http://www.michaelgreenaudio.net/tunable-speakers
here's the latest review
"Michael Green Audio became well known in the late ‘80s for developing RoomTune acoustical products, and generally as a pioneer in the field of acoustically treating listening rooms for optimum sonic performance. Since that time, the company has also been producing loudspeakers and other devices such as equipment racks that can be tuned via various mechanical adjustments built into the designs. Michael Green’s loudspeaker designs are “free resonant” in that they are built so that the cabinet’s natural (but intentionally designed) vibration is an integral part of the speaker’s sound reproduction, just as a violin, piano or trumpet naturally produce their signature vibrations. In other words, MGA has always been building each of its speaker designs as a tunable musical instrument.
In 2017, after extensive research and testing of various cabinet construction materials and driver design modifications, MGA introduced a new monitor-sized speaker. While the conventional wisdom today among speaker designers is to use a cabinet as inert as possible and then damp it further, in order to limit the sound energy dispersion to only the drivers, the Rev6, like its MGA predecessors, employs the free resonant design and is also tunable using a mechanical device that allows the user to expand or contract the focus/soundstage produced by the speaker. This adjustment can be set-it-and-forget-it or can even be adjusted for each piece of music. It allows the listener to adjust the sound specifically for his listening preference, potentially superseding limitations of the room’s acoustical characteristics.
I’ve had these speakers in my listening room now for over 6 months and have gotten to know them quite well. The break in period was fairly fast. The first couple of weeks were rough as the drivers sounded a bit tizzy as they flexed their muscles, but after that they smoothed out and after a month the speakers sounded smooth and refined and eminently musical. I have known other monitor type speakers to take months to get to a solidly broken-in state. I was enjoying these Rev6’s fully after a couple of weeks and they only got better and are still getting better at this moment. MGA instructs that since they are a free resonant design, they will improve in their already substantial musicality and efficiency as they are played and age (like a good guitar). I’m looking forward to that.
The speaker dimensions are 11.75” x 7.75” x 6.0” (30cm x 18cm x 15.5cm) and they come in a variety of lacquered finishes. Mine are a lovely cherry with great matched veneers and add a refined look to my otherwise fairly plain looking system. They are lightweight speakers, weighing only 9 lbs. and placement on 28” hollow wood stands, also available through Michael Green Audio, is recommended. With respect to the MGA stands, they are designed to couple to the speakers such that the stands become an integral part of the speaker and extend the speaker’s frequency response and body in the bass region. The company provides an assortment of spikes with which the owner can experiment to find their preferred configuration. The front baffle on the Rev6 is made of instrument grade solid poplar wood (a little research revealed that poplar typically is used in the construction of drums and other percussion instruments such as vibraphones, stringed instruments such as guitars, violins, cellos and harps, and even some woodwind instruments such as flutes), and each driver is direct coupled to the baffle, eschewing the typical employment of a gasket. The remainder of the cabinet is constructed from a proprietary formula of treated compressed soft pulp wood source material. The internal tuning bar that serves as the mechanical tuning device is also made of poplar, and the solid brass tuning bolts on the outside of the speaker that adjust the tuning bar are the same ones used in other MGA tunable products such as Pressure Zone Controller acoustical devices and the MGA Tunable Room. Internal wiring in my pair consisted of MGA Type I speaker wire to the tweeter, and MGA Type II to the woofer. An upgrade of internal wiring to the new MGA White speaker wire is also now available. The speaker 5-way binding post assembly is a lightweight design, and direct connection of speaker cable, rather than spade or banana terminations, is recommended by MGA for best signal transfer.
Due to the free resonant tunable design, Michael Green Audio recommends that the speakers be placed facing straight forward, with no toe-in. In my experimentation with different positions, I found the straight forward approach to provide by far the best clarity and soundstaging. These guys do soundstage amazingly, and of course you can adjust the primary width of your soundstage by how far you place the speakers apart in the room. The Rev6’s naturally produce an expansive soundstage that goes outside the speakers, and that can also be tuned further using the speakers’ built-in tuning bars. Their efficiency is 91-93db (room dependent), so they don’t take much power to sound their best.
In my listening, these speakers strike an incredible balance between musical ease, refinement, clarity, punch, and spot-on harmonic completeness and accuracy. Paradoxically, they are able to exhibit effortless control and a sense of unbounded energy at the same time. I understand that Michael Green treats the drivers with a proprietary reinforcing compound, so that may be what’s behind this remarkable quality. I’ve done many a double take when I think I hear an actual piano, saxophone or cymbal playing while I’m in the other room on the computer. The attack and decay envelopes produced by the Rev6’s are fully rendered and precisely reproduced. In fact, this characteristic may be the speaker’s most identifiable quality and at the core of what makes the speaker sound so natural and realistic. The speaker’s rendering of all forms of percussion, for example, is simply head-turning and serves to naturally connect the listener’s body and soul to the music. Audiophile friends that have listened to my system have made similar comments about these speakers.
