[Paul[_13_]]

12" Woofer cone distorts badly, due to torn paper
cone:

http://www.jblpro.com/pub/obsolete/Control_12sr.pdf

I believe the tweeter is fine.

Can anyone recommend a replacement woofer?

I've never tried re-coning: Is it relatively successful
the first time? I am good with my hands.

Thanks for any good feedback.....

[david gourley[_2_]]

Paul said...news

12" Woofer cone distorts badly, due to torn paper
cone:

http://www.jblpro.com/pub/obsolete/Control_12sr.pdf

I believe the tweeter is fine.

Can anyone recommend a replacement woofer?

I've never tried re-coning: Is it relatively successful
the first time? I am good with my hands.

Thanks for any good feedback.....


You can find recone kits on eBay or SimplySpeakers.com. I got an edge kit
for some JBL 4408s and that turned out ok.

I would verify the type of voice coil before ordering to ensure a match.

david

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Scott Dorsey]

In article , Paul wrote:
12" Woofer cone distorts badly, due to torn paper
cone:

http://www.jblpro.com/pub/obsolete/Control_12sr.pdf

I believe the tweeter is fine.

Can anyone recommend a replacement woofer?

You want an exact equivalent from JBL. You might be able to make something
else work by selecting parameters carefully, but you really don't want to do
that.

The Control 12 is not sufficiently precision equipment that I'd worry about
replacing just one woofer in the pair, though.

If it were me, I'd pull the old woofer and send it to Cardinal Sound and
Motion Picture in Baltimore and have them recone it. They are a JBL factory
repair shop and do good work.

I've never tried re-coning: Is it relatively successful
the first time? I am good with my hands.

Ten years ago I would have told you not to try it unless you had someone with
you who had done it to show you exactly what it should look like lined up,
but these days with a million Youtube videos out there, you might do well
enough just to watch a few of them and see what everything is supposed to
look like. It's not rocket science, but it's fairly precise work making sure
everything is shimmed up and moves straight.

The problem is getting the kit from JBL if you aren't an authorized dealer.
And I would suggest avoiding the third-party kits which are fine if you are
just replacing the surround but aren't going to be a perfect match for the
voice coil and spider.

If it were me, I'd ship it to Cardinal but if you want to do it yourself it's
a good thing to learn to do. And this is a comparatively easy driver to learn
on.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[geoff]

On 7/02/2017 7:42 AM, Scott Dorsey wrote:

The problem is getting the kit from JBL if you aren't an authorized dealer.
And I would suggest avoiding the third-party kits which are fine if you are
just replacing the surround but aren't going to be a perfect match for the
voice coil and spider.

If it were me, I'd ship it to Cardinal but if you want to do it yourself it's
a good thing to learn to do. And this is a comparatively easy driver to learn
on.
--scott



Generally a straightforward procedure, if you don't panic !

But doubt the idea of a generic re-cone kit, as there may well be
significant(?) differences in weight, stiffness, compliance, etc of
cone, surround, leadout, and spider material. And then there are the
voice-coil material/gauge/wire-shape/windings/fluid, former, etc.

So I'd say go with a genuine recone kit if you can get it, or if not
maybe recone both woofers with the same kit.

..... if you consider the speakers worth it.

Or pick up another used pair complete, then you'll still have a spare
for next time !

geoff

[[email protected]]

Or pick up another used pair complete, then you'll still have a spare
for next time !



depending upon how bad the rips.... some well applied Elmer's glue could work?

m

[Scott Dorsey]

In article ,
wrote:

Or pick up another used pair complete, then you'll still have a spare
for next time !

depending upon how bad the rips.... some well applied Elmer's glue could work?

I'd never recommend that on a precision device since it's going to change
the breakup behaviour considerably. But on a Control 12, I might try it
before investing any money.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul[_13_]]

On 2/6/2017 11:42 AM, Scott Dorsey wrote:
In article , Paul wrote:
12" Woofer cone distorts badly, due to torn paper
cone:

http://www.jblpro.com/pub/obsolete/Control_12sr.pdf

I believe the tweeter is fine.

Can anyone recommend a replacement woofer?

You want an exact equivalent from JBL. You might be able to make something
else work by selecting parameters carefully, but you really don't want to do
that.

The Control 12 is not sufficiently precision equipment that I'd worry about
replacing just one woofer in the pair, though.

If it were me, I'd pull the old woofer and send it to Cardinal Sound and
Motion Picture in Baltimore and have them recone it. They are a JBL factory
repair shop and do good work.

Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?



I've never tried re-coning: Is it relatively successful
the first time? I am good with my hands.

Ten years ago I would have told you not to try it unless you had someone with
you who had done it to show you exactly what it should look like lined up,
but these days with a million Youtube videos out there, you might do well
enough just to watch a few of them and see what everything is supposed to
look like. It's not rocket science, but it's fairly precise work making sure
everything is shimmed up and moves straight.

The problem is getting the kit from JBL if you aren't an authorized dealer.
And I would suggest avoiding the third-party kits which are fine if you are
just replacing the surround but aren't going to be a perfect match for the
voice coil and spider.

If it were me, I'd ship it to Cardinal but if you want to do it yourself it's
a good thing to learn to do. And this is a comparatively easy driver to learn
on.

[Phil Allison[_4_]]

Paul wrote:



Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?


** The JBL 2206H would be a good one, the magnet is bigger so make sure there is room for it .

http://www.parts-express.com/jbl-220...river--294-480


..... Phil

...... Phil

[Scott Dorsey]

In article , Paul wrote:

If it were me, I'd pull the old woofer and send it to Cardinal Sound and
Motion Picture in Baltimore and have them recone it. They are a JBL factory
repair shop and do good work.

Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?

Not without knowing the T-S parameters of the original driver and even then
you will take some fiddling around to make sure it matches well. If you pull
the working driver and measure Fs and Vas and estimate Xmax by eye you can
likely get fairly close.

But really, I wouldn't do this. Because you'll find you wind up spending a
lot more money than you would just getting the replacement from JBL. It
won't be that expensive.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul[_13_]]

On 2/6/2017 5:18 PM, Phil Allison wrote:
Paul wrote:



Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?


** The JBL 2206H would be a good one, the magnet is bigger so make sure there is room for it .

http://www.parts-express.com/jbl-220...river--294-480


Whoa! 600 Watts continuous!

I only need 200 Watts!

[Mike Rivers[_2_]]

On 2/6/2017 7:50 PM, Paul wrote:
Whoa! 600 Watts continuous!

I only need 200 Watts!

Then you won't blow it up.



--

For a good time, call http://mikeriversaudio.wordpress.com

[Scott Dorsey]

In article , Paul wrote:
On 2/6/2017 5:18 PM, Phil Allison wrote:
Paul wrote:



Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?


** The JBL 2206H would be a good one, the magnet is bigger so make sure there is room for it .

http://www.parts-express.com/jbl-220...river--294-480


Whoa! 600 Watts continuous!

I only need 200 Watts!


Speaker power ratings are pretty random, and are actually the least important
of all the numbers that you care about.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul[_13_]]

On 2/6/2017 6:49 PM, Scott Dorsey wrote:
In article , Paul wrote:
On 2/6/2017 5:18 PM, Phil Allison wrote:
Paul wrote:



Ok, I'm going to use this speaker as a stand-alone unit: There is
no other speaker, so I don't need to match anything.

Let's say I wanted to just buy a speaker replacement: Can anyone
recommend a good one?


** The JBL 2206H would be a good one, the magnet is bigger so make sure there is room for it .

http://www.parts-express.com/jbl-220...river--294-480


Whoa! 600 Watts continuous!

I only need 200 Watts!


Speaker power ratings are pretty random, and are actually the least important
of all the numbers that you care about.

What kind of a retarded statement is that?

Ok, I'll just put a 50 Watt speaker into it, and then drive it
with 200 Watts RMS continuous!

NOT A GOOD IDEA!

[Paul[_13_]]

On 2/6/2017 6:31 PM, Mike Rivers wrote:
On 2/6/2017 7:50 PM, Paul wrote:
Whoa! 600 Watts continuous!

I only need 200 Watts!

Then you won't blow it up.


True, but I don't want to over-engineer it!

:/

[Phil Allison[_4_]]

Paul wrote:
On 2/6/2017 6:31 PM, Mike Rivers wrote:
On 2/6/2017 7:50 PM, Paul wrote:
Whoa! 600 Watts continuous!

I only need 200 Watts!

Then you won't blow it up.


True, but I don't want to over-engineer it!



**The original speaker used a 3 inch voice coil and smaller magnet while the 2206H uses a 4 inch voice coil and larger magnet - hence the extra power rating.

Otherwise they are nearly identical as both have JBL's "Vented Gap Cooling" which really works.



