Reprinted from "THE ABSOLUTE SOUND®"
Volume 13 Issue 56 - November/ December 1988
Choosing a Personal Best:
The Apogee Diva Loudspeakers
The choice of a reference speaker is always a highly personal one and a choice that takes prolonged listening to confirm. A number of speakers have passed through my home that I liked for a few hours or days, but that soon revealed inherent limitations I found I didn't want to live with. I have used several speakers for weeks or months that were outstanding in most ways, but that still had enough flaws so I never regarded them as of reference quality. The few speakers I have really liked enough to classify as reference speakers-designs like the Quad ESL-63s, the Infinity RS- 1 Bs, and Thief 3.5s have had a special magic that has gone beyond good technical performance and even an excellent ability to reproduce music.
While I suspect that the Apogee Divas are not my last reference speaker-if only because their designer Leo Spiegel is certain to trump himself in time-they very definitely have that special magic. I have never gotten as much consistent pleasure out of any speaker that I have used as a reference After a solid year of listening, after using more than a dozen different sets of reference-quality electronics and front ends, and after moving several competing reference quality loudspeakers into my own listening room for comparative listening tests, I still find the Divas have a special magic. I also have found them to be consistently musically natural and revealing with all types of music, including the kind of chamber music, voice, and jazz I love most.
Part of this magic maybe a matter of luck. The Divas blend in with the sonic characteristics of my particular listening room in a way no other speaker has yet matched, and this allows them to deliver an extraordinary combination of frequency range, dynamics, and detail Magic is not always catching, and I cannot guarantee you will get the same level of performance and pleasure from the Apogee Divas that I have loudspeakers are simply too room- and system dependent I can virtually assure you, however, that you will get outstanding performance if you exercise a little good judgment and care, and that the Divas are the kind of speakers that demand auditioning by any serious audiophile
Set-Up and System Compatibility
I would normally reserve the issue of set-up and system compatibility for the end of a review, but previous Apogees have had a reputation for being extremely amplifier sensitive, and it is worth pointing out at the start that this is not true of the Divas AS you can see from the impedance curve in Graph 1, the Divas have an exceptionally smooth impedance curve over the entire audio band, and one that is far easier to drive than that of many small box monitors. The curve varies from 4.5 to 2.7 ohms, and remains at around 3.9 ohms up to about 8000 Hz (You may also be interested to know that the Apogee Signature Duettas and Calipers have the same smooth impedance curve-a change that makes the Signature versions of the Duettas and Calipers some 3 to 5 dB more efficient than the older versions and far easier for most audiophiles to live with.)
You still have to pay the same attention to matching your drive electronics and cables as you would with any other top-quality speaker. Nevertheless, any really good high-current amplifier that can drive a 4-ohm load can drive the Divas. I'd normally avoid any amp below 100 watts per channel but high current capability is not a function of wattage, and you need to focus on current capability and not just rated watts. You also need to be careful about tube units with limited output capacity Nevertheless, I did not encounter any reference-quality High End transistor amplifier that presented problems with the Divas, and they will work well with the Audio Research M-300, They perform superbly with the Classé Audio DR-9s and Krell-100 watt monos. but others have found that you can get excellent performance with a PS Audio 200CX or Belles 450.*
* It is always a bit dangerous to list recommended amplifiers because you end by excluding good products Nevertheless Apogee reports good results with the Aragon 4004; Audio Research M-300; Belies 450; Bryston 6B; Cello Performance; Classé DR-9; Counterpoint SA-20; Denon POA-6600; Eagle 7A; Krell KSA-80, KSA-200. KMA-160, KRS-200; Lazarus; Levinson 20 and 23; Meitner MTR-101; Mirror Image 1.1S; PS Audio 200CX; Rowland 3.5 and 7; Tandberg 3016; and Threshold SA-1 and S-500A.
You should also be aware that these are speakers that can really use the high power levels that some of the best amplifier designs can now deliver Although the Divas are much more efficient than previous Apogee designs, they do present a demanding mix of low efficiency and the ability to deliver a maximum SPL that can give you full orchestral power.
The efficiency of the Divas is rated at 80 dB, measured with one watt of power at one meter, and the maximum SPL is rated at 115 dB SPL in a large 18 x 24-foot listening room with an 8-foot ceiling. This level of efficiency is not bad, but it isn't good. While a very solid 100 watts, with solid reserves of power over the entire frequency spectrum, will provide convincing High End performance, you will need a great deal more power to take advantage of the maximum achievable power level.
