Driver to drive?

[MK]

On 02/02/2013 04:12, Phil Allison wrote:

"Uncle Steve"
Phil Allison wrote:

"Uncle Steve"

( snip appalling load of drivel )

Comments and constructive criticism is welcome.

** You are making a fundamental error.

NFB loops ( in audio amplifiers) compare only the INPUT and OUTPUT
signals -
so the output *replicates* the input signal at a greater magnitude.

You must know that inductive loads are different from resistive loads.
How do you account for that difference?

This cannot and does not correct for non-linearities or other flaws in
the
load.

All I am suggesting is that speaker efficiency is a player in NFB amp
systems. Totally hypothetical, but you've not said anything that
would invaldiate the hypothesis.

** You are clearly a demented half wit.

Fuck off.



.... Phil


Sometimes I think Phil's responses are over the top, but not this time !

MK

 

[John Walliker]

On Feb 2, 2:14 am, Uncle Steve <stevet...@gmail.com> wrote:

Speakers are an inductive load, AFAIK,

Only at some frequencies. The electro-mechanical interaction that
you mention causes a single drive unit to be inductive below the
resonant frequency, resistive at resonance and capacitive above
resonance. At much higher frequencies it looks more resistive
and may become inductive again.

When several drive units are combined with a crossover things
get more complicated with multiple changes between inductive
and capacitive impedance.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected.  I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

There is some delay through the amplifier, but so long as the input
bandwidth is limited to something sensible the signal is changing
slowly enough for this not to cause any problems.

If you feed a very sharp edge into a badly designed feedback amplifier
there can be momentary distortion which might be audible.
However, in a well designed amplifer there will be a passive input
low-pass filter to smooth off such signals and prevent this effect.
The fashion for specifying bandwidths that are only audible to bats
can make things worse than tailoring audio equipment to what is
actually audible to humans.

Don't believe everything in "the literature".

John

 

[mook johnson]

On 2/2/2013 4:47 AM, MrTallyman wrote:

On Sat, 2 Feb 2013 14:30:16 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:


"Uncle Steve"

( snip appalling load of drivel )

Comments and constructive criticism is welcome.

** You are making a fundamental error.

NFB loops ( in audio amplifiers) compare only the INPUT and OUTPUT signals -
so the output *replicates* the input signal at a greater magnitude.

This cannot and does not correct for non-linearities or other flaws in the
load.



... Phil


Yep, and any such corrections would take place AFTER the distortion
event already occurred as well. That would make it worse, IMO.
This whole concept is a fucking joke.
It is like a Doctor attacking the symptom instead of the root problem.

Or a asshole who covers his mouth *after* or *as* he sneezes.

This has been argued forever to the Nth degree. Its like religion and
politics one side will never correct the other.

As a builder of loudspeakers for 20+ years I know that the drivers are
all characterized (acoustic output vs frequency) with a "VOLTAGE
SOURCE". Not a power source, not a current source.

NFB make the audio amp act more like a voltage source than a current or
power source since dynamic load currents are not allowed to change the
shape of the waveform.

I have seen and heard various concoctions of amp with no feedback (open
loop), local feedback only in the stages but no global feedback.

All produced distortion on the output that was substantially higher than
a well designed NFB audio amp.

Some liked the sound of the no feedback amps just like the Tube guys
like the sound of 1% distortion if it contains mostly even harmonics.

The speaker impedance in not totally inductive but very complex with the
average "impedance" at the stated 8 ohms. between 20 and 20Khz it goes
inductive, resistive and capacitive over and over again. For a 8 ohm
speaker the impedance can be as high as 100+ ohms and as low a 5-6 ohms
over the acoustic range.

In my opinion it is these impedance peeks and valleys that make people
believe certain speaker wires "sound" better than others. The speaker
wire impedance in series with the speaker impedance makes a sort of
equalizer that they happen to like.

As a speaker designer we take some steps to tame the nasty resonances in
impedance to make a smoother ride for the amp but not overly so.

Its all about faithful reproduction of the voltage signal generated by
the microphone in the studio. Anything you add to that is "WRONG" even
if you prefer this sound to the correct answer.

However, From a marketing perspective Bose makes a lot of money selling
the WRONG answer.....technically correct or not..make with the customer
likes.

 

[Dennis]

On 1/02/2013 10:40 PM, Michael A. Terrell wrote:

Dennis wrote:

On 1/02/2013 2:30 AM, Michael A. Terrell wrote:

Spehro Pefhany wrote:

On Thu, 31 Jan 2013 16:53:54 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:


"Paul Hovnanian P.E."