..... Phil

[Mike Rivers[_2_]]

On 2/6/2017 11:58 PM, Paul wrote:
Ok, I'll just put a 50 Watt speaker into it, and then drive it
with 200 Watts RMS continuous!

NOT A GOOD IDEA!

No, it isn't a good idea, but then why would you do that other than to
see if you can blow the speaker? A loudspeaker's power rating is more a
limit than a requirement. Sensitivity is what describes how loud it will
be for a given input power. If you're going to use published
specifications as your guide to choosing a component (and indeed there
are good reasons to do that, sometimes, for some components), you should
understand what those specifications actually mean.

You wouldn't want to use an electrolytic capacitor rated at 250 volts in
a circuit where it never sees more than 2 volts across it, because it
may not be close to its specified value that far away from its rated
working voltage. Nor would you put a 25 volt capacitor in a circuit
where it sees 250 volts - but there's a different reason for that.

Remember, too, that the difference between 400 watts and 200 watts is
only 3 dB.

--

For a good time, call http://mikeriversaudio.wordpress.com

[Paul[_13_]]

On 2/7/2017 4:50 AM, Mike Rivers wrote:
On 2/6/2017 11:58 PM, Paul wrote:
Ok, I'll just put a 50 Watt speaker into it, and then drive it
with 200 Watts RMS continuous!

NOT A GOOD IDEA!

No, it isn't a good idea, but then why would you do that other than to
see if you can blow the speaker? A loudspeaker's power rating is more a
limit than a requirement. Sensitivity is what describes how loud it will
be for a given input power. If you're going to use published
specifications as your guide to choosing a component (and indeed there
are good reasons to do that, sometimes, for some components), you should
understand what those specifications actually mean.

You wouldn't want to use an electrolytic capacitor rated at 250 volts in
a circuit where it never sees more than 2 volts across it, because it
may not be close to its specified value that far away from its rated
working voltage. Nor would you put a 25 volt capacitor in a circuit
where it sees 250 volts - but there's a different reason for that.


There shouldn't be a problem using a 250V rated cap in that
situation, but you would have way over-engineered it!

Only a retard wouldn't consider the wattage rating of a
speaker!


Remember, too, that the difference between 400 watts and 200 watts is
only 3 dB.


That's obvious, but try driving a 200 Watt rated speaker with
400 Watts, and see what happens!

DUUUUUHH!!

[Mike Rivers[_2_]]

On 2/7/2017 4:50 AM, Mike Rivers wrote:
On 2/6/2017 11:58 PM, Paul wrote:

You wouldn't want to use an electrolytic capacitor rated at 250 volts in
a circuit where it never sees more than 2 volts across it, because it
may not be close to its specified value

On 2/7/2017 12:17 PM, Paul wrote:
There shouldn't be a problem using a 250V rated cap in that
situation, but you would have way over-engineered it!

I just explained why there could be a problem using a capacitor with a
working voltage that's well over the actual working voltage in the
circuit. Electrolytic capacitors are rated for _working_ voltage, not
destruction voltage. If a 10 uF 250 v capacitor is only 1 uF because
it's seeing only 10% of its working voltage (that's not a formula, by
the was, just an "if") then it's not doing what it's supposed to do, and
that could be a problem.

Only a retard wouldn't consider the wattage rating of a
speaker!

No. Only someone ignorant of how loudspeakers are rated would interpret
it as the maximum power rating of the amplifier that's driving it. A
poorly built and stupidly rated speaker (both cases are not uncommon)
driven by a 50 watt amplifier that's clipping badly is more likely to
suffer damage than when driven by a 500 watt amplifier that's
undistorted when running 100 watts.

A lower powered amplifier doesn't necessarily protect a loudspeaker -
but a properly rated fuse might.

Remember, too, that the difference between 400 watts and 200 watts is
only 3 dB.

That's obvious, but try driving a 200 Watt rated speaker with
400 Watts, and see what happens!

A 400 watt amplifier doesn't always put out 400 watts. Only a retard
would turn it up until the speaker failed. But some do anyway.


--

For a good time, call http://mikeriversaudio.wordpress.com

[Scott Dorsey]

In article , Paul wrote:

Speaker power ratings are pretty random, and are actually the least important
of all the numbers that you care about.

What kind of a retarded statement is that?

Ok, I'll just put a 50 Watt speaker into it, and then drive it
with 200 Watts RMS continuous!

Might be perfectly fine. Might not be.

