Was this speaker intended to be used with the "wonderful original QUAD 1 Acoustical Manufacturing Co power amplifier" shown at [ wonderful original QUAD 1 Acoustical Manufacturing Co power amplifier
]? It's the Model "CR" (Corner Ribbon) loudspeaker, S/N 211, from the "Acoustical Manufacturing Company Ltd" in Huntingdon. According to one source ( http://en.wikipedia.org/wiki/Quad_Electroacoustics
In late 1949 (or early 1950), the company launched the CR corner ribbon loudspeaker. This used a Goodmans Axiom 150 cone loudspeaker for the lower frequencies and an electromagnetic ribbon loudspeaker, designed by Acoustical, for the higher frequencies. Fewer than one thousand units were sold.
And another source adds ( http://www.quadesl.org/index.php/history/quad-history
After the Second World War, Quad had the Quad corner ribbon as its premier loudspeaker. This consisted of some folded electrostatic membranes and moving-coil drivers that (as the name suggests) had to be placed in a corner to get the bass end to work properly. In Peter Walker's (1994) own words, again:
"The ribbon was a hybrid; the ribbon itself was very good from 2000 cycles upwards and the bass unit was very good up to 500 cycles. Not very good in the middle, which I can admit now, but there you are. During the ribbon speaker's life we sold less than a thousand units. It wasn't pairs, it was all mono; there wasn't any stereo then. And they were 95 pounds a time, which in present-day money is quite a lot."
So anybody considering purchase of the amplifier mentioned above may be encouraged to know there are still a few of these floating around, so it's possible to assemble a complete system from that era for display in a collection, museum, etc.
The bass section uses a 12" paper cone driver, the Goodmans Axiom 150. It seems to have a cult following even today. I presume it's an Alnico magnet under the dust cover.
It's mounted in a ported labyrinth. Some kind of damping material, encased in blankets, covers the interior surfaces but doesn't fill the cabinet.
The ribbon tweeter has its own enclosure, with the necessary impedance matching transformer mounted outboard. This particular speaker has a blown ribbon in the ribbon tweeter, but appears to be repairable by somebody with the knowledge and skill in such things.
I haven't worked out the crossover schematic but it appears to be more elaborate than what I expected from a 1950 design.