spudrick wrote:
From an old Magnavox tube stereo. It used two cabinets, each with 3
speakers. The largest is 15" but it only has a 1 inch or so magnet.
This is to save money

Yes. These systems were never intended to be high-fidelity
systems. Often, far more effort went in to trying to make
them look like expensive furniture than sound good.

or is there another reason?

Several possible reasons:

1. The designers had no real clue what they were doing
2. The marketing department was hoping that their intended
market either had no idea what was going on or simply
didn't care.

By your description, these are probably from the late-50's or
early- to mid-60's vintage systems. This was from a time when
few people in the industry had a comprehensive understanding
of the notion of designing speakers using a systems approach
as described by Thiele and then later Small.

But the overwhelming factor is that these speakers were INTENDED
as junk, DESIGNED as junk, MANUFACTURED as junk, all to save lots
of money, and then intended to be SOLD to people who didn't know
or didn't care much about the quality of the sound.

The other two
speakers had similar sized magnets on 6" and 2" speakers. It looks
like they had a capacitor across each speaker to divide the signal
into bass, mid, treble sections.
I salvaged the speakers to make a bass amp but they look kind of
anemic now that they're out of the cabs. What say all of you?

They're junk. Give them the death they deserve and that
has eluded them for oh so many years.

On Mon, 20 Jun 2005 06:37:41 GMT, spudrick
wrote:

From an old Magnavox tube stereo. It used two cabinets, each with 3
speakers. The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason? The other two
speakers had similar sized magnets on 6" and 2" speakers. It looks
like they had a capacitor across each speaker to divide the signal
into bass, mid, treble sections.
I salvaged the speakers to make a bass amp but they look kind of
anemic now that they're out of the cabs. What say all of you?
Some tube sets had 12-15" speakers with electro magnets (extra leads
to a coil near the typical magnet position) wired in series with the
B+ supply. IIRC these speakers also had a 3.2 ohm VC

, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org

On 20 Jun 2005 04:07:36 -0700, wrote:

By your description, these are probably from the late-50's or
early- to mid-60's vintage systems. This was from a time when
few people in the industry had a comprehensive understanding
of the notion of designing speakers using a systems approach
as described by Thiele and then later Small.

But the overwhelming factor is that these speakers were INTENDED
as junk, DESIGNED as junk, MANUFACTURED as junk, all to save lots
of money, and then intended to be SOLD to people who didn't know
or didn't care much about the quality of the sound.

I think you're being too hard on them. Did they know as much back
then as we do today? Of course not. As to Thiele and Small, AFAIK
that's for bass-reflex designs, which that old stuff was generally
not.

I have no doubt that (at least the more thoughtful) designers back
then made reasonable attempts to design systems with decent
performance, within the limitations of the technology and design
practices of the time. Large magnets as what are common today simply
were not appropriate back then.

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

"spudrick" wrote in message
...
From an old Magnavox tube stereo. It used two cabinets, each with 3
speakers. The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason? The other two
speakers had similar sized magnets on 6" and 2" speakers. It looks
like they had a capacitor across each speaker to divide the signal
into bass, mid, treble sections.
I salvaged the speakers to make a bass amp but they look kind of
anemic now that they're out of the cabs. What say all of you?

These speakers were designed to play loudly with only a few watts input. You
might notice that the cones are made of a thin taut paper not unlike a
guitar amp speaker. They probably can't handle any more than 10 or 20 watts.
For a bass amp, you might look at true woofer drivers.
John

dizzy wrote:
On 20 Jun 2005 04:07:36 -0700, wrote:

By your description, these are probably from the late-50's or
early- to mid-60's vintage systems. This was from a time when
few people in the industry had a comprehensive understanding
of the notion of designing speakers using a systems approach
as described by Thiele and then later Small.

But the overwhelming factor is that these speakers were INTENDED
as junk, DESIGNED as junk, MANUFACTURED as junk, all to save lots
of money, and then intended to be SOLD to people who didn't know
or didn't care much about the quality of the sound.

I think you're being too hard on them. Did they know as much back
then as we do today? Of course not.

Didn't I just say something to that effect:

"This was from a time when few people in the industry
had a comprehensive understanding of the notion of
designing speakers using a systems approach as described
by Thiele and then later Small."