The speaker power ratings make a lot of assumptions about the waveform they
are being sent, and involve a whole lot of handwaving. They often owe more to
the marketing department than any actual engineering.

Remember that the difference between 50 watts and 200 watts is only 6dB.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[geoff]

On 8/02/2017 6:17 AM, Paul wrote:


Only a retard wouldn't consider the wattage rating of a speaker!


Call me a retard then. Have been running one set of speakers rated at a
mere 50W on a 200W amp for years without a problem.

Wouldn't recommend that for everyone in every situation though ....

geoff

[JackA]

On Monday, February 6, 2017 at 11:01:37 AM UTC-5, Paul wrote:
12" Woofer cone distorts badly, due to torn paper
cone:

http://www.jblpro.com/pub/obsolete/Control_12sr.pdf

I believe the tweeter is fine.

Can anyone recommend a replacement woofer?

I've never tried re-coning: Is it relatively successful
the first time? I am good with my hands.

Thanks for any good feedback.....

That's an efficient speaker, but sure to match woofer characteristics or replace both woofers.

Jack

[Neil[_9_]]

On 2/7/2017 12:47 PM, Scott Dorsey wrote:

Remember that the difference between 50 watts and 200 watts is only 6dB.
--scott

Hmm. I would think that the dB difference would depend on the efficiency
performance of the driver, not just the input wattage. One challenge
when matching drivers is picking those that have the same input power to
dB characteristics over the rated range.

Then again, I'm admittedly "old school", and maybe modern drivers are
much better matched than they used to be.

--
best regards,

Neil

[Scott Dorsey]

In article , Neil wrote:
On 2/7/2017 12:47 PM, Scott Dorsey wrote:

Remember that the difference between 50 watts and 200 watts is only 6dB.

Hmm. I would think that the dB difference would depend on the efficiency
performance of the driver, not just the input wattage. One challenge
when matching drivers is picking those that have the same input power to
dB characteristics over the rated range.

That would be output power, not input power.

Input power is just a function of voltage and load impedance.

Which, incidentally, is one of the reasons why 'rated power' is such a
doubtful number, that the load impedance varies so much on the speaker.
You'll see some woofer systems that drop down to 3 ohms at one frequency
than rise up to 50 ohms at some other frequency.

But.... even so.... if the speaker is linear, if you add 6dB input power
you'll get another 6dB output power.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Neil[_9_]]

On 2/7/2017 4:29 PM, Scott Dorsey wrote:
In article , Neil wrote:
On 2/7/2017 12:47 PM, Scott Dorsey wrote:

Remember that the difference between 50 watts and 200 watts is only 6dB.

Hmm. I would think that the dB difference would depend on the efficiency
performance of the driver, not just the input wattage. One challenge
when matching drivers is picking those that have the same input power to
dB characteristics over the rated range.

That would be output power, not input power.

Input power is just a function of voltage and load impedance.

Which, incidentally, is one of the reasons why 'rated power' is such a
doubtful number, that the load impedance varies so much on the speaker.
You'll see some woofer systems that drop down to 3 ohms at one frequency
than rise up to 50 ohms at some other frequency.

But.... even so.... if the speaker is linear, if you add 6dB input power
you'll get another 6dB output power.
--scott

What I was saying is basically the same thing; a speaker receiving xW (I
called it "input wattage", which may not be modern jargon) will put out
YdB. The "efficiency performance" addresses your point about
frequency-dependent impedance variations and includes physical qualities
of the driver that affect variable frequency linearity (IOW, a driver
that may have linear I/O power at a single frequency may not have a
linear variable frequency response).

I agree that 'rated power' is a very general reference.

The enclosure adds a barrel full of other variables, which is why I
wonder what the OP is really going to wind up with. I'd be hesitant to
spend $450 to find out. ;-)

--
best regards,

Neil

[Paul[_13_]]

On 2/7/2017 10:33 AM, Mike Rivers wrote:

On 2/7/2017 4:50 AM, Mike Rivers wrote:
On 2/6/2017 11:58 PM, Paul wrote:

You wouldn't want to use an electrolytic capacitor rated at 250 volts in
a circuit where it never sees more than 2 volts across it, because it
may not be close to its specified value

On 2/7/2017 12:17 PM, Paul wrote:
There shouldn't be a problem using a 250V rated cap in that
situation, but you would have way over-engineered it!

