[Trevor]

On 2/12/2014 12:19 AM, wrote:
geoff: My 1995 JVC receiver specifies 8-16ohms. Guess that's an oldie then!


Many cheap receivers with limited current capability specify 8 ohms or
more, regardless of age. Conversely many good amps can handle loads as
low as 2 ohms without a problem.

Trevor.

[[email protected]]

Thanks Trevor! Everyone who visits my place think I have a nice sounding system, cheapo receiver aside. smh...

http://www.hifiengine.com/files/imag....prev iew.jpg

[Trevor]

On 3/12/2014 10:28 AM, wrote:
Thanks Trevor! Everyone who visits my place think I have a nice sounding system, cheapo receiver aside. smh...

http://www.hifiengine.com/files/imag....prev iew.jpg


As always, as long as it can drive your speakers, the speakers and room
(and quality of source material) determine the sound quality, NOT your
receiver! And your friends probably have no idea what good sound is
anyway. Most don't.

Trevor.

[[email protected]]

Trevor wrote:

"On 3/12/2014 10:28 AM, wrote:
Thanks Trevor! Everyone who visits my place think I have a nice sounding system, cheapo receiver aside. smh...

http://www.hifiengine.com/files/imag....prev iew.jpg


As always, as long as it can drive your speakers, the speakers and room
(and quality of source material) determine the sound quality, NOT your
receiver! And your friends probably have no idea what good sound is
anyway. Most don't.

Trevor. "

Well, perhaps we could arrange for you to come and listen to my cheap, crappy receiver & speakers and decide for yourself, thank you very much.

[Trevor]

On 5/12/2014 12:08 AM, wrote:
Trevor wrote:
"On 3/12/2014 10:28 AM, wrote:
Thanks Trevor! Everyone who visits my place think I have a nice sounding system, cheapo receiver aside. smh...

http://www.hifiengine.com/files/imag....prev iew.jpg


As always, as long as it can drive your speakers, the speakers and room
(and quality of source material) determine the sound quality, NOT your
receiver! And your friends probably have no idea what good sound is
anyway. Most don't.

Well, perhaps we could arrange for you to come and listen to my cheap, crappy receiver & speakers and decide for yourself, thank you very much.

I seriously doubt that's gonna happen, but the real question is "why do
you care what others think anyway"? As long as YOU are happy!

Trevor.

[Mark Zacharias]

"Trevor" wrote in message
...
On 2/12/2014 12:19 AM, wrote:
geoff: My 1995 JVC receiver specifies 8-16ohms. Guess that's an oldie
then!


Many cheap receivers with limited current capability specify 8 ohms or
more, regardless of age. Conversely many good amps can handle loads as low
as 2 ohms without a problem.

Trevor.




Speaker impedances have not really changed - they are rating them a bit more
accurately these days.

Mark Z.

[Trevor]

On 3/12/2014 12:21 AM, Mark Zacharias wrote:
"Trevor" wrote in message
...
On 2/12/2014 12:19 AM, wrote:
geoff: My 1995 JVC receiver specifies 8-16ohms. Guess that's an
oldie then!


Many cheap receivers with limited current capability specify 8 ohms or
more, regardless of age. Conversely many good amps can handle loads as
low as 2 ohms without a problem.



Speaker impedances have not really changed - they are rating them a bit
more accurately these days.

Mark Z.


Partly true to the second part, mostly no to the first part. Some
manufacturers use the impedance minimum fairly closely these days.
Others are just an estimate of what they think the amp rating should be.
But speaker impedances HAVE generally dropped over the last 50 years or
so. First with the change from valve amps they generally went from
~16ohm to 8ohm. Then with the improvement in current handling of
transistor amps (and the increase in multiple small bass drivers vs one
larger driver), many have dropped from ~8ohm to ~6 or 4 ohm.
In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but the voice coil *resistance* of
many drivers has decreased. That affects the system impedance, and is
easy to measure. And some manufacturers still produce their drivers with
voice coil resistance options, or even custom make them if you buy enough.

Trevor.

[[email protected]]

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?

[chuck]

On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard, the manufacturers can list whatever
impedance they want; within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.

[[email protected]]

chuck:

That's the problem: No standards. I was told about some standard for audio(measurement) that was abandoned in the '70s or thereabouts. Forgot the name of it.

[Trevor]

On 5/12/2014 2:42 AM, wrote:
chuck:

That's the problem: No standards.
I was told about some standard for audio(measurement) that was
abandoned in the '70s or thereabouts.
Forgot the name of it.


