Fried Compact 7 loudspeaker Measurements
In "The Fifth Element" in this issue, John Marks expresses his disappointment with the sound of Fried Products' Compact 7 two-way, stand-mounted loudspeaker. "There was...something that struck me as a bit off," he writes. "Certain parts of [Brian] Cheney's range sounded a bit veiled or hollow (the singing term is covered), while others did not. What crystallized the problem for me was listening to Attention Screen's Live at Merkin Hall [CD, Stereophile STPH018-2]. The applause at the end of 'Mansour's Gift' sounded hollow, as if the audience were clapping with cupped hands. Once I'd heard a clear example of this coloration, I could hear it on other recordings."
John sent me the review samples to see if I could find a reason for the coloration. I performed a full set of measurements, but reproduce here only the relevant graphs.
The Compact 7's Owner's Manual recommends using 28"-tall stands, which places a seated listener's ears level with the bottom edge of the woofer. The Fried's step response (fig.1), taken on this axis, reveals that the tweeter's output clearly leads that of the woofer, with both drive-units connected in the same positive polarity (footnote 1). The start of the woofer step actually overlays the negative-going overshoot of the tweeter's step, meaning that there would be a better blend between the steps on this axis were the woofer's polarity inverted. I don't see how this time-domain behavior squares with Fried's claim that the speaker emits a "plane wave," for which the speaker would need to be both time-coincident and very tall. There is also some lower-frequency ringing evident in this graph, with a cycle of around 1.75 milliseconds, this equivalent to a frequency of about 570Hz.
Fig.1 Fried Compact 7, step response on listening axis at 50" (5ms time window).
Turning to the frequency domain, and again with the Compact 7 measured on the axis that appears to be recommended by the owner's manual, the farfield anechoic response, averaged across a 30° horizontal window, is shown in fig.2 as the black trace above 300Hz. While it must be borne in mind that a speaker's anechoic response does not tell the whole story, I'm not surprised that JM found the Compact 7 to sound hollow on applause. The use of a first-order crossover with a flat baffle and both drive-units in the same polarity means that the tweeter's and woofer's outputs are out of phase throughout the crossover region. The result is the huge presence-region "hole" in the response in fig.2. Some people prefer such a response because it "nicefies" typically "hot" modern recordingsfor a less extreme example, see Robert Deutsch's review of the Silverline Prelude a year or so agobut this is still suboptimal crossover design, in my opinion. There is a response peak between 500 and 600Hz that is, not coincidentally, the frequency of the ringing seen in the step response, with another suckout evident in the region below those frequencies.
Fig.2 Fried Compact 7, anechoic response on listening axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield responses of the woofer (blue trace) and port (red), plotted in the ratio of the square roots of their radiating areas below 300Hz and 900Hz, respectively, with the complex sum of the individual responses (black) also plotted below 300Hz.
On the left side of fig.2 are shown the nearfield responses of the woofer (blue trace) and the "line tunnel" opening (red), weighted in the ratio of the square roots of their radiating areas, as well as the complex sum of those responses (black, below 300Hz). The "line tunnel" appears to behave no differently from a reflex port tuned to 67Hz or so, though the rolloff below the port resonance is steeper than usual. A second port resonance is evident at 250Hz.
While there is on-axis cancellation between the Compact 7's tweeter and woofer, there will be axes on which the drive-unit outputs do add in phase. Fig.3 shows the Fried's vertical dispersion normalized to the listening-axis response. The optimal axes appear from this graph to be 20° and more above the woofer axis or below the tweeter axis. The latter suggests that Fried's recommendation that the Compact 7 be used on a 28"-high stand with its woofer above its tweeter will not get the most neutral balance from the speaker.
Fig.3 Fried Compact 7, vertical response family at 50", normalized to response on listening axis, from back to front: differences in response 455° above axis, reference response, differences in response 545° below axis.
Fig.4 shows the Fried's lateral dispersion, again normalized to the listening-axis response, with the behavior on the woofer side of the baffle shown to the rear of this graph. The on-axis suckout in the crossover region can be seen to fill in somewhat to the speaker's sides, though less so on the tweeter side of the baffle than on the woofer side. The audibility of the suckout will be ameliorated if the speakers are not toed-in to the listening position and their tweeters are on their outside edges. However, fig.4 indicates that the Compact 7's top octave will then be a little suppressed. Some experimentation with toe-in angle will be required, therefore, to balance the hollow coloration against too little top-octave "air."
Fig.4 Fried Compact 7, lateral response family at 50", normalized to response on listening axis, from back to front: differences in response 905° off axis on woofer side of baffle, reference response, differences in response 590° off axis on tweeter side of baffle.
These graphs indicate that, in-room, the Fried Compact 7's presence-region hole in its on-axis output will be filled in to some extent by the room's reverberant field, which is why it took JM a while to identify the problem. But the problem will always be present, and some signals, such as applause, will unmask it.
In October 1990, Robert Harley reviewed for Stereophile the Fried Q/4, which was of similar size and specifications to the Compact 7 and sold for $449/pair. While the Q/4 did have some measured problems, I feel that it performed very much better, overall, than its 2008 descendant.John Atkinson
Footnote 1: It appears the review samples were incorrectly wired. See "Manufacturers' Comments." A Follow-Up review will be published in the December 2008 issue of Stereophile.John Atkinson