Speaker Design

[WoolyBully]

I doubt it. Speaker coils warm up from time to time (depending on what
the music is asking them to do, and this changes the temperature and
the permeability of the iron (or whatever) in the magnetic path. The
non-linearities won't be the same from one moment to the next.

Bullshit.

The speaker is stable right up to the point the coil opens from
overcurrent, because you are going to do that far sooner than reaching
the curie point temperature of the magnet or iron local to it.

Stop making shit up.

 

[Phil Allison]

"Bill Slowman PITA Bullshitting Old Fool"

Magnetic properties start changing way below the Curie point.

http://www.epcos.com/web/generator/...F/PDF__N87,property=Data__en.pdf;/PDF_N87.pdf


** All TOTALLY IRRELEVANT !!

The magnetic gap area is NOT ferrite - fuckwit !!

It is HEAVILY magnetically saturated, mild steel !!!!!!!

Moderate heating has NO significant effect on the field strength * in the
gap * whether the magnet is Ferrite, Neo or Alnico.

What DOES alter the field strength is the opposing field from the voice coil
at high power levels - along with temp rise in the copper wire, it adds to
"thermal compression" in high powered bass drivers.

A measurable effect, but not normally an audible one.



.... Phil

 

[Jamie]

"Bill Slowman PITA Bullshitting Old Fool"

Magnetic properties start changing way below the Curie point.

http://www.epcos.com/web/generator/...F/PDF__N87,property=Data__en.pdf;/PDF_N87.pdf


** All TOTALLY IRRELEVANT !!

The magnetic gap area is NOT ferrite - fuckwit !!

It is HEAVILY magnetically saturated, mild steel !!!!!!!

Moderate heating has NO significant effect on the field strength * in the
gap * whether the magnet is Ferrite, Neo or Alnico.

What DOES alter the field strength is the opposing field from the voice coil
at high power levels - along with temp rise in the copper wire, it adds to
"thermal compression" in high powered bass drivers.

A measurable effect, but not normally an audible one.



... Phil

Phil, I always enjoy it when you blast people like SLow-Man, it brings
a smile to my face!

Btw, you are correct in your correlation of the thermal effects in
copper coils, curie points etc.. Which is why we use current amps for
the beam scan coils.

Of course, the current amps also are used to generate a linear
magnetic field in the sweep, but who's counting! Also, there are
feed back coils so a lot the diagnoses can be done on the fly.

We have a Lecroy scope monitoring part of that circuit with a current
and voltage probe on the amp output. It gives us a general idea of what
is taking place in there and when it's time to replace them.

What we have found that seems to work, if you know how to read the
data is the ability to know what area's of the scan horn is heating up,
just by monitoring the curie effects, which result in changes of feed
back information verses what is going in.

Jamie

 

[Phil Allison]

"BillSlowman PITA Bullshitting Old Fool"

Magnetic properties start changing way below the Curie point.

http://www.epcos.com/web/generator/Web/Sections/ProductCatalog/Ferrit...

** All TOTALLY IRRELEVANT !!

The magnetic gap area is NOT ferrite - fuckwit !!

I never said it was - EPCOS N87 was just a convenient example

** Conveniently wrong example.

It is HEAVILY magnetically saturated, mild steel !!!!!!!

If it was heavily magnetically saturated, it might as well not be
there. And what do you mean by "the magnetic gap area"?

** FFS - get a grip.

You are beating a very dead horse to death.

( snip repetitive drivel )

Moderate heating has NO significant effect on the field strength * in the
gap * whether the magnet is Ferrite, Neo or Alnico.

Actually, it does - the field of a permanent magnetic drops as you
warm it up towards the Curie point.

** And the Curie temp of mild steel is ??

While the running temp of a speaker magnet is rarely more than 50 degrees C.

What DOES alter the field strength is the opposing field from the voice
coil
at high power levels - along with temp rise in the copper wire, it adds to
"thermal compression" in high powered bass drivers.

That's not a thermal effect,

** Duuuhhh ......


..... Phil

 

[Phil Allison]

"BillSlowman PITA Bullshitting Old Fool"

I never said it was - EPCOS N87 was just a convenient example

** Conveniently wrong example.

Really?

