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Equipment Review

October 2000

Heybrook Duet Loudspeakers

by Tom Lyle

 

Review Summary
Sound "The quality of the Duets' bass was very good," and Tom "was also impressed with these speakers' ability at revealing low-level detail"; however "there was no sense of envelopment that [Tom hears] from even the most affordably priced minimonitors" because "the soundstage…was lacking."
Features Gold piezo polymer tweeter; relatively high quoted efficiency, 91dB/W/m, and easy 8-ohm load.
Use BFA speaker posts are not compatible with banana plugs; bi-wiring is possible.
Value Competitively priced, but warrant a close in-home audition.

I've always thought it would be cool to write a review for which I used only one type of music, and this single musical genre would determine whether or not I recommend a component. What would I choose? I might decide on classic rock, or maybe just small jazz ensembles on the Blue Note label recorded in the '60s. On the other hand, I suppose I might choose '70s progressive-rock albums, or perhaps psychedelic GOA-trance techno from Europe. Or Beatles CDs might be a good choice.

"I played no other albums through the Thingamabob Mark IIa preamplifier other than those that featured Mellotron. Therefore, I endorse this component because I became slightly lightheaded when listening to Tangerine Dream’s Rubycon album [Virgin 2454C]."

Of course, this passage sounds more than a bit silly. Yet it wasn’t such a long time ago when classical music was thought of as the only appropriate music to cite in a hi-fi review. And there are more than a few audiophiles who still feel that this is the only criterion for judging an audio product’s worth -- how well it reproduces an acoustic performance recorded in a real space. Sure, I listen to classical music. In a perfect world, using perfect equipment, the musicians on these recordings would sound as if they were playing in my home, or that I was somehow sonically transported to the actual event. But I’m just as likely to spin a disc of Can, Bjork, Miles Davis, John Coltrane, PJ Harvey, Joy Division, or Kraftwerk. I put just as much importance on how my system reproduces these as when I spin an EMI LP of Andre Previn conducting a Shostakovich symphony.

This might have very much to do with why I’m not a big fan of small speakers -- because I listen to so many different types of music. I need a speaker that can reproduce an emotional, delicate string quartet as well as a frenzied, throbbing electronic-industrial 12" slab of vinyl. But just because I’m not a big fan doesn’t mean I don’t use small speakers. In the recording studio, that’s practically all I use (however, studio tasks can be considerably different from the experience of enjoying tunes on the stereo). I have also had more than my fair share of minimonitors pass through my home system, and have spent many enjoyable hours listening to them.

But in my main system, I choose large speakers as my reference. Small speakers certainly have their merits, and it’s easy to understand why many listeners prefer them. Those with very small listening rooms have no choice, and for a second system where volume isn’t going to be pushed upward, they make perfect sense. I’d rather not discuss home-theater setups because that’s hardly my forte, but you find minimonitors in practically every one of these systems too.

Duet to me

So I agreed to review the Heybrook Duet for a couple of reasons. First, these speakers were to be one of my first reviews for Soundstage!, and I did not want to seem ungrateful. Secondly, and of course most importantly, I was looking forward to reviewing what I thought was a good-looking and, considering its specifications and apparent build quality, relatively affordable speaker.

The British company Heybrook may be new to most Americans, but they’ve been in business since 1978. Heybrook states in their literature that they have had quite a few models lauded by the British audio press, although most of those accolades were conferred on models designed and marketed in the 1980s. Nevertheless, Heybrook has a large line of speakers and has expanded their catalog to include electronics, stands and cables, although as far as I know, their speakers are their only components currently being imported into the US.

While unpacking the Duets, I was immediately impressed with their appearance, so I wasn’t too surprised to learn that their cabinets are not the veneered MDF, as with most speakers within their price range. They are particle-board cabinets that are finished with a wood veneer in one’s choice of rosewood, cherry or black finishes. Heybrook says that the reflex-tuned cabinet is constructed with a "figure eight" internal brace and a 30mm-thick laminated cabinet top and front baffle. The front and top are rounded to decrease diffraction.

