[SoundStage!]Max dB with Doug Blackburn
Back Issue Article
February 1998

Michael Green of Room Tune and Michael Green Designs

Spending more than a few minutes on the phone with a high-end manufacturer can be quite an interesting experience. About a year and a half ago, I spent most of a day with Michael Green, founder of Room Tune and Michael Green Designs. Recently we spent a second day together. When I arrived at the new factory/office they were busy assembling orders for rack systems and Room Tune products. A short drive took us to Michael’s home which is becoming even more of a showcase for Tunable Room technology. M.G.’s Tunable Room products provide some unique sonic attributes unachievable by other means. Tunable Rooms can be done to any degree the owner desires. There are products and construction methods applicable to new rooms, rooms being remodeled to various degrees, as well as products for existing rooms. Tunable Rooms are perhaps the final and largest benefactor from all M.G.’s experimentation with mechanical resonance control, system tuning, and room tuning. Rather than jump into Tunable Rooms first, some orientation about Michael Green Designs and Room Tune products is in order.

Room Tune

The original product line remains in production in free-standing and pin-onto-the-wall formats. These products absorb from the back and reflect from the front. These products are very cost effective room treatments.

The new line of Pressure Zone Controllers expands the capability of wall mounted and floor standing, room treatment devices. Cost of these are a little higher then the originals due to more complex construction and materials used. In many rooms, the effect/results are better than what can be achieved with the original Room Tune products.

Both original Room Tune and PZC products are intended for home use, however the PZC line is gaining inroads in commercial installations.

In-wall tuners are designed to attach to wall studs under the dry-wall. These are for remodeling and new construction since wall studs and ceiling/floor joists have to be exposed for installation. These are major components in Tunable Rooms.

Acoustic ceiling molding enhances room acoustics in existing rooms, remodel jobs and new construction. Looks and paints like normal wood ceiling molding.

Michael Green Designs

New line of brass cones with advanced profiles and surface finishes, called MTDs (mechanical transfer devices) offer enhanced performance. They come in a variety of sizes and with and without mounting threads.

New shelves for amplifier platforms (tuning boards) and rack systems enhance sonic performance.


Rack system products continue, now incorporating the improved shelves; 5 "levels" available… economy (Justarack Jr.), standard (Justarack), deluxe (Deluxe Justarack), clamp (Deluxe Clamp Rack), and the new Signature series with unbelievable construction and finish quality. When you see a Signature shelf or tuning board in Midnight Rose for the first time, you will be amazed (photo below, though it hardly does justice to the finished product). All racks feature threaded rod legs for infinite shelf height adjustment. Standard racks have .75" thick shelves, while Deluxe and Signature shelves are 1.5" thick. Brass bottom cones and polished brass top caps used to be extra cost options but are standard now. Extra deep shelves are available for more rack stability and/or larger components.

Tuning bases for symphonic instruments. First models are commissioned by the San Francisco Symphony to overcome sonic problems when they reconfigure the stage for different combinations of musicians/instruments and when they play in new/unfamiliar venues. The sound of instruments change and setup becomes laborious in new locations. The most problematic instruments have been grand piano, tympani and bass. So the first tuning platforms are for these instruments. Using a tuning platform removes the variable of location on the floor from setup.

Consulting work on commercial acoustic tuning jobs. Customers so far have included: Klipsch’s tunable room at their design/manufacturing center; Mobile Fidelity Sound Labs’ mastering facility; a large number of PARA audio and home theater dealers tunable demo rooms; and in M.G.’s local area several churches and performance halls are fitted with PZCs and Tuners in the walls, ceiling and floor.

Tunable sound reinforcement systems for commercial installations.


Tunable Speakers for home audio – from small $900 bookshelf models to the expensive floor standing Chameleon series. Each speaker in this series can be tuned by adjusting the tightness of tuning nuts on 2 or more sides of the speaker. M.G. believes being able to tune the speakers permits them to sound great in a much wider variety of rooms than non-tunable speakers.

Every time I think about this long list, it seems like too much for one person to do. One thing is certain, the shops in New Philadelphia, Ohio are kept buzzing with one project or another. M.G. seems always to be in forward motion – moving towards the goal of perfecting and broadening applications of tunable technology. You see and hear evidence of this in every subject you engage M.G. in during conversation.

Conversation with M.G. gets complicated very quickly because explaining how room tuning devices, instrument platforms, component feet, tunable speakers and equipment racks are all interrelated is a complex subject. Some examples:

Instrument tuning platform research resulted in new construction methods for the mdf shelves and tuning boards. When the instrument platform construction method was applied to rack shelves and tuning boards, sonic performance of the racks improved.

