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Using Adcom GFA-555s as monoblocks to power magnepan 3.3s in active biamp

Yeah, a long title but it says it all.  Presently I have my rebuilt Magnepan 3.3rs actively biamped through a Marchand active crossover, then using 2 stereo amps to power bass and mid/treble respectively.

I am considering taking two Adcom GFA-555s and bridging them and using one each to power the bass panels of the maggies. 

Since the Magnepans are 4 ohm rated, however it's only the bass panels I'd be powering, what are your thoughts on stability?

Appreciate the help.  Don't need suggestions on "selling all my amps and buying one bigger one" - I have a lot of different amp options but am a tinkerer and want to see if the power of a bridged adcom would be good to control the bass panels. 

Ag insider logo xs@2xjji666
invalid
1,073 posts
 

I wouldn't do it, the adcom would be seeing a 2ohm load when bridged, plus if they haven't been serviced your definitely asking for trouble.

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jji666 OP
441 posts
 

Thanks.  You really think they'd see a 2 ohm load with just the bass panels?

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cleeds
5,642 posts
 

The amps should still see a 4 ohm load but if they’re used bridged, they’ll lose power into low impedances. Even unbridged, these amps have trouble with low-z (they do not double power as impedance is halved). Further, distortion rises in a bridged amp. The OP likes to tinker, so I suggest he do just that. But I wouldn’t be optimistic about the outcome.

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jji666 OP
441 posts
 

Thanks again. There are some posts in various forums that it's worked, but just about as many opinion that it won't.  

I guess bridged mode isn't all that useful, given that most of the really power hungry speakers are 4 ohms.  I 'm sure there are exceptions. 

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