Keith G wrote:
"Serge Auckland" wrote in message
...
Keith G wrote:


IOW, is a pair of subs a possible complication that might be best *not*
bothered with....??




Should work wonderfully well using one of your 4W SETs............



Well, on my *8W* SET/InFidelios the results are astounding - 'listening' by
leaning my head back against the (drywall partition) wall, the bass from
Bjork's 'Headphones' without the sub rattles my head anyway. With the sub
though, it is not really bearable for long and quite queasy but there is
some 'wuffa wuffa wuffa' roll-off after a seriously deep bit!

Interestingly, the bass with the sub doesn't actually really sound any
deeper than the speakers on their own, only *feels* it...!!

More, much more, to do yet - mebbe even some recording comparisons....


Seriously, in your room, a single sub should be more than ample.


Sure, I don't think I could stand more than the one!!


As to
phasing, I really don't understand the point of a variable phase control.
0 & 180 switched should be provided to phase up the sub with the mains
(which hopefully will be in phase with each other), but apart from that, I
can't see it's possible to match the phase of the main LF, as it will be
frequency dependant. As you suggest, with two subs, trying to get the
phase right would be a nightmare.


I've twiddled it back and forth and can't say it makes a lot of difference
anyway and it ends up back at 0 deg!


Other controls needed are a crossover frequency selector and a level
control. Ideally, if the main speakers are small (say don't go below 70Hz)
then the extreme bass should be rolled-off to the mains considerably
improving their power handling and lowering distortion.


Not sure I understood that....??


If the main 'speakers are small, they won't reproduce deep bass. Feeding
them with deep bass from the power amp will only serve to stress the
bass unit suspension and heat up the voice coil without actually
producing any sound. It is therefore better to limit the bass drive to
small speakers so that they are only given what they can deal with. It
is actually much better if the bass reduction can be done *before* the
power amplifier so that the PA isn't being asked to generate unusable
volts. This way, the power amp driving the small 'speakers will be able
to generate more volts that the 'speakers *can* handle, and so
effectively produce a higher output.

For my son's Christmas present some years ago, I built him a subwoofer
system consisting of an electronic filter removing bass below a preset
frequency, a mono combiner and filter providing a balanced output to a
single subwoofer. The filter frequencies were selectable as was levels
to the subwoofer. The main 'speakers (small Missions) were connected to
the L&R output of a Quad 303 and were driven from 70Hz upwards. 70Hz
downwards was monoed to a balanced output driving a 100wpc AIWA power
amp in bridge mode into the subwoofer which was a large bass-reflex box
tuned to 20Hz. It was most successful, and saw him through his
University days and afterwards, not always to the pleasure of his
neighbours however....

S.