fid writes:
Peter Wieck wrote:
On Nov 12, 6:52 pm, fid wrote:
After I installed a single Rel subwoofer into my system I realized
that it would be in phase with one speaker and not with the other.
What you are writing is that your satellite speakers are out of phase
with each other? Otherwise, how could the SW be out of phase with one-
or-the-other and *not* both?
A couple of questions:
a) Does the SW have an internal crossover such that it does not feed
full-spectrum to the satellites? This would seem pretty obvious, but I
have to ask.
b) Have you tried (temporarily) placing the SW somewhere else and
measuring the results? Perhaps equi-distant and similar attitude
towards both satellites?
You may be getting "cancellation waves" for lack of a better term -
which makes no sense if there is a good crossover in the SW. *IF*
there is a crossover and *IF* it is adjustable, raise the cut-off
frequency to the satellites and see if that does not solve your
problem.
One last problem that is unusual but certainly possible especially in
rooms with hard parallel surfaces. Are you aware of the concept of a
"standing wave"? Try setting your speakers asymetrically about the
room and remeasuring. You may have to try various configurations
before you determine what gives you the best results.
But, keep in mind your initial statement as-written is questionable,
as properly connected speakers will always be in phase with each
other, all things being equal (no deliberate alterations made).
Peter Wieck
Wyncote, PA
first off thank you for your reply.
I must apologize for not being specific in my question. the two main
speakers are full range, five drivers floorstanders, rated to 22hz.
the rel stadium III subwoofer is connected with the typical neutrik
cable. in paralel (high level?), the crossover setting is 22hz, which
is what bugs me... the reason I have the sub is to complement only
the last octave of the sound spectrum.
I still get this strange mid bass suckuout problem in one of the two
speakers whenever the sub is activated and dependently from the phase
setting, 0 or 180, the L or R speakers will be affected.
the mains are in phase with each other. I checked the connections
several times.
unfortunately the system is located in an L shaped living room. one
speaker seats in the corner with the sub behind, and the other
speakeris in the open, meaning that it does not have a side wall and
associated reflections. just the wall behind.
I cannot move speakers around, they are heavy and the living room is
saturated with objects and furniture.
my question is: why the subwoofer appears to be in phase with one
speaker only -while the two mains are in phase with each other? Is
phase problrem directly proportional to the distance between sub and
speakres? I say that because one speaker is definitely closer to the
sub then the other.
however I could easily live with this "problem",
I would like to understand why that happens.
thank you.
also I must apologize for my english.
Mike's point about the crossover slope being 12 dB/octave is very
relevent, although I'm not sure we can conclude that is the slope of the
Stadium IIIs' crossover.
I would also add that this problem is exacerbated if you have the level
of the sub pumped up so that "0 dB" of the sub is higher than "0 dB" of
your mains. Regardless of where your level is now, reducing it is sure
to improve the cnacellation problem, but of course it will reduce the
low bass energy as well.
You mention the furniture and speaker weight problems, but just in case
you've got a conceptual error, ideally all the speakers should be
positioned at the same distance from the listening position. The
distance from the sub to the mains is not what's important - rather, the
difference in distance between sub-to-listener and mains-to-listener.
This difference should ideally be 0.
I see only two alternatives: 1) rearrange things so that the speakers
all lie at the same radius from the listener, or 2) add a crossover
system that will roll off your mains and or your sub (or both) more
agressively.
--
% Randy Yates % "The dreamer, the unwoken fool -
%% Fuquay-Varina, NC % in dreams, no pain will kiss the brow..."
%%% 919-577-9882 %
%%%% % 'Eldorado Overture', *Eldorado*, ELO
http://www.digitalsignallabs.com