Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

2- How can I know how much ampere the amp is using to drive one
loudspeaker?

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Thank you.

"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


2- How can I know how much ampere the amp is using to drive one
loudspeaker?

It varies constantly with the program (music, voice, whatever).


3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Thank you.

"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


2- How can I know how much ampere the amp is using to drive one
loudspeaker?

It varies constantly with the program (music, voice, whatever).


3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Thank you.

"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


2- How can I know how much ampere the amp is using to drive one
loudspeaker?

It varies constantly with the program (music, voice, whatever).


3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Thank you.

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

--
cyrus

*coughcasaucedoprodigynetcough*

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

--
cyrus

*coughcasaucedoprodigynetcough*

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

--
cyrus

*coughcasaucedoprodigynetcough*

cyrus writes:

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion, and those high
frequency components can overload the high freuqncy driver
even through the total power to the speaker is much less
than the speaker power rating. The reason for this is
that the high freuqncy driver has typically much lower
power rating then the other drivers on the speaker, because
normal sounds do not have much high frequency signals.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

cyrus writes:

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion, and those high
frequency components can overload the high freuqncy driver
even through the total power to the speaker is much less
than the speaker power rating. The reason for this is
that the high freuqncy driver has typically much lower
power rating then the other drivers on the speaker, because
normal sounds do not have much high frequency signals.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

cyrus writes:

In article ,
"Billw" wrote:

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion, and those high
frequency components can overload the high freuqncy driver
even through the total power to the speaker is much less
than the speaker power rating. The reason for this is
that the high freuqncy driver has typically much lower
power rating then the other drivers on the speaker, because
normal sounds do not have much high frequency signals.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

(you're probably more likely to hurt it with too LITTLE
power).

How does that happen?

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Jean wrote:

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

The key is to understand what the ratings mean.

The speaker is able to withstand 19W of clean signal before it fries.
The amplifier is capable of putting out 40W of power before it blows
up or distorts the signal excessively.

An amplifier that only puts out 10W cleanly will be distorting heavily
at 15W. This is VERY likely to blow up the tweeter in your speakers.
An amp that can put out more than 19W cleanly (in this case, 40W) is
probably NOT going to blow up your speakers at 15W output.

Consider it this way: Your speakers will blow up at 19W with a clean
signal, or sooner with a bad signal.

Something else to consider is that for an average home, 10W continuous
into typical speakers is almost enough to make your ears bleed! In my
(small and hard-surfaced) living room, the loudest I can stand listening
to my stereo leads to peaks of about 2W on the VU meters--continuous is
less than 1W.

So hook 'em up, and don't worry about it.

Jean wrote:

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

The key is to understand what the ratings mean.

The speaker is able to withstand 19W of clean signal before it fries.
The amplifier is capable of putting out 40W of power before it blows
up or distorts the signal excessively.

An amplifier that only puts out 10W cleanly will be distorting heavily
at 15W. This is VERY likely to blow up the tweeter in your speakers.
An amp that can put out more than 19W cleanly (in this case, 40W) is
probably NOT going to blow up your speakers at 15W output.

Consider it this way: Your speakers will blow up at 19W with a clean
signal, or sooner with a bad signal.

Something else to consider is that for an average home, 10W continuous
into typical speakers is almost enough to make your ears bleed! In my
(small and hard-surfaced) living room, the loudest I can stand listening
to my stereo leads to peaks of about 2W on the VU meters--continuous is
less than 1W.

So hook 'em up, and don't worry about it.

Jean wrote:

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

The key is to understand what the ratings mean.

The speaker is able to withstand 19W of clean signal before it fries.
The amplifier is capable of putting out 40W of power before it blows
up or distorts the signal excessively.

An amplifier that only puts out 10W cleanly will be distorting heavily
at 15W. This is VERY likely to blow up the tweeter in your speakers.
An amp that can put out more than 19W cleanly (in this case, 40W) is
probably NOT going to blow up your speakers at 15W output.

Consider it this way: Your speakers will blow up at 19W with a clean
signal, or sooner with a bad signal.

Something else to consider is that for an average home, 10W continuous
into typical speakers is almost enough to make your ears bleed! In my
(small and hard-surfaced) living room, the loudest I can stand listening
to my stereo leads to peaks of about 2W on the VU meters--continuous is
less than 1W.

So hook 'em up, and don't worry about it.

"Tomi Holger Engdahl" wrote

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

Rudi Fischer
--
....and may good music always be with you

"Tomi Holger Engdahl" wrote

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

Rudi Fischer
--
....and may good music always be with you

"Tomi Holger Engdahl" wrote

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

Rudi Fischer
--
....and may good music always be with you

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

That Rane note says exactly the same thing. Only they refer to the
introduction of additional high frequency components as dynamic compression.

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

That Rane note says exactly the same thing. Only they refer to the
introduction of additional high frequency components as dynamic compression.

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

That Rane note says exactly the same thing. Only they refer to the
introduction of additional high frequency components as dynamic compression.