At the same time, you should be aware that far more is involved than power, in choosing an amplifier The Divas produce an immense amount of power in the region from 25-50 Hz, and you will hear far more of an interface between amplifier, speaker, and room in the bass than you will with any speaker that does not have true deep bass. If you haven't worked with a speaker or subwoofer that can deliver this kind of bass before, be aware that some amplifiers appear to tighten the deep bass of a given speaker, and others make it seem warmer and/or more powerful,
I found most tube amplifiers to be too warm in this regard, and to lack bass extension and definition; but tube-oholics seem to love this kind of bass in other speakers, and who am I to tell you to say no to tubes? However, I feel transistor amplifiers offer you a more valid set of choices. The Classé DR-9 Research amplifiers, for example, give a very tight bass with the Divas and a great deal of depth. They are detailed in the soundstage, and this shows up in their imaging, In contrast, the Krells give the feeling of immense power in the bass and seem more forward and "live". If you are a perfectionist, you will want to experiment until you find the combination that delivers the bass that suits your taste and room, as well as the combination that delivers the proper amount of transparency and musical detail.
I would also strongly avoid using two types of amplifier, or even amps of the same brand but different power levels. The Divas are very coherent and revealing speakers, you will never hear them at their very best if one amp on a given channel performs or sounds slightly different from another.
As for speaker cables, let me say right now that to my ears, the issue in choosing speaker cables is never which cable is best with all speakers, but rather which cable sounds best with a given combination of amplifier and speaker. This is one reason I have found most recent cable surveys to be worse than useless they ignore the fact that speaker cables link a highly interactive system, and they tell audiophiles to buy - top ranked cables that may well not suit a particular system. You need to decide on the cable that suits your amplifier and speaker, and not tailor the amplifier and speaker to suit your cable.
These cautions are important because the Divas clearly reveal the sonic character of any speaker cable-perhaps more so than any other speaker I have heard. They also seem to favor those cables that have a flatter and more extended upper-octave performance As for specific brands, SYMO cable really does seem to interface with the Apogee Divas in a way that makes this particular cable seem ideal for this speaker with many amplifiers SYMO cables, however, are only available from some Apogee dealers or directly from Apogee In terms of readily available cables, I would give a slight preference to the Straight Wire line, followed by the LiveWire products and Kimber. In each case, the more expensive cables of each brand sound better. I like the MIT and Monster products in many systems, but I have yet to hear them perform well with any Apogee speaker, and I'd experiment with comparative listening before I tried them.
I recommend that you experiment with bi-wiring and bi-amping. Interestingly enough, I found that I got the most coherent results bi-wiring from one really good amplifier channel per speaker. The manufacturer and many others disagree and tend to go for bi-amp systems Nevertheless, you will find that two amplifiers sound better than four-and it will save you one hell of a lot of money.
You need a reasonably large listening room -one that allows you at least a meter of space between the rear and sides of the Diva and the rear and side walls of your room. You need enough distance from the Divas to your listening position to allow proper integration of the soundstage. You need a room that will not vibrate if it is subjected to truly deep bass at high power levels and that has smooth reflective rear walls behind the Divas. These, however, are requirements that many homes and apartments can meet, and which are a sine qua non for High End listening to any reference-quality, full-range speaker with genuine deep bass.
Loudspeakers and Listening Rooms
Be aware that moving the Divas around near a room boundary will significantly affect their bass response and the amount of reflected energy you can hear. Even a few inches can radically change the bass performance, if you get them too close to a rear wall, and you should be cautious about any large absorptive objects in the rear or sides. I have watched these speakers being placed in many rooms, they are similar to the large Infinitys and Magneplanars in demanding a great deal of experimentation This is one reason that they rarely deliver their best in a dealer showroom.
I find the Divas perform best parallel to the rear wall and spaced as far apart as your room and listening position permit. You want to preserve a fully coherent soundstage, with all the imaging and depth these speakers can deliver, so you don't want them so far apart that you begin to get a lack of coherence in the center of the soundstage. You do want the large open soundstage that wide spacing creates. You also need to adjust the floor spikes on the stands to rigidly couple the Divas to the floor.
As for the visual aspects of the Divas something I find important in anything I really have to live with in my home-they look like pieces of modern sculpture, and I have quite a number of friends who have paid far more for works of modem art that do not look as good and do not produce any sound at all. Like the more expensive Infinitys, and a handful of other top-quality speakers, the Apogees allow form to follow function without sacrificing style or visual distinction.
