On 06/06/2011 01:45, Marc Lavallée wrote:
Le Fri, 03 Jun 2011 10:47:23 +0100,
dw<surso...@dwareing.plus.com> a écrit :
I did a basic experiment with twos subs and a sound generation
software (PureData with the equal_power_pan extension). I panned a
bass sine tone from left to right and back, changing the frequency
between 40Hz and 160Hz. I was able to localize the sine tone at
certain frequencies, depending on my position in the room; at 70Hz
the tone was very easy to localize. So it's definitely possible to
create a sound field with directional bass, intentionally or not.
I suspect you are just modulating the standing wave pattern..
Yes, I was probably just doing that.
Room modes, standing waves, etc. But...
The consumer audio industry stated with authority that bass should just
fill the room, and that that's what sounds good. I was not supposed to
buy a second sub, I was supposed to stick one in some corner and be
happy forever.
One paper caught my attention: "Spatial auditory display using multiple
sub-woofers in two different reverberant reproduction
environments" (easy to google). It studies our ability to localize a
pair of left/right subs and front/back subs, in an anechoic room and a
small domestic room, for frequencies ranging from 40 to 100Hz. In
both rooms, our ability to localize front or back bass tones is very
bad (about 40% accuracy). In a anechoic room we can localize the
left/right bass tone without error. In a domestic room the results are
not as good, but we are still able to localize L/R bass tones down to
80Hz with 80% accuracy. I suppose that the same test in a small room
with bass traps would give better results.
I once asked Fons A. what kind of speakers I should get for Ambisonics
and he replied that full range speakers are mandatory. With my small
room and small budget it was a challenge. It took me a while to figure
how to build lots of bass reflex enclosures for small full-range
drivers, and I was ready to build them. Then I learned that a dedicated
decoder can be used with three subs. Someone mentioned the KEF "Eggs" as
good domestic speakers, and I was lucky to find three sets of
discontinued KEF home theatre speakers at a very good price (with the
smallest "Eggs" and the "Kube-1" sub). The Eggs are excellent. The Kube
doesn't have much bass extension, but it works. So now I am playing
with my new toys, but I'm not ready to install an ambisonics setup (I
need to find a sound card with 16 outputs).
In the meanwhile I am adapting my XTC setup in order to use two
satellites and two subs. I must admit that your filter is my favourite
right now, although I should compare it with the others (RACE, BACCH)
later this summer.
Here is the 'uncut' version, if you would like to compare. I think it
is less suitable for general use, so don't want it to be the offical
distributed version. You seem to be the only one interested. The file
will be removed in a day.
There's a bit more bass coming out of your "uncut" filter, but
there's some cancellation when the bass signal is mono (equal in both
channels). I still prefer when the stereo signal is sent directly to a
pair of subs at +-30 degrees.
Thank you very much for trying it, and your comments. I am a bit
disappointed that you are the only one who has reported listening to the
filters. I did not mean that you were the only one interested in bass
localization.. I plan to get some eggs for myself!
BTW did you try the speakers close up and with a movable baffle between
them? If you don't get a bunch of clapping Irishmen in your garden with
my preprocessed sample, it is not working properly yet..
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