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

On Wed, 23 Jun 2004 16:56:51 -0400, "MZ"
wrote:

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

On Wed, 23 Jun 2004 16:56:51 -0400, "MZ"
wrote:

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

On Wed, 23 Jun 2004 16:56:51 -0400, "MZ"
wrote:

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the waveform
that's the killer, but rather the amount of power being delivered to the
driver. When you just say that square waves blow tweeters, then this
implies that this is true independent of the amount of power being
delivered. This is what feeds the myth that "distortion blows speakers."
Many people, if not most, believe in this myth - that is, a "distorted"
waveform, even when absent a sufficient amount of power, can blow a speaker.
This idea is simply untrue.

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the waveform
that's the killer, but rather the amount of power being delivered to the
driver. When you just say that square waves blow tweeters, then this
implies that this is true independent of the amount of power being
delivered. This is what feeds the myth that "distortion blows speakers."
Many people, if not most, believe in this myth - that is, a "distorted"
waveform, even when absent a sufficient amount of power, can blow a speaker.
This idea is simply untrue.

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the waveform
that's the killer, but rather the amount of power being delivered to the
driver. When you just say that square waves blow tweeters, then this
implies that this is true independent of the amount of power being
delivered. This is what feeds the myth that "distortion blows speakers."
Many people, if not most, believe in this myth - that is, a "distorted"
waveform, even when absent a sufficient amount of power, can blow a speaker.
This idea is simply untrue.

Jean wrote:

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


I agree with all of the above. In fact, it can be advantageous to
have an amp that is rated higher in power than the rating on the
speakers. I've seen a 40 watt amp fry a pair of speakers rated at
100 watts each due to significant abuse of the system (they were
trying to use it in a hall much larger than they should have).


Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)


That really is kinda reversed. You want an amp that can produce
clean undistorted power over the range that the speakers are
rated for. It's only a rough reference and does not mean as much
as some sales people would have you think. All things being even,
a 40 watt speaker can be driven to a louder level than a 20 watt
one before it begins to distort (i.e., is being driven beyond its
physical capabilities).

The problem is that things are almost NEVER all even! For
example, if the 40 watt speakers were 3dB less sensitive than the
20 watt ones, driving them at 40 watts would produce the SAME
loudness as driving the 20 watt ones at 20 watts. If you had 100
watt rated headphones and fed 100 watts of audio power into them,
you still couldn't fill a dance hall with music. You could though
with some very efficient speakers such as a horn type design, etc.

Frequently, in order to get extremly "clean" sound from a
speaker, exotic designs are used that can be very inefficient and
have strange reactive characteristics. This has the interesting
effect that on a lower power or moderate quality amplifier, the
exotic (and usually pricey) speaker can sound much worst that
some other bargin bin speaker. It won't start to really sing
until it is coupled with a high quality, highly resolving
amplifier, etc.

The really important thing is, can you get the maximum volume
that you want to listen to out of the speakers with it sounding
clean and without distortion? If you can, then you need an amp
with a higher power rating than the speakers, that will help to
ensure that you will always be sending clean audio to the
speakers. If the amp is MASSIVELY powered compared to the
speakers it just means you might only use a tiny part of your
volume control before things get too loud and start to distort
(or if you have children in the house, the possibility of blowing
the speakers are greater when someone leaves the volume dial at
100% :-).

You pick your speakers for the volume level and distortion free
sound that you want, then make sure your amp can provide
distortion free audio at that level and somewhat above. Your
system should be fine and you need no "adapter" of any sort. In
fact, you don't want anything between the two components that
would affect the sound.


3- A better suitable newsgroup to post this question?



This is not a "Pro" audio group, its a "Recreation-Audio" group
so my opinion is that this one is fine (although it HAS been a
while since I read the charter :-) However, there are also folks
here with very advanced understanding (or some that just THINK
they do :-) so some basic questions can spin off some more
complicated threads. I appreciated the reference to the RANE
article that was mention earlier by someone in this thread. I was
not aware of some of the issues that it addressed.


Search on the internet:
4- What words should I use to find some appropriate technical texts?


Not sure here. You are looking at many different issues when you
start dealing with loudspeakers. E.g., did you know that the 8
ohm rating is only nominal? that actual impeadance can vary from
as low as 4 ohms and go as high as 15,000 ohms depending on the
frequency that the impeadance is being measured at. Some basic
introductory texts on speaker theory might work for you.

Hope this helps some.

- Jeff

Jean wrote:

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


I agree with all of the above. In fact, it can be advantageous to
have an amp that is rated higher in power than the rating on the
speakers. I've seen a 40 watt amp fry a pair of speakers rated at
100 watts each due to significant abuse of the system (they were
trying to use it in a hall much larger than they should have).


Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)


That really is kinda reversed. You want an amp that can produce
clean undistorted power over the range that the speakers are
rated for. It's only a rough reference and does not mean as much
as some sales people would have you think. All things being even,
a 40 watt speaker can be driven to a louder level than a 20 watt
one before it begins to distort (i.e., is being driven beyond its
physical capabilities).