TO-92 package

markings:

"650"
"B24"

** Two legs or three?


... Phil


Three legs good, two legs better.


Have you ever sat on a two legged stool?


If my stools had legs I'd be off to the doctor very quickly.


You'd have to walk. You'd never be able to sit in your car. ;-)

Mmmm, I'd have to call a locum.

 

[Uncle Steve]

On Sat, Feb 02, 2013 at 02:47:54AM -0800, MrTallyman wrote:

On Sat, 2 Feb 2013 14:30:16 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:


"Uncle Steve"

( snip appalling load of drivel )

Comments and constructive criticism is welcome.

** You are making a fundamental error.

NFB loops ( in audio amplifiers) compare only the INPUT and OUTPUT signals -
so the output *replicates* the input signal at a greater magnitude.

This cannot and does not correct for non-linearities or other flaws in the
load.



... Phil

I'm not an idiot, but I can treat you like one if that's what you
prefer.

Yep, and any such corrections would take place AFTER the distortion
event already occurred as well. That would make it worse, IMO.

Actually, the distortion (or at least as much as can be compensated by
the NFB loop) never occurs.

This whole concept is a fucking joke.

I agree that it is really funny that people can't understand simple
concepts like feedback. If only I'd known as a kid I'd have studied
control theory and had the entire field virtually to myself.

It is like a Doctor attacking the symptom instead of the root problem.

Or a asshole who covers his mouth *after* or *as* he sneezes.

Don't worry, I'm not saying that my $150.00 amp is equal to audiophool
equipment. Now if you'll excuse me I have to go build some pylons so
I can get the speaker-wire off the floor. I hope Brazilian mahogany
will do as it's all I have on hand.



Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[John Larkin]

On Fri, 01 Feb 2013 21:14:21 -0500, Uncle Steve <stevet810@gmail.com> wrote:

Recently, I had the experience of re-manufacturing the tweeters in a
pair of speakers I had bought. Due to a "senior moment", I fried the
tweeters in a pair of Quadral Chromium Style 50 speakers, and
the local dealer decided to fuck me over even though I admitted the
mistake and paid for replacements. Why they decided to screw with me
is another story, no doubt involving elements of the RCMP who would
prefer not to be named. At any rate, I was left with a pair of
drivers with unequal efficiency, and it annoyed the living snot out of
me.

So I decided to take the two broken tweeters and rehabilitate them.
If you look into the Quadral speaker line, you will discover that the
tweeters use a filament suspended between two powerful magnets in
series with a 5.1 ohm resister. The filament is apparently a piece of
aluminum coated with a thin layer of titanium, or something to that
effect. My replacement is somewhat thinner, and required the
manufacture of unique tooling to shape.

The result has less mass and consequently improved the sensitivity of
the driver, with obvious implications to the resultant sound quality.

My amplifier is an Onkyo M282, which is apparently an amplifier that
uses negative feedback, and made in Japan. On the Web, there are a
number of articles which articulate the controversy over NFB amp
designs, with numerous manufacturers shunning the technique for
various reasons. None of the descriptions or reviews take into
account the most important factor in an audio system -- the
interaction of the speakers with the amplifier.

I believe I have achieved such good results primarily because I
reduced the "mass" of the tweeter, which in combination with the
amplifier design, has helped produce a superior sound. The key to
understanding the thinking behind this is the interaction of the
amplifier with the speakers.

Speakers are an inductive load, AFAIK, which means they present some
of the same problems as electric motors in the design of driver
circuitry. In the instance of an audio signal, the drivers have a
hysteresis contingent upon their ability to accelerate in the presence
of a electrical impetus. In my nascent understanding of electronic
circuits, this resistance to movement will interfere with the
amplifier output in the same way a naive power supply will drop-out
under load.

The negative feedback circuitry in the amplifier will detect this
drop-out and drive its input harder as a result, thereby reducing
perceived distortion.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected. I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

It is worth noting that distortion at the amplifier output is a result
of two sources: firstly there is the distortion introduced by the gain
stages in the amplifier, and secondly, distortion introduced by the
mass of the drivers, which interact with the magnets and impose an
inductive signal on the amplifier output. In either case, the
negative feedback circuitry should nearly instantaneously apply a
corrective factor to the input signal which will effectively coerce
the drivers to conform to the shape of the input signal -- if the NFB
circuitry is not too weak or slow.

My suspicion is that by reducing the mass of the tweeters in my
system, I have relieved a burden from the NFB circuitry in the Onkyo
M282, and thereby improved the resultant sound quality by an order of
magnitude or so.