** Yes- you LYING tenth wit.

If it was heavily magnetically saturated, it might as well not be
there. And what do you mean by "the magnetic gap area"?

** FFS - get a grip.

You are beating a very dead horse to death.

( snip repetitive drivel )

Phil prefers to ignore the question ...


** The Q was insane, like you.

Actually, it does - the field of a permanent magnetic drops as you
warm it up towards the Curie point.

** And the Curie temp of mild steel is ??

"Mild steel" covers a range of alloys, but google says that it is
generally between 500C and 600C.


** I saw 770C quoted for " low carbon steel " .

While the running temp of a speaker magnet is rarely more than 50 degrees C.

FOAD you crazy old ****.


..... Phil

 

[DreadKnot]

On Tue, 29 May 2012 23:04:04 -0700 (PDT), Bill Sloman

<snip>

Billy snips when he is proven absurd, and he fails to refute the proof.

Case closed.

The speaker coil will fail (and assuredly smoke profusely) long before
the steel or the magnet surrounding it heats up... at all.

I regularly ran 1500W low end (the audio range, not the driver quality)
drivers in a live, tri-amped performance set-up and the speaker magnets
and their surrounds which completed their magnetic circuit always
remained cool.

These speakers had forward excursions of nearly two inches.

Ever "seen" "middle C" driven so hard the cone moves an inch out and an
inch in? It *will* break wine glasses.

These were 12" drivers.

 

[DreadKnot]

Neat trick. The coils are dissipating 1500W and the adjacent metal-
work doesn't heat up at all.

Show me where the voice coil is connected to the "adjacent metalwork".

Now, show me where that connection is thermally conductive.

Ever heard of viscous damped and cooled voice coils?

And the coils are not dissipating 1500W, they are reacting to 1500W.

Pretty sure there isn't as much heat. Granted, they do get hot, but
that is the COIL, not the magnet around it.

A mag lev train suspension magnet doesn't "heat up" either. Even after
thousands of miles.

 

[DreadKnot]

And were horribly non-linear. Not that anybody exposed to that level
of noise would have enough hearing left to notice.

Bullshit, They were pro gear elements. Made by one of the best in the
industry. Electrovoice.

Not that you would have any clue as to what a good audio transducer is.

Much less any details of its operation.

 

[DreadKnot]

For a rock group who liked their sound loud and distorted.

No. For the same exact application they are manufactured for.

They are what the pros use, and you have no clue what the world has to
offer because you haven't gotten up off of your thumb in years.

Grind on it harder, idiot. You'll slip even further behind the curve.

 

[Mac Decman]

"Bill Slowman PITA Bullshitting Old Fool"

Magnetic properties start changing way below the Curie point.

http://www.epcos.com/web/generator/...F/PDF__N87,property=Data__en.pdf;/PDF_N87.pdf


** All TOTALLY IRRELEVANT !!

The magnetic gap area is NOT ferrite - fuckwit !!

It is HEAVILY magnetically saturated, mild steel !!!!!!!

Moderate heating has NO significant effect on the field strength * in the
gap * whether the magnet is Ferrite, Neo or Alnico.

What DOES alter the field strength is the opposing field from the voice coil
at high power levels - along with temp rise in the copper wire, it adds to
"thermal compression" in high powered bass drivers.

A measurable effect, but not normally an audible one.



... Phil

This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

 

[Mac Decman]

This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

Sorry that was 0.05-0.08T... Haha.

Neo ain't that bad!

 

[josephkk]

This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

I hope you don't mind me asking, How many people are crazy enough to try
dealing with over 250 W in a single speaker (voice coil or other
transducer [not including {military} sonar]).

?-)

 

[Mac Decman]

This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

I hope you don't mind me asking, How many people are crazy enough to try
dealing with over 250 W in a single speaker (voice coil or other
transducer [not including {military} sonar]).

?-)

Almost all pro-audio subwoofers are 3000-4000W AES rated.

 

[Mac Decman]

"Bill Slowman PITA Bullshitting Old Fool"

Magnetic properties start changing way below the Curie point.

http://www.epcos.com/web/generator/...F/PDF__N87,property=Data__en.pdf;/PDF_N87.pdf


** All TOTALLY IRRELEVANT !!

The magnetic gap area is NOT ferrite - fuckwit !!

