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Positive Feedback ISSUE 53
january/february 2011


sjofn hifi

The Clue Loudspeakers

as reviewed by Kent Johnson








Magneplanar MG10's in a bi-amplified set up using custom bass boxes for frequencies below 80 Hertz.

Dodd Audio Midline tube preamplifier. Wyred 4 Sound STI-500 Integrated. Rogue 90 Stereo tube amplifier for the MG10s; a Hafler 9270 for the bass boxes. The crossover is a Dahlquist DQ-LP1.

Sony SCD-XA5400ES SACD/CD player for SACD. The Sony feeds a Cullen Circuits DL3 Stage III modded PS Audio DAC for CD replay.

DH Labs Revelation, Zentara Reference, and Supra Sword 3.0, Zentara Reference. My digital cable is two meters of Belden 1694A video cable terminated with Eichmann Bullet Plugs. It works great. Here is the article that the information for making it came from: PFO Issue 14, "Why longer is generally better for an S/PDIF Digital Cable," by Steve Nugent.

Monster 3600 Mk II line conditioner, PS Audio Soloist Premier, AC cords from PS Audio, Shunyata, and Zentara. I have four dedicated circuits available to me, three twenty amp and one fifteen amp. The amps are each on their own twenty amp circuits. The front-end equipment is on another. The fifteen amp circuit is not in use at the moment. I have a pair of AKG K240 headphones.


Sjofn Hi Fi of Seattle, Washington has recently introduced a new loudspeaker they have named The Clue. I was very impressed with this speaker at Rocky Mountain Audio Fest. The Clue is modest in size but a complete extrovert in terms of musical presentation. Its design offers full range bass performance from a cabinet and driver that any reasonable person would consider too small to be capable of such low frequency response. It is also designed to offer a very large sweet-spot thanks to its control of the tweeter's directivity.

There is a lot of technology present in(The Clue and I noted some of it in my Rocky Mountain Audio Fest report. You can read that report in PFO Issue 52.


The Clue loudspeakers are classic mini monitors where size and design are concerned. They measure 14 by 8 by 10.5 inches (HWD) and weigh 16.5 pounds each. Their small size makes them feel quite dense. The driver complement consists of a woofer/mid and tweeter.


Both drivers are proprietary designs. The woofer/midrange, made by Scan Speak, measures 5.5 inches in diameter and consists of a paper substrate with a constrained-polymer damping layer. The dust cap is a silk dome.

The Vifa tweeter is 7/8-inch in diameter and is situated in a controlled directivity waveguide (acoustic lens) machined to tolerances of one-one thousandth of an inch. It also has a silk dome with a large roll surround, multiple back chambers, and copper shorting ring. The crossover between the two drivers is approximately 2300Hz. The actual crossover technology lies beyond my ability to explain it. Both drivers are matched to within +/- .5dB tolerances of the original The Clue prototype.

The Clue's efficiency is 87dB, nominal impedance is 6 Ohms, and the frequency response is given as 28-32Hz on the low end and 42kHz on the high. Both of these figures are excellent for any speaker but the low end response is extraordinary for a speaker this small.

The cabinets of my review speakers were beautifully veneered in a natural maple finish. The front baffle is one-inch thick MDF; the sides are .75-inches thick and well-braced. Other finishes include piano black and cherry veneer.

The Clues (I'm dropping the parentheses for the duration of this review.) come with a six year warranty and list for $1500 per pair.

Set Up

I spent considerable time in Sjofn's room at Rocky Mountain Audio Fest, so I had a pretty good idea of what the set-up basics were. I placed each speaker on a 20-inch stand with the rear inside corner about 2 inches from the wall; they were toed-in strongly toward my listening position. My thought was to get some additional break-in time on them (they had 35 hours when I got them; they need about 60.) and then refine the set up.

I received these speakers in late November, so I spent a lot of time listening to Christmas music. The first CD that I played sounded pretty good but since both the speakers and Supra Sword speaker cables had been unused for a while, I knew it would take at least an hour or so for the music to come to life. At the start of A Charlie Brown Christmas, the second CD, it became clear that I was hearing something very special from what is a very average quality recording.

The first track, "O Tannenbaum" placed the drum set deep within the left rear of the soundstage, a positive indication that soundstaging was going to be a high priority with these speakers. The piano sounded very good but what impressed me most was the way the piano keys sounded finessed rather than struck. I had never noticed this sort of subtlety from this CD before. The acoustic bass near the right channel had good weight and definition. These same qualities were evident on many of the tracks on this album as they share a common soundstage organization. The short piece "Skating" came through The Clues with a level of charm that I simply had not noticed before—now, it seemed entirely too brief.