As to Thiele and Small, AFAIK that's for bass-reflex designs,

Wrong. Consider the series of articles written by Small in the JAES:

Direct Radiator Loudspeaker System Analysis (1972 June)
Closed-Box Loudspeaker Systems, (1972 Dec, 1973 Jan-Feb)
Vented-Box Loudspeaker Systems. (1973 Jun, July/Aug, Sep, Oct)
Passive-Radiator Loudspeaker System Design, (1974 Oct, Nov)

which that old stuff was generally not.

Also not correct. Most of the stuff made by Magnavox and the like
were nowhere near sealed box. Typical configurations where very
light, flexible cones in stiff suspensions with small voice coils
and magnets. The result was a moderate efficiency, high resonant
frequency (60 Hz for a 15" cone would be quite typical) and VERY
underdamped (free-air total Q factor in the range of 2-4). These
drivers were then often placed in cabinet volumes that were dictated
NOT at all by the acoustical and mechanical requirements of the
driver but by the requirements of the furniture designer. Usually,
the rear of these systems was little more than a perforated masonite
board, sometimes it was plywood, and a gratutious port is punched
through the front baffle.

I have no doubt that (at least the more thoughtful) designers back
then made reasonable attempts to design systems with decent
performance,

Yes, and NONE of them have worked represented by the likes of
Magnovox.

within the limitations of the technology and design
practices of the time.

Then explain the ENORMOUS disparity in the design and implementation
in the early 1960's by, oh, Acoustic Research and, say, Magnavox.
The same PHYSICAL limitations were imposed on both. Why did the
Magnovox have such a tiny magnet and the AR no if they were both
contrained by limitations of the technology of the time?

Oh, it's those pesky "design practices" that must be it. You know,
the ones where the cabinet designers ruled and basically handed
the "speaker designer" a given cabinet, and they bascially stuck
any ol piece-o'-**** collection of utterly unsuitable drivers in
it, threw a couple of caps in and then they're done.

Large magnets as what are common today simply
were not appropriate back then.

Not "appropriate?" Do you mean to say that physics has changed,
and what is "appropriate" now wasn't then?

Or maybe that, given the fact that the portion of the design and
manufacturing budget alloted to speakers was SO paltry, that junk
HAD to be the rule.

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

wrote:

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.


So I take it, then, that you don't like Magnavox, circa 1960s. LOL

CD

On 21 Jun 2005 04:13:10 -0700, wrote:

dizzy wrote:
As to Thiele and Small, AFAIK that's for bass-reflex designs,

Wrong. Consider the series of articles written by Small in the JAES:

Direct Radiator Loudspeaker System Analysis (1972 June)
Closed-Box Loudspeaker Systems, (1972 Dec, 1973 Jan-Feb)
Vented-Box Loudspeaker Systems. (1973 Jun, July/Aug, Sep, Oct)
Passive-Radiator Loudspeaker System Design, (1974 Oct, Nov)

I stand corrected, but this doesn't change the overall point I was
making.

which that old stuff was generally not.

Also not correct. Most of the stuff made by Magnavox and the like
were nowhere near sealed box.

Suffering from reading comprehension problems? "Not bass-reflex" does
not equal "sealed box".

I have no doubt that (at least the more thoughtful) designers back
then made reasonable attempts to design systems with decent
performance,

Yes, and NONE of them have worked represented by the likes of
Magnovox.

Wrong.

Large magnets as what are common today simply
were not appropriate back then.

Not "appropriate?" Do you mean to say that physics has changed,
and what is "appropriate" now wasn't then?

Idiot. Technology has changed.

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

So what? That doesn't make the old stuff "junk".

dizzy wrote:
On 21 Jun 2005 04:13:10 -0700, wrote:

dizzy wrote:
As to Thiele and Small, AFAIK that's for bass-reflex designs,

Wrong. Consider the series of articles written by Small in the JAES:

Direct Radiator Loudspeaker System Analysis (1972 June)
Closed-Box Loudspeaker Systems, (1972 Dec, 1973 Jan-Feb)
Vented-Box Loudspeaker Systems. (1973 Jun, July/Aug, Sep, Oct)
Passive-Radiator Loudspeaker System Design, (1974 Oct, Nov)

I stand corrected, but this doesn't change the overall point I was
making.

Which was what?

which that old stuff was generally not.

Also not correct. Most of the stuff made by Magnavox and the like
were nowhere near sealed box.

Suffering from reading comprehension problems? "Not bass-reflex" does
not equal "sealed box".

Then what, in your estimation, were they?

