![]() ![]() 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. (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. 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). 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). 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. ![]() ![]() 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. 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. 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. 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. Next on my list has to be measuring some rooms.(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 sight resonant bump above the corner frequency was in evidence with the 80Hz setting being noticeably flatter than the rest and the 160Hz and particularly the 300Hz setting having much more pronounced bumps. What Is The Slope Of The HPF In A 1073?ġ8dB/Oct - Through looking at the precise measurements I found a little variation around this figure with most of the slopes being closer to 20dB/Oct. The manual is clear and complete but isn’t a primer in acoustic measurement and if you don’t know what you are doing you probably wont find the answers in the manual. If you are expecting to be able to get the results you want from Fuzzmeasure without having to understand the process then you’ll likely be disappointed. Learning Curveįuzzmeasure poses more questions than it answers and I quickly realised where the gaps in my knowledge lie. In this case the Frequency Response graph is the relevant one, for acoustic measurements the waterfall plots are fascinating and distortion, phase and group delay graphs are all available along with many other options. There are templates provided for different uses but I prefer to create them manually. ![]()
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