The apparent controversy over the effectiveness of NFB amp designs
seems to ignore the amplifier-speaker relationship, and the role it
plays in fidelity. An ideal speaker would have no electric mass, and
would therefore have zero influence (or load, I guess) on the
amplifier, and would obviously reproduce the amplifier signal
perfectly. Loudspeakers must necessarily have mass, if only
represented by the air they displace, and will therefore affect the
amplifier by virtue of inductance. Consequently it is my feeling that
negative feedback amplifier designs represent a good solution to the
practical problem of signal reproduction.

In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal. Even ambient noise in the listening
environment might affect the negative feedback circuitry.

Perhaps obviously, I have no test equipment to use to measure the
effects or phenomenon that is at issue. Just my common sense. But
if you were here, you would be able to attest to the fidelity of the
ultimate result.

Comments and constructive criticism is welcome.


Regards,

Uncle Steve

Audio is such nonsense.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[Uncle Steve]

On Sat, Feb 02, 2013 at 08:50:37AM -0600, mook johnson wrote:

On 2/2/2013 4:47 AM, MrTallyman wrote:
On Sat, 2 Feb 2013 14:30:16 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:


"Uncle Steve"

( snip appalling load of drivel )

Comments and constructive criticism is welcome.

** You are making a fundamental error.

NFB loops ( in audio amplifiers) compare only the INPUT and OUTPUT
signals -
so the output *replicates* the input signal at a greater magnitude.

This cannot and does not correct for non-linearities or other flaws in the
load.



... Phil


Yep, and any such corrections would take place AFTER the distortion
event already occurred as well. That would make it worse, IMO.
This whole concept is a fucking joke.
It is like a Doctor attacking the symptom instead of the root problem.

Or a asshole who covers his mouth *after* or *as* he sneezes.



This has been argued forever to the Nth degree. Its like religion and
politics one side will never correct the other.

I agree. It seems that some people are wedded to particular designs.
A really good amplifier without NFB is probably a neat challenge for
the designer, but the whole point of NFB is that it makes the job
easier. (I use 'easier' advisedly as I'm speaking of the concept of
negative feedback generally).

As a builder of loudspeakers for 20+ years I know that the drivers are
all characterized (acoustic output vs frequency) with a "VOLTAGE
SOURCE". Not a power source, not a current source.

NFB make the audio amp act more like a voltage source than a current or
power source since dynamic load currents are not allowed to change the
shape of the waveform.

I have seen and heard various concoctions of amp with no feedback (open
loop), local feedback only in the stages but no global feedback.

All produced distortion on the output that was substantially higher than
a well designed NFB audio amp.

Some liked the sound of the no feedback amps just like the Tube guys
like the sound of 1% distortion if it contains mostly even harmonics.

I suppose the point there is that the human ear doesn't care much if
the distorted waveform is similar to the original. RF entering the
speaker-cables and going down the feedback path to the input is
something else entirely.

The speaker impedance in not totally inductive but very complex with the
average "impedance" at the stated 8 ohms. between 20 and 20Khz it goes
inductive, resistive and capacitive over and over again. For a 8 ohm
speaker the impedance can be as high as 100+ ohms and as low a 5-6 ohms
over the acoustic range.

I almost understand what you are saying. I've not quite wrapped my
head around the concept of impedance, impedance matching or why it is
so important.

In my opinion it is these impedance peeks and valleys that make people
believe certain speaker wires "sound" better than others. The speaker
wire impedance in series with the speaker impedance makes a sort of
equalizer that they happen to like.

As a speaker designer we take some steps to tame the nasty resonances in
impedance to make a smoother ride for the amp but not overly so.

Its all about faithful reproduction of the voltage signal generated by
the microphone in the studio. Anything you add to that is "WRONG" even
if you prefer this sound to the correct answer.

Many years ago I was happy with a small stereo system that had quite
decent sound. Used it for years and years. More recently I have
heard the real difference that accurate reproduction makes, and now
nearly all my mp3s are just so much digital litter, and I no longer
have the records they were made from. Replacing that lot is going to
be rather expensive.

However, From a marketing perspective Bose makes a lot of money selling
the WRONG answer.....technically correct or not..make with the customer
likes.

The other side of the coin is the use-case scenario. I can't
concentrate on much other than the music if the stereo is playing
something richly detail. If someone wants music to fill a room
without overwhelming them, then the Bose crap is going to be more
appropriate than an expensive system. But if the difference is in the
basic _availability_ of quality stereo components, the trend towards
mp3 player docking stations and crap source material from iTunes is a
step backwards. Lots of kids today have no clue what good sound is.

