Why not closed loop speaker amplification?

[Ross Herbert]

On Tue, 07 Jun 2005 12:58:41 -0400, Kalman Rubinson <kr4@nyu.edu>
wrote:

On 7 Jun 2005 09:45:24 -0700, bill.sloman@ieee.org wrote:

It has been done - some years ago Philips used to sell loudspeakers
that worked on this principle. They weren't all that good, probably
because the position of the diaphragm is measured at one point, and the
diaphragm, not being infinitely rigid, distorts under load.

IIRR Philips used an accelerometer mounted on the drive coil as their
"position" sensor.

And it is currently being done on many 'servo' subwoofers.

Kal

Audio Express 9/04 described a 12" Dual Voice Coil Subwoofer system
designed by Daniel L. Ferguson. The second voice coil is used as the
feedback transducer.

 

[Ban]

Ross Herbert wrote:

On Tue, 07 Jun 2005 12:58:41 -0400, Kalman Rubinson <kr4@nyu.edu
wrote:

On 7 Jun 2005 09:45:24 -0700, bill.sloman@ieee.org wrote:

It has been done - some years ago Philips used to sell loudspeakers
that worked on this principle. They weren't all that good, probably
because the position of the diaphragm is measured at one point, and
the diaphragm, not being infinitely rigid, distorts under load.

IIRR Philips used an accelerometer mounted on the drive coil as
their "position" sensor.

And it is currently being done on many 'servo' subwoofers.

Kal

Audio Express 9/04 described a 12" Dual Voice Coil Subwoofer system
designed by Daniel L. Ferguson. The second voice coil is used as the
feedback transducer.

That has been tried a lot, but the mutual coupling between the coils make
this approach pretty much useless.
--
ciao Ban
Bordighera, Italy

 

[Fred Bartoli]

"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...

On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)

Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.


--
Thanks,
Fred.

 

[mike]

Fred Bartoli wrote:

"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...

On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)





Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

Can someone tell me why no-feedback is all that important?

You've got a live performance into a microphone with feedback,
to some recording process with feedback, to some mixing session with
feedback, to some digitizing process with feedback and a bunch of other
nasty sampling things, to a distribution medium, to a CD player that
puts it back to analog. And horror of horrors, older recordings had
TAPE!!!! in the mix.

Worrying about whether the speaker driver has feedback seems
like...well...it seems as insane as worrying about the grain structure
of your silver speaker wires...
mike

 

[Kevin Aylward]

mike wrote:

Fred Bartoli wrote:
"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message
de news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...

On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If
you want real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)





Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.


Can someone tell me why no-feedback is all that important?

It isn't. The writer of that site is completely clueless concerning
amplifier design, and how such designs relates to sound. He's a
technical quack.

Correctly applied feedback is absolutely wonderful. End of story.

Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Jim Thompson]

On Wed, 08 Jun 2005 02:12:09 -0700, mike <spamme0@netscape.net> wrote:

Fred Bartoli wrote:
"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...

On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)





Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.


Can someone tell me why no-feedback is all that important?

You've got a live performance into a microphone with feedback,
to some recording process with feedback, to some mixing session with
feedback, to some digitizing process with feedback and a bunch of other
nasty sampling things, to a distribution medium, to a CD player that
puts it back to analog. And horror of horrors, older recordings had
TAPE!!!! in the mix.

Worrying about whether the speaker driver has feedback seems
like...well...it seems as insane as worrying about the grain structure
of your silver speaker wires...
mike

Aha! "Temporal distortion"... the headache I get listening to
audiophools ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Larkin]

On Wed, 8 Jun 2005 10:20:42 +0200, "Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:

"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...
On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)




Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

The emitter bypasses on the output transistors are hilarious. As is
the claim of 75% efficiency.

And it *does* have feedback!

John

 

[Fred Bartoli]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news:ak1ea1l4q90q2i63dfdif8s39mldp0le5k@4ax.com...

On Wed, 8 Jun 2005 10:20:42 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...
On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you
want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)




Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

The emitter bypasses on the output transistors are hilarious. As is
the claim of 75% efficiency.

