Bass response of Electrostatic loudspeakers
 

I wonder if anyone knows how Electrostatic loudspeakers can have any sort of
bass response.

An ESL is a doublet that radiates equally front and back. With a normal cone
loudspeaker on a finite baffle, the bass starts to roll off at a frequency
whose quarter-wavelength corresponds to the smallest dimension of the
baffle. Looking at the dimensions of, for example, the ESL63, the bass
should start rolling off below about 320Hz, but in fact is maintained down
to a -6dB point of 34Hz.

How is this possible? Is there some extreme EQ built-in to the ESL63 which I
am unaware of, or does the physics work in a different way for a panel
driven over its entire width or what?

Similarly, other electrostatics have small dimensions, yet can go fairly
deep in the bass, even those ultimately assisted by cone woofers.

I have Roger Sander's Electrostatic Cookbook, but he doesn't make clear how
ESL's bass response is maintained, except to use an external woofer or
savage EQ. His graphs for the response of an ESL panel shows the output
dropping from mid-frequencies, then a resonance rise at quite low
frequencies. It doesn't explain how to fill in the upper-bass/lower mid hole
except with extreme EQ. In the QUAD ELSs, I wasn't aware of any EQ.


Thanks

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

Bass response of Electrostatic loudspeakers
 

"Serge Auckland

I wonder if anyone knows how Electrostatic loudspeakers can have any sort
of bass response.

An ESL is a doublet that radiates equally front and back. With a normal
cone loudspeaker on a finite baffle, the bass starts to roll off at a
frequency whose quarter-wavelength corresponds to the smallest dimension
of the baffle. Looking at the dimensions of, for example, the ESL63, the
bass should start rolling off below about 320Hz,

** Huh ???????????????

The width of an ESL 63 is circa 1 metre.

A wave of 4 metres has a frequency of 80 Hz.


but in fact is maintained down to a -6dB point of 34Hz.


** It really does too.

Cos it is taller than 1 metre and there is little back to front sound
transfer - a huge SPL null exists all round at 90 degrees to the central
axis.


How is this possible?

** You cannot do math - or much else, can you.

BTW:

There are many examples of modest sized speakers which radiate back and
front and yet have quite good bass output.

Ever seen a combo guitar amplifier ????

Most have open back cabinets with 2 or maybe 4 x 12inch speakers fitted
neatly inside - so are less than 1 metre square. Output is well
maintained to at least 80 Hz and is still strong at 60 Hz. Been testing them
with sine generators most of my life.

Also, the famous Wharfedale SFB-3 open back 3-way speaker of 1956:

http://www.troelsgravesen.dk/Wharfed...iles/SFB-3.pdf

Pre-dates the Quad ESL57.

Response down to 35 Hz is claimed.

Magic ??



...... Phil

Bass response of Electrostatic loudspeakers
 

Phil Allison wrote:
"Serge Auckland

I wonder if anyone knows how Electrostatic loudspeakers can have any sort
of bass response.

An ESL is a doublet that radiates equally front and back. With a normal
cone loudspeaker on a finite baffle, the bass starts to roll off at a
frequency whose quarter-wavelength corresponds to the smallest dimension
of the baffle. Looking at the dimensions of, for example, the ESL63, the
bass should start rolling off below about 320Hz,


** Huh ???????????????

The width of an ESL 63 is circa 1 metre.

A wave of 4 metres has a frequency of 80 Hz.



but in fact is maintained down to a -6dB point of 34Hz.



** It really does too.

Cos it is taller than 1 metre and there is little back to front sound
transfer - a huge SPL null exists all round at 90 degrees to the central
axis.



How is this possible?


** You cannot do math - or much else, can you.

BTW:

There are many examples of modest sized speakers which radiate back and
front and yet have quite good bass output.

Ever seen a combo guitar amplifier ????

Most have open back cabinets with 2 or maybe 4 x 12inch speakers fitted
neatly inside - so are less than 1 metre square. Output is well
maintained to at least 80 Hz and is still strong at 60 Hz. Been testing them
with sine generators most of my life.

Also, the famous Wharfedale SFB-3 open back 3-way speaker of 1956:

http://www.troelsgravesen.dk/Wharfed...iles/SFB-3.pdf

Pre-dates the Quad ESL57.

Response down to 35 Hz is claimed.

Magic ??



Yep, look out for the books Gilbert Briggs wrote about loudspeaker
design. Also in the case of the SFB-3 (and for that matter my own open
baffle speakers) the tapered side panels also increase the front/back
length.

--
Nick

Bass response of Electrostatic loudspeakers
 

"Nick Gorham" wrote in message
...
Phil Allison wrote:
"Serge Auckland

I wonder if anyone knows how Electrostatic loudspeakers can have any sort
of bass response.

An ESL is a doublet that radiates equally front and back. With a normal
cone loudspeaker on a finite baffle, the bass starts to roll off at a
frequency whose quarter-wavelength corresponds to the smallest dimension
of the baffle. Looking at the dimensions of, for example, the ESL63, the
bass should start rolling off below about 320Hz,


** Huh ???????????????

The width of an ESL 63 is circa 1 metre.

