Magnepan 3.7

Do Ribbons use 'foil'? I would expect the driver portion to be thicker than foil. Maybe .050" or so. No?
Isn't the driver portion of a ribbon under some tension? (pull)

The difference between QR and 'regular' panels is that the QR uses foil. The weight / area is about the same as the wire, but being flat is sticks to the mylar way better.
I, too, think that 'QR' is slightly misleading.

Wesixas, when you say 'all foil diaphragms will have some sort of mylar backing' are you referring to Magnepan style ribbon drivers? They have mylar and a conductor laminated together? Then stretched or at least put under tension?

Is the ringing you refer to out of band hi or lo? Or perhaps just poor damping? The mylar would than make sense.

Magfan, there are three types of drivers Magnapan employ in their speakers. First is the true ribbon tweeter. This has a thin aluminum foil that is suspended on its ends (top and bottom). The magnets flank the tweeter foil so there is nothing to get in the way of the sound front and back of the tweeter foil. Note there is no mylar in tweeter, just aluminum alloy.

The quasi ribbon driver is not a true ribbon driver as defined above. This driver has flat ribbons of aluminum that has been bonded to mylar by glue, and the driver is attached and tension on all four sides, not just the top and bottom as in the true ribbon tweeter. Also, the magnet array is located either on the front or back (or both) of the driver, not on the sides like the true ribbon tweeter. The sound comes out of slots between the magnet array. So the magnet array does get in the way of the sound to some extent. It is still a planar magnetic driver and can be used for tweeter, midrange, and bass applications. The quasi ribbon should be less prone to delamination and is essentially the same as the driver used in Eminent Technology speakers.

The traditional round wire bonded to mylar planar magnetic driver is their oldest technology driver, and has been known to delaminate. It too has magnet array either in front or back (or both) of the driver. It has been used for tweeter, midrange, and bass application as well. But the wire is heavier than the ribbon foil used in the quasi ribbon drivers. Whether wire driver sound better than the quasi ribbon driver is still up to debate if you search the forums. Some feel the wire driver is better for bass application.

Gmorris,

That's interesting and a bit surprising! I think everyone was expecting the 3.7's to use foil in the woofer.

"That's interesting and a bit surprising! I think everyone was expecting the 3.7's to use foil in the woofer."

Yes it is, I thought they would be a full foil/"ribbon" design. I would still like to see an official overview. Magnepan's comments don't really talk about the bass at all just the mid and tweeter.

Hello Magfan,

Maggie is not using a foil backing on their tweeters,they are using corrugation to move/control the resonant freq. Some do it this way, others use damping. IMO corrugation works on the tweeters ( which maggie do ) but have found that damping the foil is much better sonically than corrugation. They use mylar with foil elsewhere and describe the 20.1 as,

"3-Way / Ribbon Tweeter - Planar-Magnetic"

Mylar is necessary if you are running foil traces. On ribbons with more than 1 foil trace, you have to use some kind of backing , mylar is used when this is necessary, if running a straight foil then no mylar backing is necessary unless for sonics.

Extra foil traces are necessary to make the impedance more realistic to the amplfier ( 3 or 4 ohm vs .25ohm) Maggie apparently is running there ribbon direct
(.25ohm) and is then compensating in the xover, 99% of ribbon speakers are built with multiple foil traces and mylar.

IMO direct ( no foil traces) is the best way, a direct ribbon ( my choice also) is the correct approach unfortunately it does not lend itself readily to most amplifiers and efficiency is lost in the xover.

3.6 description:

Description: Three-way, floorstanding, planar dipole loudspeaker. Drive-units: 500-in2 planar-magnetic bass driver, 199-in2 planar-magnetic midrange driver, 0.16" by 55" ribbon tweeter. Crossover frequencies: 200Hz and 1.7kHz. Frequency response: 34Hz-40kHz, ±3dB. Impedance: 4 ohms nominal, constant, resistive (4.7 ohms bass, 4.2 ohms midrange/tweeter, 3.3 ohms tweeter only). Sensitivity: 86dB/2.83V/m. Recommended power: 75-250W.

Making only the tweeter a true ribbon ....