While studying the sound of the instrument platform affected the sound of the instrument, M.G. discovered one of the critical elements for good sound was what happened during the decay of a note. He found that the size, shape and surface finish of the brass bottom cones on the legs of the instrument platform would change the decay characteristic. Changes were most obvious in the length of the decay and whether there was a pitch increase or decrease during the decay. He found a new profile and surface finish for the brass bottom cones which gave a long decay with no pitch change. Applying this knowledge to AudioPoint brass cone feet for high-end equipment resulted in better sounding equipment feet which are now called MTDs to differentiate them from AudioPoints.

Development of increasingly better sounding/performing in-wall tuners came from researching the surface finish on the brass bottom cones of the instrument tuning platforms.

In-wall tuner and tunable speaker research led to development of the Room Tune Pressure Zone Controllers.

You can imagine how conversations could start out innocently enough and before ending, touch on 2 or 3 related subjects involving other products. Keeping this evolution and the inter-locking product relationships straight requires some concentration and asking repetitive questions. It is quite clear that M.G. has all this stuff well sorted out in his mind. But being so interwoven, it is difficult to present to a single person or audience in a single linear train of thought.

"Who is this guy really?"

You’ve probably seen the new Room Tune / Michael Green Designs advertising with Michael Green prominent. You may end up with the wrong impression about M.G.-the-person from these ads if you read too much into them. There may be a tendency to associate this self-promotion with a big ego. Having had a couple of long visits with M.G. I can report that there is definitely an ego. However, it is not what you might expect. M.G.’s ego leans toward wanting to do something important for the advancement of room acoustics and audio system tuning. He likes to fantasize about sitting at a table with Bell, Beethoven, Edison and others, explaining and demonstrating his ideas and products to them and have them nod their approval. A big dream. But M.G.’s person-to-person interactions aren't loaded with self-importance - at least not that I can identify based on my 2 days of immersion in his world. He just seems like a regular guy who’s excited about some interesting stuff.

"But he is a high-end millionaire or multi-millionaire, right?" If he is, he sure is hiding it well. His home is what you would expect of anyone in their 30s or 40s with a comfortable income - except for tearing down and rebuilding the Tunable Room every 1 1/2 to 2 years. There are no "millionaire" trappings anywhere. To get to M.G.'s house, you go up a driveway. As you reach the tree line, on the drivers side, a neighbor's dog trailing a 20 foot chain seems to be launched at our car from a dog house. One foot from the fender, the chain tensions and the dog drops to the ground on all fours looking madder than hell. We calmly motor by into the trees and up a rise to the house. Average size, a deck with a small grill, quiet... perfect for those long late night listening sessions.

"With long hair like that, it must be a freaky place though, right?" No, not at all. Perfectly normal looking. If pressed, M.G. will admit "using" the hair to get people to notice Room Tune and Michael Green Designs. It is part of the marketing strategy. A way to stand out from the crowd. It must work. People aren't often without opinion about Room Tune, M.G. Designs or M.G. himself. People do tend to respond to ads where "the guy" puts himself right there up front with the products. So Room Tunes/M.G. Designs is taking advantage of that. Nothing sinister to it at all. Besides, M.G. likes having his picture taken.

Building the Perfect Tunable Room

At M.G.’s home, the tunable room I saw during my previous trip was completely stripped down to the studs. They were in the process of updating it to all the latest knowledge and products. In the process they learned something interesting… take a raw 2x4 or 2x6 from a lumber yard and thump on it. You get a fuzzy buzzy thud out of it. Varnish the stud by rolling the varnish on, let it dry for a couple of days and thump on it… the sound becomes almost musical! There is a tone to the thump and the fuzzy-buzzy character is all but gone. Studying the weight and composition of the varnish has led M.G. to a formula that is perfect for finishing studs during a remodel or new construction. The varnish changes the mechanical transfer function of the stud or joist which causes the big change the character of the resonance. When in-wall tuners are used, there is a significant performance/sonic improvement when the studs and joists are varnished with the secret blend. Notice in the photo of the in-wall tuner that there is a big brass boss… this is flush with the back side of the wall when the bracket is properly installed. You do not pull or push on the wall, you turn the Tension Nut using an allen wrench to control how tightly the wall is coupled to the brass boss… which is coupled to the bracket… which is coupled to the studs… which are varnished for better mechanical transfer… which are coupled to the foundation… which is coupled to the ground. The tightness of the tuning nut is what controls how the wall behaves in a Tunable Room, not tension or pushing forces..