Class B is 78%. This is probably a class B Class_A_amplifier.

And it *does* have feedback!

No, it's written : No feedback, even locally. ))

You'd better update your knowledge by reading his white paper (
http://www.royaldevice.com/WhitePaper.htm ) and you'll know where is cutting
edge audio technology today.

If you ask politely, he may grant you the rights to use his no feedback
technology for your NMR amplifiers. Should be interesting


--
Thanks,
Fred.

 

[John Larkin]

On Wed, 8 Jun 2005 19:31:16 +0200, "Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news:ak1ea1l4q90q2i63dfdif8s39mldp0le5k@4ax.com...
On Wed, 8 Jun 2005 10:20:42 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...
On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If you
want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)




Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

The emitter bypasses on the output transistors are hilarious. As is
the claim of 75% efficiency.


Class B is 78%. This is probably a class B Class_A_amplifier.


And it *does* have feedback!


No, it's written : No feedback, even locally. ))

The "blu eyes" output stage sure does have local feedback; just follow
straight down from the first 'e' in "even locally"

You'd better update your knowledge by reading his white paper (
http://www.royaldevice.com/WhitePaper.htm ) and you'll know where is cutting
edge audio technology today.

Gaah: unreadable!

John

 

[Fred Bartoli]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news:e9mea15ch61909an1rl1ena5vqr3m65f9c@4ax.com...

On Wed, 8 Jun 2005 19:31:16 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans
le
message de news:ak1ea1l4q90q2i63dfdif8s39mldp0le5k@4ax.com...
On Wed, 8 Jun 2005 10:20:42 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...
On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If
you
want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)




Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

The emitter bypasses on the output transistors are hilarious. As is
the claim of 75% efficiency.


Class B is 78%. This is probably a class B Class_A_amplifier.


And it *does* have feedback!


No, it's written : No feedback, even locally. ))


The "blu eyes" output stage sure does have local feedback; just follow
straight down from the first 'e' in "even locally"

Sure. I _did_ see that. Was just joking about him.


--
Thanks,
Fred.

 

[John Larkin]

On Wed, 8 Jun 2005 23:24:53 +0200, "Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news:e9mea15ch61909an1rl1ena5vqr3m65f9c@4ax.com...
On Wed, 8 Jun 2005 19:31:16 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans
le
message de news:ak1ea1l4q90q2i63dfdif8s39mldp0le5k@4ax.com...
On Wed, 8 Jun 2005 10:20:42 +0200, "Fred Bartoli"
fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:


"Boris Mohar" <borism_-void-_@sympatico.ca> a écrit dans le message de
news:0rhca1l1u4oafdu78am2a96t1oe9kq2m1d@4ax.com...
On Tue, 07 Jun 2005 17:24:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


You want horns?

http://www.scrounge.org/speak/burwen/

John

You call those horns? That is a whole house heating system. If
you
want
real horns you'll need a shovel

http://www.royaldevice.com/custom.htm (Scroll down)




Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

Hope the horns work better.

The emitter bypasses on the output transistors are hilarious. As is
the claim of 75% efficiency.


Class B is 78%. This is probably a class B Class_A_amplifier.


And it *does* have feedback!


No, it's written : No feedback, even locally. ))


The "blu eyes" output stage sure does have local feedback; just follow
straight down from the first 'e' in "even locally"


Sure. I _did_ see that. Was just joking about him.

Yup, I figured you did. Irony doesn't work well in newsgroups, as I've
discovered.

John

 

[Pooh Bear]

Fred Bartoli wrote:

Did you notice their high end amp schematics?

http://www.royaldevice.com/BEmeasures.htm

What a staggeringly bad amplifier !

I really think I'm in the wrong business sometimes.

Graham

 

[Mike Monett]

Chris Carlen wrote:

Greetings:

My recent experiences with motion control, coupled with an interest in
audio, have led me to the following question:

Why aren't speakers driven closed loop? Ie, have a position sensor on
the speaker diaphragm, and drive the speaker in a servo loop?

I realize this would be challenging particularly for tweaters (which
also don't necessarily exhibit "stiff" diaphragm movement), but the
concept is more of what I am interested in.

