On 28/01/14 10:51, John Williamson wrote:
On 28/01/2014 10:24, Chris J Dixon wrote:
John Williamson wrote:

On 27/01/2014 16:41, Chris J Dixon wrote:
I boxed up an L-pad
http://cpc.farnell.com/_/lp-200-8/speaker-l-pad-stereo/dp/LS00544?Ntt=LS00544

and installed it a while ago, but it doesn't really seem to have
sufficient adjustment.

I find that odd, as if it's wired correctly, an L-pad should give an
adjustment range from 0- 100% of full power.

Well, AFAUK I have done it right, but I suppose that is a bit of
a circular argument. ;-)

Indeed. Obviously, you'd not deliberately or knowingly do it
incorrectly. :-)

Another alternative would be to install a 100 volt speaker system with
independent volume controls in each room, but that would mean buying a
new amplifier,and some matching transformers and volume controls.

So, significant expense, compare with my proposal which you
snipped. Just for the record, what would its advantages be?

Completely independent control of levels on all speakers. Only one
amplifier to go wrong, and 100 volt line amplifiers tend to be designed
and built to last for ever even when abused. The downside is that the
transformers can degrade the sound quality slightly, which may obviously
be an issue.


as can ANY form of passive attenuation to a loudspeaker designed to be
driven from a 0.1 ohm source. 100V line or not.

100V line is merely a way to transmit audio POWER over long distances
using less than arm sized cabling.

The fact that it is in general more robust is not inherent in the
100V-ness of it, but more because such systems tend to be deployed out
doors or in large buildings where the integrity of cabling and its
immunity from lightning strikes or induced surges or shorts cannot be
guaranteed, and into professional applications where a lack of
robustness is not tolerable either.

A better way in domestic situations is to deploy active loudspeakers fed
from e.g a 1V line source, preferably balanced 600 ohm., and possibly
with power being fed to them via the wires, and then attenuate that and
feed it to a local low output impedance amplifier.

In short pretty much what a pair of 'computer speakers' already does.


--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.