(In fact, their operation is just as well covered by the Thiele
Small model).

I have no doubt that (at least the more thoughtful) designers back
then made reasonable attempts to design systems with decent
performance,

Yes, and NONE of them have worked represented by the likes of
Magnovox.

Wrong.

Well I guess that settles it, then.

You want to provide at least SOME substance to your assertion?

Large magnets as what are common today simply
were not appropriate back then.

Not "appropriate?" Do you mean to say that physics has changed,
and what is "appropriate" now wasn't then?

Idiot. Technology has changed.

Utter nonsense. Ferrite magnet technology has been available
since the early 1950's. Manufacturers had substantially larger
magnet assemblies, specifically, larger Bl products since
the early 50's. The technology WAS there. You just don't know it.

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

So what? That doesn't make the old stuff "junk".

Try reading. There's more functionality and acoustical performance
in a $400 boom box of today than there was in a similarily or higher
priced Magnavox system of 40 years ago. You claimed the stuff back then
is less "junk" than the stuff sold now, and other than your personal
opinion and insistance, you have no data to back that up.

"spudrick" wrote in message
...
From an old Magnavox tube stereo. It used two cabinets, each with 3
speakers. The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason? The other two
speakers had similar sized magnets on 6" and 2" speakers. It looks
like they had a capacitor across each speaker to divide the signal
into bass, mid, treble sections.
I salvaged the speakers to make a bass amp but they look kind of
anemic now that they're out of the cabs. What say all of you?

The speakers are junk, of course. Take off the magnets and use them
on the 'fridge. Clip the caps off, they may be useful. Put the rest
in the metal recycling bin.
Your "bass amp" needs much bigger magnet speakers (and some serious
design input, too!)
Cheers,
Roger

On 21 Jun 2005 17:01:11 -0700, wrote:

Idiot. Technology has changed.

Utter nonsense. Ferrite magnet technology has been available
since the early 1950's. Manufacturers had substantially larger
magnet assemblies, specifically, larger Bl products since
the early 50's. The technology WAS there. You just don't know it.

Utter nonsense. Speaker technology hasn't changed, huh? How about
amplifiers?

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

Try reading. There's more functionality and acoustical performance
in a $400 boom box of today than there was in a similarily or higher
priced Magnavox system of 40 years ago.

So what? That doesn't make the old stuff "junk".

Christ, what's next, all computers made in the 50's were "junk"
because you can buy a Dell for $400 that blows them away? Sheesh,
what a maroon!

You claimed the stuff back then
is less "junk" than the stuff sold now,

In general, it was. What we have today is greatly improved
technology, and greatly improved manufacturing efficiencies. The
stereo gear sold today to the masses IS "junk", more so than what was
sold back in the "old days" you lament.

and other than your personal
opinion and insistance, you have no data to back that up.

Bull****. The hardware still exists as evidence.

"dizzy" wrote in message
...
Try reading. There's more functionality and acoustical performance
in a $400 boom box of today than there was in a similarily or higher
priced Magnavox system of 40 years ago.

So what? That doesn't make the old stuff "junk".

It sure as hell makes that old MaggotBox junk. When you think how many hours
a person had to work to buy one at the time, it almost makes you weep.
There were speakers made in the sixties however that are still considered
more than acceptable by today's standards. Some are now collectors items.

Christ, what's next, all computers made in the 50's were "junk"
because you can buy a Dell for $400 that blows them away? Sheesh,
what a maroon!

Why someone of Dick's knowledge and experience would waste his time trying
to educate someone as ignorant and unwilling to learn as yourself, amazes
me.
Maybe he *IS* a "maroon" after all.

MrT.

Codifus wrote:
wrote:

There's more functionality and acousticalt performance in
a $400
boom box today than there was in a 1960's Magnavox stereo
console.
Hell, there's even more magnet on them.


So I take it, then, that you don't like Magnavox, circa
1960s. LOL

Indeed. Maybe you had to be there...

I was.

The brown-box goods of the 60s were pretty horriffic.

dizzy wrote:

On 21 Jun 2005 17:01:11 -0700,
wrote:

Idiot. Technology has changed.

The basics haven't changed, the implementations have
improved.

Utter nonsense. Ferrite magnet technology has been
available
since the early 1950's.

Agreed.

Manufacturers had substantially larger
magnet assemblies, specifically, larger Bl products since
the early 50's.

Agreed.

