In article , Don Pearce
wrote:


OK, got that. Why didn't they think to use a log horizontal scale rather
than that muddle?

I think it is just the standard B&K penchart from the period. They used the
usual B&K sweep generator and associated equipment.

It is the bit over 5kHz that is the problem though. That centre panel is
a fair bit bigger than your average tweeter and will get rather beamy.

Yes. Difficult to avoid that with most ESL designs. Although you can try to
curve the diaphragm like some do, that can add its own problems.

That said, for reasons I give elsewhere, I am not personally worried by
this as I suspect it actually can be used to tweak the imaging to work
better! And in practice although people think of 'treble' reaching to 20k
or more, most of what affects our perception tends to be at much lower
frequencies.

Slainte.

--
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
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Audio Misc http://www.audiomisc.co.uk/index.html

On Sat, 06 Aug 2011 09:52:46 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:


OK, got that. Why didn't they think to use a log horizontal scale rather
than that muddle?

I think it is just the standard B&K penchart from the period. They used the
usual B&K sweep generator and associated equipment.


I used a B&K audio sweep setup myself back in the seventies. It had a
Bowden cable drive between the oscillator and the chart recorder -
which used a stylus on waxed paper. That definitely had a log
frequency scale, though.

It is the bit over 5kHz that is the problem though. That centre panel is
a fair bit bigger than your average tweeter and will get rather beamy.

Yes. Difficult to avoid that with most ESL designs. Although you can try to
curve the diaphragm like some do, that can add its own problems.

That said, for reasons I give elsewhere, I am not personally worried by
this as I suspect it actually can be used to tweak the imaging to work
better! And in practice although people think of 'treble' reaching to 20k
or more, most of what affects our perception tends to be at much lower
frequencies.

Slainte.

In the parlance of the music biz, "air" is about 12kHz, "sparkle" at
6-8kHz. I think air is about the highest you need, mostly.

I can't hear much above the air band anyway (14.5kHz is my limit now)
so I'm not bothered by it either way.

d

On Sat, 06 Aug 2011 09:48:02 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Fri, 05 Aug 2011 21:25:11 +0100, Eiron
wrote:

On 05/08/2011 17:36, Jim Lesurf wrote:

The behaviour breaks down about 5kHz because you are now just using
the central element of the array (the center disc) and so the angles
then fall with frequency in the usual way.

I thought the annuli were fed from a delay line rather than a
crossover....

They are.

Yes. But this line does roll away the HF to the outer rings as well as
introduce delays. This is partly because some power has already been
radiated by inner elements of the array. Also because each coil in the
delay line has an extra 'shorted turn' to act as a resistance. This is a
clever idea as it also cancels the dispersion that otherwise can arise with
loaded lines. The result is to reduce frequency dependence of the time
delays between elements and stabilising the apparent phase center ( 'point
source') Those who understand transmission lines will recognise this as an
interesting application of the Heavyside Criterion which was initially
devised to get transatlantic cables to work correctly back in Victorian
days! :-)

Jim is referring to the fact that the central portion doesn't get any
smaller with rising frequency, and at 5kHz its size is starting to
become appreciable.

Yes.

In principle PJW could have added one or more smaller rings to the center
and ended with a smaller center disc. Then had few more stages on the
transmission line. However I guess he didn't do this for two reasons.

Firstly, my impression from listening is that the beaming above 5k has
little real impact on imaging. Perhaps because the reality is that there
often isn't much up there or it doesn't have much effect on perception once
the region below 5k work well.

Secondly, there is some spreading, partly due to fringe fields, partly due
to the diaphragm material. So the smallest 'spot' you can actually drive
'independently' is limited.

Also, I always find that the 63 design works best when the speakers are
angled to cross in front of me, below my ear height. This makes the image
more stable and less affected by small head movements. I guess this is for
the same reason people use a similar alignment for conventional speakers.
It allows a trade off in the change in time difference and signal amplitude
at the ears at HF so that the effects tend to cancel when you move your
head sideways a little.

So overall, I think PJW got this about right.

But of course, this will depend on the room. listener, and choice of music.
My taste is probably like PJWs. The tradiational 'BBC' sound for classical
music, etc. Indeed, I still prefer Radio 3 to many commercial recordings,
and prefer the sound on the BBC Music Mag discs as well!

Personally, my only hesitations tend to be the way the 63 design exposes
things like 'grainy' or 'scratchy' massed violin playing/recordings and the
lack of heavy bass that may suit some music.