In spite of their beautiful cabinets, it was the tweeters that were the first thing I noticed when I removed the speakers from their packing. They have an elliptical diaphragm that is sort of egg-shaped, very shiny, and very gold-colored. The tweeter itself is gas-filled, and the piezo polymer diaphragm is coated on both sides with pure gold. Heybrook claims that the design has ideal dispersion characteristics, and offers cleaner transients and less distortion. They go on to declare that the tweeter "has the clarity of electrostatic transducers without the confusion of multiple signal paths and produces excellent dynamic range, power handling, and efficiency."

The approximately 6.7" bass/midrange driver is composed of a "composite acrylic polymer gel" cone. (I’m not usually one to gripe about a manufacture’s hype, but isn’t polymer a composite? Maybe the cone itself is made of a composite acrylic and the gel a polymer?) The hard-wired crossover is first order, and crosses over at 4kHz. On the speaker cabinet’s rear panel are four BFA speaker binding posts to allow for bi-wiring. These posts, presumably a British invention, are not compatible with banana plugs. I guess if you do a little minor customizing of the posts, bananas would fit, but like almost every piece of British hi-fi equipment, they will not accept dual plugs. Near the connections is a label that says to "use BFA sockets or make bare-wire connections." Ignorant Yank that I am, I do not own (and have not even seen) BFA sockets, but I managed to wrestle the spades of the MIT bi-wire speaker cable onto the terminals without too much trouble.

The Duets’ claimed frequency response is from 45Hz to 35kHz. They operate with a nominal impedance of 8 ohms and with a sensitivity of 91dB/W/m. The cabinets measure roughly 17" high, by 9" wide, and are 11" deep. Each weighs 19 1/2 pounds, which is relatively considerable for their size. The review pair was shipped without grilles, but the Heybrook normally includes a rubber-mounted black grille that snaps into the four mounting holes in the front of the cabinets -- although I cannot imagine displaying these speakers without their gleaming ovoid gold tweeters exposed.

Just Duet

After the speakers were broken in with what I would estimate to be more than 50 hours of continuous play, I started some serious listening. I set the Duets on the 24" stands that I use with the almost identically sized PSB Stratus Minis that I normally use in my recording studio, also small two-way speakers (their retail price is $1095 USD per pair). The stands are filled with marble chip, so they’re rather weighty; as a result, they are very stable. I can bolt the PSBs to the stands to make speaker and stand almost a one-piece unit, but when I compared the PSBs and Heybrooks in my listening room I simply placed either pair of speakers directly on the stand’s platform. I used a bit of DAP Fun-Tak to secure the speakers. Fun-Tak is identical to the audiophile-approved Blue-Tak (it’s also colored blue, if that’s important to you), but it sells for about 20% of the price. It's available at most large hardware stores. I set the speakers a bit closer together than the distance to my listening seat, which was about eight feet away. After much experimenting, I ended up placing the rear of the cabinets about two and a half feet from the front wall, and I toed in the speakers toward the listening position.

Throughout the review period I used the Duets in quite a few configurations, with both low- and high-powered amplifiers, and some changes in source components. Although the Duets seemed to perform best with certain types of equipment, certain characteristics of the speakers became apparent regardless of the associated gear. I always had the similarly sized and spec’d PSB Stratus Minis on hand for comparison, which have been my reference for affordable small speakers for quite some time.

Associated Equipment

Loudspeakers – Legacy Classic, PSB Stratus Mini.

Amplifiers – Krell KAV-250a, Muse Model 150 monoblocks, Shearne Phase 2 Reference integrated amp.

Preamplifiers – Audible Illusions Modulus 3A, Conrad-Johnson PV-12a.

Analog – Heavily modified Oracle Delphi turntable, Wheaton Triplaner VI tonearm (with Discovery Cable wired directly to preamp), Benz-Micro H2.O and Lyra Clavis DC phono cartridges, Klyne SK-2 moving-coil preamplifier (when using Clavis cartridge with C-J preamp).

Digital – Meridian 263 DAC, Meridian 200 transport, Pioneer DV-525 DVD player (used as transport), AH! Tjoeb 99 CD player (used as either CD player or transport).