Art cannot totally hide the fact that the Divas measure 31 " wide by 73' high and 3" deep and weigh 150 pounds each. Nevertheless, I suspect that most people will probably find the Divas far more attractive than many competing speakers that deliver the same sound quality. *
* I have suggested a version of Divas with purple diaphragms and covered in pink fur to, the Beverly Hills set, and one in gilt Baroque, with nymphs and satyrs,. for the traditionalist. I am informed, however, that Apogee refuses to deal in animal skins, and that the Baroque version has been delayed until Benvenuto Cellini is again available to work on the design.
The Technical Merits
This is one of the few cases where a detailed description of the technology gives you some insight into something far more important than technobabble: The reasons why the speaker sounds the way it does.
To begin with, the Divas are a full-range, three-way ribbon system with dipole radiation. The "ribbon" aspect is important not only for sheer technoglitz, but because a ribbon allows somewhat easier control of a low-mass diaphragm than competing technologies. Electrostatics can use inherently lighter diaphragm material than the aluminum foil in ribbons, but the ribbon design does not require a step-up transformer. The powerful magnets in a ribbon design (47 pounds in magnets per speaker, in the case of the Diva) also present less risk of breakdown than the high voltage required to polarize an electrostatic; they are less prone to failure.
While I gather that several speaker designers are currently having religious wars over what is and is not a pure ribbon speaker, the distinction is meaningless in a practical sense. *
* In a ribbon Speaker, a thin metal ribbon is suspended in a magnetic held and takes the place of both the voice cool and diaphragm of cone or dome drivers. The result is that the field of magnets moves the entire no~ directly, the voice cool of a dynamic speaker only contacts the diaphragm along a circle.
The Apogees are unquestionably "pure" ribbons in terms of the treble and midrange ribbon, and the use of separate high-frequency and midrange ribbons allows Apogee to use a tweeter ribbon only two-tenths of an inch wide. This allows extended upper-octave response and excellent treble radiation. This is something that is possible to approach only in a multiple-diaphragm electrostatic: this is one reason most electrostatics tend to roll off and beam their highs.*
* Some readers may remember that the host Quad had a separate tweeter and on some ways outperform the Quad ESL-63 m the upper octaves.
To the extent that there is any debate over whether the Divas and other Apogee speakers are really full-range ribbon speakers, it hinges on whether the ribbons in the woofer are fastened only at two ends or at all four sides. I can't find any audio engineering book that defines either the number of sides a ribbon must be fastened on, or the number of angels that can dance on that ribbon. As nearly as I can figure out, other ribbon speakers, such as the Strathearn, have been fastened on four sides, and Apogee is what Stanley Kelly-the father of the modern ribbon speaker--would call a ribbon. *
* Nevertheless I caution our readers, many authorities do not consider the Apogee a full-range ribbon speaker but rather a hybrid, whose bottom octave is handled by what is effectively a planar magnetic driver.
What is most important is that the ribbons in the Apogee Divas deliver an amazing degree of apparent speed and detail. I have never heard an electrostatic or cone speaker provide the same mix of extension in the lowest and upper octaves and still provide the musically convincing detail arid coherence at every part of the frequency spectrum of these speakers.
The three drivers in the Divas have a remarkable coherence. I don't know how much this really reflects the ribbon technology (-pure or not), but the only full-range rivals I've yet heard with this coherence are the Infinity IRS and Wilson Audio Monitor. The Quad ESL-63 is a potential rival but has a narrower bandwidth, much less extension into the deep bass, and far less apparent detail in the treble. While the Infinity IRS Beta may well become a rival, I have yet to how a pair that does not have a lingering sight discontinuity between the lower midrange and the bass.
As for the details of the Diva's frequency response, it has a rated bandwidth of 25 Hz to 25 kHz. This is the kind of extension into the highs and deep bass that most speaker buyers can only dream of-particularly in the deep bass and upper octaves. It also is the kind of performance that is claimed far more often than it is delivered. My ears tell me, however, that the Divas have the kind of deep bass you normally only get with a separate woofer column or expensive subwoofer: they also deliver a very extended treble without any apparent hardening or overemphasis of the upper midrange. While my ears don't function equally well up to 25 kHz, my measuring equipment confirms that the speakers can deliver outstanding power beyond 20,000 Hz-the limit of my test gear.
The Divas deliver this bandwidth with the kind of flat overall frequency-response curve that most speaker buyers dream about. The manufacturer's measurement of this curve is shown in Graph 2, and although there again are debates over the way in which this response curve is measured, my ears fail me that Apogee has achieved one of the few curves that complements-rather than dissects-music at every part of the frequency spectrum.