Turning to "Linus and Lucy" the left/right soundstage presentation completely disappeared with the jazz ensemble now filling the space between the speakers and The Clues themselves utterly disappearing.

In fact, by the time I finished A Charlie Brown Christmas, the sound was sufficiently good that I decided to actually read the instructions and set The Clues up properly. The set up instructions are comprehensive and humorous. Following them to the letter makes the set up easy and the results remarkable.

There are four aspects of set up that need to be performed to get The Clues to work properly within the room.

The first of these is to place them on a stands from 19 to 22-inches in height. I had already done this. This places the mid/woofer in correct proximity to the floor where it can capitalize on bass reinforcement from it.

The second consideration is that the inside rear corner of each Clue needs to be within 2.5-inches of the rear wall, the closer the better. Running my Supra Sword speaker cables straight into the very good quality Supra binding posts using 4mm plugs would not allow the speakers to get within this distance. Fortunately, these binding posts have an internal hole large enough to accommodate 4mm plugs. I ran the wires up into the posts from below. I could now place the rear corner of the speaker right up against the wall if I wanted to. I ended up with the inside corners one inch from the wall. This location takes advantage of bass reinforcement from the front wall itself.

clue supra

Third, the Clues need to be toed-in 22.5 degrees. I had guessed at this in my initially setup and guessed badly. So I made a cardboard template. It took longer to find my protractor than to make it but it was well worth the minimal time and trouble. The stands also need to be toed-in and the template took all the guess work out of that set up as well.


The fourth, final, and most important aspect of set up, is to position the speakers so that the ratio of The Clue's distance apart to their distance from the listener is 1:1.2. More specifically, the distance to the listener, measured from the front plane of the speakers, divided by their distance apart, center-to-center, should be as close to 1.2 as possible.

I placed the stands as far from each other as my listening space allowed while making certain that at least one of the speakers had its woofer at least 28-inches from a side wall (another recommendation in the instructions).

The biggest problem that I had was getting the speakers level both side to side and front to back. I am not a fan of speaker stands because most of them are badly designed—mine are no exception. The stands I own have blind holes in the bottom for the threaded spikes and their platforms are not actually parallel to their bottom plates. It was tedious but I eventually got the speakers almost perfectly level with very good stability on my carpeted floor.

I then measured their center-to-center distance. It was 86 inches. I was somewhat surprised. The diminutive size of The Clues made them look much farther apart. This distance multiplied by 1.2 is 103. I measured from the front plane of the speakers to my listening position; it was right at 109 inches. I thought about moving the couch forward by about six inches but had better sense than to actually do it. My wife has been very tolerant of my turning the living room into my smaller listening room but I did not see her going for this alteration.

In fact, there was no reason to do so. The instructions also mention that when The Clues are properly set up, the listener should just barely be able to see the outside panels of the speakers. From my position, I could see a sliver of maple veneer around 1/8th inch wide. Moving my position farther forward would have eliminated any possibility of seeing an outside panel. The set up was complete. It was time to do some serious listening.


I listened to a lot of Christmas music through The Clues. Some of it, the Scandinavian music in particular, was eerily lovely and superbly recorded, if perhaps something of an acquired taste. The system that I used consisted of the following equipment:

Integra DPS-10.5 Universal player purchased recently at an estate sale.

Xindak XA3200MKII tube line stage.

PS Audio A-100 Class D amplifier.

Speaker cables were 3 meter lengths of Supra Sword.

Interconnect cables were 1 meter DH Labs Revelations.

AC cords were Shunyata Diamondback Platinum IIs on the amplification and a Supra LoRad 1.5 on the Integra. Everything was plugged into a Monster HTS 3600 MKII power conditioner.

Sjofn Hi Fi recommends listening to The Clues without their grills, which is the way I auditioned them.

Antiphone Blues

Antiphone Blues (Proprius PRCD 7744) was reproduced by this system through The Clues as an enormous space, dominated by the organ, in which the saxophone is a Roman candle spraying musical sparks throughout the interior. The way the sound reverberates and decays within the space is spectacular. The lower registers of the organ were impressively reproduced as well. The low end of around 28Hz is genuine; it is not a hump in the response curve that gives the impression of low bass. In fact, The Clues, top-to-bottom balance is as remarkable for its failure to emphasize any part of its frequency response as it is for its high and low extremes.

Diana Krall's Christmas Songs

Almost every track of Diana Krall's Christmas Songs (Verve B0004717-02) put some aspect of The Clue's performance on display.

