Medallion

Jennifer White-Wolf Crock of Jena Labs originally designed the Medallion II cabinet. She has graciously allowed me to post the plans here.

She had designed these with several improvements in order to reduce cabinet induced noises. These changes are described briefly here:

Use thick felt on the back, top, and sides of the compression chamber. Wool felt is the best, and 1/4" thickness is minimum. This both helps prevent midrange information from traveling down the horn, and also keeps sound from bouncing back from the rear baffle back through the cone.

Similar felt should line the top, bottom, and sides of the horn mouth up as far as about 18" from the bottom of the horn mouth. This keeps midrange information which has gone through the horn from interfering with the information radiated directly from the cone.

There should be a 1/4' thick piece attached to the front of the front baffle. It should be cut so that the driver sits flush with the front face of this piece of wood. This wood should be covered with wool felt to absorb sound traveling along the baffle, creating baffle diffraction effects at the edge of the cabinet.

Jennifer also recommend a 47 ohm "swamping" resistor in parallel with the driver to help bass response. This is amp specific, so try it and see if it works.

The plans below were drawn using metric dimensions. If you wish to convert to inches, simply divided the dimension in mm by 25.4 to get inches.

I would like to thank Ms. Crock for allowing these to be posted, and Mr. Cobham for drawing them. Please enjoy:

Medallion Plans Download

A back loaded horn, the Medallion is a direct descendant of the famous Acousta 115. The design allows the driver to direct radiate from 350 Hz. up. Below 350 hz, the rear of the driver "loads" a compression chamber, which then feeds into the throat, or beginning, of the horn. The horn expands the compressed air along its length, ending up at the mouth of the horn where the bass exits. The arrangement allows the driver to work full range, reproducing from 65 Hz up. By using a small, lightweight cone to reproduce the bass, there is no "boom" to the bass, no overhang, and the nuances of the performance are accurately reproduced. If lower bass is required, placing these into a corner will allow bass reproduction to 40 Hz.

Shown on the right is the Medallion II. Commonly used with the PM2A, it works very well with all 8" Alnico drivers except the PM4A, and all of the 8" DX series of drivers. Minor modification of the compression chamber is all that is required to run the various drivers optimally.

The space below the horn mouth is there to keep floor bounce from adversely affecting the bass quality. This space has been used to insert a subwoofer, extending the system to full range.

On the left is the Medallion III+. The Medallion III is meant to be used only with the 8" DX series of drivers. The III+ adds a ribbon tweeter to get that last bit of "sparkle" in the highs. Since this photograph, a Tonian Labs tweeter has been used with greater dynamic effect.

Medallions are no longer available for purchase. The plans have been published, and demand no longer warrants us manufacturing them.