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You already knew it. Live music doesn't image like hifi. Move out of the center during a concert. Does it collapse the stereo illusion into a mono speaker? Not! If it did, even suckers wouldn't pay for seats in the wings. There's a small shift but things mostly stay put. And they definitely retain massive width even far off to one side. Yet the stereophonic illusion depends on equidistant path lengths to come off properly. Unless omnis get involved. That's what Mbl's radialstrahler are. And Duevel's upfiring dispersion-lens stackers. And German Physik's 360° Walsh-derivative widebanders coupled to downfiring woofers. Like actual instruments, those deliberately radiate in all directions at once. Like singing in an empty bathroom enriches your voice with heavily mixed reflections; like artificial reverb does the same; so omnis enrich tone with a more energized reverberant field aka room sound.

 
 
Aside from true or full omnis, there are also quasi or partial omnis. Anthony Gallo's Reference 3.5 belongs into that group. So do most Boenicke speakers. And Mr. Linkwitz's Pluto. This type tends to combine a forward-radiating tweeter with up, down or sidefiring mid/woofers which trigger heavier earlier reflections than conventional direct radiators (all of which turn circular or 4pi at lower frequencies too). Our human species localizes sounds by their high-frequency content. Disconnect your tweeters and watch imaging get less specific. Like others of its kind, Pluto combines the image focus of a front-radiating tweeter with the tonally more redolent enhanced midband derived from reflected not direct sound. Hence even a potentially dry amp—we can't test Pluto's amp with anything else—won't prevent such a speaker from expressing more natural tone than the conventional beamier lot. By having its big inverted tweeter roll off sooner than standard Pluto merely adds to that midrange quality.

 
With just two paragraphs we've already encircled and nailed Pluto's two chief assets: more natural far less sweet-spot restricted soundstaging; and more natural ambient-rich wet tone. Next we eliminate near ubiquitous bass ports and their endemic ringing. Whilst bass power is directly proportionate to cone surface and air movement—here Pluto is an obvious wimp—pitch accuracy, timing and transient precision can favor smaller woofers especially when loaded into sealed enclosures. And, Pluto makes up for its lack of raw woofer size with some electronic equalization to be quite solid to ~40Hz.

 
 
Because of its ceiling orientation the bass won't generate the power-region slam or guttural impact one gets from front-firing drivers. On sonic materialism (which isn't about size but substance) this sounds like a small speaker. On staging it works like a miniature speaker. Point-source type radiation and absence of usual box talk and edge diffractions create the type of lateral immensity one expects and gets from small monitors. Their sort simply won't go this low this evenly. If they do, it's nearly always with vented alignments and their looser woollier textures. Pluto's sealed bass Q is an ideal 0.5.

 
 
Pluto and ambient music with solid infrasonics like Mercan Dede go well together. What one lacks in raw displacement and concomitant skin impact one gains in total absence of room interference, boom and resultant masking of midband clarity. Recorded phase trickery, broad panning and such arise on a huge lateral stage with high precision if a bit less depth than the best. If you're used to direct radiators—most of us are—you will have to adjust for the less direct handling of transient impulses. After all, what fundamentals do the tweeters cover? Precious few. As such this sound is rhythmically softer. It's literally less direct than you know from drivers which look at you. Unless you sat really close to stage, that too is more realistic and natural. If you reference live sound that is, not standard playback conventions.

 
 
Omron protection relays.

  Card-carrying 'philes tend to claim that they pursue realism. What they usually imply is relative to hifi, not live music. Nothing wrong with that. Hifi is an illusion. Build the one you find most persuasive. With Pluto you simply get a designer whose goal is actually oriented towards live music and how to best approximate it. Consequently this small fully active speaker with strategic response correction illuminates your room more evenly—uniformity of the power response is the proper tech term—and in turn disappears very effectively from the equation. The usual baffle step transition from circular to directional sound occurs at +/-500Hz. Here it's been upshifted to 3kHz. That's different from nearly every box speaker. It also sounds different because it won't play the room the same. And though it reads counter intuitive, moving Pluto far apart whilst being toed in steeply creates a cavernous virtual panorama without any collapse in the center whatsoever.

