at 40 and 70?
- The wavelength at 50Hz is 6,86m, approx 1,5 times the measurements of the room, does the standing wave cancel itself?
- What can be done to fix this?
Then there is the roll-off after 10K, this seems to fall a lot more than other REW-plots I have seen. Questions:
- Is this an error in the test, or an attribute of the room?
- How can I check this?
Other than this, the measurements seem reasonably flat above 300Hz, is there a need for any treatment except the bass-issues?
Measurements:
Room sim: this is as exact I can get different distances, but of course the actual room is more complicated than the simulation.
Moving the simulated speakers a few centimeters adds a deep well:
