[Sonnova]

On Sat, 12 Jan 2008 07:58:04 -0800, Arny Krueger wrote
(in article ):

wrote in message


Consumer reports used to test them when they did high
priced speaker systems.

This led to a lengthy lawsuit that Bose eventually lost on first
amendment-related grounds.

The had their usual graphs. You
also have to know how CR tests speakers. They play back
noise while they are rotated 360 degrees. I don't know if
anybody else does this.

Polar response curves are fairly common where loudspeakers are implemented
as technical tools, such as live sound. Lots of loudspeaker development labs
have turntables for rotating speakers while they are being measured.

If you understand this, one can make certain judgments.

Polar response is very important for predicting the performance of a
loudspeaker in a given environment.

The 901's after the series II's
have no internal damping, very BAD.

Not necessarily.

Its easy to add some.

Certainly Bose is not leaving it out to save the big bucks.

The overall response is fairly smooth, with peaking
around 300 Hz, and not much above 12 kHz.

Bose sort of broke ground by applying the theory that one can equalize a
system for flat response below the bass resonance, if the bass drivers have
enough linear excursion. It takes a lot of power, but these days clean power
is relatively cheap.


But that wasn't necessarily true in the late sixties when the 901 was
introduced. In those days, 60 watts/channel was considered a BIG amplifier
and most people had amps in the 25-40 watt/channel region (the Dyna MKIII and
the McIntosh 60/260 being pretty much the top of the power output game).
Transistor amps were just becoming widely available then, and when Dynaco
came out with their ST-120, It was considered a breakthrough in
price/performance for such a big transistor amp*.

*Barely! They were using the output transistors (2n3055s IIRC) at so close
to the ragged edge with respect to Vce, that they had to hand pick the
transistors that they used. I know first hand the rather dubious "pleasures"
of trying to get one's ST-120 up and running again after blowing a channel by
circumventing Dynaco's parts department and buying generic replacement
transistors locally. I'd get the thing put back together, clean the heat -
sink goop off of everything, turn the amp on and listen for an hour, maybe
two hours, and then Bang! Blown again! Trials and tribulations with early SS
amps blowing their output (and often driver) transistors (the H-K Citation 12
had a similar problem) might be the basis of my preference for tubes :-)