One Thing Audio
Quad
ESL 63, Reviews, The Quad ESL 63 vs The Stax
F-81 Electrostatic (The Absolute Sound Vol.7, No. 26, June 1982)
The following information was provided by Christian Steingruber (May 2001). This article first appeared in The Absolute Sound , number 32 , December 1983 and was written by John Nork
The Quad ESL 63 vs The Stax F-81 Electrostatic
I have been nurturing a desire to offer a different view of the Quad ESL-63 loudspeaker system since our original review of the Quads over two years ago [Issue 23]. In that review the Quads were evaluated vis a vis the Acoustats and were, largely, found wanting. I have encountered Quads in a variety of settings since their introduction, and was convinced that the original review had not fully conveyed some of the remarkable qualities of this speaker. Since my experiences with the ESL-63 were limited, this conclusion was tentative. When an opportunity to audition the Quads in my reference system presented itself, I immediately accepted it.
My initial listening sessions with the newer Quads were somewhat disillusioning. Although I could clearly hear its positive qualities, the speaker displayed a number of shortcomings that had not been very evident in my prior, brief exposure to it. After only a moderate amount of experimenting, I placed the ESL-63s in approximately the same position in my listening room that had allowed other dipole speakers to perform optimally.
I was taken aback by the veiled, recessed character of the Quads. The sound was distant and muffled, as though some opaque pillow had been interposed between the music and the listener. Bass was boomy and uneven, the midrange was somewhat thin, pinched, hollow, and hard. A lower midrange resonance was overshadowed by a plastic tonal quality, which was overshadowed itself by a modicum of raw, metallic glare in the upper midrange. Highs were somewhat ragged and noticeably down at the very top. The speaker sounded "dark" in character and rather dead as well. There was a lack of the elusive sense of "aliveness" that characterizes real music and, to a lesser extent, the best of loudspeakers.
Through all this, though, I still discerned some real excellence in the Quads. Most arresting was their ability to resolve subtle musical detail at low listening levels. It is my belief that this will become one of the criteria by which great speakers are judged. As anyone who has smuggled a sound pressure level meter into a symphonic concert knows, the SPL of a live performance is surprisingly low by hi-fl system standards [This includes HP.]. With virtually every audio system it seems necessary to play reproduced music at higher sound levels to recapture even a part of the sense of detail and aliveness that are indigenous to the live concert. Most of today's highly touted super-speakers sound less than convincing when played at true concert hall levels. There have been pitifully few speakers that can approximate this quality of music. The Quad ESL-63 may indeed be the best of them. It offers superb resolution and definition at real-world live music levels. I cannot say whether there is some as-yet-unmeasured masking distortion that plagues most speakers that the Quad is comparatively free of. I do know that this quality is very much a part of the live listening experience, and it is conspicuously absent from the world of "high" fidelity.
During my initial listening tests I also noticed promise of a fundamental neutrality in the Quads, despite the audibility of the above colorations. My appetite was also whetted by the excellent sonic stage generated by the system. Perhaps additional work would yield more from this vaunted speaker.
The first change I tried involved altering my speaker placement strategy by moving the Quads much closer to the listening position. This resulted in a more linear frequency balance that mitigated some of my original reservations i.e., bass response became more even, the tonal balance of the midrange became fuller, the sound was somewhat less distant.
Buoyed by this finding, I continued to work and refine placement of the speakers. After extensive experimentation I ended up with the speakers closer yet to the listening position. Please remember, though, that I have a large listening room (17 feet by 27 feet) and I normally attain the best results from dipoles with the speakers at some distance from the listening position. The speakers were toed in, with the center of each speaker aimed just to the outside of my shoulder (i.e., the center of the left speaker was aiming at my left shoulder, etc.) My experience with the Quads indicates that they are relatively easy to place for "good" performance and very difficult to place for optimum performance.
The primary benefits I reaped from this placement work were improved balance and imaging. I was still not satisfied with a number of other aspects of the speaker's performance. So I tried two other, less orthodox suggestions. Bear in mind that it was the considerable potential evident in the Quads that provided the motivation for these further explorations. The first thing I did was to obtain a set of the lethally pointed Quadrapod speaker feet from Linn products. I attached these feet to the bottom of the unstable (and overpriced) speaker stands that are provided by Quad for use with the ESL-63 (it goes without saying that the Quad ESL-63s must be used with elevating speaker stands.) The Linn/ Bowie (Jim that is, not David) feet penetrate down through carpet (and your hand) and lock the speaker stands more rigidly to the floor. This alteration to the speaker stands yielded an immediate improvement in bass response. Focus and soundstage solidity were also better. Clearly the inherent performance of the speaker was being limited by the wobbly stands.
