Room 'deadness' for audio playback.

In message , Woody
writes
"Jim Lesurf" wrote in message
...
In article , Woody

wrote:
I once attended a talk given by Cliff Collinson who worked for
Harold
Leak for many years then moved on to Wharfedale before ending
up
working for Peter Walker at Quad where I think he had
something to do
with the design of the 33/303.

He told us how they tested speakers at Wharfedale. Unable to
afford an
anechoic chamber of their own or to hire one they came up with
an
effective solution. They dug a large hole in the lawn
surrounding the
factory and lay the speaker cabinet on its back in the hole.
They then
suspended an expensive mic above it in the open air and did
their
frequency sweeps. He recollected that the neighbours
complained at
first but got used to it after a time, especially when they
dug the
hole deeper and less sound escaped 'sideways.'

What you describe may be a useful way of testing loudspeaker
*units* as it
avoids problems with resonances in the box material. Although
you'd have to
take any pressure effects from behind it into account.

But it wouldn't necessarily be a very good way to test how
complete
assembly of units in their cabinet would behave in a room.
Particularly if
the unit was some way down a hole. That way it has to drive an
acoustic
line rather than open air. And one that has an acoustic
impedance
discontinuity at the top.

Better may be the way I think people did it later. Raise the
speaker well
up into the air and use the open space to avoid reflections
from nearby
objects. Alternatively, lay the speaker flat on its back and
have the mic
well clear above. Then treat the ground as an ideal wall behind
the
speaker. Fine for speakers designed to work near a wall, but
for others,
better to raise it a suitable distance from the ground.



Remember JIm that most speakers made by Wharfedale in the 70's
and early 80's were infinite baffle or had an ABR so I would have
thought that lying them in a hole and sending the sound skyward
would have been better than nothing?

It begs the question where is Wharfedale now..................


Still near Wensleydale, Swaledale and Nidderdale. :¬)
--
Ian

On Wednesday, 27 November 2013 20:46:36 UTC, wrote:
Hello all,



Are there any guidelines for this? I have noticed that I MUCH prefer the sound of my lounge when the two sets of curtains are drawn. There is much less echo - or not quite echo but perhaps reverberation? (I don't really know much about this sort of stuff) and the TV and stereo sound much better.



I did a quick search of the internet but all I could really find were somewhat technical discussions about the quality of recording rooms which I didn't quite understand - probably the result of some sort of BBC left-wing bias, I'm sure you'll all agree.



I got thinking about recording rooms and saw this photo of an Abbey Road studio:



http://www.guy-farley.com/sessions_landoftheblind.jpg



which seems to be a hollowed-out house (I have never been there, just seen photo's) which has big spaces for recording. So would this room sound dead? If the space is larger, surely sound behaves like light in that the further away from the point source, the weaker the power level, and therefore the weaker any resulting reflections will be.



I really hope someone can imagine what I am trying to describe here!



Thanks in advance,



David Paste.

On Thursday, 28 November 2013 09:53:57 UTC, Jim Lesurf wrote:

FWIW I did something on room acoustics some time ago at

http://www.audiomisc.co.uk/HFN/RoomF...rors/rfom.html


Thanks Jim, a lot for me to digest there!

On Thursday, 28 November 2013 11:02:08 UTC, Bill Wright wrote:
You've had Jim's erudite reply, now here's my daft one. As a teenager I

was a bit obsessed with hi-fi and I decided that my bedroom was too

resonant. I scrounged as many egg boxes as I could and glued them to the

walls over a period of years.

An eggstraordinary eggsample of what you can do with a found resource.

I remember a Lenny Henry character from the 80s or early 90s who ran a radio station from an eggbox covered room.

On Thursday, 28 November 2013 13:31:19 UTC, Johny B Good wrote:

It's worth noting the advice given to DiY 'speaker builders' that
when such damping material is used within the cabinet of an "Infinite
Baffle" loudspeaker enclosure, the optimum arrangement is to hang a
'curtain' of the material attached to a diagonal line in the top panel
with a twist to allow it to be attached to the other diagonal on the
bottom panel.