I just explained why there could be a problem using a capacitor with a
working voltage that's well over the actual working voltage in the
circuit. Electrolytic capacitors are rated for _working_ voltage, not
destruction voltage. If a 10 uF 250 v capacitor is only 1 uF because
it's seeing only 10% of its working voltage (that's not a formula, by
the was, just an "if") then it's not doing what it's supposed to do, and
that could be a problem.


The capacitance value is also dependent on ESR and parasitic
inductances, so it's frequency and temperature dependent too:


http://www.kemet.com/Lists/Technical...or%20lower.pdf

And from
http://electronics.stackexchange.com...citance/195211

"Long story short, you can replace an electrolytic cap with another one
of the same value but higher voltage rating.

Electrolytic capacitors usually have a very lose tolerance to begin
with, and with age and heat their capacitance drops a lot. They also
change their characteristics with applied DC voltage, but this effect is
a less drastic as in multi-layer ceramic types.

Given that you can't really trust the exact capacitance longer than a
few weeks, it is very unlikely that someone designs in an electrolytic
capacitor and expects the value to be exact. That's why you will often
find them in non critical situations where a capacitor of some ballpark
capacitance is needed but the exact value does not matter much.

Such applications are buffer capacitors and smoothing capacitors in
power supplies. In cheap audio devices you'll sometimes find them as DC
blocking capacitors as well.

In all of these cases the performance of the device will not change much
if the real capacitance changes by ... lets say ... 50 percent. So a
change to a different voltage-rated part won't hurt.

Using capacitors with a higher voltage rating as strictly required is
btw a good thing because the capacitor will not age as quickly as one
working on it's limit."


But yours is a bull**** argument anyways: There would be no
problem driving a 250 Watt speaker with 2 Watts, unless the rating
was insanely off!




Only a retard wouldn't consider the wattage rating of a
speaker!

No. Only someone ignorant of how loudspeakers are rated would interpret
it as the maximum power rating of the amplifier that's driving it. A
poorly built and stupidly rated speaker (both cases are not uncommon)
driven by a 50 watt amplifier that's clipping badly is more likely to
suffer damage than when driven by a 500 watt amplifier that's
undistorted when running 100 watts.

A lower powered amplifier doesn't necessarily protect a loudspeaker -
but a properly rated fuse might.

Remember, too, that the difference between 400 watts and 200 watts is
only 3 dB.

That's obvious, but try driving a 200 Watt rated speaker with
400 Watts, and see what happens!

A 400 watt amplifier doesn't always put out 400 watts. Only a retard
would turn it up until the speaker failed. But some do anyway.


I never said it did. Only a retard would rather use a lower
Wattage rated speaker than the driving amplifier, because even if the
ratings are inexact, you'd still have a better chance of not blowing
the speaker if you match a 400 Watt speaker to a 400 Watt system!

[None]

"Neil" wrote in message
news
Remember that the difference between 50 watts and 200 watts is
only 6dB.

Hmm. I would think that the dB difference would depend on the
efficiency
performance of the driver, not just the input wattage.

The ratio of 50 W and 200 W is difference of 6 dB, regardless of the
efficiency.

[Paul[_13_]]

On 2/7/2017 4:07 PM, Neil wrote:
On 2/7/2017 4:29 PM, Scott Dorsey wrote:
In article , Neil
wrote:
On 2/7/2017 12:47 PM, Scott Dorsey wrote:

Remember that the difference between 50 watts and 200 watts is only
6dB.

Hmm. I would think that the dB difference would depend on the efficiency
performance of the driver, not just the input wattage. One challenge
when matching drivers is picking those that have the same input power to
dB characteristics over the rated range.

That would be output power, not input power.

Input power is just a function of voltage and load impedance.

Which, incidentally, is one of the reasons why 'rated power' is such a
doubtful number, that the load impedance varies so much on the speaker.
You'll see some woofer systems that drop down to 3 ohms at one frequency
than rise up to 50 ohms at some other frequency.

But.... even so.... if the speaker is linear, if you add 6dB input power
you'll get another 6dB output power.
--scott

What I was saying is basically the same thing; a speaker receiving xW (I
called it "input wattage", which may not be modern jargon) will put out
YdB. The "efficiency performance" addresses your point about
frequency-dependent impedance variations and includes physical qualities
of the driver that affect variable frequency linearity (IOW, a driver
that may have linear I/O power at a single frequency may not have a
linear variable frequency response).

I agree that 'rated power' is a very general reference.