I have never become fatigued listening to the Rev6’s. Indeed, for most speakers with careful listening their limitations become obvious and one learns to adjust to them. With the exception of the very low bass range (below 42 hz), I have yet to find anything that is lacking or irritating, though if I did I would certainly be willing to forgive it. I typically listen to jazz, classical, blues, Americana, blue grass, pop, and some rock. I don’t play loud rock or symphonic music very much, and at very loud levels the speakers can be mechanically adjusted to keep that refinement and openness, but they are a small speaker and thus have certain low end limitations. See below how MGA addresses this issue.
The speaker’s lower range extension is beyond what I would have expected, and with the exception of very low bass, these speakers maintain the qualities I’ve described across the frequency range. I estimate the bass energy starts to roll off quite audibly at 40-45 hz. I drive them together with a MGA subwoofer (also free resonant and tunable) that I have had for quite a while, and they paired seamlessly after adjustment of the sub’s kick-in frequency, phase and volume, which didn’t take all that much experimentation to arrive at. With the sub in the system I run the satellites and sub at the most open tuning positions, and the Rev6’s full range at all times (as recommended by Michael Green Audio). MGA also suggests that for those heavy rock and symphonic listeners the Rev Combo, which includes the Rev6’s and the MGA subwoofer designed to match the Rev6, can be configured to run either with the Rev 6’s running full range, or with them running through the MGA sub crossover first rather than full range. This latter alternative configuration allows adjustment of the extreme low end and avoids extra stress to the Rev6 woofers. I heard them that way not too long ago when I met Michael Green at the MGA home base in Las Vegas, appropriately called "TuneLand".
These speakers, even after months of listening, still amaze me with their unvaryingly believable and natural sounding reproduction of the source material. On solo piano pieces, you literally hear every sound that the piano makes from ppp to fff with incredible lifelike precision, including the acoustic in the recording venue. That said, these speakers have never sounded overly detailed to me. Rather, they are preternaturally balanced, so you hear whatever is on the recording completely in all of its harmonics but with a tremendous sense of effortlessness. Accordingly, the 6’s reproduce human voice performance so fully that you clearly hear things like a bit of spittle or a subtle breath as a perfectly natural part of the singing, and not as an accentuated artifact as one can hear with other speakers. Sometimes the emotions conveyed in a performance I’ve experienced on these speakers has given me the chills. I’ve found them to be uniformly clean sounding, but in no way sterile. And while the Rev6’s will accurately reproduce the sound quality of components further up the audio chain, they are forgiving and non-analytical. In fact, Michael Green says that you may even be able to some extent ameliorate issues that an upchain component has by how you tune this speaker.
A little more about the soundstage. These Rev6’s are soundstage monsters. They are very sensitive in this respect. You can create your desired width and depth of the soundstage by placement proximity to the room boundaries, and by where you sit in relation to the speakers. There is no theoretically ideal placement like with so many speakers that have some rule to follow that defines their optimal placement in order to sound good. These speakers easily disappear into a grand soundstage that extends beyond the boundaries of your room if you prefer to listen that way. Notably there is no loss of detail or accuracy with a big soundstage. And if you like a more directed-to-the-listening-spot sound you can tailor the speakers to that as well. The tunable, free resonant design approach I’ve found allows for a great deal of flexibility in using these speakers to create the kind of soundstage you like.
I drive these speakers with 50W/ch of tube power, but I suspect they would sound glorious driven even by 8-10W/ch of good single-ended tube amplification.
On MGA’s internet forum (http://tuneland.forumotion.com) Michael Green likes to work directly with MGA speaker owners in determining the optimal placement and tuning for MGA speakers, and additionally, with interested music lovers that want to investigate what kinds of tuning options may be available for their listening room and their system (this online service is encouraged and gratis).
In my 30 years as an audiophile, these Rev6’s, coupled with my MGA sub, are the best speakers I have owned. I can’t imagine wanting to change. Unless, perhaps, MGA someday comes out with a full-range floor standing Revolution speaker again.
Associated equipment include Audolici A25M integrated amplifier, Magnavox 2100 CD player with MGA tuning modifications, MGA Bare Essence Type 2 speaker cable, MGA RoomTune CornerTunes and RT Squares."
Michael Green