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Re: 2 source interference



Two points:

Monster cable may actually make the conditions worse -- I don't know why, but some
speakers do poorly if the amplifier's damping is too great (stiff). I've heard the
difference demonstrated by inserting a small amount of resistance in series wit the
speaker; the result was a better "sound." However, for long runs (>ten yards) I've
always used the heaviest zip chord available. This is important if the speakers have a
low impedance and are inefficient. Another factor to consider is capacitive load. Some
amps. are unstable if the capacitance is too great. I've also heard (seen on o'scope)
this demo'd. All of this was with tube amps. though. The early xister amps. used a lot
of feed back and were not fast, which I'd guess would make these matters worse.
(Transistors were a step backwards for hi-fi!) Modern hi-fi amps are tube amps (FET) and
so now the "tube sound" is a myth (they are probably better than tube amps. now), but not
back in the early days! That's why the "Golden Ear" people's claimed that field
recordings with the old tube Revoxes were the best. Both my G36 (tube) and A77 (ca. 1975)
Revoxes are in the garage. I use a Sony 501 (pulse code modulator) and a Sony vcr to do
my recording. I used spaced pair omni's until a B & K engineer suggested that I try
placing them back to back and depend only on the phase diff. for stereo imaging. If the
soloists are not "front and center", I use a very old pair of Electro Voices (667 --
Cardioid) in the same configuration for them). BTW, people find it hard to believe my
results with the $40 Lafayette omni's!

I haven't "ear" tested the wave radio, but I do have, I presume, a similar system, the
Model 88 (H. Kloss the same person, I think, as AR and KLH -- originally). It is
impressive, not only is the tuner very selective and sensitive, but the audio frequency
response and stereo imaging is very good. I don't know how they do it -- the case is only
14' X 8' X 5'. It obviously is ported (one can plug it up to note the difference) and
probably has well designed base boos compensation. Now that it's a year old, and when I
find the time, I'll open it. Furthermore, because the speakers have only a foot
separation, it includes a "wide" function that increases the phase differences to increase
the separation. It's very realistic.

What is "green ink?"


bc


There's a family of Renaissance musical instruments that have an unexpectedly very low
range for their size. They're a wooden cylinder with a tortuous cylindrical bore. The C
-Tenor-Alto instrument (one octave below mid. c) is sl. larger than a Campbell's soup
can. For the tenor, bass, etc. instruments the folding of the hole is necessary for the
finger holes to be played. It's called a Rackett and it's like an Oboe (double reed --
the mouth piece plugs into the middle of one end.) and a Flute (cylindrical not conical).
Perhaps the wave radios have a long path port.


Leigh Palmer wrote:

At 1:53 PM -0700 4/10/00, Michael Edmiston wrote:
After reading John Denker's and Leigh Palmer's responses, I'll back off
partly from what I said about crossovers. I'll back off from my statement
that the phasing through the crossover is important for this experiment.
Yes, if each speaker of a 2-way systems is getting a sine wave, then the
linear combination of the two is also a sine wave, no matter what the
phasing.

However, I still believe getting the phasing correct is very important for
stereo imaging.

Michael was certainly correct in his statement that the crossover network
will introduce an artificial phase shift between the speakers. I didn't
say that he was wrong; I only meant to say that I didn't think that the
phase shift was responsible for the difficulty encountered in getting an
interference pattern.

The business of "time aligned" speaker systems is a bit of a joke given
the unavoidability of such a phase shift. I have a set of speakers that
are staggered in this manner. It occurred to me that staggering might
make a difference in the delivery of sharp transients, but these are
almost completely delivered by the tweeters anyway, so why worry? In the
end I just decided to put this feature in the same bag with other things
physicists don't understand because they understand physics, like "tube
sound", green ink on CD rims, and "Monster" speaker cables.

I am interested, however, in another high fidelity innovation or two. Is
the Wave Radio sold mailorder by Bose really as startlingly good as its
ads say? Are the small speaker systems marketed by the same outfit good
for imaging, Michael?

(For calibration's sake, when you give an opinion, please include also
your opinion of, say, "Monster" speaker cables. I like to use my
religious prejudices as discriminators in these matters, and i really
don't know very much about modern audio equipment - except "Monster"
speaker cables!)

Leigh