Re: current amplifiesr for speakers now "degraded"?

"GregS" <zekfrivo@xxxxxxxxxxxxxxxx> wrote in message
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In article <QlEYj.22113$sX5.5434@trnddc02>, "Earl
Kiosterud" <someone@xxxxxxxxxxx> wrote:


"Arny Krueger" <arnyk@xxxxxxxxxx> wrote in message
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"Earl Kiosterud" <someone@xxxxxxxxxxx> wrote in message
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"Arny Krueger" <arnyk@xxxxxxxxxx> wrote in message
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(1) Many speakers are maybe 1/4 as efficient as AR2s

(2) In the old days 95 dB was loud. These days 105 dB
is not all that much
for many people.


10 dB louder is 40 times the power. Do the math: 40
times 20 watts is 800 watts.


For an increase of 10 dB, you need 10 times the power.

Agreed. See point 2 above.

Then see point 1, to see how I got to 40 times.

Hey Arny,

I failed to combine your 1/4 efficiency with your 10 dB
difference. Now I see what you
mean.

1/4 efficiency is a confusing term not normally used in
reference to loudspeakers.
It gives me a headache. I had a pair of 2's for a bit
while, while I was rebuilding them.

Whats the AR3 , about 83 dB ?

That varies. The actual configuration of AR3s varied somewhat over the
rather long life of the model designation. And that's not even talking about
the AR3a which was a little more efficient.

I did some google searching, and found 85 dB/w for the AR3. That of course
depends on frequency. Efficiency decreased with increasing frequency for the
AR3. I had a pair of AR3 woofers. I would put their efficiency at more like
88 dB/w.

I remember a Klipsh add saying something like it takes
500 watts into an AR3 compared to 1 watt for the
Klipshhorn.

500 = + 27 dB.

Another reference put the efficiency of the Klipschorn at 104 dB/w.

104 - 85 = 19 dB.

That equates to about 80 watts for the AR3 as compared to 1 watt for the
Klipschorn.

There are modern speakers running as low as 80 dB/w.

Note that speaker efficiency is one of those specs that is very susceptible
to specsmanship. You can tweak a crossover to give a few dB extra response
at precisely the frequency you rate its efficiency. Efficiency is usually
speced in the midrange either 400 Hz or 1 kHz, which for a 3 way speaker,
may be in the range of the midrange driver, not the woofer. It's easy to
make a midrange driver that is highly efficient. If you make the speaker
sound just a little forward, you have just stepped up the speaker's
specified efficiency, while providing impressive bass extension at the same
old cost in efficiency.




.

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