It seems that the audio electronics industry has no Moore's Law
equivalent which would see the price for accurate sound reproduction
converge on some reasonable ideal value as the design of amplifier
electronics matured and stabilized. You'd think that after fifty
years or so the best way to amplify audio frequency signals and drive
speakers would be well established and inexpensive integrated
components would be mass produced by the likes of Motorola, NS, and
TI. To be fair, the digital domain is easier to work with because
it's all software. Even the hardware is software if you consider all
the microcode and VHDL. And shrinking feature size is easier than
reimplementing a technology from first principles.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sat, Feb 02, 2013 at 12:39:01PM +0800, Bruce Varley wrote:

"Uncle Steve" <stevet810@gmail.com> wrote in message
news:4d4f9fba73d6b43-04af3@gmail.com...
In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal.

Talk to your hifi supplier, he'll give you an objective assessment.

I bet he will. Right after he's finished telling me all about the
dangers of DC current coming out of my amp. I'm going to be needing
another one as I appear to have broken him.

Even ambient noise in the listening
environment might affect the negative feedback circuitry.

FGS

I'm pretty sure God doesn't have anything to do with it.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sat, Feb 02, 2013 at 08:58:28PM +1300, Gib Bogle wrote:

On 2/02/2013 3:14 p.m., Uncle Steve wrote:
a NFB amp will perform better if the speakers it drives are more expensive
than
another

This common misperception makes the hifi scam business profitable.

When I've properly broken in my new drivers I'll make a youtube video
so you can hear the results for yourself. No need to thank me, it
will be a public service.



Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[George Herold]

On Feb 2, 10:28 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 01 Feb 2013 21:14:21 -0500, Uncle Steve <stevet...@gmail.com> wrote:
Recently, I had the experience of re-manufacturing the tweeters in a
pair of speakers I had bought.  Due to a "senior moment", I fried the
tweeters in a pair of Quadral Chromium Style 50 speakers, and
the local dealer decided to fuck me over even though I admitted the
mistake and paid for replacements.  Why they decided to screw with me
is another story, no doubt involving elements of the RCMP who would
prefer not to be named.  At any rate, I was left with a pair of
drivers with unequal efficiency, and it annoyed the living snot out of
me.

So I decided to take the two broken tweeters and rehabilitate them.
If you look into the Quadral speaker line, you will discover that the
tweeters use a filament suspended between two powerful magnets in
series with a 5.1 ohm resister.  The filament is apparently a piece of
aluminum coated with a thin layer of titanium, or something to that
effect.  My replacement is somewhat thinner, and required the
manufacture of unique tooling to shape.

The result has less mass and consequently improved the sensitivity of
the driver, with obvious implications to the resultant sound quality.

My amplifier is an Onkyo M282, which is apparently an amplifier that
uses negative feedback, and made in Japan.  On the Web, there are a
number of articles which articulate the controversy over NFB amp
designs, with numerous manufacturers shunning the technique for
various reasons.  None of the descriptions or reviews take into
account the most important factor in an audio system -- the
interaction of the speakers with the amplifier.

I believe I have achieved such good results primarily because I
reduced the "mass" of the tweeter, which in combination with the
amplifier design, has helped produce a superior sound.  The key to
understanding the thinking behind this is the interaction of the
amplifier with the speakers.

Speakers are an inductive load, AFAIK, which means they present some
of the same problems as electric motors in the design of driver
circuitry.  In the instance of an audio signal, the drivers have a
hysteresis contingent upon their ability to accelerate in the presence
of a electrical impetus.  In my nascent understanding of electronic
circuits, this resistance to movement will interfere with the
amplifier output in the same way a naive power supply will drop-out
under load.

The negative feedback circuitry in the amplifier will detect this
drop-out and drive its input harder as a result, thereby reducing
perceived distortion.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected.  I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

It is worth noting that distortion at the amplifier output is a result
of two sources: firstly there is the distortion introduced by the gain
stages in the amplifier, and secondly, distortion introduced by the
mass of the drivers, which interact with the magnets and impose an
inductive signal on the amplifier output.  In either case, the
negative feedback circuitry should nearly instantaneously apply a
corrective factor to the input signal which will effectively coerce
the drivers to conform to the shape of the input signal -- if the NFB
circuitry is not too weak or slow.

My suspicion is that by reducing the mass of the tweeters in my
system, I have relieved a burden from the NFB circuitry in the Onkyo
M282, and thereby improved the resultant sound quality by an order of
magnitude or so.

The apparent controversy over the effectiveness of NFB amp designs
seems to ignore the amplifier-speaker relationship, and the role it
plays in fidelity.  An ideal speaker would have no electric mass, and
would therefore have zero influence (or load, I guess) on the
amplifier, and would obviously reproduce the amplifier signal
perfectly.  Loudspeakers must necessarily have mass, if only
represented by the air they displace, and will therefore affect the
amplifier by virtue of inductance.  Consequently it is my feeling that
negative feedback amplifier designs represent a good solution to the
practical problem of signal reproduction.