I was stunned by the improvement wrought by the next modification. Although HP Himself recommended it in his original comments on the ESL-63, I (of little faith) did not expect such a difference to result from simply removing the speaker's grille cloth and top wood panel. It is truly amazing that Quad would spend so many years developing a very fine loudspeaker and then seriously compromise its performance with grille cloth that sounds like it was fashioned from Sonex. Clarity and transparency were significantly better. The sound stage opened up in all three planes (width, depth, and height). In fact, the combination of adding the Linn feet, re-positioning the speakers much closer to the listening position, and removing the covers and top blocks allowed the Quad to offer one of the finest sound-stages I have ever heard. Laterally the imaging is seamless, with excellent focus, width, and center fill. The stage is open, spacious, and unbounded at most frequencies. Depth placement is first rate, with a convincing sense of the relative distance between the listener and the various performing sections being purveyed. The speaker's rendition of hall acoustics is superb. Recording studio mini-booths juiced up with artificial reverberation stand patently revealed. This is one of the few speakers that can genuinely convey a realistic sense of the recording site. One's listening room can take on the properties of a large cathedral, a small nightclub, or a school auditorium when the Quads are employed. This ability adds markedly to the sense of musical authenticity.
These modifications unquestionably improved the sound of the Quads. Not surprisingly, they did not eliminate all of the speaker's problems. Some of the shortcomings detailed in the beginning of this review remain. They are as follows:
1 Bottom End Limitations
Deep bass is nonexistent. By deep bass, I refer to frequencies below 40 Hz or so. This limitation robs some music of a fundamental underpinning. Lower midbass is mildly loose and ill-defined. Properly positioned, the rest of the midbass region is quick, and well-defined. Upper bass is still somewhat drummy. There is also a plastic flavour to the bottom end of the Quad that lends a "bonk-bonk" quality to bass instruments. Lastly, the bottom end is severely limited in amplitude (see Dynamic and Output Limitations below).
2 High Frequency Irregularities
Although moving the speaker closer to the listening position and removing the grille cloth helped extreme high frequency reproduction, the Quad still sounds noticeably shy at the very top end. The brilliance of upper overtones is not reproduced as well as the latest Infinity EMIT, or the Stax F-81 are capable of. There is still some mild grain and roughness in the mid-treble region as well.
3 Resonant Colorations
As mentioned above, the upper bass range of the speaker sounds somewhat drum-like. There is also an audible metallic character to the Quad that is at its worst in the upper midrange. When the speaker is taxed, this slight metallic quality merges with a definite glare, and the result mars soprano vocalists, trumpets, and the like. The speaker also adds a mild but audible plastic quality to the music it reproduces. This plasticity (quite similar to a bent Visa card, approximately two years of age) is more detectable on some material than on other. Sharp transients, such as those on The Sheffield Drum Record, seem to provoke it. Most electrostatics that I have auditioned seem to bespeak their Mylar origins in this manner.
4 Lack of Transparency
Although the modifications greatly helped the clarity of the Quads, they are still somewhat lacking in this regard. Again, the latest from Infinity Systems and Stax offer a greater sense of lucidity and palpability. The ESL-63 is somewhat reticent and distant. This quality (like the transient limitations below) can be beneficial on some source material in that rough edges are less offensive. Nevertheless, I miss the clarity and immediacy available from those speakers that set the standard in this area. The Quads sound slightly hazy by comparison.
5 Transient Limitations
Although the transient response of the Quads is far better than most speakers, and was improved by the modifications, the speaker still seems to round off the bite or leading edge of transients to a degree. This effect was in evidence when the speaker tried to reproduce well recorded Scruggs-style banjo picking. When heard live, the initial attack of the metal picks sharply plucking the strings is explosive. The Quads reduce the "snap" generated by this instrument. Still, the Quads are not plagued by the sluggish distortion so evident in the transient response of the majority of speakers.
6 Dynamic and Output Limitations
Not surprisingly, the ESL-63s will not play at extremely high levels. Audible compression takes place, and the music simply will not get any louder. More disturbing to me is the speaker's inability to deal with powerful low bass information. The sound actually gets garbled when deep bass signals are present at even moderately loud listening levels. This ceiling on the output of the speaker effectively limits the sense of dynamic contrast it can generate. This is unfortunate because the Quad is so extraordinary in its performance at the quiet end of the dynamic continuum. The bottom end and output limitations alone will eliminate this speaker from consideration by those whose primary listening taste is rock music at near-concert sound pressure levels. That acknowledged, I was impressed by the improvement in output level and dynamic range the new Quad offers over the old (and over the Stax F-81 for that matter). The ESL-63 is reasonably efficient and will play at surprisingly loud levels, even in a large room.