A wave of 4 metres has a frequency of 80 Hz.



but in fact is maintained down to a -6dB point of 34Hz.



** It really does too.

Cos it is taller than 1 metre and there is little back to front sound
transfer - a huge SPL null exists all round at 90 degrees to the
central axis.



How is this possible?


** You cannot do math - or much else, can you.

BTW:

There are many examples of modest sized speakers which radiate back and
front and yet have quite good bass output.

Ever seen a combo guitar amplifier ????

Most have open back cabinets with 2 or maybe 4 x 12inch speakers fitted
neatly inside - so are less than 1 metre square. Output is well
maintained to at least 80 Hz and is still strong at 60 Hz. Been testing
them with sine generators most of my life.

Also, the famous Wharfedale SFB-3 open back 3-way speaker of 1956:

http://www.troelsgravesen.dk/Wharfed...iles/SFB-3.pdf

Pre-dates the Quad ESL57.

Response down to 35 Hz is claimed.

Magic ??



Yep, look out for the books Gilbert Briggs wrote about loudspeaker design.
Also in the case of the SFB-3 (and for that matter my own open baffle
speakers) the tapered side panels also increase the front/back length.

--
Nick

The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a frequency
of 130Hz (I mistakenly multiplied by 2, not 4 in my original post, my
apologies.) So, I would expect the ELS63 to have a reducing bass output
below 130 Hz. Why doesn't it? What about other ELS loudspeakers, like the
Dutch Audiostatic that were about 30cm wide, and yet had a decent bass
response. What about the Magneplanar MG3, which were not electrostatic, but
nevertheless doublets, and had excellent bass response.

What am I missing?

S.


--
http://audiopages.googlepages.com

Bass response of Electrostatic loudspeakers
 

"Serge Auckland"
"Nick Gorham"
Phil Allison wrote:

I wonder if anyone knows how Electrostatic loudspeakers can have any
sort of bass response.

An ESL is a doublet that radiates equally front and back. With a normal
cone loudspeaker on a finite baffle, the bass starts to roll off at a
frequency whose quarter-wavelength corresponds to the smallest dimension
of the baffle. Looking at the dimensions of, for example, the ESL63, the
bass should start rolling off below about 320Hz,


** Huh ???????????????

The width of an ESL 63 is circa 1 metre.

A wave of 4 metres has a frequency of 80 Hz.


but in fact is maintained down to a -6dB point of 34Hz.


** It really does too.

Cos it is taller than 1 metre and there is little back to front sound
transfer - a huge SPL null exists all round at 90 degrees to the
central axis.



How is this possible?


** You cannot do math - or much else, can you.

BTW:

There are many examples of modest sized speakers which radiate back and
front and yet have quite good bass output.

Ever seen a combo guitar amplifier ????

Most have open back cabinets with 2 or maybe 4 x 12inch speakers fitted
neatly inside - so are less than 1 metre square. Output is well
maintained to at least 80 Hz and is still strong at 60 Hz. Been testing
them with sine generators most of my life.

Also, the famous Wharfedale SFB-3 open back 3-way speaker of 1956:

http://www.troelsgravesen.dk/Wharfed...iles/SFB-3.pdf

Pre-dates the Quad ESL57.

Response down to 35 Hz is claimed.

Magic ??



Yep, look out for the books Gilbert Briggs wrote about loudspeaker
design. Also in the case of the SFB-3 (and for that matter my own open
baffle speakers) the tapered side panels also increase the front/back
length.

--
Nick

The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a
frequency of 130Hz (I mistakenly multiplied by 2, not 4 in my original
post, my apologies.)

** This is simply not true either.


So, I would expect the ELS63 to have a reducing bass output below 130 Hz.
Why doesn't it?


** Your original assertion is 100% WRONG.

Go look up the *actual LF behaviour* of speakers mounted on flat rectangular
baffles.

Allow that a baffle COVERED in similar bass speakers has deeper LF response
than when only one is sited in the middle.

You really are a clueless turd.



...... Phil

Bass response of Electrostatic loudspeakers
 

In article ,
Serge Auckland wrote:
The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a
frequency of 130Hz (I mistakenly multiplied by 2, not 4 in my original
post, my apologies.) So, I would expect the ELS63 to have a reducing
bass output below 130 Hz. Why doesn't it?

Aren't they figure of eight DP - so no output on one axis?

--
*The most common name in the world is Mohammed *

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

Bass response of Electrostatic loudspeakers
 

In article , Serge Auckland
wrote:


The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a
frequency of 130Hz (I mistakenly multiplied by 2, not 4 in my original
post, my apologies.) So, I would expect the ELS63 to have a reducing
bass output below 130 Hz. Why doesn't it?

What am I missing?

Note that the 'piston mass' for an ESL is tiny compared with a dynamic
speaker unit. This means that when you apply a drive voltage to the plates
of an ESL you generate a pressure differential between the front and back
surfaces of the diaphragm. At LF some air can easily whoosh around from
front to back. But this simply allows the diaphragm to move more quickly in
response to the applied E-field, and so maintains the same pressure
difference between front and back.

