DIAMOND ROOM MEASUREMENT REPORT

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Belinda Norton
8 years ago
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1 DIAMOND ROOM MEASUREMENT REPORT

2 Frequency response Frequencies between 20 and Hz are sent out with the same amplitude to be offered to the signalpath. In theory we should receive a straight line if the influence of the room acoustics would be excluded. The image shows the frequency respons of the Diamond Room before any acoustical treatment. The result of what we call front wall cancelation is very clear: in the range between 30Hz and 80Hz and between 200Hz en 500Hz the room falls short of 5dB in the bass and midtones. The image of the frequency respons of the Diamond Room after the acoustical treatment shows a beautifull balance between bass, midtones and treble, when reaching the listening position. The low bass response is more stable, the curve flatter. In both the measurements, the Bowers & Wilkins DB- 1 active subwoofers are excluded. The Bowers & Wilkins 800 Diamond covers the full sound spectrum. Under 28Hz the Bowers & Wilkins DB- 1 active subwoofers kick in. They will close the small gap on the lower side of the spectrum when the cross over frequency will be set at 30Hz. The range of the Bowers & Wilkins DB- 1 active subwoofers goes down to as low as 15Hz, but with a actual soundwave of nearly 23 meter, it s not possible to execute a proper measurement. Note from Marco Lisi (Diamond Room): after a series of listening sessions, the cross over frequency between the Bowers & Wilkins 800 Diamonds and the DB- 1 active subs has been set at 80Hz, which is also the THX standard.

The result of what we call front wall cancelation is very clear: in the range between 30Hz and 80Hz and between 200Hz en 500Hz the room falls short of 5dB in the bass and midtones.

3 Impulse respons The impulse respons diagram shows us at which time the direct sound and reflections arrive. With this data, the dimensions of the room and the position of the speakers we can determine were the sound reflects. This allows us to take on frequency fluctuations. Reflections within the first 20 milliseconds need to be 10dB quieter compared to the direct sound. The image shows that after the acoustical treatment the room performs within these parameters. Reverberation time The image show the reverberation time, measured in RT20, shown in octaves. The reverberation time depends on the volume and purpose of the room. For listening room purposes, a linear reverberation time across all frequencies is desirable. For home theater purposes, the reverberation time should not be linear. To get a true cinema experience we use the 500Hz octave as target. The reverberation time must decline in the higher frequencies and mount in the lower frequencies. For the Diamond Room we took the average to experience both high end hi- fi and cinema. Watch the S form in the measurement: low frequencies have a longer reverberation time, the midtone area is beautifully balanced and the high frequencies decline early.

Reflections within the first 20 milliseconds need to be 10dB quieter compared to the direct sound. The image shows that after the acoustical treatment the room performs within these parameters.

4 Waterfall plot In the waterfall plot we can evaluate the time behaviour of the frequency response. A tiny standing wave at 28Hz is visible, luckely out of the hearing range. The standing wave at 35Hz lays just within the hearing range, but is not present at the sweet spot. This standing wave cannot be broken by the diffusors, due to their range. Frequencies within the normal hearing range do not exhibit standing waves in the Diamond Room.

The standing wave at 35Hz lays just within the hearing range, but is not present at the sweet spot.

5 Conclusion and advice The frequency respons contours of the combined listening room / home theater look fine. Frequency fluctuations are minimal and well within margins. The same can be said about the impulse respons. Reflections have been sufficiently reduced. The result: a sound image without turbidity and coloration. The RT20 reverberation time measurement show a nearly linear respons down to the low frequencies. From the different measurement results we can conclude that the Diamond Room is very suitable as listening room or home theater. The influence of the room has been minimized, to make honest reviews of both the equipment and recordings possible.

The result: a sound image without turbidity and coloration. The RT20 reverberation time measurement show a nearly linear respons down to the low frequencies.

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