On Feb 6, 9:36*am, "Serge Auckland"
wrote:
"David Looser" wrote in message

...

"Karl Uppiano" wrote in message
...

Fortunately, long wavelengths and large excursions are mostly in the low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).

More to the point as far as subwoofers are concerned, the ability of human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where the
subwoofer is in relation to the subs either.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

On Feb 6, 9:36*am, "Serge Auckland"
wrote:
"David Looser" wrote in message

...

"Karl Uppiano" wrote in message
...

Fortunately, long wavelengths and large excursions are mostly in the low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).

More to the point as far as subwoofers are concerned, the ability of human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where the
subwoofer is in relation to the subs either.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

d
--
Pearce Consulting
http://www.pearce.uk.com

In article ,
Don Pearce wrote:
On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

I'vw wondered about this for two reasons. One being the idea implied in
what you say - that the subwoofers may sometimes also radiate audible
amounts of higher frequencies. The other being that perception of LF
directionality might be strongly dependent on the room acoustic, etc..

I find one sub is fine in our living room. But it is a small room, which
makes me wonder if the room reverb might muddle up directional perceptions
at a higher frequency than would be the case in free space or a larger
room. Indeed, I get better directional/imaging behaviour in the hifi room
which is larger. But also more symmetric, so hard to decide what is doing
what! :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Don Pearce" wrote in message
...
On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

On Feb 6, 9:36 am, "Serge Auckland"
wrote:
"David Looser" wrote in message

...

"Karl Uppiano" wrote in message
...

Fortunately, long wavelengths and large excursions are mostly in the
low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).

More to the point as far as subwoofers are concerned, the ability of
human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well
non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where
the
subwoofer is in relation to the subs either.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least
the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

d
--
Pearce Consulting
http://www.pearce.uk.com

My subs (Meridian D1500) are designed to work with the D5000 mains, and have
a 2nd order Butterworth response at 36 Hz. And yet, having one to the side,
it's very obvious where the bass is coming from.

I built a single sub for my son some years ago, and it had to integrate with
a pair of small Missions, which meant a rollover around 70Hz, 2nd order.
That was very noticeable, and disturbing when not between the main
'speakers. Either my room acoustics are peculiar, or I'm particularly
sensitive to bass positioning. Perhaps to make up for my complete
insensitivity to cables, CD players, amplifiers, spikes, cable lifters etc
etc.

S.
--
http://audiopages.googlepages.com

On Fri, 06 Feb 2009 17:51:47 +0000 (GMT), Jim Lesurf
wrote:

In article ,
Don Pearce wrote:
On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

I'vw wondered about this for two reasons. One being the idea implied in
what you say - that the subwoofers may sometimes also radiate audible
amounts of higher frequencies. The other being that perception of LF
directionality might be strongly dependent on the room acoustic, etc..

I think vestigial HF content may be something to do with it. My sub
empties into the room in the corner behind a sofa, which would
suppress any HF quite nicely.. I chose the corner because that deals
most equitably with room modes - and because that was where the
understairs cupboard I used for an enclosure was.

I find one sub is fine in our living room. But it is a small room, which
makes me wonder if the room reverb might muddle up directional perceptions
at a higher frequency than would be the case in free space or a larger
room. Indeed, I get better directional/imaging behaviour in the hifi room
which is larger. But also more symmetric, so hard to decide what is doing
what! :-)

Reverb or modes? I wonder which is the more important for this.

d
--
Pearce Consulting
http://www.pearce.uk.com

In article , "Serge Auckland" wrote:

"Don Pearce" wrote in message
...
On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

On Feb 6, 9:36 am, "Serge Auckland"
wrote:
"David Looser" wrote in message

...

"Karl Uppiano" wrote in message
...

Fortunately, long wavelengths and large excursions are mostly in the
low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).

More to the point as far as subwoofers are concerned, the ability of
human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well
non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where
the
subwoofer is in relation to the subs either.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least
the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

d
--
Pearce Consulting
http://www.pearce.uk.com

My subs (Meridian D1500) are designed to work with the D5000 mains, and have
a 2nd order Butterworth response at 36 Hz. And yet, having one to the side,
it's very obvious where the bass is coming from.