The great thing about standards is there are so many to choose from! :-)

Trevor.

[[email protected][_2_]]

On Thursday, December 4, 2014 8:42:57 AM UTC-7, wrote:
chuck:

That's the problem: No standards.

Nope, IEC 60268-5 (and its predecessor IEC 268-5) has been in effect
for decades and is quite current. There are any number of nationalized
versions of the same standard as well.

I was told about some standard for audio(measurement) that
was abandoned in the '70s or thereabouts.

No, it was never "abandoned" by anyone. Any number of manufacturers
may fail to follow it, but it is hardly abandoned.

Forgot the name of it.

IEC 60268-5

Dick Pierce

[geoff]

On 5/12/2014 4:40 a.m., chuck wrote:
On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:

Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard, the manufacturers can list whatever
impedance they want; within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.



Some do specify a 'minimum impedance', and some even at what frequency
that occurs. And the minimum *is* the most relevant.


geoff

[[email protected]]

On Thursday, December 4, 2014 8:40:49 AM UTC-7, chuck wrote:
On Thu, 4 Dec 2014 05:10:48 -0800 (PST), wrote:
So given that, the question should be, are mfgs listing the
avg, max, or min impedance on the cabinet spec sticker?


Since there is no standard,

Wrong, there has been in existence for several decades, a widely
accepted standard for measuring ans specifying impedance. IEC
60268-5:
16 Impedance and Derivative Characteristics
16.1 Rated impedance - characteristic to be specified
NOTE This is a rated condition in accordance with 3.2.1.
The lowest value of the modulus of the impedance in the
rated frequency range shall be not less than 50% of the
rated impedance. If the impedance at any frequency
outside this range (including d.c.) is less than this
value, this shall be stated in the specifications.
16.2 Impedance curve
16.2.1 Characteristics to be specified
The impedance curve shall be specified, with represen-
tation of the modulus of the impedance as a function of
frequency.
16.2.2 Method of measurement
16.2.2.1 The loudspeaker shall be brought under normal
measuring conditions in accordance with 3.2.2
conditions a), b), and d).
16.2.2.2 A constant voltage or current shall be supplied,
the former usually being preferred. The value of voltage
or current chosen for the measurement shall be sufficiently
small to ensure that the loudspeaker operates in a linear
region.
Note Measurement of impedance may be strongly influenced
by drive level. If the level is either too low or too
high, inaccurate results may be obtained. The data should
be examined for consistency at several drive levels in
order to establish the best conditions.
16.2.2.3 The modulus of impedance shall be measured at least
over the range of 20 Hz to 20 000 Hz.
16.2.2.4 The results shall be presented graphically as a
function of frequency. The value of the voltage or the
current shall be stated with the results.

the manufacturers can list whatever impedance they want;

Well, more accurately: the manufacturers can choose to ignore
common, well established and agreed upon standards and can
thus make up any damned number they want. Unfortunately,
not a few do just that.

within the range of impedances that the speaker
has in its frequency range. For example, some speakers rated at 4
ohms dip below 2 ohms at certain frequencies.

And, if they so choose to follow the standard, they must state so.

Dick Pierce

[Trevor]

On 5/12/2014 12:10 AM, wrote:
Trevor wrote: "In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but"

So given that, the question should be, are mfgs listing the avg, max, or min impedance
on the cabinet spec sticker?

The simple answer to that is no (unless by chance), no, and some.

Trevor.

[Mark Zacharias]

"Trevor" wrote in message
...
On 3/12/2014 12:21 AM, Mark Zacharias wrote:
"Trevor" wrote in message
...
On 2/12/2014 12:19 AM, wrote:
geoff: My 1995 JVC receiver specifies 8-16ohms. Guess that's an
oldie then!


Many cheap receivers with limited current capability specify 8 ohms or
more, regardless of age. Conversely many good amps can handle loads as
low as 2 ohms without a problem.



Speaker impedances have not really changed - they are rating them a bit
more accurately these days.

Mark Z.


Partly true to the second part, mostly no to the first part. Some
manufacturers use the impedance minimum fairly closely these days. Others
are just an estimate of what they think the amp rating should be. But
speaker impedances HAVE generally dropped over the last 50 years or so.
First with the change from valve amps they generally went from ~16ohm to
8ohm. Then with the improvement in current handling of transistor amps
(and the increase in multiple small bass drivers vs one larger driver),
many have dropped from ~8ohm to ~6 or 4 ohm.
In any case ALL speakers vary wildly in *impedance* across the frequency
range, especially ported speakers, but the voice coil *resistance* of many
drivers has decreased. That affects the system impedance, and is easy to
measure. And some manufacturers still produce their drivers with voice
coil resistance options, or even custom make them if you buy enough.