So how do you go about installing in-wall tuners? Start with wall studs or ceiling/floor joists, 16" on center. The Room Tune Hotline (1-800-roomtune) will tell you how many you need based on the size of the room. You stagger these across wall surfaces. You then apply 7/16" plywood of a type specified by Michael. Holes are made in the plywood to clear the threads of the Tuning Nut, but when tightened, the shoulder of the Tuning Nut presses on the plywood. 3/8" drywall (thinner than the normal 1/2" or 5/8" drywall in most walls) is applied over the plywood and larger holes are put in the drywall so that the entire Tuning Nut is clear of the drywall. This leaves an ugly hole in the drywall. M.G. has a small plastic cover something like a switch plate to cover these holes and make them look insignificant.

On my previous trip, the tunable room demo was a stunning experience. While seated and listening to music, M.G. would adjust a Tuning Nut and the entire soundstage would be affected… not unlike a radical phase shift in the recording. When balanced correctly, the tuning seemed to eliminate the room. Hearing the new version of the Tunable Room is high on my list of things to do in the near future.


The first attempt at tunable speaker production was compromised by substitution of inappropriate materials so M.G. has reclaimed production of the tunable speakers. He is personally overseeing production at a fabrication facility in Canada. There they have found an mdf (medium density fiberboard) made from Canadian hardwood logged not too far from the fabrication facility. M.G. was very excited about the improvement in sound quality that this material has produced. Mdf is made of wood fiber and like regular wood, the type of fibers used in the mdf change the "sound" of the mdf significantly. Along with returning to the original design and making some other changes like studying the solid woods used in the quarter-round corner pieces. The changes have resulted in a Tunable Speaker line that for the first time meets M.G.’s design and sonic goals. As of September 1997, the Rev (Revolution) series of smaller tunable speakers and the higher-end Chameleon series are made under M.G.'s watchful eye to his design specifications.

Tunable speakers are not intended to be the last word in high-end speakers. They are intended to be the first "loudspeaker-as-musical-instrument". There are small sonic differences between pairs. Just like there are small sonic differences between any two Martin guitars or between any two high quality violins from the same maker. Being able to tune the speaker at home insures the buyer will be able to adapt the speakers to a new room or new components in the system. Tunable speakers made of maple, cherry, mahogany or other woods will not only look different, they will sound a little different, just as musical instruments made from different woods sound different. The main goal for the tunable speakers is for performance that is musical. Drivers are not glued into the cabinet because M.G. finds that the glue causes bad sounding response problems. Instead, drivers are precision fitted to the front baffle. The precision is so great, that glue is not needed as a sealant. M.G. avoids rubber, plastic and other materials he feels cause bad sounding resonances and replaces them with aluminum, brass, mdf or other materials he knows have better resonant signatures. 40 different screws were listened to before deciding on the screws to use to attach the drivers to the front baffle.

Some critics think if you make a speaker tunable, there is no way it will ever sound right once it leaves the factory. M.G.'s reply is... every speaker that is not tunable leaves the factory and sounds different in the owner's listening room because the owner's room and the room at the factory where the speaker was "voiced" are not the same acoustically. M.G. believes that more Rev and Chameleon speakers will sound as he intended them to sound in owners' rooms because the owners can tune the speakers. I wondered how you know when the speaker is tuned correctly. It seems with multiple tuning points (from 2 Tuning Nuts up to 6) on each speaker that knowing when each adjustment was correct would be a big problem. Interestingly, it isn't that hard. During my previous trip, M.G. adjusted a Tuning Nut on a Chameleon speaker while it was playing music. It was quite obvious that the preferred settings were within a narrow adjustment range and once outside of that range, sonics suffered enough to be pretty obvious, but not enough to make the speaker sound really bad.

Anatomy of a Pressure Zone Controller

M.G.'s PZCs take room tuning a significant step farther than original Room Tune products. While the originals still offer good value for the money, PZCs use some things M.G. has learned about room acoustics to make them more effective. For example, there is an area a couple of inches above the surface of each wall and the ceiling and the floor where much of the sound in the room travels. M.G. calls this the laminar region. PZCs work on the principle that if you control the laminar region near the walls, you can control the acoustics of the room. Wall mounted PZCs are built to be a little thick so that their open sides, top and bottom are right there in the laminar region. Floor standing PZCs are thinner because the entire back is "open" and because they are intended to stand away from walls.

