Discussion:
Fisher STV-875 speakers-need specs
(too old to reply)
duty-honor-country
2006-09-10 16:16:53 UTC
Permalink
does anyone know the efficiency rating of these vintage speakers ??

they are:

100 Watt power rating rms per cabinet

15" woofer
4" midrange
3" tweeter

36" H x 17" W x 13" D cabinets
Peter Wieck
2006-09-10 22:17:18 UTC
Permalink
Post by duty-honor-country
does anyone know the efficiency rating of these vintage speakers ??
They are very typical Junk Speakers from the late 70s, when Fisher went
Pacific Rim and the buyer of the name attempted to cash in on their
former reputation. About anything with a 15" woofer of that era, that
could be lifted by one person without assistance were of similar ilk
and similar value... essentially nothing. As to efficiency, given that
the heaviest magnet inside those beasts might approximate 10 ounces,
they will make lots-O-noise on not much power... a good match to
Fisher's Pacific rim electronics of the time measuring power in IPP vs.
RMS. So, likely greater than 90dB SPL @ one meter @ one watt... However
what comes out will be at-best the second cousin of what went in.

Run, don't walk away.

Peter Wieck
Wyncote, PA
duty-honor-country
2006-09-14 23:18:53 UTC
Permalink
Post by Peter Wieck
Post by duty-honor-country
does anyone know the efficiency rating of these vintage speakers ??
They are very typical Junk Speakers from the late 70s, when Fisher went
Pacific Rim and the buyer of the name attempted to cash in on their
former reputation. About anything with a 15" woofer of that era, that
could be lifted by one person without assistance were of similar ilk
and similar value... essentially nothing. As to efficiency, given that
the heaviest magnet inside those beasts might approximate 10 ounces,
they will make lots-O-noise on not much power... a good match to
Fisher's Pacific rim electronics of the time measuring power in IPP vs.
what comes out will be at-best the second cousin of what went in.
Run, don't walk away.
Peter Wieck
Wyncote, PA
Pete- the magnets on those woofers weigh several POUNDS. You better
have 2 hands on them when you pick them up too.
Peter Wieck
2006-09-15 00:43:54 UTC
Permalink
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS. You better
have 2 hands on them when you pick them up too.
With respect, the entire set of drivers may weigh pounds, but I doubt
very seriously that any single magnet exclusive of the spider, frame
and center armature (all inert parts) weighs more than the 10 ounces I
originally suggested.

These were cheap Pacific Rim speakers manufactured for flash and visual
impact. They were not manufactured to anything approaching the
standards of even their mid-quality US contemporaries such as AR,
Advent, ADS and others. And they most certainly cheaped out on the
magnets.

They are going to look something like this:

http://cgi.ebay.com/Fisher-3-Way-Speakers-STV-9538-Studio-Standard_W0QQitemZ320025955207QQihZ011QQcategoryZ14993QQrdZ1QQcmdZViewItem

And possibly be marked as those: "Assembled in USA", but the only parts
of them that are American is the particle board and glue. The drivers
were made by Sanyo.

Junk.

Peter Wieck
Wyncote, PA
duty-honor-country
2006-09-15 21:45:27 UTC
Permalink
Post by Peter Wieck
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS. You better
have 2 hands on them when you pick them up too.
With respect, the entire set of drivers may weigh pounds, but I doubt
very seriously that any single magnet exclusive of the spider, frame
and center armature (all inert parts) weighs more than the 10 ounces I
originally suggested.
These were cheap Pacific Rim speakers manufactured for flash and visual
impact. They were not manufactured to anything approaching the
standards of even their mid-quality US contemporaries such as AR,
Advent, ADS and others. And they most certainly cheaped out on the
magnets.
http://cgi.ebay.com/Fisher-3-Way-Speakers-STV-9538-Studio-Standard_W0QQitemZ320025955207QQihZ011QQcategoryZ14993QQrdZ1QQcmdZViewItem
And possibly be marked as those: "Assembled in USA", but the only parts
of them that are American is the particle board and glue. The drivers
were made by Sanyo.
Junk.
Peter Wieck
Wyncote, PA
Peter- have you ever removed a 15" woofer from any cabinet ?

The magnets on those are HUGE- they weigh a lot more then 10 oz.
duty-honor-country
2006-09-15 21:46:02 UTC
Permalink
Post by Peter Wieck
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS. You better
have 2 hands on them when you pick them up too.
With respect, the entire set of drivers may weigh pounds, but I doubt
very seriously that any single magnet exclusive of the spider, frame
and center armature (all inert parts) weighs more than the 10 ounces I
originally suggested.
These were cheap Pacific Rim speakers manufactured for flash and visual
impact. They were not manufactured to anything approaching the
standards of even their mid-quality US contemporaries such as AR,
Advent, ADS and others. And they most certainly cheaped out on the
magnets.
http://cgi.ebay.com/Fisher-3-Way-Speakers-STV-9538-Studio-Standard_W0QQitemZ320025955207QQihZ011QQcategoryZ14993QQrdZ1QQcmdZViewItem
And possibly be marked as those: "Assembled in USA", but the only parts
of them that are American is the particle board and glue. The drivers
were made by Sanyo.
Junk.
Peter Wieck
Wyncote, PA
ps- I pulled the 15" woofers from the JVC speakers I just sold on Ebay,
to inspect the inside of the cabinet- you could not hold the woofer
with one hand, that's how heavy it was. And it wasn't the spider frame
that weighed that. It was the magnet.

