Planar Speaker Asylum

RE: Current Maggies run full range compared to high pass and subs.

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In Reply to: RE: Current Maggies run full range compared to high pass and subs. posted by ColinB on December 28, 2020 at 19:47:17

There's a certain amount of IM distortion "built in" to the speaker because of the mechanical crossover between the drivers. You can see this by exciting the woofer transducer and monitoring voltage on the tweeter transducer. (Or vice-versa....although not nearly as easy to see.)

The "first-order" series crossovers obviously broaden the drive levels to each transducer and "blend" the drivers even further. And the single-ended operation causes more even-order distortion components. These are speakers not without significant distortion. :)

The electro-mechanical nature of these transucers has an inherent 2nd-order roll-off below resonance. Including dipole cancellation you net an approximate 3rd-order roll-off. Thus, I think it's appropriate to add a first-order electrical filter to the power amp drive that matches up (the best you can) with that 3rd-order roll-off point.
You then have a 4th-order acoustic roll-off which can be matched up to a subwoofer low-pass pretty well.
That's my preferred way to operate the smaller Maggies.
Higher-order crossovers are popular too but, to me, it's difficult to blend them correctly.

That said, and all other things being equal, rolling off the bass frequencies to the main panel will reduce all forms of distortion from the speaker....driven at the same nominal SPL level. That's just basic physical limitations at work.

Dave.

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