It is HEAVILY magnetically saturated, mild steel !!!!!!!

Moderate heating has NO significant effect on the field strength * in the
gap * whether the magnet is Ferrite, Neo or Alnico.

What DOES alter the field strength is the opposing field from the voice coil
at high power levels - along with temp rise in the copper wire, it adds to
"thermal compression" in high powered bass drivers.

A measurable effect, but not normally an audible one.



... Phil




This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

I hope you don't mind me asking, How many people are crazy enough to try
dealing with over 250 W in a single speaker (voice coil or other
transducer [not including {military} sonar]).

?-)

Almost all pro-audio subwoofers are 3000-4000W AES rated.

Hah sorry again I keep making typos. 3000-4000 program rated.
1500-2000 AES rated or more. I just made a 15" which would sustain
2700W average power given a pink noise weighted signal from
80Hz-500Hz. Most pro audio amplifiers are capible of 2500W/5000W
bridged + into a 2/4 ohm load on a 208V/240V system with no problem.
120V systems have been known to have problems with fast trans.

Mark DeArman

 

[Phil Allison]

"Mac Decman"

Hah sorry again I keep making typos. 3000-4000 program rated.

** Both figures are totally fake.

1500-2000 AES rated or more. I just made a 15" which would sustain
2700W average power given a pink noise weighted signal from
80Hz-500Hz.

** So you have tried it and cannot do such a test.

Most pro audio amplifiers are capible of 2500W/5000W
bridged + into a 2/4 ohm load on a 208V/240V system with no problem.

** That is UTTER BOLLOCKS !!!!!!!

It is nothing like " most" but only few models "top end" and they cannot
sustain those sort of levels for long enough to do the AES test in bridge
mode.



.... Phil

 

[MadManMoon]

This is a real problem in high output >2000W magnet designs. The
combination of reduced flux density in the gap and increased Re will
change the total impedance enough to make subwoofers sound tubby
because the porting / air-spring constant of the enclosure is no
longer correct.

Normally I measure a reduction of 0.5-0.8T in the magnetic gap of 35H
NdFeB magnets which are raised to 300degF temp to cure epoxy.
Typically a 3000W AES rated speaker will reach 250degF during heavy
usage. Coil former breakdown occurs at 250degC and the coils will
operate at this temp when cadmium solder is used.

Mark DeArman

This man, I trust, in this realm.

 

[Mac Decman]

"Mac Decman"


** Both figures are totally fake.


** So you have tried it and cannot do such a test.




** That is UTTER BOLLOCKS !!!!!!!

It is nothing like " most" but only few models "top end" and they cannot
sustain those sort of levels for long enough to do the AES test in bridge
mode.



... Phil

I do power testing with a Lab fp14000 in bridge mode on a 240V
circuit. It will do 3000W of band limited pink noise easily. It will
not do it's rated 14000W except peaking. And as I noted, it seems
that the design of the 120V versions can not sustain the peak output
long enough to make them useful for low frequency applications.

Other amplifier manufactuers I can't speak for because I haven't
measured them. But I would imagine in the pro-audio world that they
are comparable.

Mark DeArman

 

[Phil Allison]

"Mac Decman"
"Phil Allison"

I do power testing with a Lab fp14000 in bridge mode on a 240V
circuit.

** That example is NOTHING like "most amps"

- you lying stupid twat.

It will do 3000W of band limited pink noise easily.

** Like hell it can.

What about your 5kW at 2/4 ohms load in bridge ??

You context shifting jerk.

It will not do it's rated 14000W except peaking.

** ROTFL !!

Other amplifier manufactuers I can't speak for because I haven't
measured them. But I would imagine in the pro-audio world that they
are comparable.

** Fuckheads like you imagine the tooth fairy is real.



.... Phil

 

[Mac Decman]

"Mac Decman"
"Phil Allison"


** That example is NOTHING like "most amps"

- you lying stupid twat.



** Like hell it can.

What about your 5kW at 2/4 ohms load in bridge ??

You context shifting jerk.




** ROTFL !!




** Fuckheads like you imagine the tooth fairy is real.

What there is no tooth fairy! Not fair!

... Phil

Mark DeArman