Just about any cheapo or expensive 15" woofer made after 1975, had a
huge magnet on it. You are thinking pre-1970, in that case yes, there
are some large 12" and 15" speakers that had smallish magnets on them-
in the old console stereos.

Not so in the later floor standing speakers. The one thing those
speakers DID have was bass hit- and that's how they got it, with huge
magnets.
Peter Wieck
2006-09-15 23:16:00 UTC
Permalink
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS. You better
have 2 hands on them when you pick them up too.
Charlie:

You really need to look at those speakers from a practical point of
view. No matter how much you wish to believe otherwise, they are crap.
And no matter how much they weigh, as another has noted, the actual
magnet is the weakest link in the chain. Again, I would suggest that
you pull the woofer and really look at what is actual "magnet" and what
is not. Even from 100 miles away, I can guarantee that you will be
unpleasantly surprised.

I may need two hands and a Sherpa Guide to lift the tweeter, much less
the woofer, but that does not make the speakers overall any better than
$0.02 cents per pound yard-sale leavings.

Peter Wieck
Wyncote, PA
d***@cartchunk.org
2006-09-16 01:28:16 UTC
Permalink
Post by duty-honor-country
Not so in the later floor standing speakers. The one thing those
speakers DID have was bass hit- and that's how they got it, with huge
magnets.
Actually, quite the opposite is true. All other things being
equal, the smaller the magnet the MORE relative bass
the speaker can have. Having TOO much magnet results
in the system being overdamped. The result is a frequency
response which is substantially lowered in the bass
relative to the midrange. As you decrease the flux density
in the gap, the damping of the speaker is reduced and
the response in the bass relative to the midrange increases
until the speaker reaches a point where the bass output
exceeds that of the midrange.
Chris Malcolm
2006-09-22 18:31:55 UTC
Permalink
Post by d***@cartchunk.org
Post by duty-honor-country
Not so in the later floor standing speakers. The one thing those
speakers DID have was bass hit- and that's how they got it, with huge
magnets.
Actually, quite the opposite is true. All other things being
equal, the smaller the magnet the MORE relative bass
the speaker can have. Having TOO much magnet results
in the system being overdamped. The result is a frequency
response which is substantially lowered in the bass
relative to the midrange. As you decrease the flux density
in the gap, the damping of the speaker is reduced and
the response in the bass relative to the midrange increases
until the speaker reaches a point where the bass output
exceeds that of the midrange.
Quite, but if you are improving bass power delivery by reducing
damping, you're using resonances to boost output, and thus reducing
the fidelity with which the acoustic output tracks the detail of the
electrical input, are you not?
--
Chris Malcolm ***@infirmatics.ed.ac.uk DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]
d***@cartchunk.org
2006-09-15 21:47:08 UTC
Permalink
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS.
You better have 2 hands on them when you pick them up too.
So?

Magnet weight is in fact, a poor indication of quality and
design integrity. The material used for those magnets,
a barium or strontium ferrite ceramic, is not particularily
expensive. There's an important rule about loudspeaker
magnets:

"The right amount of magnet is the right
amount of magnet."

That means that a magnet can be too large as easily as it
can be too small.

Basically, you cannot judge the quality of a speaker by
how many hands it takes to lift it. It's possible (and, given
the type of system you're talking about, not unlikely at all),
that despite the size of the magnet, the actual flux density
in the voice coil gap and the volume of the voice coil gap
is fairly low. No matter how much magnet you stick, the
soft iron portions of the magnet circuit limit the flux density,
with all the extra energy from the large magnet simply
being wasted in leakage flux. We also don't know yet
what the parameters of the voice coil are, and that's
just as important as the magnet. In the vast majority of
these kinds of speakers, you'd be far better off reducing
the size of the magnet to something that's more efficient,
doing a better job of designing the magnet circuit to better
utilize the total flux you have, and then spending the money
saved on better cone materials, better crossover, better
drivers and a real design.

Fisher was once a fairly prestigious company 30-40 years
ago. The only piece of that legacy that remains is the name,
and names such as Fisher and Scott and Sherwood and
KLH are simply commodity items that are to be and have
been bought and sold on the open market. They are applied
to whatever mass-market crapola the current owner thinks
will make his investment in the name worth it. If it doesn't,
then sell the name to the next merchant.