Trevor.




What I meant to suggest is that so-called "8-ohm" speakers have always
actually been closer to 5 or 6 ohms. Should have been clearer.

mz

[Peter Larsen[_3_]]

"Mark Zacharias" skrev i en meddelelse
...

What I meant to suggest is that so-called "8-ohm" speakers have always
actually been closer to 5 or 6 ohms. Should have been clearer.

And this is because the loudspeaker impedance spec still just tries to tell
you what tap on an output transformer it is suggested that you should use.

It does however appears to be so that some manufacturers "slide" some of
their "8 ohm" designs down in load impedance to get them just a wee bit
louder in practical use because it allows them to use less magnet or because
more magnet does not fit the chassis well, as could be the case with the
Coral 8F60.

Unfortunately it didn't have the powerhandling to match the increased power
drawn from the amplifier and/or was optimistically spec'ed by Coral, be
warned ye that gather Coral stuff, divide its powerhandling spec by 2 or 3,
there are no more repkits, even if the 2420 kit will fit a M100 physically.

I don't really know whether they also get away with using less copper, that
would be a win win. But I wonder, I remember Dick Pierce explaining how
design parameters fit in a way that suggests that a nominal 8 Ohm design is
the most cost & power efficient.

On a more serious note: transistor amplifiers should be able to drive half
the nominal loudspeaker load because that is how the real world loudspeaker
load is likely to look anyway once phase between voltage and current is
allowed for. Note that this phase angle issue between voltage and current
means that the zero crossing in AC is an unplesant place to be for an
amplifier with current being ordered from the loudspeaker and no output
voltage available.

mz

Kind regards

Peter Larsen

[geoff]

On 7/12/2014 1:01 p.m., Mark Zacharias wrote:

Trevor.




What I meant to suggest is that so-called "8-ohm" speakers have always
actually been closer to 5 or 6 ohms. Should have been clearer.

mz

That is equally false. An 8 ohm driver will often have a DC RESISTANCE
often around 6 ohms, but it's impedance will likely be very different,
and change with frequency.

Then throw in a crossover network and you'll have even wider variation.


geoff

[Mark Zacharias]

"geoff" wrote in message
...
On 7/12/2014 1:01 p.m., Mark Zacharias wrote:

Trevor.




What I meant to suggest is that so-called "8-ohm" speakers have always
actually been closer to 5 or 6 ohms. Should have been clearer.

mz

That is equally false. An 8 ohm driver will often have a DC RESISTANCE
often around 6 ohms, but it's impedance will likely be very different, and
change with frequency.

Then throw in a crossover network and you'll have even wider variation.


geoff


Exactly. If you plot the impedance curve of an 8-ohm speaker, the impedance
will generally, but not always, drop below 5 ohms at resonance. This has
been true for over 40 years.

When I said impedance, I meant impedance, not DC resistance.

This is getting to be just tiresome nit-picking. You aren't even making a
distinction here, because I essentially said the SAME thing.


Mark Z.

[geoff]

On 10/12/2014 12:31 a.m., Mark Zacharias wrote:
"geoff" wrote in message
...
On 7/12/2014 1:01 p.m., Mark Zacharias wrote:

Trevor.




What I meant to suggest is that so-called "8-ohm" speakers have always
actually been closer to 5 or 6 ohms. Should have been clearer.

mz

That is equally false. An 8 ohm driver will often have a DC
RESISTANCE often around 6 ohms, but it's impedance will likely be very
different, and change with frequency.

Then throw in a crossover network and you'll have even wider variation.


geoff


Exactly. If you plot the impedance curve of an 8-ohm speaker, the
impedance will generally, but not always, drop below 5 ohms at
resonance. This has been true for over 40 years.

When I said impedance, I meant impedance, not DC resistance.

This is getting to be just tiresome nit-picking. You aren't even making
a distinction here, because I essentially said the SAME thing.


Mark Z.


"5 or 6 ohms" is a bit specific for impedance, - which could be over a
wider range. DC resistance is almost universally around 6.3
ohms....ish. But less "ish" than your impedance figure.

But we are splitting hairs, so let's drop it.

geoff