The technology WAS there. You just don't know it.

Utter nonsense. Speaker technology hasn't changed, huh?

Speaker technology has been considerably refined since the
60s, but old boxes like the AR3 and AR5 differ from modern
products primarily in the details.

How about amplifiers?

Solid state made building really good, really powerful amps
a very low cost proposition.

However, there's a reason why many of us would pronounce
"Magnavox" as maggotbox, back in the day of. The brown good
boxes that the OP described were really horriffic-sounding.
Perhaps you had to be there. In the late 60s my after-in-law
proudly showed me his $400 Magnavox console. I spent about
the same money on Dynakits and AR. Vastly different audible
results to say the least.

dizzy wrote:
On 21 Jun 2005 17:01:11 -0700, wrote:

Idiot. Technology has changed.

Utter nonsense. Ferrite magnet technology has been available
since the early 1950's. Manufacturers had substantially larger
magnet assemblies, specifically, larger Bl products since
the early 50's. The technology WAS there. You just don't know it.

Utter nonsense. Speaker technology hasn't changed, huh?

Not in any fundamental way, it hasn't.

How about amplifiers?

What about amplifiers? What does that have to do with anything?
We were talking about the availablility or, in your words,
appropriatey of large vs small magnets. The technology for achieving
higher Bl products has existed for a half century, whether it's
by the use of large volumes of barrium or strontium ferrite
ceramics or by sufficient sizes of Almico and other alloys.
Amplifier have nothing to do with it.

Most stuff sold back then was not nearly as "junk" as most stuff sold
today...

There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

Try reading. There's more functionality and acoustical performance
in a $400 boom box of today than there was in a similarily or higher
priced Magnavox system of 40 years ago.

So what? That doesn't make the old stuff "junk".

It means that the old stuff that was junk is still junk.

Christ, what's next, all computers made in the 50's were "junk"
because you can buy a Dell for $400 that blows them away?

On the assumption that you were at all serious, if you
cannot see the inherent absurdity of your statement, then
you are clearly not at all interesting in pursuing a
technical discussion formthe viewpoint of its technical
merits.

Unless there is some other reason which you have decided not
to reveal for buying such products OTHER THAN the functionality
they provide, then your assertion seems nonsensical.

Sheesh, what a maroon!

Hmmm. "Idiot" and "maroon." Seems that the last resort of
someone unable to engage in a technical discussion based on
technical merits is to resort to name calling.

You claimed the stuff back then
is less "junk" than the stuff sold now,

In general, it was. What we have today is greatly improved
technology, and greatly improved manufacturing efficiencies. The
stereo gear sold today to the masses IS "junk", more so than what was
sold back in the "old days" you lament.

and other than your personal
opinion and insistance, you have no data to back that up.

Bull****. The hardware still exists as evidence.

And you have yet to provide a SINGLE example to bolster
your point. Certainly a driver with a woefully undersized
magnet from some random Magnavox product is, indeed, an
existance proof to the contrary. Why not actually pick some
real data, like speaker from a number of manufacturers in England
and Europe, of even some from the UNited states, like AR, JBL, EV,
and others, ALL of whom produced drivers with magnet assemmblies
that were substantially larger and more to the task than the
puny examples you've decided to champion. Indeed, the
existance of these example further demonstrates the Magnavox
stuff as true junk, even by contemporary standards.

Perhaps your agenda is colored by circumstance. Maybe you have
invested large amounts of money in collecting old Magnavox
speakers with an eye towards cashing in on some as yet unknown
market. Perhaps then rather than our technical assistance, what
you really need is our pity.

dizzy wrote:

Try reading. There's more functionality and acoustical performance
in a $400 boom box of today than there was in a similarily or higher
priced Magnavox system of 40 years ago.

So what? That doesn't make the old stuff "junk".

Go check what JBL and Altec was building back then. The technology and
the understanding was there.

and other than your personal
opinion and insistance, you have no data to back that up.

Bull****. The hardware still exists as evidence.

Yes, but it is Dick's point that is made by it, not yours. Go see
http://www.audioheritage.org ....


Kind regards

Peter Larsen



--
*******************************************
* My site is at: http://www.muyiovatki.dk *
* The Vienna Copyright convention applies *
*******************************************

wrote:

existance proof to the contrary. Why not actually pick some
real data, like speaker from a number of manufacturers in England
and Europe, of even some from the UNited states, like AR, JBL, EV,
and others, ALL of whom produced drivers with magnet assemmblies
that were substantially larger and more to the task than the
puny examples you've decided to champion. Indeed, the
existance of these example further demonstrates the Magnavox
stuff as true junk, even by contemporary standards.

