David Sokol
STEVIE WONDER: Songs in the Key of Life
Motown 374 630 340 2 (2 CDs). 1976. Stevie Wonder, prod.; John Fischbach, Gary Olazabal, engs. AAD. TT: 104:42 Staggering as it is, Stevie Wonder was barely 26 when he released this musical monolith, a 21-song exploration that bridged the pop and soul worlds with compassion and spirituality, was the rage in the mid-'70s, and continues to sound utterly fresh today. Although Wonder was already a major star (this was his 16th album, after all), the scope of Songs earned him a spot beside Dylan, Lennon, and McCartney as one of the…
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David Vernier
BENJAMIN BRITTEN: Britten the Performer
Fauré: La Bonne Chanson, Op.61. Purcell: Five Songs (realized by B. Britten). Schubert: Three Songs. Schumann: Liederkreis, Op.39.
Peter Pears, tenor; Benjamin Britten, piano
BBC Music BBCB 8006-2 (mono CD). 1958-59/1999. Ivor Walsworth, prod.; Derek Horsman, remastering eng. ADD. TT: 74:58 We are very fortunate to have such priceless musical treasures as this document, recorded live, of one of this century's most fruitful and mutually inspiring artistic partnerships. That something very special is going on in these…
BENJAMIN BRITTEN: Britten the Performer
Fauré: La Bonne Chanson, Op.61. Purcell: Five Songs (realized by B. Britten). Schubert: Three Songs. Schumann: Liederkreis, Op.39.
Peter Pears, tenor; Benjamin Britten, piano
BBC Music BBCB 8006-2 (mono CD). 1958-59/1999. Ivor Walsworth, prod.; Derek Horsman, remastering eng. ADD. TT: 74:58 We are very fortunate to have such priceless musical treasures as this document, recorded live, of one of this century's most fruitful and mutually inspiring artistic partnerships. That something very special is going on in these…
This series of articles is based on a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, www.aes.org, offers a secure transaction page for credit-card orders.
In the first two articles in this series, I examined the loudspeaker's electrical behavior and how it behaves in the time domain. But the on-axis amplitude response is the most…
Second is the microphone mounting arrangement. The MLS technique is very sensitive to reflections of the sound emitted by the loudspeaker. It is important, therefore, to mount the microphone so that any reflections from the stand and its associated hardware occur after or at the same time as the inevitable reflections from the room boundaries. The B&K microphone is held endwise by a female XLR plug that is flush-mounted into a 2m length of ½" plumbing pipe. This pipe is held in a conventional microphone stand, but with the upright and clamp 1.5m away from the microphone capsule. Fig.23…
A final matter should be discussed. It is a hidden assumption when measuring a loudspeaker's amplitude response that the microphone is in the far field; ie, is more than a couple of wavelengths away at the lowest frequency of interest. An alternate way of looking at the matter is that the microphone should be at least as far away as the largest dimension of the loudspeaker to be measured. With my standard microphone distance of 50", this assumption will no longer be true for large loudspeakers. With big speakers, such as the various kinds of panel speakers, there will be a proximity effect […
By contrast, Fig.25 shows a similar measurement for a loudspeaker that a Stereophile blind listening panel thought sounded quite colored, with a skewed presentation of instrumental timbres. The speaker is quite flat in the midrange and has reasonably good bass extension. However, there is a severe suckout in the mid-treble. In all but large rooms, this will produce a characteristic, hollow-sounding coloration. There's some peakiness in the mid-treble region above the suckout that will add a little bit of "zing" to the perceived balance. The designer presumably was trying to compensate for…
It's also apparent that a speaker with a basically smooth, flat response but a single area of unevenness—due perhaps to a strong woofer-cone breakup mode or a cabinet resonance—will be downgraded accordingly. The same holds true for crossover or drive-unit integration problems. Similarly, if a speaker has a flat response but limited high-frequency dispersion, its appeal will be limited due to the room reverberant field tending to sound too lifeless. And no matter how flat a speaker's midband, a somewhat loose, underdamped bass is an almost unforgivable fault for many listeners, except when…
Nearfield Responses
Because the time data need to be truncated to eliminate room reflections, a farfield MLS-derived amplitude response is of little use in characterizing a loudspeaker's behavior at low frequencies. However, a classic 1974 paper by Don Keele [64] discusses the technique of taking a loudspeaker's response in the nearfield, with the microphone capsule placed very close to the radiating diaphragm. This appears to give a response that accurately reflects a loudspeaker's low-frequency output as assessed in the farfield, a conclusion more recently confirmed by Struck and…
Because the time data need to be truncated to eliminate room reflections, a farfield MLS-derived amplitude response is of little use in characterizing a loudspeaker's behavior at low frequencies. However, a classic 1974 paper by Don Keele [64] discusses the technique of taking a loudspeaker's response in the nearfield, with the microphone capsule placed very close to the radiating diaphragm. This appears to give a response that accurately reflects a loudspeaker's low-frequency output as assessed in the farfield, a conclusion more recently confirmed by Struck and…
Polar Response/Dispersion
Looking at the anechoic response at one point in space can be instructional, but it must not be forgotten that loudspeakers emit sound in a full sphere [67]. I examine how a loudspeaker's amplitude response changes in two planes, vertical and horizontal, using the DRA Labs system's ability to plot an arbitrary number of FFT-derived response plots against a third, arbitrary variable [68]. The loudspeaker is rotated on a commercial stepper motor-driven turntable (made by the Italian company Outline and available from Old Colony Sound Lab) in 5 degree steps, an…
Looking at the anechoic response at one point in space can be instructional, but it must not be forgotten that loudspeakers emit sound in a full sphere [67]. I examine how a loudspeaker's amplitude response changes in two planes, vertical and horizontal, using the DRA Labs system's ability to plot an arbitrary number of FFT-derived response plots against a third, arbitrary variable [68]. The loudspeaker is rotated on a commercial stepper motor-driven turntable (made by the Italian company Outline and available from Old Colony Sound Lab) in 5 degree steps, an…
In-Room Amplitude Response
Unlike other audio components, the perceived sound of a loudspeaker is affected by factors other than its intrinsic performance. All the previous measured acoustic parameters that have been discussed examine the loudspeaker in isolation. But loudspeakers are used in reverberant rooms rather than anechoic chambers, and the interaction between the two is complicated [69, 70, 71, 72, 73, 74]. However, my experience has been that different models of loudspeakers sound different in a consistent manner when similarly set-up and auditioned in different rooms. But it…
Unlike other audio components, the perceived sound of a loudspeaker is affected by factors other than its intrinsic performance. All the previous measured acoustic parameters that have been discussed examine the loudspeaker in isolation. But loudspeakers are used in reverberant rooms rather than anechoic chambers, and the interaction between the two is complicated [69, 70, 71, 72, 73, 74]. However, my experience has been that different models of loudspeakers sound different in a consistent manner when similarly set-up and auditioned in different rooms. But it…