"Chris J Dixon" wrote in message
...
Serge Auckland wrote:
"Chris J Dixon" wrote
My amplifier has two outputs. One is switched, and used for the
speakers in the living room. The other is taken via a separate
switch box to speakers in the dining room and kitchen.
Originally, the relative sound levels in all three rooms were
reasonably matched. However, during a kitchen refit, I had to
get rid of the conventional speakers, and fitted a pair of small
KEF in-ceiling units. These have a rather lower output level. If
I deselect the dining room pair, the kitchen is well enough
matched to the living room.
As a least cost work-around, it strikes me that I might be able
to improve the situation by inserting series resistors in the
feed to the dining room. Would this work? Living in a semi, I
don't run at particularly high sound levels.
If the dining room application is for background music during meals, then
it
should work fine by attenuating the 'speakers relative to the others.
Unless
you know how many dBs you need to attenuate, and can then calculate the
series resistance value,
It is hard to say exactly, my ear isn't calibrated ;-)
I reckon that if I picked a figure out of thin air, then bought
two resistors for each speaker totaling that figure, ( say 1R &
2R2) by experimenting with using them singly or series/ parallel,
I would get quite a range.
If I wanted, for example, 3 dB attenuation, what resistor would
you calculate?
Chris
--
Chris J Dixon Nottingham UK
Have dancing shoes, will ceilidh.
For a 3dB attenuation on an 8 ohm 'speaker you need a series resistance of
3.27 ohms. For 6 dB you need 8 ohms. But note that this assumes a nominal 8
ohm load, and loudspeakers are not pure 8 ohm loads. Also, by putting such a
series resistance in the loudspeaker lead you will change the frequency
response of the loudspeaker considerably. However, as this seems to be for
background music rather than critical listening, it will probably be
perfectly acceptable. I suggest you use 10 watt resistors. Alternatively
again, a 20 ohm 10 watt wire wound pot wired in series will allow you to
make adjustments.
S.
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