Intimus 522D-PT Measurements and Analysis
The Intimus 522D-PT are a moderately efficient loudspeaker system. I had no problems powering these speakers with a Yamaha RX-V2400 A/V receiver, but based on their moderately low sensitivity (88dB SPL @ 1 watt/meter, I highly encourage an amplifier of at least 100 watts/ch to power the non active portion of these speakers (mid woofers & tweeters). The amps powering the subs are very capable, thus I don't recommend skimping power for the critical mids and highs.
On Axis (white trace):
Shows relatively smooth frequency response with a rising trend of 4-7dB between 4kHz and
18kHz. The high end frequency response was well extended as indicated by the -1dB at 20kHz. The notches
in low frequency response at 80Hz and 170Hz were likely a result of the side firing woofer not fully
acoustically summing at the mic position 1 meter away. This is a fault in measurement technique, NOT
the speaker as it is quite difficult to make an accurate nearfield measurement of a speaker with
drivers located off axis to the main front baffle. I could have measured the response further away from
the speaker, but that would have resulted in more room influences as indicated in Figure 2.
30 Degree Off Axis (orange trace):
We see the slightly energetic top end of the speaker smooth out off axis, but at the
expense of more profound roll off at the high frequency limits (-10dB at 20kHz). This is NOT atypical
of any dynamic cone speaker. I would recommend slight toe-in for these speakers to achieve the
smoothest frequency response and integration at the listening position. This would certainly help in
lively rooms to cut down on side wall reflections. As you can see the lower end bass null at 170Hz has
been greatly diminished since the microphone is now closer towards the plane of the side firing
woofer.
This measurement was taken about 11ft from the center point (sweet spot) of the Intimus towers. As you can see there is a slight recession (3-4dB) in the midrange region between 1kHz to 3kHz (also seen in the quasi nearfield measurement, likely a sonic attribute of the speakers) and a rising trend between 4kHz and 7kHz (though not as dramatic as the nearfield response indicating that the room was helping to soften the top end a bit). At the listening position, the high frequency 3dB point measured around 16kHz making you wonder just how important those esoteric cables really are compared to the dramatic effect room acoustics play on loudspeakers. The 12-13dB bump centered around 40Hz, and the 10dB suck out at 94Hz is mostly a result of axial room modes as illustrated in Figure 4.
Figure 3. Listening Position Low Frequency Response (1/12 th Octave FFT Analysis)
To get a better look at the bass response of the Intimus loudspeaker system, and how it integrated into my listening room, I ran a 1/12th octave low frequency FFT analysis focusing from 20Hz to about 300Hz. As you can see, room gain was partly responsible for the impressive 3dB point of 27Hz. The manufacturer states a low frequency response of 30Hz and these speakers certainly delivered that and then some without any fuss.
Figure 4. Analyzing Listening Room Modes
It is interesting to note that when I ran my room dimensions into the Quest Room Mode calculator factoring in loudspeaker position (treating each Intimus Tower as a subwoofer) and my listening position, we see fairly similar dips at 47Hz and 94Hz with the bumps around 40Hz. The nulls were being attributed to the listening position located at the 4th axial / 2nd width room mode, while the bump at 40Hz seemed to be a result of the 1st , 2nd and 3rd axial modes (1st length, 1st width, 2nd length modes, respectively). While my room certainly isn't an ideal rectangle as this room calculator assumes, it still portrays a fairly accurate representation of what is going on in the listening position measurements for bass frequencies in figures 2 and 3.