Tuner – Magnum-Dynalab FT-101a.

Interconnects, digital cable and speaker cables – Cardas Quadlink 5 interconnects; MIT 330-plus and Terminator 2 interconnects; MIT Terminator 3 digital cable; MIT Terminator 2 bi-wire speaker cables.

Accessories – Sennheiser HD-600 headphones, Headroom Little More Power headphone amp, PS Audio P300 Power Plant (for front-end), Chang Lightspeed ISO9300 power conditioner, MIT Z-Cord II power cable, Target TT5-sa equipment rack, German Acoustics cones (under digital), 2" concrete slab (under analog), LAST stylus cleaner and Stylast stylus treatment, Record Doctor II record-cleaning machine, Record Research Vinyl Wash and home-brew record-cleaning fluids.

I started out with some jazz. The saxophonist Charlie Rouse’s album Yeah! [Epic BAI7012] re-issued on Classic Records is out of print, but some dealers still have stock. It is worth searching for just for the recording quality, but also because it’s an excellent performance by Rouse and his small combo. The Heybrook speakers reproduced this recording as well as I had hoped, with no segment of the frequency range calling that much attention to itself, except for the bass -- but not in the negative sense. I guess the first thing I notice with most modern speakers this size is the amount of bass that they manage to produce. However, more significantly, the quality of the Duets' bass was very good. It was the equal of the PSBs' bass, with a solid, pitch-stable sound. Of course, this bass didn’t go any lower than the specified 45Hz, so much of the perceived weight of the bass was from the midbass on up. Yet there wasn’t much of an attempt to pump up this midbass to make the low end appear any fuller than it was on the recording. The port was judiciously tuned to fill out the low-frequency sound, and the bass remained stable enough even during complex passages to give a very natural portrayal of the acoustic bass. Unless I really went overboard with lots of power and lots of volume, the port didn’t make any "chuffing" sound. That is, unless I placed the speakers too close to the rear wall. It is interesting that a British speaker would be designed with a rear port rather than one on the front baffle. Many listening rooms in the UK are on the small side, and quite often English audiophiles have no choice but to locate the speakers near the walls.

I was also impressed with these speakers' ability at revealing low-level detail, as there was occasionally a glitch in this recording, such as a slight amount of distortion that was perceivable. When I was reviewing the John Shearne Audio Phase 2 Reference integrated amp, I thought a good match would be it and the Duets. While listening to this combo, I threw on Jimi Hendrix’s Live at the Fillmore East [MCA D2 11931]. It was patently evident that this recording was cleaned up considerably since its very much younger sister, the album Band of Gypsies [CAP 93446B], was mixed down in the late '60s. The Duets' clarity was mostly due to this treble being both clear and natural-sounding. The slight bit of grain that I noticed on this CD was almost certainly due to the recording or the integrated amp, not the speakers.

The treble was one of the Duets' best characteristics. This album might not have been the best choice to demonstrate this attribute, but it was apparent even on this program material that the tweeters were indeed capable of reproducing whatever the recording or source components delivered. If I played an "audiophile approved" album such as the gold CD of Miles Davis’ Kind of Blue [CBS 64935B], sure, it sounded great. Yet what more often occurred was noticing the Duets' qualities on old favorites, since the speakers were set up in my listening room for quite a while, and I played a host of different types of music through them. As long as I didn’t get carried away with playing music that was clearly not appropriate for this type of speaker, such as power orchestral, techno, etc., all the Duets' positive traits that I've mentioned were clearly identifiable. That goes for the aforementioned Hendrix album too. It was good as long as I didn’t pump up the volume too much. So I didn’t.

Duet yourself

I’m a sucker for a distinctive female vocalist. I guess that’s why I picked up the Macy Gray On How Life Is CD [Epic EK 69490]. This is really not a bad recording for a modern pop album. When I listened to this CD on the "big system" (to be precise, through the Legacies and with lots of power), it was much easier to tell that the tracks were either recorded or mixed at various recording studios. As good as the Duets' low-level resolution was, these differences weren’t nearly as noticeable. Still, even with only 50Wpc driving them from the Shearne integrated, it was still easy to tell that the recording was good, but not perfect. Many times when listening to small speakers, I find they are so enjoyable because they are not as critical of the recording or source that is feeding them. The Duets were still high-end, high-resolution loudspeakers worthy of high-end systems, although they possessed some of this "non-criticalness" too.