FWIW I have been tentatively feeling that the new 2805s do have a 'drier'
bass than my old 63s. But can't do any direct comparisons, so am not sure
if this is my imagination as yet. So I may start twiddling with
positioning, etc, and maybe even sometime have another try at using a sub
to find out if that can now make an improvement rather than just adding
mud!

Slainte,

Jim

It definitely is possible to add a sub without mud, it just has to be
done right. Mine is a sealed box of about 50 cubic feet (a breeze
block cupboard under a staircase) and a nice 15 inch driver with a low
Fr and plenty of throw. An Adire Tempest, I seem to recall. It sits
right in the corner of the room and rolls away from about 45Hz, so it
does't really fight the main speaker woofers at all. Takes an age to
get the phasing and levels just right, but when they are there, you
really don't notice it unless you turn it off.

d

In article , Don Pearce
wrote:
On Sat, 06 Aug 2011 09:48:02 +0100, Jim Lesurf
wrote:

FWIW I have been tentatively feeling that the new 2805s do have a
'drier' bass than my old 63s. But can't do any direct comparisons, so
am not sure if this is my imagination as yet. So I may start twiddling
with positioning, etc, and maybe even sometime have another try at
using a sub to find out if that can now make an improvement rather
than just adding mud!


It definitely is possible to add a sub without mud, it just has to be
done right.

Agreed. I managed this in the living room, but gave up without success in
the hifi room. However with the change in speakers it may be time to have
another go.

An alternative that tempts me is to try a decent equaliser/correction
system. That might also let me switch on or off some reduction in the
presence region for more 'grainy' recordings. I tend to choose music on the
basis of performance, so often have CDs where I love the music and
performance but can hear imperfections like this.

FWIW I've had the habit of using a (modified) Quad 34 as a control box
beside my listening chair to tweak volume, balance, and also sometimes use
the low-bass boost/shelfdown control. As provided by Quad this was too
'powerful' but I altered some of the components to reduce the amount of
frequency response alteration it gives to being more suitable. Also to get
closer channel matching for the adjustments.

Question is: What decent, flexible, high quality adjustment boxes are there
that would let me do what I want? I don't want one of the multiband
'graphic equalisers' as they may well do more harm than good!

Slainte,

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

In message , Jim Lesurf
writes
Question is: What decent, flexible, high quality adjustment boxes are there
that would let me do what I want? I don't want one of the multiband
'graphic equalisers' as they may well do more harm than good!

Slainte,

Jim


Jim.
Have a look at www.minidsp.com

Very nice bits of kit, with useful software 'plug-in' applications.
--
Chris Morriss

On 06/08/2011 13:19, Jim Lesurf wrote:
In , Don Pearce
wrote:
On Sat, 06 Aug 2011 09:48:02 +0100, Jim
wrote:

FWIW I have been tentatively feeling that the new 2805s do have a
'drier' bass than my old 63s. But can't do any direct comparisons, so
am not sure if this is my imagination as yet. So I may start twiddling
with positioning, etc, and maybe even sometime have another try at
using a sub to find out if that can now make an improvement rather
than just adding mud!


It definitely is possible to add a sub without mud, it just has to be
done right.

Agreed. I managed this in the living room, but gave up without success in
the hifi room. However with the change in speakers it may be time to have
another go.

An alternative that tempts me is to try a decent equaliser/correction
system. That might also let me switch on or off some reduction in the
presence region for more 'grainy' recordings. I tend to choose music on the
basis of performance, so often have CDs where I love the music and
performance but can hear imperfections like this.

FWIW I've had the habit of using a (modified) Quad 34 as a control box
beside my listening chair to tweak volume, balance, and also sometimes use
the low-bass boost/shelfdown control. As provided by Quad this was too
'powerful' but I altered some of the components to reduce the amount of
frequency response alteration it gives to being more suitable. Also to get
closer channel matching for the adjustments.

Question is: What decent, flexible, high quality adjustment boxes are there
that would let me do what I want? I don't want one of the multiband
'graphic equalisers' as they may well do more harm than good!

My idea, before I moved to a smaller house and had to sell my 57s,
was to cross over with 4th order L-R filters to a woofer at about 100Hz.
Something like a Behringer DCX2496 would have been suitable.
With adjustable time delay, it should be possible to get a seamless
integration.
And it just seems better to feed the ESLs through a highpass filter
and avoid driving them at frequencies they can't reproduce.

--
Eiron.

