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Join Date: Feb 2010
Location: Monument CO
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Check out the specs on the ML website, Stereophile measurements, or other reviews. Nominal ratings are just that -- most speakers exhibit significant variations from their nominal impedance over their operational frequency range. The ML Aerius speakers are nominal 4 ohms but dip to below 2 ohms at high frequency. This is characteristic of electrostatic panels due to their design. The good news is there are no other low-Z dips I saw in the impedance plots, although they are capacitive over much of their range (of course).
I would also assume the Adcom can handle loads below 4 ohms in normal mode, but not in bridged. A 4-ohm load looks like a 2-ohm load to a bridged amp, and that 2-ohm HF dip the MLs have thus looks like 1 ohm to a bridged amp, and capacitive which can cause stability issues. I have heard the Adcom on low-impedance speakers (Apogees) in the primordial past. It did not fail, but ran very hot and after a little while (do not recall, less than an hour) of moderately loud playing shut down (thermal protection). That was NOT in bridged mode, but was a very low (~1.5 ohm) load.
I do not know if the Adcom would be OK in bridged mode with those ML speakers or not. If it was an 8-ohm speaker I'd say go for it; if 4 ohm I'd be nervous but if the impedance was fairly flat, or at least no large dips, I'd probably try. We obviously have our own opinions but with the MLs I just don't know. I imagine the OP will try and let us know; I suggest he monitors the amps closely at first.
In any event I have had my say and do not feel this debate adds anything significant. It will be interesting to see how the amps work on the MLs (or not).
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley