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Dave Moulton presiserer noe her om hvordan romkorreksjonen er lagt opp i BL5 høyttalerne.
In this particular case (different from all other room calibration systems I know), the BL5, using the integral microphone, detects what Jan Abildgaard Pedersen calls "Room Radiation Resistance." This is not reverberance as such, but the sum of all energies at each frequency reflected back to the particular speaker position. This, in turn, is essentially the same as "power response" (which can be thought of as "the average of all frequncy responses at all positions in the room").
The microprocessor in the speaker calculates an inverse curve to the power response for that speaker position, essentially flattening the "average frequency reponse" throughout the room from about 10 Hz. to 300 Hz.
Are you with me so far?
What this means is the the average response is flat, but at any given position in the room it may not be flat, although it is usually fairly close. So, ABC is a generalized average correction for low frequencies throughout the room. It does not correct for a specific listening position. Further, it does not and cannot correct for the problems presented by standing waves in a room. Those waves are specific to the room dimensions and cause there to be changes in level at the standing wave frequency as a function of the listening position in the room. Hard to think about!
Interestingly, traditional room correction systems place a microphone at the listening position, calculate the frequency response at the position (after "windowing out" the room reflections, sort of), and yielding an optimized response for that position. Sounds good, in theory. Unfortunately, it often makes the speaker sound quite bad at other positions in the room, some of them quite close to that optimized listening position.
The upside is that such a system can be used for full bandwidth, and if you want ONLY that listening position, it can be fine. The downside is that the calibration is not simple and requires the services of an expert. In addition, the calibration needs to be redone every time the room changes (furniture, occupants, doors, windows, etc.). A pain.
ABC is an elgant low-frequncy solution that is automated. It's now been 7 years, and I continue to be impressed by how effective and practical it is.
With all that said, you may wish to experiment with seating position and speaker position, especially to deal with standing waves. Check out an article about control rooms in home studios I wrote a couple of years ago:
http://www.moultonlabs.com/more/making_your_home_control_room_the_best/
In this particular case (different from all other room calibration systems I know), the BL5, using the integral microphone, detects what Jan Abildgaard Pedersen calls "Room Radiation Resistance." This is not reverberance as such, but the sum of all energies at each frequency reflected back to the particular speaker position. This, in turn, is essentially the same as "power response" (which can be thought of as "the average of all frequncy responses at all positions in the room").
The microprocessor in the speaker calculates an inverse curve to the power response for that speaker position, essentially flattening the "average frequency reponse" throughout the room from about 10 Hz. to 300 Hz.
Are you with me so far?
What this means is the the average response is flat, but at any given position in the room it may not be flat, although it is usually fairly close. So, ABC is a generalized average correction for low frequencies throughout the room. It does not correct for a specific listening position. Further, it does not and cannot correct for the problems presented by standing waves in a room. Those waves are specific to the room dimensions and cause there to be changes in level at the standing wave frequency as a function of the listening position in the room. Hard to think about!
Interestingly, traditional room correction systems place a microphone at the listening position, calculate the frequency response at the position (after "windowing out" the room reflections, sort of), and yielding an optimized response for that position. Sounds good, in theory. Unfortunately, it often makes the speaker sound quite bad at other positions in the room, some of them quite close to that optimized listening position.
The upside is that such a system can be used for full bandwidth, and if you want ONLY that listening position, it can be fine. The downside is that the calibration is not simple and requires the services of an expert. In addition, the calibration needs to be redone every time the room changes (furniture, occupants, doors, windows, etc.). A pain.
ABC is an elgant low-frequncy solution that is automated. It's now been 7 years, and I continue to be impressed by how effective and practical it is.
With all that said, you may wish to experiment with seating position and speaker position, especially to deal with standing waves. Check out an article about control rooms in home studios I wrote a couple of years ago:
http://www.moultonlabs.com/more/making_your_home_control_room_the_best/