Has this been done? It would seem to be the "holy grail" to have the
speaker cones move in lockstep with the signal waveform.

Just pondering.

Good day!

Christopher R. Carlen

I think this is done on shake tables, which can have fair bandwidth.
Whether it would play Bach is another question

Bose uses linear actuators with feedback on all 4 wheels in a new
suspension system they are developing. (Sorry I have no urls handy).

So it should work. Let us know when you make your first million

Mike Monett

 

[Frank Bemelman]

<bill.sloman@ieee.org> schreef in bericht
news:1118162730.230120.327060@g44g2000cwa.googlegroups.com...

Chris Carlen wrote:
Greetings:

My recent experiences with motion control, coupled with an interest in
audio, have led me to the following question:

Why aren't speakers driven closed loop? Ie, have a position sensor on
the speaker diaphragm, and drive the speaker in a servo loop?

I realize this would be challenging particularly for tweaters (which
also don't necessarily exhibit "stiff" diaphragm movement), but the
concept is more of what I am interested in.

Has this been done? It would seem to be the "holy grail" to have the
speaker cones move in lockstep with the signal waveform.

It has been done - some years ago Philips used to sell loudspeakers
that worked on this principle. They weren't all that good, probably
because the position of the diaphragm is measured at one point, and the
diaphragm, not being infinitely rigid, distorts under load.

They were incredibly good, and were capable of delivering an
enormous loud bass without distortion. In 1973 (?) I heard
this speakers for the first time. Of cource it was demonstrated
with a soundtrack containing large timpanis, and it was 2*LOUD*2
and it was incredible. For an extra dramatic effect, the
demonstration was with (thin) curtains in front, that were opened
shortly after an impressive intro of the demonstration.

IIRR Philips used an accelerometer mounted on the drive coil as their
"position" sensor.

http://www.homestead.com/whaan/files/pagemfb.html

Still worth a fortune, in particular the 22RH532 if you can
find someone who wants to sell. I don't think Philips has
sold many, too expensive probably for the average guy.

--
Thanks, Frank.
(remove 'q' and 'invalid' when replying by email)

 

[Arie de Muynck]

"Chris Carlen" <crcarleRemoveThis@BOGUSsandia.gov> schreef in bericht
news:d84gbm01bfc@news2.newsguy.com...

Greetings:

My recent experiences with motion control, coupled with an interest in
audio, have led me to the following question:

Why aren't speakers driven closed loop? Ie, have a position sensor on the
speaker diaphragm, and drive the speaker in a servo loop?

I realize this would be challenging particularly for tweaters (which also
don't necessarily exhibit "stiff" diaphragm movement), but the concept is
more of what I am interested in.

Has this been done? It would seem to be the "holy grail" to have the
speaker cones move in lockstep with the signal waveform.

Search for "Motional Feedback" speakers from Philips (AFAIK used for woofers
only)

Regards,
Arie de Muynck

 

[Dave]

Chris Carlen wrote:

Greetings:

My recent experiences with motion control, coupled with an interest in
audio, have led me to the following question:

Why aren't speakers driven closed loop? Ie, have a position sensor on
the speaker diaphragm, and drive the speaker in a servo loop?

What the point of developing sophisticed electronics to improve sound
quality, when there are enough fools willing to part with their money
with pure hype?

I think this author has hit the nail on the head.

http://www.g8wrb.org/useful-stuff/audiophools.pdf

 

[Jim Thompson]

On Fri, 10 Jun 2005 23:08:29 +0100, Dave <nospam@nowhere.com> wrote:

Chris Carlen wrote:
Greetings:

My recent experiences with motion control, coupled with an interest in
audio, have led me to the following question:

Why aren't speakers driven closed loop? Ie, have a position sensor on
the speaker diaphragm, and drive the speaker in a servo loop?

What the point of developing sophisticed electronics to improve sound
quality, when there are enough fools willing to part with their money
with pure hype?

I think this author has hit the nail on the head.

http://www.g8wrb.org/useful-stuff/audiophools.pdf

Bwahahahahaha! Marvelous!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.