At 10:41 PM 5/24/02 -0400, you wrote:
>If you want good bass, haunt Ebay for some of the better 15" systems
>made in the 70's. And don't ever turn the volume way up on them. Don't
>worry, even at nice low volumes you will get plenty bass and they will
>put out more sound energy than anyone who values their ears should be
>listening to. Crank one of the modern amps designed to coax some sound
>out of the stiff stuff of today and all you will get is fuzz floating
>around the room and maybe the smell of frying voice coil.
Ah, the elusive bass.
Ever looked at the impedance curve from a speaker as you raise the
frequency? Very interesting. Of course it depends a lot on what box it is
in, etc.
My dad designed folded horn enclosures from about 1953 to 1960, all for his
own amusement, a la Paul Klipsch. He would typically use a good (heavy
magnet) 8" speaker facing the room at the top of the box, then a very small
rear chamber and throat (about 5 sq. inches in area). From that throat, he
used wood and metal to expand the cross-sectional area to double exactly
every "X" inches of travel through the horn, from a formula he
had. Essentially it was an acoustic cross-over network. The highs came
from the front, and the lows from the folded horn in the back. It worked
best flat on the floor, so the bottom member of the horn was flat to the
room floor.
The patterns he came up with were amazing. We had one very solid box about
4 ft wide and three high, where the entire opening was for the lows, minus
the square at the top containing the front sound for the highs. The
crossover frequency depended, if I remember correctly, on "X" and the rear
throat area. The mechanical cross-over principle rather reminds me of how
a violin works, with its sound peg and asymmetrical bridge and box.
Now, I still use a pair of Acoustic Research AR-3s in my living room
(serial nos. 59399 and 405), @ 4 ohms. It was fun to go in their showroom
in Harvard Square and watch their demo, mid-sixties. They had removed the
speaker cloth from an AR-3, and fed it 1 Hz sine wave. The cone moved
"soundlessly" in and out, as if it was breathing, through about an inch of
travel. The key, here, is soundlessly = linear. They work very poorly for
some 50's rock music, because they utterly lack the huge resonance peak of
a juke-box, so every thud came out as a thud, not a boom, as in bars.
At AR, switching the HP Audio Oscillator (it was HP's only product in the
early sixties) from sine to square wave was a spectacular experience at the
same voltage level. Two loud pistol shots per second. We didn't leave it
at that setting very long! But no dust, no fuzz, no frying.
With AR-3, as you visually compared their cones to all previous attempts,
by Electrovoice, Altec Lansing, Harmon-Kardon, etc you could see why it was
so good - lots of compliance at the cone edge, with the cone very stiff and
an air-cusion behind it providing very linear and resilient bounce forces.
In the early 50's, I had been spoiled by our livingroom wall mounted (the
vestibule was the infinite baffle - all those hats, coats, etc) a Warfdale
12" speaker; it must have weighed about 20 lbs! I used to magnetize
needles on the external magnet, for floating cork compasses. A whole bunch
of Gausses.
For my computers recently, I have gone to Acoustimass (sp?) Bose systems,
and they sound pretty good, too, especially for the weight. I will soon
try Rich's file out on them. . .. thanks, Rich.
my very best,
Marty Michener
MIST Software Associates
75 Hannah Drive, Hollis, NH 03049
coming soon : EnjoyBirds bird identification software.
________________________________________________________________________
________________________________________________________________________
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|