I built a single sub for my son some years ago, and it had to integrate with
a pair of small Missions, which meant a rollover around 70Hz, 2nd order.
That was very noticeable, and disturbing when not between the main
'speakers. Either my room acoustics are peculiar, or I'm particularly
sensitive to bass positioning. Perhaps to make up for my complete
insensitivity to cables, CD players, amplifiers, spikes, cable lifters etc
etc.

I suspect some crossovers having cutoff at some point, but may not
be true at the second and third harmonic, depending how good
the design is. Easy on active crossovers but requiring Zoebles otherwise.
I can sometimes hear spyder noise and of course wind noise.
In general I would prefer using a bandpass box, but you still have to
watch wind noise.

greg

On Fri, 06 Feb 2009 18:53:10 GMT, (GregS)
wrote:

In article , "Serge Auckland" wrote:

"Don Pearce" wrote in message
...
On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

On Feb 6, 9:36 am, "Serge Auckland"
wrote:
"David Looser" wrote in message

...

"Karl Uppiano" wrote in message
...

Fortunately, long wavelengths and large excursions are mostly in the
low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).

More to the point as far as subwoofers are concerned, the ability of
human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well
non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where
the
subwoofer is in relation to the subs either.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least
the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

d
--
Pearce Consulting
http://www.pearce.uk.com

My subs (Meridian D1500) are designed to work with the D5000 mains, and have
a 2nd order Butterworth response at 36 Hz. And yet, having one to the side,
it's very obvious where the bass is coming from.

I built a single sub for my son some years ago, and it had to integrate with
a pair of small Missions, which meant a rollover around 70Hz, 2nd order.
That was very noticeable, and disturbing when not between the main
'speakers. Either my room acoustics are peculiar, or I'm particularly
sensitive to bass positioning. Perhaps to make up for my complete
insensitivity to cables, CD players, amplifiers, spikes, cable lifters etc
etc.

I suspect some crossovers having cutoff at some point, but may not
be true at the second and third harmonic, depending how good
the design is. Easy on active crossovers but requiring Zoebles otherwise.
I can sometimes hear spyder noise and of course wind noise.
In general I would prefer using a bandpass box, but you still have to
watch wind noise.

greg


My sub is IB and over 50 cu. ft., so no wind noise.

d
--
Pearce Consulting
http://www.pearce.uk.com

wrote in message
...
That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

So true, I find it annoying that what we once called simply a woofer, is now
called a "sub woofer" by many manufacturers. Many don't go anywhere near
20Hz, and may go well over 200Hz by design. And many more go there simply
because of inadequate filtering.

MrT.

"Serge Auckland" wrote in message
...
My subs (Meridian D1500) are designed to work with the D5000 mains, and
have
a 2nd order Butterworth response at 36 Hz. And yet, having one to the
side,
it's very obvious where the bass is coming from.

I built a single sub for my son some years ago, and it had to integrate
with
a pair of small Missions, which meant a rollover around 70Hz, 2nd order.
That was very noticeable, and disturbing when not between the main
'speakers. Either my room acoustics are peculiar, or I'm particularly
sensitive to bass positioning.

Nah you really need to use a fourth order network, or greater. Remember you
ear is more sensitive at higher bass frequencies than low bass, so a second
order network may hardly attenuate the higher bass frequencies much at all,
as far as your hearing is concerned anyway.

MrT.

"David Looser" wrote in message
...
"Karl Uppiano" wrote in message
...



Fortunately, long wavelengths and large excursions are mostly in the low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).


More to the point as far as subwoofers are concerned, the ability of human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where the
subwoofer is in relation to the subs either.

But... the physics behind it are related. We don't perceive low frequency
directionality because given the spacing between our ears (as opposed to the
space between our ears) doesn't allow for much phase difference at low
frequencies. Recording setups with widely spaced microphones can produce
artificial phasing artifacts, but it isn't what we normally hear. Blending
to mono at low frequencies for cutting records or driving subwoofers is
relatively benign for all the same reasons.