However, there was a shortcoming that was very noticeable, especially when the Duets were compared to the lower-priced PSBs: the soundstage of the Duets was lacking. As good as their frequency response, natural sound, and low-level resolution were, there was no sense of envelopment that I get from even the most affordably priced minimonitors. When they were compared directly to the PSBs, this was painfully obvious. I don’t expect to have an epiphany every time I turn on the stereo, but I still expect a kind of wonderment that comes from a high-end rig. The Duets just didn’t do that. Yes, I occasionally was impressed by the realism of the sound of a single instrument in an ensemble, but usually the speakers' lack of soundstaging and imaging was too noticeable to ignore. I could cite recordings that exhibited this flaw, but it was across the board. I just couldn’t coax much of a soundstage from these speakers, regardless of positioning, associated equipment, or recording.

There was a center image with the Duets, although when it was made up of many instruments, these instruments didn’t vary much in their depth. Nor did the instruments bunch up in the center of the speaker as with a cheap-o consumer-grade audio appliance. Plus, with judicious positioning (as far away from the rear walls as possible, but not too far apart from each other), I was able to get more of a soundstage out of them, albeit a rather two-dimensional one. Still, these are small speakers, and one of the reasons many folks are partial to speakers this size is because of their soundstaging and imaging prowess. The Duets were a disappointment in this important area. I know -- this is an extremely subjective observation, and this failing may bother some folks more than it may others. But I didn't hear what I didn't hear.

Conclusion

The Heybrook Duets, for all of their merits, are a mixed bag. They look great, have an ample amount of quality bass for their size, have transparent mids and highs, and natural sheen in the treble. They seem very efficient, which might make them perfect for the SET crowd, and they are competitively priced. These traits might be all you are looking for in a small speaker. However, their imaging and soundstaging were upstaged by the abilities of PSB Stratus Minis in these areas -- and probably a good number of other speakers too. Audio equipment involves trade-offs for sure, and for the Heybrook Duets, these mean some good sound in some ways, not so good in others.

...Tom Lyle
tom@soundstage.com

Heybrook Duet Loudspeakers
Price:
$1795 USD per pair.
Warranty: Five years parts and labor.

North American distributor:
O. S. Services, Inc.
10558 Camarillo Street
Toluca Lake, CA 91602
Phone: (818) 760-0692

E-mail: info@ossaudio.com
Website: www.ossaudio.com


O.S. Services responds:

Thanks to Tom for his mostly accurate and flattering review of the Heybrook Duets. Their qualities of tonality, detail, coherence and transparency are remarkable at their price point, as noted by Tom. I do take exception to his comment that the Duets do not present a deep soundstage, as I have personally heard a wonderfully deep and spacious soundstage with the Duets with a variety of amplifiers and source material, so I can only assume that Tom’s listening room or setup did not let the waveform develop properly at the listening position to achieve the performance that I have heard, or that there were possibly other speakers in the listening room at the same time as the Duets whose drivers may have been sympathetically vibrating while the Duets were playing, which could result in colorations and phase anomalies at the listening position. I’ve heard a wonderfully deep and holographic soundstage from the Duets in a 16' x 24' x 9' listening room without other speakers left in the room, so it may be possible that some early reflections or sympathetic vibrations caused anomalies due to notch-filter effect and phase problems that collapsed the soundstage in Tom’s listening room. Tom doesn’t mention if the large tower speakers he likes were left in the listening room during the Duet listening sessions, so this is just a surmise on my part.

A note about the Audax tweeter used in the Duet: Heybrook has always designed and produced loudspeakers with more life and involvement than most of the traditional British loudspeaker companies, and the Duet continues this philosophy while incorporating technological advancements such as the Audax gold-foil, gas-filled peizo tweeter. There is no voice coil in this tweeter; there are two gold-foil layers deposited on the outer and inner surface of a flexible "bubble," and when current is passed through the two layers of gold foil, the bubble pulsates, which results in a smoothly extended high-energy treble waveform with very wide dispersion characteristics.