I do not want to renew all the old arguments over how to measure flat power response in loudspeakers, but ever since the days of Edmund Vilchuf, it has been clear that speaker designers need to exercise extreme care in how they measure and tailor the upper five octaves of a loudspeaker. Far too many designers approach measuring flat response in such a way that the speaker provides so much upper-octave power that you hear far more upper midrange and treble than you will ever hear in a live performance. This can be subjectively acceptable in some cone units, but it is always painful with dipole speakers. To its credit. Apogee has chosen a frequency balance that reflects the sound of live music arid is not just an exercise in theoretical engineering. *
* I wouldn't normally bother to get into the details of how a manufacturer does its frequency-response measurements, Apogee speakers, however, have gotten a bum rap in some other magazine tests that were glorified home tests rather than real lab efforts; the readers should of least know the background behind Apogee's design concept.
The response curve shown in this review is measured at one meter, using a 2.3-volt warble with a one-third-octave filter. The Apogees are designed however, using a number of frequency measurement techniques. These utilize sine waves, one-third octave warbled tones, pink noise and impulse with time gating inputs (all of which produce, somewhat different curves). The results are tested in the near held both one and four meters from the speaker (which also produce different response curves). Microphones are set both on and off axis (producing still more variations).
It is the designer's choices among these methods that lead to such sharp differences over what response curve is flat and what curve is right. The Apogee designers for example use the Neutrix Audio Test equipment and an IVIE pink-noise generator with a B&K 4133 condenser microphone and calibrator to measure one-third octave warble tones, sine waves, and pink noise from a range of 20-40,000 Hz. They believe sine-waves tests are best for frequency response and warble tones, and pink noise help reduce standing-wave affects and show perceived response.
Apogee uses a B&K Type 1034 two-channel FFT Analyzer and the B&K 4133 condenser mike to test free-field data. They use the Impulse gating equipment when they want to avoid measuring room effects, or when very detailed measurements are needed up to 40,000 Hz They use IVIE visual display instruments with a C-Scale weighting to measure the spectrum at high sound pressure levels in a way that approximates perceived loudness at high sound levels.
The key message to, audiophile readers is that high technology can aid the designer in improving his speaker, but no set of measured curves will ever substitute for listening, and no designer can make valid choices without a great deal of subjective judgment.
Another reason for the coherence and detail in the Divas is their excellent phase response (Graph 3). This phase response is unusually flat for even the best High End speakers and is a major achievement in a complex three-way ribbon design. While I should immediately note that there are still people who argue the merits of linear phase response, recent books on audio engineering take it increasingly seriously. My subjective experience has also shown me that designers who pay attention to phase response produce consistently more natural and detailed systems, and that the resulting products avoid sudden changes in the imaging with frequency and have a more cohesive soundstage.
The Divas outperform my listening room in the sense that they can deliver more depth and focus than my room size permits. They do, however, present a unique combination of detail in every aspect of the soundstage and natural musical sound. I don't know, how much of this is the product of phase and frequency response or the advantage of a large bipolar speaker with many of the character of a line source, but the result is stunning. It also never accentuates or glamorizes the soundstage. Most other speakers favor some aspect of the soundstage over others, and many etch the imaging to emphasize left-to-right spread in a two-dimensional way.
The Divas sound natural.
Much of the reason for this phase response and coherence lies in the fact that the Divas have carefully designed crossovers, with crossover points at 300 Hz and 11,000 Hz and an initial slope of 6 dB per octave, with secondary slopes of 12 dB per octave at the crossover between the woofer and the midrange. Further, there are three-way adjustment switches for the midrange, upper midrange, and tweeter level with a range of about ± 1.5 to 2 dB and a switch that allows you to cut the woofer by 2dB.
These controls provide a considerable amount of tailoring of the Divas to match a given room arid system (and you can even adjust them to provide the best performance on individual recordings if you happen to be heavily into aerobics and audio masochism). The small adjustments in the Diva's crossover do minimal damage to the phase and frequency coherence of the speaker, and they seem to be chosen with real care as to what audiophiles are likely to need. If you really want to tailor your sound, Apogee will soon release a dedicated active crossover, called the DAX. This will provide a six-window, digital display, provide another 3dB of efficiency, and adjust the crossover for differences as small as 0.1dB. This not only may help with music, it offers up the wonderful prospect of seeing whether your friends can actually hear a 0.1dB shift in the crossover. *
* A party trick that should about as safe to play on fellow audiophiles as cutting in front on a fellow driver on the LaLa Land freeway!