I have two pairs of Fostex T825 treble drivers. The design date on the
drawing that came with them is in 1953.


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
* The Vienna Copyright convention applies *
*******************************************

dizzy wrote:

[lots of arguing about not very much]

On 21 Jun 2005 04:13:10 -0700, wrote:
There's more functionality and acousticalt performance in a $400
boom box today than there was in a 1960's Magnavox stereo console.
Hell, there's even more magnet on them.

So what? That doesn't make the old stuff "junk".

Budget was what determined the size of the magnet then, and it is today.
One difference that has not been discussed is that the magnet probably
is alnico, even if small, and thus stronger pr. cubic inch of magnet
that the magnet in a boom box.

Just as today the component cost allowable was derived by the retail
price range specified for the product. The design process for such a box
was not based on theory, it was a "practitioners throw together" within
the frame defined by price and by outer design. A lot of old radios and
stuff actually do have a "good sound", they were often good
practitioners,
but theory - nah, not a part of the design and perhaps not really all
that well understood. My brothers father in law was a jukebox repairman
from that period in the audio industry and I know some of the people
from the quality part of danish audio manufacturing (Movic), I don't
think I am unfair to the state of the art of the general "audio
furniture" industry back then.

There are manufacturers still building the same general kind of
loudspeakers that the old Magnavox thing in question had. Efficiency pr.
currency unit of manufacturing costs is good, and they can have a decent
lower midrange, but they are not bass loudspeakers. If you want to use
them for something, they are perhaps best deployed on what they are
designed for: an open, or semi-open, baffle, powered by no more than 5
watts. It is possibly possible to get the innards of that old Magnavox
to do good "wall to wall music" in a living room by proper deployment
within their limits and design genre - it could even be fun - but they
are not for HiFi, and was not so then.

What you need to understand that the target frequency range for such a
product back then was from something 100 Hz to something 5000 Hz, the
main use for the Magnavox was assumed to be AM reception or similar
quality broadcasts. The state of the art of the Audio industry back then
was considerably more advanced, products like the Magnavox are mostly
from the furniture industry.


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
* The Vienna Copyright convention applies *
*******************************************

"spudrick" wrote in message
...
The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason?

I imagine it's because the speaker was designed to handle only a few watts,
not the hundreds of watts of today's designs. It may have an alnico magnet,
too, which is I believe a more powerful magnetic material than modern
ceramic magnets.

Tim

Tim Martin wrote:
"spudrick" wrote in message
...
The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason?

I imagine it's because the speaker was designed to handle only a few watts,
not the hundreds of watts of today's designs. It may have an alnico magnet,
too, which is I believe a more powerful magnetic material than modern
ceramic magnets.

This has been mentioned elsewhere in this thread, but there's a
misconception that needs to be cleared up.

The "strength" of the magnet, in term that are important to the
operation of the speaker, is directly related to the flux density
in which the wire of the voice coil is immersed. The relevant
parameter is referred to as the "Bl product" (that's "bee-ell").
It is the product of the flux density, B, measured in Tesla and
the length of the wire, in meters, that's immersed in that field.
The Bl product is measured in units of Tesla-meters, and is
equivalent to the amount of force per amount of current (actually
1 Tesla meter is equal to 1 Newton of force per ampere of current).

Speaker magnets using Alnico have traditionally been claimed as
being "more powerful" than magnets using ferrite ceramics, but
this is simply not the case.

WHat IS true of Alnico is that it is capable of storing more
total energy per unit volume than ceramics can. But the SIZE
of the hard magnet material is NOT what determines the important
factor here, and that is the flux density in the voice coil cap.
That's something the magnet material used cannot determine.

In BOTH the cases of Alnico- and ferrite ceramic-based magnet
structures, the material used to actually focus and concentrate
the magnetic field in the gap is almost always common, soft,
low-carbon steels, for several reasons:

1. They're inexpensive

2. They're ductile and malleable and thus can be shaped using
common metalworking methods (stamping, forging, diecutting)
into the desired shapes and configuration,

3. They are capable of supporting substantially flux densities
than most hard magnetic materials such as alnico or the
ceramic ferrites.