Her voice on all the tracks sounded in-room real and all of the abundant nuances and inflections she brings to her singing were simply there as if you were hearing her live. As was the sound of the accompanying air forming the words that she was singing. There is something of a brusque quality to her voice. Diana uses a minimum of vibrato and rarely extends a note simply for the sake of displaying what her voice is capable of doing. The Clues neither sweetened her voice nor exaggerated its somewhat incisive character. This neutrality allows her voice to perform "Christmas Time is Here" with a minimum of overt emotion leading in turn to a profound identification with everything that the song has to say.

"The Christmas Song" opens with Diana playing the piano. The lower chords are reproduced by The Clues with realism and weight. Shortly, the acoustic bass and drums join in.  The bass also has excellent weight and is upfront with Diana; the brushes on the drum have all their high harmonics intact. They sound like wires on skins, not white noise as they sit in the middle of the rear of the soundstage. It was impossible not to be immediately absorbed into the performance 

"Winter Wonderland" opens with Diana's voice and only acoustic bass accompaniment. It is simply wonderful and the whole song could have been performed this way as far as I was concerned. The nuances of her singing are so natural that they almost go unnoticed. The acoustic bass is deep and detailed. I think a certain amount of time is needed when listening to The Clues for your brain to accept that these modest-sized speakers are actually reproducing the bass sources heard in the recording. You expect excellent midrange from a speaker this size and having well-extended treble is no surprise either. But bass this realistically formed…

Soon, Diana is joined by the orchestra itself in the center-right of the soundstage and clearly behind her. There are both saxophone and guitar solos just inside the left channel. You have to be concentrating on the soundstaging to be conscious of how well The Clues are locating everything. This is hard to do since the music itself is so compelling.

The Clue's soundstage is located about two feet in front of the speakers and has excellent height. The soundstage depth extends well beyond the wall behind them. The soundstage reproduced by The Clues extends to the outside edges of the speakers. I have not encountered a recording going outside of the speakers yet but virtually every recording unfurls to fill the space between them, whether the ensemble is large or small. The thing is, the soundstage is so disconnected from the speakers that you are rarely aware of their locations. Music has to be at the absolute edge of the soundstage to sound as if it is coming from within either speaker.

The acoustic space within which Diana is singing was also very well reproduced by The Clues. Low level detail is not the first quality that you notice with these speakers. It creeps up on you the more you listen however and you realize that there is a lot of subtle information coming through.

A CD I discovered last year has become one of my favorites as well as a useful sonic reference. Yo-Yo Ma & Friends, Songs of Joy & Peace (Sony Classical 88697-24414-2) is one of the best sounding CDs that I have encountered. Track 1 begins with solo cello that is rich enough to cause gout, as woody and resonant as the real thing, and absolutely lovely. If the only thing I heard The Clues reproduce was this track, it would have been enough to make me fall in love with them.

There are five different interpretations of Dona Nobis Pacem by different types and groups of instruments. When Edgar Meyer and Christ Thile play this music, you can sense Edgar Meyer restraining his acoustic bass to keep from overwhelming the sharper more delicate output of the mandolin. Then he switches from plucking the bass' strings to bowing them. The low frequencies he generates are as impressive for their detail as they are for their weight.

The atmosphere generated by "My One and Only Love" featuring Yo-Yo Ma and Joshua Redman filled my listening room. The tangibility of the air emerging from the saxophone, intermingled with the resonances of the cello, took complete control over the listening space and replaced it with the recording venue. I just love this kind of stuff.

"Wu Tong, The Silk Road Ensemble" featured drumming that was almost floor-shaking through The Clues. Though they could not actually vibrate the flooring, they went low and loud enough that there was certainly never any doubt as to the power being generated by these drums.

"Happy Christmas (War is Over) featuring ukulele and cello is heart-achingly lovely. The high notes have purity and speed as a result of the forceful plucking that generates them from the ukulele's strings. The notes float upward and then fade like cooling embers. I have mentioned how good I feel this recording is and The Clue's reproduction of this track will leave no listener in doubt as to what I am referring to. It was bitter-sweet to hear this music performed so incredibly so close to the anniversary of John Lennon's death.

Other Christmas music that was beautifully reproduced by The Clues included Holly Cole's, Baby It's Cold Outside (Alert 6152810382), The Cherry Tree by Anonymous 4 (SACD HMU807453), A Dave Brubeck Christmas (Telarc20 CD-83410), and, of course, the glee Christmas Album (Columbia 88697 78567 2). For no particular reason, I did not listen to a lot of classical music that was not also Christmas-related. A couple of jazz albums that provided sonic thrills were Sphere with Kenny Barron, Gary Bartz, Ben Riley, and Buster Williams (Verve 341 557 796-2) and Opening with the Mathias Landaeus Trio (M•A Recordings M081A).