The enclosure adds a barrel full of other variables, which is why I
wonder what the OP is really going to wind up with. I'd be hesitant to
spend $450 to find out. ;-)


Certainly Figure 4 on this site is a severe over-simplification:


http://www.st.com/content/ccc/resour...CD00298262.pdf

So how do the speaker company engineers decide on the rating for
their speakers?

If they made some reasonable guesses as to the temperature where
the voice coil insulation and glues start to break down, they could get
an idea of the power rating.

Perhaps the only accurate way is to get a few examples and perform
destructive testing with various sounds though them, at various RMS
Wattages, with the understanding that a constant 1kHz sine wave will NOT
be the same test as a good variety of REAL music.

They could then establish a Mean Time before Failure (MTBF), and
say statistically that you could use this speaker with this amp, and
expect an average of this many hours of usage before blowing the speaker.

But they can't completely pull a number out of their asses!

Or do they? Haha!

[Scott Dorsey]

In article , Neil wrote:

What I was saying is basically the same thing; a speaker receiving xW (I
called it "input wattage", which may not be modern jargon) will put out
YdB.

No. A speaker receiving X watts or X dBW puts out Y dBSPL.

The decibel is a ratio, it is not a measurement. In order for a decibel
to be meaningful you have to put a reference point on it.

We measure watts, sound pressure, and voltage all using decibel ratios.

The "efficiency performance" addresses your point about
frequency-dependent impedance variations and includes physical qualities
of the driver that affect variable frequency linearity (IOW, a driver
that may have linear I/O power at a single frequency may not have a
linear variable frequency response).

This is true. However, I was talking about input power in watts. 10 watts
is 10dB higher than one watt. This has nothing necessarily to do with the
output level in dBSPL (decibels with respect to reference sound pressure level
in air).

The enclosure adds a barrel full of other variables, which is why I
wonder what the OP is really going to wind up with. I'd be hesitant to
spend $450 to find out. ;-)

Indeed, especially when getting the existing driver rebuilt is comparatively
inexpensive and easy.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article , Paul wrote:

But yours is a bull**** argument anyways: There would be no
problem driving a 250 Watt speaker with 2 Watts, unless the rating
was insanely off!

I suggest trying it, although of course not knowing the speaker efficiency
it's hard to know. Efficiency is an actual measurement that is of some
value, as opposed to a marketing number like power ratings.

Many speakers have a minimum power rating on them, again because people in
the marketing department are afraid of people damaging them by clipping
an undersized amplifier. That rating is about as fake as the maximum
power rating too.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[PStamler]

Electro-Voice used to use a waveform for testing speakers which they claimed approximated the spectral and dynamic characteristics of a clipped electric guitar signal. Haven't heard about that for a while.

Peace,
Paul S.

[Paul[_13_]]

On 2/7/2017 5:26 PM, Scott Dorsey wrote:
In article , Paul wrote:

But yours is a bull**** argument anyways: There would be no
problem driving a 250 Watt speaker with 2 Watts, unless the rating
was insanely off!

I suggest trying it, although of course not knowing the speaker efficiency
it's hard to know. Efficiency is an actual measurement that is of some
value, as opposed to a marketing number like power ratings.

Many speakers have a minimum power rating on them, again because people in
the marketing department are afraid of people damaging them by clipping
an undersized amplifier. That rating is about as fake as the maximum
power rating too.
--scott


So if your argument is to ignore speaker power ratings, and
always use speakers that are like 6 dB less than the driving amplifier,
and never use speakers rated HIGHER than the amp, then that's a losing
argument!

The ratings can't be completely fake....they must do at least some
destructive testing on sample units.

[Scott Dorsey]

In article , Paul wrote:

So if your argument is to ignore speaker power ratings, and
always use speakers that are like 6 dB less than the driving amplifier,
and never use speakers rated HIGHER than the amp, then that's a losing
argument!

No, my arguments are that the speaker ratings have to be taken with a serious
grain of salt, that you are much better off using the efficiency and maximum
SPL envelope to size systems than an estimated rating, and that the most
important key to preventing speaker damage is to use your ears and back off
when the drivers become nonlinear.

The ratings can't be completely fake....they must do at least some
destructive testing on sample units.

For complete cabinets you can do that, and there are test waveforms that
you can use. For a raw driver you can't do that because the total excursion
of the driver depends on the cabinet; a driver that can handle one power
level in one cabinet may have totally different power handling in another.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Trevor]

On 8/02/2017 11:44 AM, Scott Dorsey wrote:
In article , Paul wrote:
The ratings can't be completely fake....they must do at least some
destructive testing on sample units.