The first two speak to the manufacturability of the assembly,
especially since both of these material are VERY hard to machine.
Try to machine Alnico, and you'll wear you tools out much faster
than the alnico, and if you try to force the issue, it will shatter
like glass. And ceramics are like trying to machine brittle rocks.

But the last point, the issue of flux density, is VERY important
in the design of the magnet.

The problem is that while both Alnico and ceramic hard magnet
materials are capable of storing large amounts of magnet
energy permanently, they have a limit: the flux density the
can store is limited. HOwever, the flux can be concetrated and
directed by using the auxiliary soft-iron structure.

Fo, for example, the typical flux density at the surface of a
ceramic magnet might be on the order of only 0.2 Tesla. But if
we could concentrate that same total flux in a smaller area, the
flux density would, obviously, be greater. Look at the relative
cross-sectionaly areas of the magnet vs the surrounding magnet
structure, and you can see how the relatively low fux density
of the magnet is conctrated to a higher flux desnity at the gap.

However, there is a limit, and that is that the amount of flux
you can direct through these auxiliary structures is limited.
At best, soft, low-carbon steels "saturate" at flux densities
of about 1.2 Tesla. Any attempt to put any more flux into them
will not result in any increase in flux desnity, the extra
flux will simple "spill out" of the structure into the air.

Because, then, BOTH Alnico-based and ceramic-based magnets rely
the same low-carbon steels to concentrate and direct the magnetic
flux, these materials impose their own limits on the maximum
flux density in the gap. The result is that, all other things
being equal (same gap depth, same diameter, same voice coil),
a speaker magnet using Alnico will not be any more "powerful"
than one using ceramic.

In essence, the "strength" of the magnet field where it counts,
that is in the voice coil gap, is limited NOT by the magnet
material, alnico or otherwise, but by the soft iron.

So what's the advantage to Alnico? In this day and age, not a lot.
For any given Bl product, an Alnico-based magnet can be physical
smaller and lighter. But it will also be more expensive, because
of the ioncreased cost of the material and the difficulty in
handling it.

So, just because a speaker has an Alnico magnet, don't assume
that it's "more powerful." In all likelihood, it's not.

wrote in message

The problem is that while both Alnico and ceramic hard magnet
materials are capable of storing large amounts of magnet
energy permanently, they have a limit: the flux density the
can store is limited.

I thought that the magnetic force in all magnets eventually diminishes,
although probably so little that the performance of a loudspeaker would not
be affected during a listener's lifetime.

Could you perhaps shed some light on this matter?

Thanks in advance.

"Peter" reply to newsgroup only wrote in message
...
I thought that the magnetic force in all magnets eventually diminishes,
although probably so little that the performance of a loudspeaker would
not
be affected during a listener's lifetime.


I think Dick already covered in previous posts how some magnetic materials
are more affected by heat etc. than others. Noticeable loss of magnetism can
occur with high voice coil temperatures or high shock loading in some
instances. Time duration alone will be much less significant I believe.

MrT.

"Arny Krueger" wrote in message
...
Codifus wrote:
wrote:

There's more functionality and acousticalt performance in
a $400
boom box today than there was in a 1960's Magnavox stereo
console.
Hell, there's even more magnet on them.


So I take it, then, that you don't like Magnavox, circa
1960s. LOL

Indeed. Maybe you had to be there...

I was.

The brown-box goods of the 60s were pretty horriffic.

For the most part. I do remember a friend of the family bought a Fisher
stereo console in 1969 that was pretty impressive, relatively speaking. It
had a Dual turntable with a magnetic pickup, a respectable AM/FM tuner,
built-in pair of air suspension speakers (might have been AR?), maybe 20
watts/channel. It actually sounded pretty good compared to the run-of-the
mill stuff back then. Of course, I doubt in the intervening 15 years, that
they ever replaced the "needle" in that Dual...