From the name and the magnet size, I would posit that
the speakers are worth no more than yard-sale prices.
duty-honor-country
2006-09-17 14:41:58 UTC
Permalink
Post by d***@cartchunk.org
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS.
You better have 2 hands on them when you pick them up too.
So?
Magnet weight is in fact, a poor indication of quality and
design integrity. The material used for those magnets,
a barium or strontium ferrite ceramic, is not particularily
expensive. There's an important rule about loudspeaker
"The right amount of magnet is the right
amount of magnet."
That means that a magnet can be too large as easily as it
can be too small.
Basically, you cannot judge the quality of a speaker by
how many hands it takes to lift it. It's possible (and, given
the type of system you're talking about, not unlikely at all),
that despite the size of the magnet, the actual flux density
in the voice coil gap and the volume of the voice coil gap
is fairly low. No matter how much magnet you stick, the
soft iron portions of the magnet circuit limit the flux density,
with all the extra energy from the large magnet simply
being wasted in leakage flux. We also don't know yet
what the parameters of the voice coil are, and that's
just as important as the magnet. In the vast majority of
these kinds of speakers, you'd be far better off reducing
the size of the magnet to something that's more efficient,
doing a better job of designing the magnet circuit to better
utilize the total flux you have, and then spending the money
saved on better cone materials, better crossover, better
drivers and a real design.
Fisher was once a fairly prestigious company 30-40 years
ago. The only piece of that legacy that remains is the name,
and names such as Fisher and Scott and Sherwood and
KLH are simply commodity items that are to be and have
been bought and sold on the open market. They are applied
to whatever mass-market crapola the current owner thinks
will make his investment in the name worth it. If it doesn't,
then sell the name to the next merchant.
From the name and the magnet size, I would posit that
the speakers are worth no more than yard-sale prices.
I asked for the efficiency rating of the speakers, not the value, or
your (misinformed) opinion on magnet size

besides, first the magnets are too small, now they're too big, so which
is it ?

you both have a severe case of contrary-net-itis
Peter Wieck
2006-09-17 16:29:51 UTC
Permalink
about contrariness...
I already gave you an efficiency rating, based on the quality of the
product. High. Keep in mind that if your contention is correct and
these beasts do have monster-magnets, the efficiency will drop like a
stone. This is not the case here.

The speakers are noise-makers designed against the Fisher electronics
of the day, which were from an emphatically low-end division of Sanyo.
So they will be very efficient of necessity not any of effort towards
quality.

Peter Wieck
Wyncote, PA
d***@cartchunk.org
2006-09-17 20:21:07 UTC
Permalink
Post by duty-honor-country
Post by d***@cartchunk.org
Post by duty-honor-country
Pete- the magnets on those woofers weigh several POUNDS.
You better have 2 hands on them when you pick them up too.
Magnet weight is in fact, a poor indication of quality and
design integrity. The material used for those magnets,
a barium or strontium ferrite ceramic, is not particularily
expensive. There's an important rule about loudspeaker
"The right amount of magnet is the right
amount of magnet."
That means that a magnet can be too large as easily as it
can be too small.
Basically, you cannot judge the quality of a speaker by
how many hands it takes to lift it. It's possible (and, given
the type of system you're talking about, not unlikely at all),
that despite the size of the magnet, the actual flux density
in the voice coil gap and the volume of the voice coil gap
is fairly low.
I asked for the efficiency rating of the speakers, not the value, or
your (misinformed) opinion on magnet size
So, you are better informed on the design and implementation
of magnet systems for loudspeakers? If so, could you kindly
point out where, in my post, I am technically "misinformed.,"
as opposed to your blanket, whitewash retort that is devoid
of any technical specifics?
Post by duty-honor-country
besides, first the magnets are too small, now they're too
big, so which is it ?
"The right amount of magnet is the right amount of magnet."

The right sized magnet is the right sized magnet. You have
provided not a single shred of evidence that the magnets
are anything other than "big." And for a properly designed
loudspeaker, "bigger" DOES NOT tyranslate to "better."
For a loudspeaker to perform correctly for a given design,
the electromagnetic induction ratio, aka, the Bl product,
needs to be the right value, not one higher or lower.

Having, in fact, measured several hundred of exactly the
type of loudspeaker you are describing, speakers which, by
the way, are NOT manufactured by the "label," but rather are
jobbed out to domestic cabinet manufacturers that have
little or no design facilities, are general simply assemblages
of the least expensive set of components available and with
little or no "design." That they have such huge magnets is
immaterial to their performance indeed to their overall
efficiency, for the reasons I stated in my earlier post.
Post by duty-honor-country
you both have a severe case of contrary-net-itis
No, I have have a case of "tell it like it is," supported by
well over a quarter of a century as a professional designer
in the loudspeaker business. Clearly, that experience is
contrary to yours. Once of the manifestations of that difference
is that I will provide the TECHNICAL reasoning behind my
TECHNICAL assertions, and those assertions can be tested
on their technical merits, as opposed to simple, technically
content free statements such as "(misinformed) opinion on
magnet size," "you better have 2 hands on them when you
pick them up," "speakers DID have bass hit- and that's how
they got it, with huge magnets," and the rest. The last is the
only one with any technical content, and it is provably incorrect.

You may or may not agree with the technical assertions
made, you may or may not, in fact, LIKE the implications
of such assertions: that's certainly your perogative. But I
might kindly suggest you deal with the implecations and
content of the message, and stop blaming the messenger
for details of the physical word that may be discordant
with your view of it.
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