In article , Chris Morriss
wrote:
In message , Jim Lesurf
writes
Question is: What decent, flexible, high quality adjustment boxes are
there that would let me do what I want? I don't want one of the
multiband 'graphic equalisers' as they may well do more harm than good!


Jim. Have a look at www.minidsp.com

Very nice bits of kit, with useful software 'plug-in' applications.

Erm... I've only had a brief look so may well be lacking the full info.
However it looks like:

A) Runs with a 48k sample rate. Not helpful if some of what I'm doing is
listening to 96k files.

B) Windows and Macs get mentioned a lot, but I don't use either of them. I
use Linux and RISC OS.

C) IIUC You have to use the plugin on a computer whenever you want to djust
the dsp action. Again not ideal for me when just playing a CD, or even old
tapes.

I'd either want something that is old-fashioned analogue, or a genuine
'stand alone' box with no need for any 'computer' to control or adjust it,
and with an internal sample rate well above 48k so it would be essentially
transparent for 24/96 material. If digitial it would make more sense if it
could lock onto an input stream at any normal rate/depth and process that.

TBH if I had in mind having a computer running all the time then I'd just
use a DSP plugin I'd write myself to process the output before being sent
to my USB DAC of choice. That way I'd also know exactly what the DSP
process was doing, and how, so would know its flaws or limits. And could do
all the DSP with IEEE double floats if paranoid. 6-]

But a *good* analogue box would be fine.

Slainte,

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

In article ,
Eiron wrote:
And it just seems better to feed the ESLs through a highpass filter
and avoid driving them at frequencies they can't reproduce.

IIRC, they don't get upset by this unlike a moving coil speaker.

--
*Sleep with a photographer and watch things develop

Dave Plowman London SW
To e-mail, change noise into sound.

"Jim Lesurf" wrote in message
...
In article , Chris Morriss
wrote:
In message , Jim Lesurf
writes
Question is: What decent, flexible, high quality adjustment boxes are
there that would let me do what I want? I don't want one of the
multiband 'graphic equalisers' as they may well do more harm than good!


Jim. Have a look at www.minidsp.com

Very nice bits of kit, with useful software 'plug-in' applications.

Erm... I've only had a brief look so may well be lacking the full info.
However it looks like:

A) Runs with a 48k sample rate. Not helpful if some of what I'm doing is
listening to 96k files.

B) Windows and Macs get mentioned a lot, but I don't use either of them. I
use Linux and RISC OS.

C) IIUC You have to use the plugin on a computer whenever you want to
djust
the dsp action. Again not ideal for me when just playing a CD, or even old
tapes.

I'd either want something that is old-fashioned analogue, or a genuine
'stand alone' box with no need for any 'computer' to control or adjust it,
and with an internal sample rate well above 48k so it would be essentially
transparent for 24/96 material. If digitial it would make more sense if it
could lock onto an input stream at any normal rate/depth and process that.

TBH if I had in mind having a computer running all the time then I'd just
use a DSP plugin I'd write myself to process the output before being sent
to my USB DAC of choice. That way I'd also know exactly what the DSP
process was doing, and how, so would know its flaws or limits. And could
do
all the DSP with IEEE double floats if paranoid. 6-]

But a *good* analogue box would be fine.

Slainte,

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, the Behringer DEQ2496 may do what you need. I use one with my Meridian
'speakers to EQ the last few dBs of error in the frequency response above
200Hz. They have both analogue and digital I/O and decent true-peak (I
think) metering. It also has a measuring microphone input if one wants to do
Real-Time frequency analysis. A great box for around £220.

S.

In article , Eiron
wrote:
On 06/08/2011 13:19, Jim Lesurf wrote:


Question is: What decent, flexible, high quality adjustment boxes are
there that would let me do what I want? I don't want one of the
multiband 'graphic equalisers' as they may well do more harm than good!

My idea, before I moved to a smaller house and had to sell my 57s, was
to cross over with 4th order L-R filters to a woofer at about 100Hz.
Something like a Behringer DCX2496 would have been suitable. With
adjustable time delay, it should be possible to get a seamless
integration. And it just seems better to feed the ESLs through a
highpass filter and avoid driving them at frequencies they can't
reproduce.

FWIW I've never experienced any problems with the ESLs coping with LF. Even
when using a lot of the bass 'lift' provided by the Quad 34 as designed.
This nominally adds well over 12dB at LF. But the reality is that I only
add some lift when the source material is *lacking* in LF. Hence the point
of a sub for me would be to make the LF that is inaudible due to the ESL's
loss of sensitivity at LF audible without any such added lift.

Slainte,

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