We had a Magnavox in my family that my dad purchased from a neighbor in
about 1960. While I was growing up, we always called it the "hi fi" (our
neighbor replaced it with a real hi fi). This thing had:

o A lousy FM tuner that drifted like crazy. You had to keep tuning it. AM
was stable and sensitive, but very narrowband.
o A rumbly record changer with a very low compliance crystal (not ceramic)
phono pickup. Tracked around 6 grams, maybe more. It sounded horrible.
o Maybe a 5 or 10 watt power amp. It might have been push-pull. I don't
remember the tube complement, but it had a 5Y3 rectifier which gives us some
idea of the amount of energy going *into* the circuit...
o The most horrible speaker system I ever saw. It had a very low compliance
12 inch "woofer" (with a very small magnet structure - the same open frame
rectangular assembly you would see on most cheap speakers built in the late
'50s), It can't have had any useful output below about 150Hz. I have no idea
why they needed a 12 inch speaker for a design like that, especially since
the cabinet was not tuned, sealed, or bass reflex. It was just open. The
sound from the back of the speaker simply radiated out of the back & bottom
of the cabinet (it stood on legs) and canceled out any wavelengths longer
than the distance from the speaker to the bottom of the front panel (about 8
inches).
o For the punch-line, it was a "two-way" speaker system. They coaxially
mounted a "tweeter" in front of the "woofer". The "tweeter" was another
conventional speaker about 4" in diameter. A non-polarized capacitor
provided the "crossover" -- or at least prevented whatever bass happened to
escape from the lousy electronics from frightening the "tweeter". The funny
thing is, they probably could have saved a lot of money, and achieved the
same mediocre result by using a single, slightly higher quality 6" speaker
with a whizzer cone.

Hi fi was certainly possible in those days, but most consumer products were
far from it. In the '60s, we called those big expensive stereo consoles
"coffins" because everything inside was dead. They were just musical
furniture, not audio equipment.

Karl Uppiano wrote:
"Arny Krueger" wrote in message
...
Codifus wrote:
wrote:

There's more functionality and acousticalt performance
in
a $400
boom box today than there was in a 1960's Magnavox
stereo
console.
Hell, there's even more magnet on them.


So I take it, then, that you don't like Magnavox, circa
1960s. LOL

Indeed. Maybe you had to be there...

I was.

The brown-box goods of the 60s were pretty horriffic.

For the most part. I do remember a friend of the family
bought a
Fisher stereo console in 1969 that was pretty impressive,
relatively
speaking. It had a Dual turntable with a magnetic pickup,
a
respectable AM/FM tuner, built-in pair of air suspension
speakers
(might have been AR?), maybe 20 watts/channel. It actually
sounded
pretty good compared to the run-of-the mill stuff back
then. Of
course, I doubt in the intervening 15 years, that they
ever replaced
the "needle" in that Dual...

That is all fine and good, but this is hardly your typical
brown-box goods of the 60s. It might not have even been a
Fisher product per se, but rather a bunch of
really-pretty-good audio components of the era assembled
into a piece of furniture by a local reseller. The tip-off
would be the AR speakers - Fisher had their own line of
speakers and they would have been used in a 100% Fisher
system.

"Arny Krueger" wrote in message
...
Karl Uppiano wrote:
"Arny Krueger" wrote in message
...
Codifus wrote:
wrote:

There's more functionality and acousticalt performance
in
a $400
boom box today than there was in a 1960's Magnavox
stereo
console.
Hell, there's even more magnet on them.


So I take it, then, that you don't like Magnavox, circa
1960s. LOL

Indeed. Maybe you had to be there...

I was.

The brown-box goods of the 60s were pretty horriffic.

For the most part. I do remember a friend of the family
bought a
Fisher stereo console in 1969 that was pretty impressive,
relatively
speaking. It had a Dual turntable with a magnetic pickup,
a
respectable AM/FM tuner, built-in pair of air suspension
speakers
(might have been AR?), maybe 20 watts/channel. It actually
sounded
pretty good compared to the run-of-the mill stuff back
then. Of
course, I doubt in the intervening 15 years, that they
ever replaced
the "needle" in that Dual...

That is all fine and good, but this is hardly your typical
brown-box goods of the 60s. It might not have even been a
Fisher product per se, but rather a bunch of
really-pretty-good audio components of the era assembled
into a piece of furniture by a local reseller. The tip-off
would be the AR speakers - Fisher had their own line of
speakers and they would have been used in a 100% Fisher
system.

This was all basically a Fisher product. Perhaps the speakers were Fisher.

I wasn't arguing with you. This was a better than average system.

"Karl Uppiano" wrote in message
news:V2jve.1173$4M1.639@trnddc07...
o For the punch-line, it was a "two-way" speaker system. They coaxially
mounted a "tweeter" in front of the "woofer". The "tweeter" was another
conventional speaker about 4" in diameter. A non-polarized capacitor
provided the "crossover" -- or at least prevented whatever bass happened
to
escape from the lousy electronics from frightening the "tweeter". The
funny
thing is, they probably could have saved a lot of money, and achieved the
same mediocre result by using a single, slightly higher quality 6" speaker
with a whizzer cone.

