In article , Andy Evans
wrote:
A couple of things about Maggies - they were my system speakers for a
few years. First, you don't need mega power amps unless you have a big
room - I used to listen to mine in a smallish room with a 10wpc valve
amp (Leak Stereo 20). People will tell you 100 watts, 200 watts etc -
that's 'american talk' - people with huge rooms. Second, people will
tell you solid state only, but many of us were happy with valves, and so
might you be if that's your taste. For a valve amp, the Maggies were
quite easy to drive - I used the 4 ohms setting on my OPT. good luck -
Andy
I would want to know the impedance-frequency properties of the 'Maggies' to
be sure. However I'd agree with the above in general terms *provided* the
user is in a situation (e.g. small room as Andy says) where the required
mean and peak output sound levels are modest, *and* the amp is chosen to
be appropriate for the specific situation/use.
The first snag is the 'logarithmic' nature of perception of sound level.
Ignoring factors like current limiting, a 200W amp would nominally give
levels only 6dB above a 50W amp. i.e. about the same as two or three
steps on the volume control of the 34 preamp. For some people the
405 might be fine with the magneplanars, but for others it would not,
and this is a matter of personal taste, in terms of kind of music,
how loud the listener wants it to be, as well as the size of the room.
The second snag is that some amps may share a nominal power rating, but
differ a great deal in how much current they can deliver into low
impedance loads.
Take, as an example, the literal implications of the '405' (40V 5A). This
implies if taken literally that into a 4 Ohm load you can only get 4x5 =
20V. i.e. 6dB down on what the same amp can deliver into a high impedance
speaker. This is an area where the 'Mk2' version is at an advantage as it
does not current limit to the same extent. Yet the nominal power ratings of
the early and later 405's are the same.
I would, therefore, be cautious of completely dismissing what some people say
as 'American talk' w.r.t. driving magneplanar speakers. The problem here is
not the power rating as such. It is in knowing the specifics of the actual
use, and the limits of the particular amp.
This is why magazines like HFN tend to state the peak current a power amp
can deliver when they list review results. With low impedance speakers this
may matter for loud musical peaks.
For the 405 to be able to deliver 40V into a 4 Ohm load, it would have to
provide 10A. (i.e. a power of 400W). This may simply not be needed in
your case, though, as you may not actually ever play music at the levels
this would provide.
I can't recall details, but my impression is that some magneplanar speakers
have impedances that fall below 4 Ohms, so may be 'difficult' loads for
some power amps.
I would, however, personally agree with the view that 'planar' speakers
like these and ESL's are capable of superb results, and may be well worth
the extra effort of finding a suitable amp, and the 'inconvenience' of the
speaker placement requirements.
Slainte,
Jim
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