In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal.  Even ambient noise in the listening
environment might affect the negative feedback circuitry.

Perhaps obviously, I have no test equipment to use to measure the
effects or phenomenon that is at issue.  Just my common sense.  But
if you were here, you would be able to attest to the fidelity of the
ultimate result.

Comments and constructive criticism is welcome.

Regards,

Uncle Steve

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?
(But I know jack $@#t about audio.)

Hey maybe we could market a line of 'fast' (thin) speaker cables.


George H.

--

John Larkin                  Highland Technology Incwww..highlandtechnology.com  jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators- Hide quoted text -

- Show quoted text -

 

On Sat, 2 Feb 2013 10:06:48 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Feb 2, 10:28 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 01 Feb 2013 21:14:21 -0500, Uncle Steve <stevet...@gmail.com> wrote:
Recently, I had the experience of re-manufacturing the tweeters in a
pair of speakers I had bought.  Due to a "senior moment", I fried the
tweeters in a pair of Quadral Chromium Style 50 speakers, and
the local dealer decided to fuck me over even though I admitted the
mistake and paid for replacements.  Why they decided to screw with me
is another story, no doubt involving elements of the RCMP who would
prefer not to be named.  At any rate, I was left with a pair of
drivers with unequal efficiency, and it annoyed the living snot out of
me.

So I decided to take the two broken tweeters and rehabilitate them.
If you look into the Quadral speaker line, you will discover that the
tweeters use a filament suspended between two powerful magnets in
series with a 5.1 ohm resister.  The filament is apparently a piece of
aluminum coated with a thin layer of titanium, or something to that
effect.  My replacement is somewhat thinner, and required the
manufacture of unique tooling to shape.

The result has less mass and consequently improved the sensitivity of
the driver, with obvious implications to the resultant sound quality.

My amplifier is an Onkyo M282, which is apparently an amplifier that
uses negative feedback, and made in Japan.  On the Web, there are a
number of articles which articulate the controversy over NFB amp
designs, with numerous manufacturers shunning the technique for
various reasons.  None of the descriptions or reviews take into
account the most important factor in an audio system -- the
interaction of the speakers with the amplifier.

I believe I have achieved such good results primarily because I
reduced the "mass" of the tweeter, which in combination with the
amplifier design, has helped produce a superior sound.  The key to
understanding the thinking behind this is the interaction of the
amplifier with the speakers.

Speakers are an inductive load, AFAIK, which means they present some
of the same problems as electric motors in the design of driver
circuitry.  In the instance of an audio signal, the drivers have a
hysteresis contingent upon their ability to accelerate in the presence
of a electrical impetus.  In my nascent understanding of electronic
circuits, this resistance to movement will interfere with the
amplifier output in the same way a naive power supply will drop-out
under load.

The negative feedback circuitry in the amplifier will detect this
drop-out and drive its input harder as a result, thereby reducing
perceived distortion.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected.  I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

It is worth noting that distortion at the amplifier output is a result
of two sources: firstly there is the distortion introduced by the gain
stages in the amplifier, and secondly, distortion introduced by the
mass of the drivers, which interact with the magnets and impose an
inductive signal on the amplifier output.  In either case, the
negative feedback circuitry should nearly instantaneously apply a
corrective factor to the input signal which will effectively coerce
the drivers to conform to the shape of the input signal -- if the NFB
circuitry is not too weak or slow.

My suspicion is that by reducing the mass of the tweeters in my
system, I have relieved a burden from the NFB circuitry in the Onkyo
M282, and thereby improved the resultant sound quality by an order of
magnitude or so.

The apparent controversy over the effectiveness of NFB amp designs
seems to ignore the amplifier-speaker relationship, and the role it
plays in fidelity.  An ideal speaker would have no electric mass, and
would therefore have zero influence (or load, I guess) on the
amplifier, and would obviously reproduce the amplifier signal
perfectly.  Loudspeakers must necessarily have mass, if only
represented by the air they displace, and will therefore affect the
amplifier by virtue of inductance.  Consequently it is my feeling that
negative feedback amplifier designs represent a good solution to the
practical problem of signal reproduction.

In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal.  Even ambient noise in the listening
environment might affect the negative feedback circuitry.

Perhaps obviously, I have no test equipment to use to measure the
effects or phenomenon that is at issue.  Just my common sense.  But
if you were here, you would be able to attest to the fidelity of the
ultimate result.