Like this?

https://lh6.googleusercontent.com/-8...nalDamping.jpg

On Fri, 29 Nov 2013 11:58:17 -0800 (PST), wrote:

On Thursday, 28 November 2013 13:31:19 UTC, Johny B Good wrote:

It's worth noting the advice given to DiY 'speaker builders' that
when such damping material is used within the cabinet of an "Infinite
Baffle" loudspeaker enclosure, the optimum arrangement is to hang a
'curtain' of the material attached to a diagonal line in the top panel
with a twist to allow it to be attached to the other diagonal on the
bottom panel.


Like this?

https://lh6.googleusercontent.com/-8...nalDamping.jpg

Exactly so!
--
Regards, J B Good

On Friday, 29 November 2013 20:31:07 UTC, Johny B Good wrote:

Exactly so!


Ha! Cheers!

In article , Woody
scribeth thus
"Jim Lesurf" wrote in message
...
In article , Woody

wrote:
I once attended a talk given by Cliff Collinson who worked for
Harold
Leak for many years then moved on to Wharfedale before ending
up
working for Peter Walker at Quad where I think he had
something to do
with the design of the 33/303.

He told us how they tested speakers at Wharfedale. Unable to
afford an
anechoic chamber of their own or to hire one they came up with
an
effective solution. They dug a large hole in the lawn
surrounding the
factory and lay the speaker cabinet on its back in the hole.
They then
suspended an expensive mic above it in the open air and did
their
frequency sweeps. He recollected that the neighbours
complained at
first but got used to it after a time, especially when they
dug the
hole deeper and less sound escaped 'sideways.'

What you describe may be a useful way of testing loudspeaker
*units* as it
avoids problems with resonances in the box material. Although
you'd have to
take any pressure effects from behind it into account.

But it wouldn't necessarily be a very good way to test how
complete
assembly of units in their cabinet would behave in a room.
Particularly if
the unit was some way down a hole. That way it has to drive an
acoustic
line rather than open air. And one that has an acoustic
impedance
discontinuity at the top.

Better may be the way I think people did it later. Raise the
speaker well
up into the air and use the open space to avoid reflections
from nearby
objects. Alternatively, lay the speaker flat on its back and
have the mic
well clear above. Then treat the ground as an ideal wall behind
the
speaker. Fine for speakers designed to work near a wall, but
for others,
better to raise it a suitable distance from the ground.



Remember JIm that most speakers made by Wharfedale in the 70's
and early 80's were infinite baffle or had an ABR so I would have
thought that lying them in a hole and sending the sound skyward
would have been better than nothing?

It begs the question where is Wharfedale now..................



In china like most everything audio;!..


On speaker testing..

I remember once seeing a pair of ESL63's being tested for matching, a
Square wave was fed in anti phase to each speaker and the result was
shown on a scope via a rather expensive B&K microphone most impressive I
bet a moving coil speaker couldn't match it!...


--
Tony Sayer

In article , tony sayer


I remember once seeing a pair of ESL63's being tested for matching, a
Square wave was fed in anti phase to each speaker and the result was
shown on a scope via a rather expensive B&K microphone most impressive I
bet a moving coil speaker couldn't match it!...

Yes. I also saw that. Most speakers wouldn't have come anywhere near as
close to generating a square pulse in the first place. And are often far
more poorly pair-matched.

In our living room I use a pair ESLs for the AV. A few DVDs of old films
have sound that is supposed to me mono but is antiphased. This is almost
inaudible in the normal listening position unless you offset the balance.
Partly due to the close speaker matching. Partly due to the directional
behaviour of the speakers.

Jim

--
Please use the address on the audiomisc page 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

Jim Lesurf wrote:
In article , tony sayer


I remember once seeing a pair of ESL63's being tested for matching,
a Square wave was fed in anti phase to each speaker and the result
was shown on a scope via a rather expensive B&K microphone most
impressive I bet a moving coil speaker couldn't match it!...

Yes. I also saw that. Most speakers wouldn't have come anywhere near
as close to generating a square pulse in the first place. And are
often far more poorly pair-matched.

In our living room I use a pair ESLs for the AV. A few DVDs of old
films have sound that is supposed to me mono but is antiphased. This
is almost inaudible in the normal listening position unless you
offset the balance. Partly due to the close speaker matching. Partly
due to the directional behaviour of the speakers.

I recall you thought some quad recordings sounded phasey in some thread
or other.

Having recently got some old Nimbus CDs I was wondering if you had any,
and if so, does the uhj encoding sound phasey like the quad on your setup?