As a result, the Duets throw out a very wide and high-energy treble waveform, and if there are early reflections present, the phase anomalies will disrupt the soundstaging significantly. There is no mention in the review about the size of the listening room, so I don't know if Tom was getting early reflections from the side walls, from the tower speakers that he may have left in the listening space, etc. or not. Does Tom leave the big Legacy speakers in the listening room while he reviews other speakers? If so, the high-frequency energy of the Duets may have been bounced back by the tower speakers' cabinets, while the PSB's may not have had enough treble energy and sufficient treble dispersion to be affected by this. Tom doesn't mention this in the review; it might be helpful to know this. My listening room is 16' x 24' x 9', and I don't have any other speakers in the room when I am listening. I found the Duet's soundstage to be extremely deep, wide, holographic, and detailed, with solid body and imaging. The extended phase-coherent treble response of the Audax tweeter provides spatial and localization information that far exceeds that of conventional tweeters, permitting whatever "depth" is in the recording to be reproduced accurately in the listening environment without the need to resort to artificially boosting the 1200Hz region, as do many mid-fi speaker vendors.

As noted by Tom, the bass of the Duets is not over-emphasized, unlike that of some other speaker vendors today, whose "thud-sqwaukers" are prevalent in every mass-merchandise store, trying to make a quick impression in a noisy, distracting environment for a quick sale. However, just like adding salt, sugar, and fat to inferior ingredients produces something with an initially pleasing taste, after a while all music starts to sound the same, with the same "thud," at the same boosted bass frequency, the same "sqwauk" at the same boosted treble frequency. The Duets are made with good ingredients and a good recipe to begin with, so no artificial flavorings are needed. Each recording sounds the way it was recorded, not the way the speaker makes it sound.

Similar to the thud-sqwauker technique, some mid-fi (and some high-end) speakers have “built-in” soundstaging, such that any program material played through them will have a deep soundstage and “envelopment.” This is a speaker-designer’s choice, to provide euphonic colorations and playback characteristics which enhance the listening experience. If Tom heard a deep soundstage on all the program material used for the review from the PSB’s, then I would like to hear these recordings on my own system, to see if they actually have a deep soundstage, or if the PSB’s or the way he had them set up introduced an artificial soundstage. The Duets are not designed to introduce an artificially deep soundstage, as pleasing as this might be to a particular listener. Also, due to the first-order crossover, they do require careful setup in order for them to perform properly. It is possible that the listening height of the speakers was a little too high, relative to Tom’s listening position, as the Duets have a tallish cabinet. Perhaps 20” or 22” stands would have been more appropriate relative to the height of Tom’s listening position. If Tom is a couch potato who sits “in” the couch rather than “on” it, his ears may simply have been too low for the intended dispersion and phase-lobe characteristics of the first-order crossover and higher-than-usual tweeter location. Just a surmise.

I do agree with Tom's recommendation to listen for yourself to see if a particular product meets your needs, and as most dealers will provide in-home evals these days, you can hear for yourself that the Duets do, in fact, present a sufficient soundstage, as well as musicality, involvement, tonality, coherence, and enjoyment.

Designer’s comments:

  1. The tweeter is about 6dB down at 30kHz, so it's not strictly true to say that it goes up to 35kHz. There would be some output at 35kHz, but not much. The Duets are down about 3dB at 25kHz.
  2. The cabinet is veneered particle board. Solid wood tends to ring at mid frequencies and wouldn't be desirable. Particle board has better self damping properties. MDF is OK for bass cabinets but again tends to join in further up the frequency range. The front baffle of the Duets is actually a double section laminate of particle board totaling 27mm thickness. The cabinet also features a figure-eight brace.
  3. The stands were probably too tall; the nature of the first-order crossovers used does make them a little more demanding in terms of their positioning than a typical speaker, and they need to be experimented with in a given room to optimize their stereo performance.

Randy Bankert
O.S. Services

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