Comments and constructive criticism is welcome.

Regards,

Uncle Steve

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?

How does that happen? Remember, the only thing that matters is the
power at the speaker and all the amp can see is the other (near) end
of the cable.

(But I know jack $@#t about audio.)

Hey maybe we could market a line of 'fast' (thin) speaker cables.

Speed isn't the issue. .67C is fast enough for audio. Even 50%
better doesn't help (though if you can do better, I'd like to hear
about it;-).

 

[John Larkin]

On Sat, 2 Feb 2013 10:06:48 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Feb 2, 10:28 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 01 Feb 2013 21:14:21 -0500, Uncle Steve <stevet...@gmail.com> wrote:
Recently, I had the experience of re-manufacturing the tweeters in a
pair of speakers I had bought.  Due to a "senior moment", I fried the
tweeters in a pair of Quadral Chromium Style 50 speakers, and
the local dealer decided to fuck me over even though I admitted the
mistake and paid for replacements.  Why they decided to screw with me
is another story, no doubt involving elements of the RCMP who would
prefer not to be named.  At any rate, I was left with a pair of
drivers with unequal efficiency, and it annoyed the living snot out of
me.

So I decided to take the two broken tweeters and rehabilitate them.
If you look into the Quadral speaker line, you will discover that the
tweeters use a filament suspended between two powerful magnets in
series with a 5.1 ohm resister.  The filament is apparently a piece of
aluminum coated with a thin layer of titanium, or something to that
effect.  My replacement is somewhat thinner, and required the
manufacture of unique tooling to shape.

The result has less mass and consequently improved the sensitivity of
the driver, with obvious implications to the resultant sound quality.

My amplifier is an Onkyo M282, which is apparently an amplifier that
uses negative feedback, and made in Japan.  On the Web, there are a
number of articles which articulate the controversy over NFB amp
designs, with numerous manufacturers shunning the technique for
various reasons.  None of the descriptions or reviews take into
account the most important factor in an audio system -- the
interaction of the speakers with the amplifier.

I believe I have achieved such good results primarily because I
reduced the "mass" of the tweeter, which in combination with the
amplifier design, has helped produce a superior sound.  The key to
understanding the thinking behind this is the interaction of the
amplifier with the speakers.

Speakers are an inductive load, AFAIK, which means they present some
of the same problems as electric motors in the design of driver
circuitry.  In the instance of an audio signal, the drivers have a
hysteresis contingent upon their ability to accelerate in the presence
of a electrical impetus.  In my nascent understanding of electronic
circuits, this resistance to movement will interfere with the
amplifier output in the same way a naive power supply will drop-out
under load.

The negative feedback circuitry in the amplifier will detect this
drop-out and drive its input harder as a result, thereby reducing
perceived distortion.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected.  I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

It is worth noting that distortion at the amplifier output is a result
of two sources: firstly there is the distortion introduced by the gain
stages in the amplifier, and secondly, distortion introduced by the
mass of the drivers, which interact with the magnets and impose an
inductive signal on the amplifier output.  In either case, the
negative feedback circuitry should nearly instantaneously apply a
corrective factor to the input signal which will effectively coerce
the drivers to conform to the shape of the input signal -- if the NFB
circuitry is not too weak or slow.

My suspicion is that by reducing the mass of the tweeters in my
system, I have relieved a burden from the NFB circuitry in the Onkyo
M282, and thereby improved the resultant sound quality by an order of
magnitude or so.

The apparent controversy over the effectiveness of NFB amp designs
seems to ignore the amplifier-speaker relationship, and the role it
plays in fidelity.  An ideal speaker would have no electric mass, and
would therefore have zero influence (or load, I guess) on the
amplifier, and would obviously reproduce the amplifier signal
perfectly.  Loudspeakers must necessarily have mass, if only
represented by the air they displace, and will therefore affect the
amplifier by virtue of inductance.  Consequently it is my feeling that
negative feedback amplifier designs represent a good solution to the
practical problem of signal reproduction.

In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal.  Even ambient noise in the listening
environment might affect the negative feedback circuitry.

Perhaps obviously, I have no test equipment to use to measure the
effects or phenomenon that is at issue.  Just my common sense.  But
if you were here, you would be able to attest to the fidelity of the
ultimate result.

Comments and constructive criticism is welcome.

Regards,

Uncle Steve

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?
(But I know jack $@#t about audio.)

If you're in a room with walls, moving your head a quarter of an inch
will change the acoustic transfer function more than practically any
change you could make in amps and cables.

Hey maybe we could market a line of 'fast' (thin) speaker cables.