The effect is to allow the speaker to maintain the ability to generate the
same sound pressures for a given applied field as you lower the frequency.
This can't be perfect, of course, as away from the local soundfield region
you will get cancellation effects. But what you may be missing is that the
relationship between the air (radiation) and mass impedances for the ESL
are unlike those for the conventional dynamic unit.

The real problem is that the diaphragm excursions become too large if you
want high sound pressures at LF

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

Bass response of Electrostatic loudspeakers
 

Serge Auckland wrote:

"Nick Gorham" wrote in message
...

Phil Allison wrote:

"Serge Auckland

I wonder if anyone knows how Electrostatic loudspeakers can have any
sort of bass response.

An ESL is a doublet that radiates equally front and back. With a
normal cone loudspeaker on a finite baffle, the bass starts to roll
off at a frequency whose quarter-wavelength corresponds to the
smallest dimension of the baffle. Looking at the dimensions of, for
example, the ESL63, the bass should start rolling off below about
320Hz,



** Huh ???????????????

The width of an ESL 63 is circa 1 metre.

A wave of 4 metres has a frequency of 80 Hz.



but in fact is maintained down to a -6dB point of 34Hz.




** It really does too.

Cos it is taller than 1 metre and there is little back to front sound
transfer - a huge SPL null exists all round at 90 degrees to the
central axis.



How is this possible?



** You cannot do math - or much else, can you.

BTW:

There are many examples of modest sized speakers which radiate back
and front and yet have quite good bass output.

Ever seen a combo guitar amplifier ????

Most have open back cabinets with 2 or maybe 4 x 12inch speakers
fitted neatly inside - so are less than 1 metre square. Output is
well maintained to at least 80 Hz and is still strong at 60 Hz. Been
testing them with sine generators most of my life.

Also, the famous Wharfedale SFB-3 open back 3-way speaker of 1956:

http://www.troelsgravesen.dk/Wharfed...iles/SFB-3.pdf

Pre-dates the Quad ESL57.

Response down to 35 Hz is claimed.

Magic ??



Yep, look out for the books Gilbert Briggs wrote about loudspeaker
design. Also in the case of the SFB-3 (and for that matter my own open
baffle speakers) the tapered side panels also increase the front/back
length.

--
Nick


The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a
frequency of 130Hz (I mistakenly multiplied by 2, not 4 in my original
post, my apologies.) So, I would expect the ELS63 to have a reducing
bass output below 130 Hz. Why doesn't it? What about other ELS
loudspeakers, like the Dutch Audiostatic that were about 30cm wide, and
yet had a decent bass response. What about the Magneplanar MG3, which
were not electrostatic, but nevertheless doublets, and had excellent
bass response.

What am I missing?

S.



I think yopu have to take both path lengths into account. Also you need
to consider that as the baffle bass response drops off, thats when the
room gain starts to kick in.

As it happens, Septembres HiFi world has a article on the SFB-3 with
some measurements. They find that the bass starts to roll off at about
100-120hz if you discount the effect of the room.

If you can't find a copy let me know and I will try and scan it in.

My OBs use a 15% base unit, the front panel is aprox 20" * 48" with
tapering sides that are 24" deep at the base up to zero at the top. They
measure flat (ish) down to about 40hz in room, when the bass starts to
fall away at about 6dB/Octave

--
Nick

Bass response of Electrostatic loudspeakers
 

Nick Gorham wrote:

I think yopu have to take both path lengths into account. Also you need
to consider that as the baffle bass response drops off, thats when the
room gain starts to kick in.


Does room gain work with an ESL?

--
Eiron.

Bass response of Electrostatic loudspeakers
 

Eiron wrote:

Nick Gorham wrote:

I think yopu have to take both path lengths into account. Also you
need to consider that as the baffle bass response drops off, thats
when the room gain starts to kick in.



Does room gain work with an ESL?


AFAIK, though it excites a null.

BTW, I am not claming to know that much about this stuff, I have some
speakers I am happy with, though they are effectivly cardioid in their
bass response due to the side panels, but that was intentional as they
have to live in my small listening room.

--
Nick

Bass response of Electrostatic loudspeakers
 

"Serge Auckland" wrote in
message

I wonder if anyone knows how Electrostatic loudspeakers
can have any sort of bass response.

The most severe problem would probably not be the E/S design, it would be
the common use of open backs.

The back sides of loudspeakers are commonly enclosed to prevent the wave
created by the back side of the driver from radiating around to the front,
and cancelling the wave created by the front side of the speaker. Since low
frequencies aren't very directional, there's a very good chance of this
happening.

I don't know about the basic bass resonances of common E/S drivers, but the
smaller ones are likely to have fairly high bass resonances, which also
restricts their bass response.

Building a large E/S driver with a low bass resonance, supporting acoustic
response down to say 20-40 Hz, shouldn't be a problem.

Finally, the bass response of the matching transformer needs to be
considered.