Aria 5R
An MTM monitor using the Raven 1.0 ribbon tweeter
Basics
The Aria 5R is a kit designed by Joe D'Appolito. It uses a Raven R1 true ribbon tweeter from Orca Design, and two Focal 5K013L mid-woofers. I had been reading the basslist, e-mail DIY loudspeaker mailing list, for a while, and had decided to try to build a speaker with the Raven R1 tweeter, and a pair of similar midwoofers, when the chance came up to buy this kit at a significant discount from the normal price. Since this was my first DIY speaker I decided to go ahead and buy the kit so that I could be reasonably assured of success in my first speaker-building venture.Box Construction
When
building a loudspeaker it is desirable to have all the acoustical energy
radiated in a controlled manner. That means you don't want the sides of
the box to vibrate or ring. There had been several discussions on the
basslist about building acoustically dead enclosures for speakers. I decided
to combine some of what I thought seemed like the best ideas:
Oriented Strand Board (OSB), or wafer board is made up of flakes
of wood with the grain running in random directions through the board.
It also has a lot of air spaces in it. This makes it a very "dead"
material. It is also hard to work with because flakes keep breaking loose.
I built a box with the inside dimensions given in the Aria plan from 1/2"
OSB. Then painted the inside with slightly thinned carpenter's glue to
keep the flakes in place.
Constrained layer damping consists of two "hard" layers
separated by a thin "soft" layer. I used a layer of vinyl floor
tile for the soft constrained layer. After applying the tile to the OSB
box, I sanded through the shiny top layer with a random orbit sander and
coarse sandpaper, so glue would stick to it.
Finally for the outer layer I built a box from 3/4" Medium
Density Fiberboard (MDF). I cut the sides to fit tightly around the floor
tile and glued it on, and glued the joints with polyurethane glue.
The
plans for the Aria 5R call for covering all the inside walls with "Blackhole
5", a multilayer foam and rubber sound deadening and absorption material.
The combination of all of the above resulted in a very dead and very heavy
speaker. Each of these little speakers weighs in at about 55 pounds.
I rounded over the vertical sides of the baffle with a 1" radius
roundover bit in my router. The faces are Walnut burl veneer, and the
sides are plain walnut veneer. I like to use oil finsh, because I prefer
a non-glossy appearance. Oil does an excellant job of bringing out the
grain, without any unnatural plastic appearance. I used these finishing
directions, except I didn't use any wax. With an oil finish I find
its a good idea to keep the finish fresh by wiping down the wood every
few months with a rag lightly moistened with the same oil used
in finishing.