7 Tonal Homogenisation
I have saved my most nebulous reservation about the ESL-63 for last. I find an overall "darkness" of tone in the Quad that reduces the marked difference in timbre one experiences with real music. When playing choral music, for example, I was struck by the lack of differentiation in tonal quality between the upper and lower sections of the choir. I am not referring to a lack of definition (i.e., that the sections were blurred and indistinguishable). Quite the opposite, the ESL-63s did an exceptional job of separating the sections of the choir. However, the light, airy character of the upper vocal registers did not stand in contrast to the lower registers, although they were clearly different in pitch. The Stax F-81, by contrast, does not have this pervasive dark quality, and consequently captures the sound of these choral sections with greater life-likeness. I noticed this same lack of lightness and brilliance on other musical sources that have their foundation higher up in the frequency stratum. This finding is no doubt interrelated with the upper bass resonance and lack of extreme highs that the Quads exhibit.
It might prove interesting at this juncture to compare the Quad ESL-63 with the Stax F-81 electrostatic speaker that I reviewed so favourably some months ago. The two systems have a great deal in common. They are both small, full range electrostatics with notable limitations in output level and bass. Both systems cost approximately $3000. Both systems also happen to be among the best speakers I have ever heard.
The Stax F-81 is a less colored device than the E5L63 on an overall basis. It imparts less character of its own on the music passing through it. It is freer of resonant colorations than the Quad. It excels in tonal differentiation and does not sound mildly glarish and metallic as the Quad can on occasion. The Stax offers a better sense of "reach-out-and-touch-it" musical presence. The Quad sounds a bit mushy and distant by comparison. The F-81 is a more transparent system. The F-81 also wins in terms of high frequency quality. Its top end is smoother, more extended, and more musically natural than that of the Quad. The Stax also has a moderate lead in midrange authenticity, due in part to its greater clarity and comparative freedom from resonance. Bear in mind, though, that the midrange of the Quad is excellent and its top end reproduction is very good.
Both speakers excel in soundstaging and definition. They are two of the finest performers I have ever heard in these areas, and constitute a real tribute to the progress of speaker design. Both systems are also ruthlessly analytical, exposing without mercy any flaw preceding them in the audio chain. This finding is particularly ironic in the case of the ESL-63, given Quad's adamant Stereo Review-like stance against the audibility of "properly designed" electronics. How anyone can change electronics on a speaker as revealing as the ESL-63 and not easily (and reliably) hear a difference is almost incomprehensible to me.
In the other corner, the Quads also have several points in their favour over the Stax. Their ability to resolve low level information (the kind found in real music) is unparalleled in my experience. The Quads are more efficient, will play significantly louder (and consequently offer greater dynamic contrasts), have substantially more bottom end, and (in my room at least) offer a more linear overall frequency balance than the Stax. Quad has also gone to great lengths in designing the ESL-63 to reduce the limited dispersion problems associated with electrostatics. This effort is largely successful. The ESL-63 does offer a respectably wide listening window and does not mandate the "head-in-a-vise" listening position demanded by most other electrostatics. Nonetheless, there is only one optimum (as opposed to adequate) listening position with the Quads. Vertical dispersion is still somewhat restricted.
In choosing one of these speakers over the other, the listener must inevitably make a subjective choice. At what arbitrary point on a line do bass and output limitations change from minor shortcomings to major irritants? In my case, the Stax F-81, for all its excellence, is just too lacking in these areas to serve as my sole set of speakers. The Quad ESL-63, on the other hand, falls just to the other side of that line. It is only on occasion that I miss the capability of rock 'em, sock 'em bottom end and sheer volume. The Acoustat speakers, to return to the comparison that prompted this review, offer immense bass and output levels, along with virtual indestructibility. They are therefore the most practical and functional of these three products. They will satisfy a wider variety of listening and musical tastes. As good as the Acoustats are, though, they are no match for either the Stax F-81 or the Quad ESL-63 in sheer musical naturalness. To my ear, they have more indigenuous character than either the Stax or Quad models. They are considerably less expensive, though, and are still very good speakers.
In summary, then, the Quad ESL-63 is one of the best speaker systems I have heard. I have described in detail in this review where I feel the Quads fall short of the ideal. Given the imperfect world of available loudspeakers, the ESL-63 stands high on the list of obtainable alternatives. To adopt a Linn like approach for a moment (and eschew the audiophile penchant for analytical categorization of the listening experience), I found that I could truly enjoy listening to music on the Quads over a long period of time. There are very few other speakers that I can say that about. As another has observed before me, "despite my reservations, the Quad ESL-63 is a more than worthy successor to the original".
The Absolute Sound , number 32 , December 1983 and was written by John Nork