There is no MUST. Reputable manufacturers do, many others do not.


For complete cabinets you can do that, and there are test waveforms that
you can use. For a raw driver you can't do that because the total excursion
of the driver depends on the cabinet; a driver that can handle one power
level in one cabinet may have totally different power handling in another.

Not necessarily true. For a tweeter the cabinet is irrelevant. For a
woofer tested at 1kHz as some do, or even 400+ Hz as some others do, the
cabinet is mostly irrelevant, other than the fact it will probably
restrict air flow to the voice coil and magnet assembly and thus reduce
the power rating.

Trevor.

[geoff]

On 8/02/2017 12:32 p.m., Paul wrote:


Such applications are buffer capacitors and smoothing capacitors in
power supplies. In cheap audio devices you'll sometimes find them as
DC blocking capacitors as well.

Only in 'cheap' ?!!!

geoff

[Mike Rivers[_2_]]

On 2/7/2017 7:39 PM, Paul wrote:

So if your argument is to ignore speaker power ratings, and
always use speakers that are like 6 dB less than the driving amplifier,
and never use speakers rated HIGHER than the amp, then that's a losing
argument!

That's two arguments. Or maybe three. I think you're looking for a rule,
when there is none. Experience and common sense are the bywords here.
You're not going to blow up a speaker unless you do something stupid.
And if you don't do something stupid, you can use any amplifier that you
want as long as you can get the volume you need without it being distorted.

In normal operation you'' hear distortion before you do any damage, and
if you continue to let it distort, whether it's the amplifier clipping
or the speaker being driven against the stops or overheating, then
you're doing something stupid. And if you let the system feed back at
full power, or plug something in that causes hum at full power, that's
something stupid, too. Most speakers will survive that for a short
period of time, and if you don't make it stop, that's stupid.

The ratings can't be completely fake....they must do at least some
destructive testing on sample units.

They know how much current it takes for how long before the voice coil
will melt open, but there are enough different ways that you can destroy
a speaker mechanically that it's really hard to relate them to amplifier
power.



--

For a good time, call http://mikeriversaudio.wordpress.com

[Paul[_13_]]

On 2/7/2017 6:56 PM, Mike Rivers wrote:
On 2/7/2017 7:39 PM, Paul wrote:

So if your argument is to ignore speaker power ratings, and
always use speakers that are like 6 dB less than the driving amplifier,
and never use speakers rated HIGHER than the amp, then that's a losing
argument!

That's two arguments. Or maybe three. I think you're looking for a rule,
when there is none. Experience and common sense are the bywords here.
You're not going to blow up a speaker unless you do something stupid.
And if you don't do something stupid, you can use any amplifier that you
want as long as you can get the volume you need without it being distorted.

In normal operation you'' hear distortion before you do any damage, and
if you continue to let it distort, whether it's the amplifier clipping
or the speaker being driven against the stops or overheating, then
you're doing something stupid. And if you let the system feed back at
full power, or plug something in that causes hum at full power, that's
something stupid, too. Most speakers will survive that for a short
period of time, and if you don't make it stop, that's stupid.


You aren't doing a good job of convincing me there isn't any
difference in the design of a 600W speaker and a 50 Watt one....


The ratings can't be completely fake....they must do at least some
destructive testing on sample units.

They know how much current it takes for how long before the voice coil
will melt open, but there are enough different ways that you can destroy
a speaker mechanically that it's really hard to relate them to amplifier
power.


If companies made some reasonable guesses as to the temperature
where the voice coil insulation and glues start to break down, they
could get an idea of the power rating. The AWG, or thickness of the
coil wire will make a difference too.

Perhaps the only accurate way is to get a few examples and perform
destructive testing with various sounds though them, at various RMS
Wattages, with the understanding that a constant 1kHz sine wave will NOT
be the same test as a good variety of REAL music.

They could then establish a Mean Time before Failure (MTBF), and
say statistically that you could use this speaker with this amp, and
expect an average of this many hours of usage before blowing the speaker.

[Phil Allison[_4_]]

Mike Rivers wrote:



No. Only someone ignorant of how loudspeakers are rated would interpret
it as the maximum power rating of the amplifier that's driving it.


** But that is often how speaker makers come up with their inflated numbers.

Its the amp power ( usually rms sine wave) that they figure is OK with the speaker under normal programme conditions with little or no clipping. The average power being delivered is then at most 1/4 ( -6dB )of the amp's rated power.

