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Equipment Measurements

March 2010

Blue Circle Audio BM2 Loudspeakers: Measurements

All  loudspeaker measurements are performed independently at the National Research Council of Canada. Please click to learn more about how we test loudspeakers there. All measurement data and graphical information displayed below are the property of SoundStage! and Schneider Publishing Inc. Reproduction in any format is not permitted.

Please note: This speaker has a switch to adjusts the output level of the tweeter. All measurements were done with the switch up. An additional on-axis frequency-response measurements is supplied with the switch down.

Chart 1 - Frequency Response and Sensitivity

Microphone measuring position: tweeter axis

Grille: off

Tweeter switch: up

Sensitivity: 83.0dB (averaged 300Hz-3kHz, 2.83V/1m)

Frequency response, 20Hz - 20kHz (measured @ 2m, plotted @ 1m)

Top curve: on-axis response
Middle curve: 15 degrees off-axis response
Bottom curve: 30 degrees off-axis response

Frequency response, 20Hz - 20kHz (measured @ 2m, plotted @ 1m)

Top curve: 45 degrees off-axis response
Middle curve: 60 degrees off-axis response
Bottom curve: 75 degrees off-axis response

Additional Measurement
Tweeter switch "down"
Frequency response, 20Hz - 20kHz (measured @ 2m, plotted @ 1m)

Curve: on-axis frequency response

Chart 2 - Listening Window

Listening Window, 20Hz - 20kHz (measured @ 2m, plotted @ 1m)

Response curve is an average of five measurements:
on-axis, 15 degrees left and right off-axis,
15 degrees up and down off-axis

Chart 3 - Total Harmonic Distortion + Noise

THD+N @ 90dB, 50Hz - 10kHz (measured @ 2m)

Top curve: frequency response @ 90dB SPL
Bottom curve: THD+N @ 90dB (50Hz - 10kHz)

Chart 4 - Deviation from Linearity at 90dB and Above

Difference @ 90dB, 50Hz - 20kHz (measured @ 2m)

Curve: difference from 70dB at 90dB

Chart 5 - Impedance Magnitude Variation and Electrical Phase

Impedance curve

Vertical axis: impedance
Horizontal axis: frequency

Electrical phase

Vertical axis: phase
Horizontal axis: frequency

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