On these CDs and more, The Clues showed their ability to reproduce all sorts of different instruments, voices, and widely diverse types of music, with a startling level of fidelity.

And what about the sweet spot?

One of the benefits of The Clue's design and set-up is that they combine to provide a very large area over which the sound is very consistent. This is one of the results of using the very sophisticated wave guide on the tweeter. At RMAF, I heard The Clues from well off center and I thought they did an excellent job of offering a coherent central image as well as keeping the output of the far speaker clearly identifiable. In my own room, I tested their limits only from the far ends of the sofa. Within that range, there was very little change is the soundstage or the sound quality. The Clues would be dynamite in a listening situation in which two people usually listen at the same time and the flexibility of listening position is certainly a plus. If you are a certifiable sound staging addict, however, you will still hear the best imaging right in the absolute center.

Wall dampening

Sjofn's set up information suggests that placing some acoustic dampening material on the walls behind The Clues can offer further sonic improvement. Doing this they state will bring the listener "a bit more into the vaunted 'you are there' listening experience." They suggest that the material be approximately 2-2.5 inches in thickness, about 24 inches wide, and tall enough to exceed the height of the speaker by 4 inches. At RMAF, they used egg crate foam on the wall.

I can state pretty definitively that putting egg-crate foam on the wall is a total non-starter around here and I suspect a lot of other homes as well. As it happened, however, I found an ad on Craigslist selling some acoustic panels made for home theater use. These panels measure 24 by 40 inches and are about an inch thick. The fronts are covered in a nice open-weave beige fabric. I contacted the seller and ended up buying two of the panels with which to experiment.

In position, with the long dimension vertical, and next to The Clues, each panel met all of Sjofn's suggested parameters, with the exception of thickness, about as perfectly as you could ask for.

In my room, listening with these panels in place did not improve the sound quality in any way that I could hear while it did damage the imaging. With the panels in place, an instrument in the vicinity of either speaker was relocated back into the speaker itself. This damaged the illusion of a soundstage floating in space between the speakers and brought unwanted attention to the location of the speakers as well. The sound quality was not affected for better or worse that I could detect but there was definitely damage to the soundstaging.

I then tried a single panel centered on the wall behind and between the speakers. In my room, this improved the focus of the central image with no drawbacks that I could hear as a result. I find the panel somewhat distracting visually, but sonically I plan on keeping it in place.

Given the exceptionally useful and thorough set-up information that Sjofn provides with The Clues, I have no doubt that the right dampening material can make a further improvement in their sound. The panels that I tried may not be that material, my room may have issues not anticipated by the designer, and I may have different listening preferences than other listeners so do not take my experience as in any way dictating yours. 

Experimenting with some acoustic dampening material is definitely worth the trouble but do NOT feel that it is necessary to get superb sound from The Clues. These speakers' design and set-up allow them to integrate into the listening room with an absolute minimum of fuss and adjustment. After putting The Clues in position, I ended up moving the left speaker forward about one-quarter inch, which brought a hi-res level of focus to the center image. I have had no need or, more strangely, any desire to do any additional adjusting. The Clues may be the most "plug-and-play" speakers on the market—follow the directions and you will hear them at their best. 


I have gone on here at some length about The Clues because they have incredible strengths. Their sound quality is superb by any parameters that you want to apply—their reproduction of treble, midrange, bass, the soundstage, and low level detail are all accomplished at a remarkably high level. Less quantifiable musical components, such as emotional connection and illuminating the filament of memory, are equally well served.

I know I have dwelled somewhat on bass performance but it is the most astonishing aspect of a completely astonishing musical performance. Almost as astonishing is the ability to purchase all of this for $1500 per pair.

I give them my absolute highest recommendation. I think they are (The inCredible). 


You may have already seen my review of the Arte Forma I-150 integrated amp in this issue. It, too, was a total rave.

I had hoped to listen to the I-150/The Clue combination at some length and report on it as part of this review. That did not work out. I will do a separate article on how these two amazing and affordable components play together. I may have the I-150 with the upgraded volume control to listen to as well. Stay tuned, things should be interesting. Kent Johnson

The Clue™
Retail: $,500 per pair

Sjofn HiFi
1020 East John Street
Suite 101
Seattle, WA 98102
Contact: Lars Erickson
TEL: 206-605-8590
web address:

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