Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum FAQ - Tuner-Technicians Forum Full perimeter plate

I knew that the Mason BB has a full perimeter plate and I just learned that the model A has switched(when I'm not sure) to one also. I am guessing that the soon to unveiled AA will have one too. What are the advantages/disadvantages of a full perimeter plate? Are there other makes that have full perimeter plates?

My understanding is the more mass in the plate, the more inert it will be, and the less it will be involved with the sound. Supposedly, this will help the energy to stay in the soundboard, improving the sustain. I think it is a similar idea to using a 300 lb piece of granite as a speaker stand. The only disadvantage I can think of, is the dirty looks you get from piano movers when you tell them the piano to be moved is a Mason & Hamlin.
The AA does have a full perimeter plate. I am sure some here will say it is overkill, or unnecesary.

How big is the AA?

Derick

I think these numbers are close Derick.
A: 5'8"
AA: 6'4"
BB: 7'0
CC: 9'2" or 10'6" in white (I'n not sure on the CC, TTTT )

The new AA has already started shipping.

I don't think anyone will be able to move the CC with a full perimeter plate.

Derick

the dreaded double post...

Most tier one pianos do not have a full perimeter plate.
Sure, the full-perimiter plates have lots of sound holes in them, but is less sound getting out of the top of the piano because all that iron is in the way?

Actually *I* don't need any more sound to get out of the top of my BB into my living room, but what about in a concert venue. . . ???

Kenny,

If anything, the sound of the full perimeter plate Masons has a bigger sound, IMHO.

Just a thought - the sound comes out of the top and the bottom at the same time.

As anyone who has ever sat under a piano while it's being played knows! Piano pile-up anyone?

penny

Theres a good picture of the original M&H CC plate at:

http://www.pianomuseum.org/pages/masonhamlin.html

Chickgrand, thanks for the link.

I've seen a CC with a full perimeter plate, made near the end of production. I've seen a Bösendorfer 170 with one, and a later one without.

I have also. Best I can recall, it had a section along the straight side with four large port holes like are seen on the curved side of the CC shown in the link. That website reports the tail of the CC as over 40 inches. By my calculations, it's right at 48 at the back of the tail before the last curves to the back, inner measure and right at 50 outer. Massive.

Any techs, dealers, rebuilders have anything to add to Keith Kerman's reply to my original question?

Wow! Out of curiousity, how does one use two lid props? Is there enough flex in the lid for one person to do it, or does it take two people?

Still looking for more answers. Only one reply to the original question thusfar!

Yes, it would be nice to get a little more feedback regarding this question.

Full perimeter plates are usually heavier. Merits are debatable, and are probably low on the scale of things. I prefer the Bösendorfer with the full perimeter plate, but I couldn't ascribe the difference in the two pianos to that.

The full parameter plate became moderately popular a century or so back. The pianos that continue to use them were pretty much all designed back in the late 1800s or very early 1900s. (The exceptions, of course, are pianos like the new M&H AA. But then, it is designed to look and feel like it had been designed back in the late 1800s or very early 1900s, deliberately recreating a bygone era.)

The benefits to this design are mostly theoretical: the more massive plate casting is supposed to draw less vibrating energy from the strings and it is supposed to stiffen the rim assembly. The first claim is dubious at best. Compared to other metals, gray iron has excellent vibration damping characteristics. That is, it readily absorbs and dissipates (as heat) vibrating energy. I don’t see how adding more iron well away from the active, structural area of the plate is going to alter this. The second represents overkill in the extreme. The well-made grand rim, especially a rim such as that used in the M&H, is already a stiff and massive structure. It is relatively easy to build an acoustically rigid rim assembly. Simply make it out of a suitably dense and stiff material and brace it adequately. Adding a few bolts to couple a full-parameter plate to the rim is not going to appreciably alter its acoustical characteristics. I know of no tests that show any acoustical benefit for the full-parameter plate design.

Having said all this, the only drawbacks to the design that I am aware of are their cost — obviously, more iron is used and they are a bit more difficult to cast and fit to the rim — and their weight. Pianos are difficult enough to move as it is.

Del