Flat flex; that's been done. Some people even try to make 4 or 8 ohm
transmission lines. Loonies.

I've designed super-low impedance (specifically, low inductance) coax
to drive NMR gradient coils. My customer was using 10 meter cables
that had more inductance than the gradient coils that we were driving.


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

 

[EVO8VIII]

On Friday, February 1, 2013 3:38:48 PM UTC-5, George Herold wrote:

On Feb 1, 2:00 pm, EVO8VIII <ravi2n...@gmail.com> wrote:

I am working on very low current (10uA) design using LHI 878. Perkin Elmer app not e recommends 47K load resistor on source pin, which make my current goal very difficult. I've come across few designs where people have used over 1M on source pin to achieve this amount current. Does any one know if is okay use over 1M value? what could be side affect?



Can you post a link to the app note?

Pyro's only respond to changes in light... so knowing very little of

the details I might worry that the larger R would reduce the maximum

frequency and thus the signal level.



George H.

http://www.szbohan.com/UploadFile/2009_10_28_44167_95118.pdf

 

[Tauno Voipio]

On 2.2.13 8:06 , George Herold wrote:

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?
(But I know jack $@#t about audio.)

Hey maybe we could market a line of 'fast' (thin) speaker cables.


George H.

It is pretty simple: The thin cables do not look as expensive
as the gold-plated fat ones with transparent insulation.

---

As far as I understand, a speaker creates a larger back-EMF from
the mechanical movement of the coil in the magnetic field than
from the self-inductance of the coil. This means that the
mechanical (acoustic) environment is determining in the impedance
bumps seen by the amplifier.

--

-T.

 

[MrTallyman]

On Sun, 03 Feb 2013 00:00:40 +0200, Tauno Voipio
<tauno.voipio@notused.fi.invalid> wrote:

On 2.2.13 8:06 , George Herold wrote:

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?
(But I know jack $@#t about audio.)

Hey maybe we could market a line of 'fast' (thin) speaker cables.


George H.

It is pretty simple: The thin cables do not look as expensive
as the gold-plated fat ones with transparent insulation.

---

As far as I understand, a speaker creates a larger back-EMF from
the mechanical movement of the coil in the magnetic field than
from the self-inductance of the coil. This means that the
mechanical (acoustic) environment is determining in the impedance
bumps seen by the amplifier.

You sure your name isn't "Vapidio"?

 

[Phil Allison]

"Uncle Steve" <stevet810@gmail.com>


** FUCK OFF DAMN TROLL !!!!!!!!

 

[Franc Zabkar]

On Fri, 01 Feb 2013 10:02:22 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> put finger to keyboard and composed:

On a sunny day (Fri, 01 Feb 2013 10:39:08 +0800) it happened Dennis
none@null.net.au> wrote in <i5edndP9R5Ytt5bMnZ2dnUVZ_vmdnZ2d@westnet.com.au>:

I wonder what mecahnism they use to generate the power & if it really is
as bright as the marketing pictures depict!

Probably some rotating turbine generator

I think it's called hydroelectricity. ;-)

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Jamie]

Phil Allison wrote:

"Uncle Steve" <stevet810@gmail.com


** FUCK OFF DAMN TROLL !!!!!!!!

and why do I find this not surprising ?

Jamie

 

[John Larkin]

On Sat, 02 Feb 2013 14:13:44 -0500, krw@attt.bizz wrote:

On Sat, 2 Feb 2013 10:06:48 -0800 (PST), George Herold
gherold@teachspin.com> wrote:

On Feb 2, 10:28 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 01 Feb 2013 21:14:21 -0500, Uncle Steve <stevet...@gmail.com> wrote:
Recently, I had the experience of re-manufacturing the tweeters in a
pair of speakers I had bought.  Due to a "senior moment", I fried the
tweeters in a pair of Quadral Chromium Style 50 speakers, and
the local dealer decided to fuck me over even though I admitted the
mistake and paid for replacements.  Why they decided to screw with me
is another story, no doubt involving elements of the RCMP who would
prefer not to be named.  At any rate, I was left with a pair of
drivers with unequal efficiency, and it annoyed the living snot out of
me.

So I decided to take the two broken tweeters and rehabilitate them.
If you look into the Quadral speaker line, you will discover that the
tweeters use a filament suspended between two powerful magnets in
series with a 5.1 ohm resister.  The filament is apparently a piece of
aluminum coated with a thin layer of titanium, or something to that
effect.  My replacement is somewhat thinner, and required the
manufacture of unique tooling to shape.

The result has less mass and consequently improved the sensitivity of
the driver, with obvious implications to the resultant sound quality.

