(I average 20 1/6-octavesmoothed spectra, individually taken for the left and right speakers in a rectangular grid 36" wide by 18" high and centered on the positions of the listener's ears. The sensitivity of human hearing decreases rapidly at low frequencies, and low-frequency sounds must be played at a much higher sound-pressure level to be perceived as being as loud as mid-frequency sounds (footnote 2).įor fig.4, I measured the BeoLab 90's spatially averaged response in each of its three modes of operation. Though this rise looks alarming (footnote 1), it was not as audible as you might thinkother than in the magnificence it added to the organ recording of mine mentioned by KR, which has significant energy below 32Hz. I suspect that the increase in level in the low bass arises from the usual boundary reinforcement in this regionKR had each speaker situated just 18" from its respective sidewall. There are still some room effects visiblethe lack of lower-midrange energy and the peak at 105Hz in the left channelbut these are mild, especially when you consider that there was no spatial averaging in this graph. Both sets of filters are applied simultaneously you can see that the amount of correction is relatively small, covering a range of +5 to ≦dB.įig.3 Bang & Olufsen BeoLab 90, Narrow mode, 1/6-octave responses of left (blue) and right (red) speakers with DSP correction at listening position. The responses of these filters, as set up by B&O's Geoff Martin, are shown in fig.1 (Mono and Side) and fig.2 (Left and Right). However, it differs from conventional correction solutions in applying not just individual filters for the Left and Right speakers, but also filters to correct the speakers' summed (Mono) output and the difference between their outputs (Side). (These were set to a sample rate of 96kHz for the measurements and I fed Fuzzmeasure's analog signal to the Master loudspeaker where it was converted at 192kHz.)įirst of all, as KR described in his review, the BeoLab 90 system uses digital signal processing (DSP) to correct the room's acoustic. I used SMUGSoftware's Fuzzmeasure 3 app running on my MacBook Pro, along with an Earthworks QTC-40 microphone and a FireWire-connected Metric Halo ULN-2, which combines a low-noise microphone preamplifier with A/D and D/A converters. This software is very compelling, and if Chris even gets a fraction of the features on the wish list done, this software alone will be a reason for speaker builders - amateur & pro - to switch to OS X.The BeoLab 90 is so massive that, rather than having it shipped to my home, I traveled to Kal Rubinson's place to take some measurements. I use this almost everyday - i was just commenting to my wife today that i didn't have sound on my G4 because my interface box was always connected (i need to add a switch and anther plug to my interface box - housed in an old 400k floppy case - to allow me to switch to my speakers. The developer is committed to making a quality product and is driven by his own interest in DIY much more than any interest in this being a way to make a living. DIY speaker builders using the Mac have been waiting for something like Fuzzmeasure for a long time.Īlready - the software is still young with a minimum of features - it offers functionality at least as good as the usual PC suspects, but with a UI & quality of output we expect from a piece of Macintosh software.
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