A "lot of money" for a crappy cone tweeter and a single capacitor?
I remember they were quite cheap even allowing for inflation.
Probably not much more than the extra cost for a whizzer cone really.
And it did give the marketing department something to write about :-)

MrT.

"Mr.T" MrT@home wrote in message
u...

"Karl Uppiano" wrote in message
news:V2jve.1173$4M1.639@trnddc07...
o For the punch-line, it was a "two-way" speaker system. They coaxially
mounted a "tweeter" in front of the "woofer". The "tweeter" was another
conventional speaker about 4" in diameter. A non-polarized capacitor
provided the "crossover" -- or at least prevented whatever bass happened
to
escape from the lousy electronics from frightening the "tweeter". The
funny
thing is, they probably could have saved a lot of money, and achieved the
same mediocre result by using a single, slightly higher quality 6"
speaker
with a whizzer cone.

A "lot of money" for a crappy cone tweeter and a single capacitor?
I remember they were quite cheap even allowing for inflation.
Probably not much more than the extra cost for a whizzer cone really.
And it did give the marketing department something to write about :-)

A lot of money is a relative term with mass-produced items. Even if the
parts are cheap, if they save a few pennies on the part, multiplied by the
number of units produced, especially when it had to be assembled by hand, it
adds up.

I agree with the marketing angle. I wonder what marketing wizard figured out
the price point where having the bullet point "two way crap speaker" made
them more money than the additional cost of the parts and assembly.

MrT.

On Mon, 20 Jun 2005 14:57:10 GMT, Steve Urbach
wrote:

On Mon, 20 Jun 2005 06:37:41 GMT, spudrick
wrote:

From an old Magnavox tube stereo. It used two cabinets, each with 3

What were the output tubes like? 50C5 and a small transformer for
each channel (class A, about two watts MAX)? or two output tubes and a
slightly larger transformer for each channel (now we're talking Class
AB power, maybe 5 to 10 watts)?

speakers. The largest is 15" but it only has a 1 inch or so magnet.
This is to save money or is there another reason? The other two
speakers had similar sized magnets on 6" and 2" speakers. It looks
like they had a capacitor across each speaker to divide the signal
into bass, mid, treble sections.
I salvaged the speakers to make a bass amp but they look kind of
anemic now that they're out of the cabs. What say all of you?

My offhand guess is they won't last ten seconds as speakers for a
bass guitar amp. You need decent woofers with large excursion, good
power handling, etc.

For good speakers, check out the outfits listed he
http://www.audioxpress.com/resource/...lace/index.htm
and also http://www.madisound.com which is inexplicably not listed in
the other link.

Some tube sets had 12-15" speakers with electro magnets (extra leads
to a coil near the typical magnet position) wired in series with the
B+ supply. IIRC these speakers also had a 3.2 ohm VC

Those are really old models (1940's, maybe?), where the
electromagnet or "field coil" was used instead of a permanent magnet.
This saved money, as the power supply generally had smallish value
electrolytic capacitors which were by themselves inadequate, and the
field coil was actually a large-inductance choke coil in the plate
supply that helped filter out the rectified plate voltage. If a
permanent-magnet loudspeaker were used, it would have still needed a
choke coil, so it was cheaper to have the coil in the speaker to
provide the field, and save the cost of the magnet.


, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org

-----
http://www.mindspring.com/~benbradley

"Karl Uppiano" wrote in message
news:lIBve.2869$J12.934@trnddc05...
A lot of money is a relative term with mass-produced items. Even if the
parts are cheap, if they save a few pennies on the part, multiplied by the
number of units produced, especially when it had to be assembled by hand,
it
adds up.

Agreed, and in this case the point I was making is that it adds up to very
little.

MrT.

"Mr.T" MrT@home wrote in message
u...

"Karl Uppiano" wrote in message
news:lIBve.2869$J12.934@trnddc05...
A lot of money is a relative term with mass-produced items. Even if the
parts are cheap, if they save a few pennies on the part, multiplied by
the
number of units produced, especially when it had to be assembled by hand,
it
adds up.

Agreed, and in this case the point I was making is that it adds up to very
little.

Ok, fine.