My amplifier is an Onkyo M282, which is apparently an amplifier that
uses negative feedback, and made in Japan.  On the Web, there are a
number of articles which articulate the controversy over NFB amp
designs, with numerous manufacturers shunning the technique for
various reasons.  None of the descriptions or reviews take into
account the most important factor in an audio system -- the
interaction of the speakers with the amplifier.

I believe I have achieved such good results primarily because I
reduced the "mass" of the tweeter, which in combination with the
amplifier design, has helped produce a superior sound.  The key to
understanding the thinking behind this is the interaction of the
amplifier with the speakers.

Speakers are an inductive load, AFAIK, which means they present some
of the same problems as electric motors in the design of driver
circuitry.  In the instance of an audio signal, the drivers have a
hysteresis contingent upon their ability to accelerate in the presence
of a electrical impetus.  In my nascent understanding of electronic
circuits, this resistance to movement will interfere with the
amplifier output in the same way a naive power supply will drop-out
under load.

The negative feedback circuitry in the amplifier will detect this
drop-out and drive its input harder as a result, thereby reducing
perceived distortion.

In the available literature there is talk of the "delay" that results
from the signal excursion that occurs from amplifier distortion before
it is corrected.  I would suggest that this "delay" is imaginary for
the reason that the negative feedback circuitry in fact operates
essentially instantaneously, and applies a continuous correction.

It is worth noting that distortion at the amplifier output is a result
of two sources: firstly there is the distortion introduced by the gain
stages in the amplifier, and secondly, distortion introduced by the
mass of the drivers, which interact with the magnets and impose an
inductive signal on the amplifier output.  In either case, the
negative feedback circuitry should nearly instantaneously apply a
corrective factor to the input signal which will effectively coerce
the drivers to conform to the shape of the input signal -- if the NFB
circuitry is not too weak or slow.

My suspicion is that by reducing the mass of the tweeters in my
system, I have relieved a burden from the NFB circuitry in the Onkyo
M282, and thereby improved the resultant sound quality by an order of
magnitude or so.

The apparent controversy over the effectiveness of NFB amp designs
seems to ignore the amplifier-speaker relationship, and the role it
plays in fidelity.  An ideal speaker would have no electric mass, and
would therefore have zero influence (or load, I guess) on the
amplifier, and would obviously reproduce the amplifier signal
perfectly.  Loudspeakers must necessarily have mass, if only
represented by the air they displace, and will therefore affect the
amplifier by virtue of inductance.  Consequently it is my feeling that
negative feedback amplifier designs represent a good solution to the
practical problem of signal reproduction.

In thinking about this subject, it has occurred to me that a NFB amp
will perform better if the speakers it drives are more expensive than
another, all things being equal.  Even ambient noise in the listening
environment might affect the negative feedback circuitry.

Perhaps obviously, I have no test equipment to use to measure the
effects or phenomenon that is at issue.  Just my common sense.  But
if you were here, you would be able to attest to the fidelity of the
ultimate result.

Comments and constructive criticism is welcome.

Regards,

Uncle Steve

Audio is such nonsense.

What I really don't get is the big fat cables.
If the load is inductive, then adding more series R to the circuit
just improves the L/R time constant. Sure you've gotta output more
voltage from the amp, is that a big deal?

How does that happen? Remember, the only thing that matters is the
power at the speaker and all the amp can see is the other (near) end
of the cable.

Voice coils have a low mechanical impedance if driven from a low electrical
impedance. They have more resonant woopie-doos if they are driven by a high
impedance source. It's the "damping factor" thing.

Some people like the resonant bass boom that they get from a higher-z amp.

I don't think that negative amp impedances, or remote sense, are popular. Maybe
there's money to be made there.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

 

[yaputya]

"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in message
news:7ibog8dgnp0su8c5o95cb3aqvdpr1jl8gv@4ax.com...

On Thu, 31 Jan 2013 21:34:21 -0800, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

EEs should be legally exempt from having to use low-flow shower heads. We get
all our best ideas in a good hot shower.

Agreed!

Last year, when I did that three month gig on Long Island, I was holed
up in an Extended America Hotel with a typical weeny shower head.

So I went to the local Lowe's and bought two channel-lock and one
needle-node pliers and a European-style hand-shower.

Nothing like a good Euro-hand-shower, especially when you are holed up
in a lonely yank hotel...........can't get no...... satisfaction etc......

Unscrewed the original shower head, and replaced it with mine (flow
restrictor removed) for the duration. (Probably a crime in NY State


FedEx'd it back to myself when I left, and put the pliers and
hand-shower into my extended travel kit ;-)

When you're onto a good thing, stick to it. (or vice versa!)

Just joking!!!!!