I have reviewed most of the sound of the Divas in discussing their technology. There are, however, a number of aspects of their performance that merit more detailed discussion.
First, as time has gone by, I have discovered that many of the initial limitations; I found in the Divas were actually the result of the equipment I was using. I have been able to find a few dynamic limits with real music. The heartbeats in Pink Floyd's tribute to the dark side of the Moonies are a case in point. By and large, however, the Divas have survived my daughter's merciless quest for ever more extreme British rock and my own tendency to trip-out on full orchestral spectaculars when work demands a mental health break. The limit to the Diva's dynamic range with real music has been the amplifier, rather than the speaker.
Second, one of the best single tests of a speaker is how well it reveals the differences in your front end and electronics. The Divas do this better than any other speaker I've heard, and in a way that reveals differences that can be heard in other installations. The best tribute to this is that several High End designers - including some whose products have drawn praise in TAS - have fine-tuned their designs after listening to them through the Divas.
Third, I could round up all the sonic spectaculars and audiophile reference recordings and tell you how well the Divas can reproduce sounds like the steam engines circling Woody Allen during his death aria. "Angst and the Single Man" - in Casino Royale. The truth is that anyone who really loves music has only a passing interest in most audiophile reference recordings. The real issue is not sound effects, it is whether a speaker allows you to really bear and enjoy the great performances of the musicians at their best. The Divas do this on recording after recording. They also allow you to adjust your system progressively and match components so that you not only get orchestral power, but you hear, in acoustic jazz and chamber music, solo instruments that actually sound natural.
One thing that has struck me consistently, since I first heard the Divas, is that you can recognize the age or type of the instrument in good recordings. Far too many speakers blur such differences-hide the character of the instrument in the lower midrange and make all violins sound like modern violins or standardize the sound of a harpsichord-which has never happened to this instrument in real life. Equally important, the Divas preserve this accuracy when a solo instrument is operating in complex orchestral passages-something that most speakers fail to do, because they can't handle the power and dynamics.
Voice can be truly lovely. I often avoid solo voice and choral music in home listening because the system alters the character of voice too much This is particularly true of medieval through Elizabethan court music and Georgian chants. Only a very few speakers really deliver classical voice at its natural potential, The Divas join that small group.
Fourth, the Divas deliver extended upper octave performance without the kind of peculiar emphasis common in most speakers that do so. HP and I disagree on some things including his ceaseless right-wing emphasis on increased military spending *
* And AHC's left-winged diatribes against nuclear power, in plants and in bombs.
But I have found over the years that we seem to find the same problems in speakers that provide treble detail and energy in a way that may measure well but simply will never occur in a live performance. I love to bear the fine details of music and the excitement you get with each new step forward in high-end transparency, but not at the cost of exaggerated treble energy, irregular or beamed energy, or a near field in which the balance of reflected energy seems unnatural. A High End system should not consistently produce a kind of upper octave sound you never hear in live music. The Divas deliver the upper midrange and treble in a way that sounds like music.
Fifth, I don't share the vestigial dislike of digital recording common to some audiophiles. I suspect that this is because much of the music I like most, including a great deal of older chamber music and voice, has been recorded since producers started using digital tape recorders. I still love my older analogue records, but I want to be able to get the very best out of CD and digital tape. The Divas reveal all the generic limits in CD sound, and they were all too capable of revealing the limitations in the first generation of DAT decks, but they also do an extraordinarily good job of taking advantage of the merits of CD. These merits are very real. The better CD recordings and players have so evolved that the fact that they can do many things (measurably) better than older analogue recordings is now important to even the most demanding audiophile. Unfortunately, many speakers lack the flat power response and dynamics necessary to keep up, and emphasize the upper midrange. Whatever you may think of digital, the last thing you want is a speaker that makes it seem worse than it really is.
I have found the Divas to be one of those few items of equipment that make audio reviewing worthwhile. They have been consistently enjoyable to listen to, and they are consistently enjoyable to live with. They allow me to indulge in high tech and feel confident about reviewing equipment, without in any way making me feel I have had to compromise my love of music for my interest in the High End.
I do not want to over praise these speakers, or give you the impression you should rush out and sell your loved ones to acquire a pair. (In any case, you could always buy a Duetta Signature or Caliper Signature and only sell half or even one-third of your loved ones) There are many great speakers in the world, including cone, planar, and electrostatic designs. These speakers legitimately compete with the Divas, and they too, deserve your attention in selecting a reference speaker. I also know of a number of existing designs I would love to try out in my listening room, and of new designs I hope to try in the future. Nevertheless, the Apogee Divas are currently my personal best.
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