 
Happy math. At an introductory £2'500, Pluto plus matching integrated with active crossover and compensation circuitry plus your choice of four automotive lacquer colors is a lot of posh for the dosh. It's also a fully field-proven design that benefited from ongoing refinements over its nearly 10-year run. Now it comes at us not as a DIY project but turn-key proposition. It's actively equalized to extend low for a 5" two-way. Only the bottom octave is merely hinted at. A subsonic filter avoids overdrive to play surprisingly loud without overtaxing the small woofer. It's very toneful and a championship 3D stager. It's a very social speaker which spreads the sweet in spot all around. It's not a super airy proposition. Neither is it an overdamped British PRATster. For that you'd want a different tweeter and front-firing midranges. Key here is textural bloom or wetness. It's not specific to certain bands but admirably of a piece. Transients aren't needly and prickly as so many modern designs tend to be. Without sacrificing focus or image specificity, this is a softer rounder sound. It's innately reverberant and thus not 'high resolution' in the current hyper-separated dry usage of the term. Here transitions are more 'watercolor', less sudden. There's a lot of connective tissue between the notes. This lowers transparency and lucidity in favor of richer more elastic tone textures.

 
 
6 x BurrBrown OPA2134 opamps per side plus 3 x LM3886T 68-watt class B chip amps bolted to the heat sinks.

  As a small speaker Pluto lacks the gravitas of 12" woofers and the physical impact which line-of-sight drivers produce. But as a small speaker it's not psychologically in the way of the outer stage sectors. As a box-less design without edge diffractions there's no discernable enclosure talk. As a fully active design its performance translates from user to user because the vital amp/filter/driver interface has been locked in by the designer. With the new Chinese full-metal pipes the cosmetics have become house-broken for most. Particularly in white the speaker is very unobtrusive.

 
 
Once LzAudio improve their remote's aim, address a few small items already mentioned and throw in thicker shipping cartons to avoid needless worries upon delivery, Pluto will net a perfect score for concept, type and price. And I nearly don't want to mention it but career upgraders could scratch their itch, bypass the clicking resistor-relay attenuator by setting it to full, then spend the long green on a European designer preamp. Not that I was compelled to even try. The whole appeal of this system is its simplicity. All the important decisions have already been made for you by a very good designer. Add source, be done. A 30-day satisfaction guarantee makes it a sure thing. In closing, particularly folks who do music and 2-channel video with one system really could take to these. No matter where you sit, voices will always come from the screen yet the lateral panorama will be immense. No need for a center channel. No, you won't get 20Hz bass. But down to 40 cycles things will be very clean, firm and rather better than an equivalent 5-inch 2-way box speaker. The same applies for music. And all of it holds true also for smaller rooms. So make no mistake. Despite being a dwarf planet, this Chinese Pluto with the Santa Rosa/CA DNA plays far bigger than it looks.
 
  Pluto Loudspeakers comments: I am sorry to hear the tweeter tube was wobbly. I just woke up the manufacturer one hour ago and had a chat with him. He agreed that there is a design flaw in the connection between tweeter tube and base. He recently dispatched 14 pairs of Pluto in China and there were two with the same issue. This will certainly be addressed very soon. Also we all agreed with your comments regarding the amplifier which is too DIYish. They will give up SL's original circuit board which is too bulky and circuit board and amplifier casing will be redesigned from the ground up. I hope they will come up with something sleeker and better integrated. Thank you very much for all the praise about the Pluto which is largely down to SL's epic design. I will seek your reviewing skills again when we have a more refined version.
Regards
Xiang

 
 
 
Pluto Loudspeakers website