No, You Cannot Bi-Amp

I ran my Maggie IIIas with an Audio Research D400 for years, then bought another D400 and used the XO1 passive crossover but quickly got myself a Marchand electronic crossover which cross to a pair of subs below 50hz then uses same slopes as Magnepan suggests bass to mid/high

To my ears the difference was pretty significant and and I haven't been a teenager for decades (sorry just being flip)

I thought one advantage was the quality of the crossover itself and limiting the bandwith each amp must produce

Supposed to audition the 3.7s in a couple weeks so will find out 1st hand what they sound like "out of the box".

Audio Research says that the D400s will drive the low impedence load presented by bridging the amps and driving Maggies so can use both amps still but again my ears will be the judge

I doubt I will pull the trigger until I can hear the 20.7 and check out some other models at the Capital Audi Fest this summer but "once you go Maggie you seldom/never go back" :-)

MikeH

Mike, I have to agree with you. I bi-amped my Apogee Duetta Signatures using a pair of totally rebuit and upgraded Threshold Stasis 2 amps and a highly upgraded/highly-modified Marchand XM-9 electronic crossover a few year ago and have never looked back. The upgrade to bi-amping was the most major improvement that I ever made to this system and I've made more than a few.

Is bi-amping a simple solution for the person who just wants to power-up the system a take a listen and not think about the details? No, not at all.

As many know, when you bi-amp a system, in most cases, you totally by-pass the existing passive crossover in your speakers. Now that your amps are connected directly to each driver - with no capacitor in series to block DC - you now need to be concerned about your power-amps' DC offset. Too much DC offset and you will cook your more delicate drivers over time - even with no music playing. Woofers and bass panels can absorb a good amount of DC without damage. Even some ribbon MRTs can survive 200mVDC without damage over time; however, most anything over 50mVDC will move the driver's diaphragm or ribbon away from its "home" position which negatively impacts the driver's design performance. Employing amps with a low DC-offset and the regular use of a multi-meter is a must with a bi-amped system.

Now, once you decide to bi-amp, not only will you need to be concerned about finding the correct crossover point, you will need to be attentive to the slope of the existing passive crossover which you will be bypassing verses the slope of the electronic crossover. If the slope is different, you may need to invert the phasing of your mid and/or tweeter drivers in order to have correct overall phasing. A lot of information about crossover slope phasing is available with a search on the Internet. At least this is a one time thing.

Anyway, what I’m saying is in addition to the added cost, is that bi-amping is not for everyone for the reasons stated above. Bi-amping does improve amp-to-driver efficiency through the elimination of the speaker's power-consuming internal passive-crossover system.

Somehow, I get the impression that some folks think bi-amping is like bi-wiring but with two amps and some sort of "Y" cable, but nothing could be further from the truth.

Bi-amping takes some effort to make sure everything is properly set up and requires some maintenance attention in order to make sure that your mid/tweeters doesn't become toast!

BTW, my guess is that Magnepan made a business decision as to not allowing bi-amping of the 20.7. Maybe to reduce ribbon warranty claims?

This thread makes me appreciate the coherent design of the Linn Aktiv system. Amps, active crossovers and speakers all designed by the same company, made specifically to work with each other. I can tell you that my Linn Katans sound a heck of a lot better in Aktiv mode (Linn active crossovers placed into my Linn amps) than they did in passive mode or passively bi-amped mode with the exact same amps.

What about bi-wiring by removing the midrange short plug?