At lot hen depends on what the speaker's intended use, ie home hi-fi, live sound, disco or guitar.


poorly built and stupidly rated speaker (both cases are not uncommon)
driven by a 50 watt amplifier that's clipping badly is more likely to
suffer damage than when driven by a 500 watt amplifier that's
undistorted when running 100 watts.


** Well, a 50watt sine wave rated amp will deliver at most 100W when heavily clipped - so matching the output of the 500watt model unclipped.

The idea of using a LARGER amp to solve speaker burn out problems is a complete nonsense.

Section 3.2 of my article on speaker failures makes the case pretty clear.

http://sound.whsites.net/articles/speaker-failure.html


..... Phil

[Phil Allison[_4_]]

Paul wrote:



"Long story short, you can replace an electrolytic cap with another one
of the same value but higher voltage rating.

Electrolytic capacitors usually have a very lose tolerance to begin
with, and with age and heat their capacitance drops a lot.


** That is just not true.

New electros have a tolerance of +/-20% on capacitance and this value does not change significantly with age throughout the useful like of the part.

As the cap nears the end of its life ( because the electrolyte has nearly all evaporated) ESR rises but the capacitance stays.

The reason for this odd behaviour is simple, makers put about 5 times more electrolyte inside a given electro than it needs to work - so a large percentage has to disappear before it affects performance.

Shame how NONE of this info is in your links.



They also
change their characteristics with applied DC voltage, but this effect is
a less drastic as in multi-layer ceramic types.


** It is never an issue, because electro are not used where capacitance value is critical - we have polystyrene film and NPO ceramic caps for that.


Given that you can't really trust the exact capacitance longer than a
few weeks,


** You plucked that out your arse ....

it is very unlikely that someone designs in an electrolytic
capacitor and expects the value to be exact.


** Correct.

That's why you will often
find them in non critical situations where a capacitor of some ballpark
capacitance is needed but the exact value does not matter much.


** The common requirement of an electro these days is to have low self impedance at its operating frequency - which might be 50 to 100kHz. Here, the ESR value is king and the capacitance incidental.


Such applications are buffer capacitors and smoothing capacitors in
power supplies. In cheap audio devices you'll sometimes find them as DC
blocking capacitors as well.


** Electros are normally used for that job, even in the most up market products -cos they do the job just perfectly. Audiophools may not agree, but they never agree on anything.



..... Phil

[Neil[_9_]]

On 2/7/2017 7:24 PM, Scott Dorsey wrote:
In article , Neil wrote:

What I was saying is basically the same thing; a speaker receiving xW (I
called it "input wattage", which may not be modern jargon) will put out
YdB.

No. A speaker receiving X watts or X dBW puts out Y dBSPL.

The decibel is a ratio, it is not a measurement. In order for a decibel
to be meaningful you have to put a reference point on it.

Got it. My "old school jargon" presumes SPL when referring to dB in the
context of a driver, but I understand the difference. ;-)


--
best regards,

Neil

[Scott Dorsey]

In article , Paul wrote:

If companies made some reasonable guesses as to the temperature
where the voice coil insulation and glues start to break down, they
could get an idea of the power rating. The AWG, or thickness of the
coil wire will make a difference too.

Okay, there are two kinds of failures. The first is due to overheating, and
the second due to overexcursion.

In the case of woofers, you can predict overheating although it's very
interesting to watch because the speakers tend to use airflow through the
voice coil to cool it. So you can get into a situation where a high power
at a low frequency is fine because there's enough excursion and enough air
moving through, but a lower power at a higher frequency isn't.

Overexcursion issues are totally different, though, and the waveforms that
cause them are totally different. Which is really why there's so much
slop in all of these, that musical waveforms vary so much between types of
music.

Perhaps the only accurate way is to get a few examples and perform
destructive testing with various sounds though them, at various RMS
Wattages, with the understanding that a constant 1kHz sine wave will NOT
be the same test as a good variety of REAL music.

That's what folks do, and then they put a big safety margin into place before
they publish it. How big a safety margin? You'll have to ask the marketing
department.

They could then establish a Mean Time before Failure (MTBF), and
say statistically that you could use this speaker with this amp, and
expect an average of this many hours of usage before blowing the speaker.

The only person who has ever even made a stab at that sort of thing is
Wolfgang Klippel. Klippel has done more to establish statistical quality
control of speaker drivers than anyone else ever, I suspect.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."