To make a PZC you start with a wood frame in the shape of a rectangular box. For example, the 36" tall PZCs are about 5 inches thick and just under a foot wide. Acoustic cloth available in a variety of colors covers the wood frame. Inside this frame there is a little batting, but not too much. A portion of the sound that enters the PZC is absorbed for control but the real work is not the absorption. A bracket inside the PZC holds a Tuning Boss related to those used in the in-wall tuners. A Tuning Board covers the side with the Tuning Boss and this faces towards the room. The Tuning Board is attached to the frame with 4 wood screws. A hole in the center of the Tuning Board allows the body of a Tuning Nut to pass through the Tuning Board into the Tuning Boss. Tightening the Tuning Nut squeezes the Tuning Board against the Tuning Boss. This does not put tension on the board, it just holds the board increasingly tightly against the Tuning Boss which is flush with the back of the board. The tightness of the Tuning Nut controls the response of the PZC as to how the energy collected by the PZC is returned to the room. Tuning boards are available in a variety of materials from natural hard woods to painted mdf. The PZCs I am evaluating have gray cloth covering the frame and solid cherry Tuning Boards with an amazing finish on them. Many other room-friendly combinations of Tuning Board and cloth are available.

Big Rooms – Big Tuning

A short field trip to a completed commercial room treatment project M.G. did was a real eye opener. A church sanctuary was treated with 48" commercial PZCs along the side walls, back wall and in the rear corners (indicated in photo with red triangles). The stage area was constructed like a horn to project sound out into the 600+ seat audience/parish area. This worked so well that without a full audience, the sound of a speaking person was quite loud enough without using a microphone. But when the church is full, sound reinforcement is needed. M.G. did a custom install fabricating tunable sound reinforcement speakers and tunable stage monitors. The PZCs did such a good job of controlling the echo in this square-ish space that it took 15 minutes of walking around for me to fully appreciate just what had happened. If you leave the sanctuary and enter the lobby area outside, you hear one of the worst cases of gymnasium acoustics you have ever. The lobby is constructed like the sanctuary but is about 1/2 the size. Multiple people talking in this lobby space quickly become louder and louder as they try to talk over the long and loud echoes in the space. Return to the sanctuary and the sound is calm, uniform, distinct – completely different and about as ideal as one could imagine. Every seat hears the same spl and the same clarity. It is a stunning achievement.

The field trip’s next stop was a performance hall that was still under construction. Here I could see floor tuners in place, in-wall tuners being installed, construction for the sound reinforcement system, and how the stage was being shaped to give it that horn shape that was so effective in the church sanctuary. At this point the day was nearly over so we headed back towards New Philadelphia. On the way back we talked about how some of the products go from raw materials to finished goods.


One of the topics of conversation on the drive was about some of the outside finishing and skills M.G. makes use of in the production of some of the wood and mdf-based products. Eastern-central Ohio is well known for its Amish population. M.G. has enlisted local Amish woodworking facilities to make the acoustic ceiling moldings and the mdf shelves/platforms for the new Signature series of racks and amplifier Tuning Boards (photo to the left). The Midnight Rose tuning board in the photo benefits not only from the improved production process, but from several man-years of research into finishes. The finish turned out to be one of the keys to getting tuning boards, rack shelves, speakers, instrument tuning platforms, and PZCs to work even better.

As we discussed the new manufacturing process for the shelves/platforms, M.G. began describing computer controlled milling machines and vacuum assisted gluing equipment. I put on the brakes… I thought these were Amish craftsmen. Everybody knows the Amish shun modern technology. Hah! Did I get an earful. There is a small Amish faction that shuns all technology. But the majority use technology selectively. They will use electricity in manufacturing facilities along with computers and all the trappings, but they may not have a telephone connection inside the plant. M.G. said the guy at the plant goes across the street to a pay phone to call him when an order is finished. There are Amish buggies running around with car batteries powering car audio sound systems. The day I was there an Amish speedboat (yes, it had a big gas engine, not a treadmill) was in a parking lot at an installer awaiting a premium sound system. In Amish homes, there may be no connection to electric company power lines but they might have a generator. There may be no connection to cable TV (even though there is a generator-powered TV) but there could well be a satellite dish behind the barn. There may be no connection to telephone lines, but cell phones might be in use. In some Amish homes, technology may not be permitted in the house. In those cases, teens and young men might build a room in the barn for stereo, home theater and computers. My head was righteously turned around with this wealth of previously unsuspected Amish-lore. Anyway, M.G. seems to have mined the local Amish talent for woodworking to help him build better sounding products.

Hi Honey, We're Home!

And so our day in semi-rural Ohio came to an end. It seems incongruous to have such interesting thinking going on so far off the beaten high-end path. Room Tune and Michael Green Designs products can make high-end audio interesting and fun – and best of all, better. You won’t find a more earnest spokesperson for his approaches to high-end sound reproduction. Nor are there many high-end personalities who have had to sell their ideas quite as hard. It's unlikely M.G. will stagnate now - a whole sequence of events is unfolding that are likely to lead to even more unusual approaches to getting better sound. As M.G. would say.. "Stay Tuned."

...Doug Blackburn

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