The problem is that things are almost NEVER all even! For
example, if the 40 watt speakers were 3dB less sensitive than the
20 watt ones, driving them at 40 watts would produce the SAME
loudness as driving the 20 watt ones at 20 watts. If you had 100
watt rated headphones and fed 100 watts of audio power into them,
you still couldn't fill a dance hall with music. You could though
with some very efficient speakers such as a horn type design, etc.

Frequently, in order to get extremly "clean" sound from a
speaker, exotic designs are used that can be very inefficient and
have strange reactive characteristics. This has the interesting
effect that on a lower power or moderate quality amplifier, the
exotic (and usually pricey) speaker can sound much worst that
some other bargin bin speaker. It won't start to really sing
until it is coupled with a high quality, highly resolving
amplifier, etc.

The really important thing is, can you get the maximum volume
that you want to listen to out of the speakers with it sounding
clean and without distortion? If you can, then you need an amp
with a higher power rating than the speakers, that will help to
ensure that you will always be sending clean audio to the
speakers. If the amp is MASSIVELY powered compared to the
speakers it just means you might only use a tiny part of your
volume control before things get too loud and start to distort
(or if you have children in the house, the possibility of blowing
the speakers are greater when someone leaves the volume dial at
100% :-).

You pick your speakers for the volume level and distortion free
sound that you want, then make sure your amp can provide
distortion free audio at that level and somewhat above. Your
system should be fine and you need no "adapter" of any sort. In
fact, you don't want anything between the two components that
would affect the sound.


3- A better suitable newsgroup to post this question?



This is not a "Pro" audio group, its a "Recreation-Audio" group
so my opinion is that this one is fine (although it HAS been a
while since I read the charter :-) However, there are also folks
here with very advanced understanding (or some that just THINK
they do :-) so some basic questions can spin off some more
complicated threads. I appreciated the reference to the RANE
article that was mention earlier by someone in this thread. I was
not aware of some of the issues that it addressed.


Search on the internet:
4- What words should I use to find some appropriate technical texts?


Not sure here. You are looking at many different issues when you
start dealing with loudspeakers. E.g., did you know that the 8
ohm rating is only nominal? that actual impeadance can vary from
as low as 4 ohms and go as high as 15,000 ohms depending on the
frequency that the impeadance is being measured at. Some basic
introductory texts on speaker theory might work for you.

Hope this helps some.

- Jeff

Jean wrote:

"Billw" wrote in message ...
"Jean" wrote in message
om...
Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.


I agree with all of the above. In fact, it can be advantageous to
have an amp that is rated higher in power than the rating on the
speakers. I've seen a 40 watt amp fry a pair of speakers rated at
100 watts each due to significant abuse of the system (they were
trying to use it in a hall much larger than they should have).


Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)


That really is kinda reversed. You want an amp that can produce
clean undistorted power over the range that the speakers are
rated for. It's only a rough reference and does not mean as much
as some sales people would have you think. All things being even,
a 40 watt speaker can be driven to a louder level than a 20 watt
one before it begins to distort (i.e., is being driven beyond its
physical capabilities).

The problem is that things are almost NEVER all even! For
example, if the 40 watt speakers were 3dB less sensitive than the
20 watt ones, driving them at 40 watts would produce the SAME
loudness as driving the 20 watt ones at 20 watts. If you had 100
watt rated headphones and fed 100 watts of audio power into them,
you still couldn't fill a dance hall with music. You could though
with some very efficient speakers such as a horn type design, etc.

Frequently, in order to get extremly "clean" sound from a
speaker, exotic designs are used that can be very inefficient and
have strange reactive characteristics. This has the interesting
effect that on a lower power or moderate quality amplifier, the
exotic (and usually pricey) speaker can sound much worst that
some other bargin bin speaker. It won't start to really sing
until it is coupled with a high quality, highly resolving
amplifier, etc.

The really important thing is, can you get the maximum volume
that you want to listen to out of the speakers with it sounding
clean and without distortion? If you can, then you need an amp
with a higher power rating than the speakers, that will help to
ensure that you will always be sending clean audio to the
speakers. If the amp is MASSIVELY powered compared to the
speakers it just means you might only use a tiny part of your
volume control before things get too loud and start to distort
(or if you have children in the house, the possibility of blowing
the speakers are greater when someone leaves the volume dial at
100% :-).

You pick your speakers for the volume level and distortion free
sound that you want, then make sure your amp can provide
distortion free audio at that level and somewhat above. Your
system should be fine and you need no "adapter" of any sort. In
fact, you don't want anything between the two components that
would affect the sound.


3- A better suitable newsgroup to post this question?



This is not a "Pro" audio group, its a "Recreation-Audio" group
so my opinion is that this one is fine (although it HAS been a
while since I read the charter :-) However, there are also folks
here with very advanced understanding (or some that just THINK
they do :-) so some basic questions can spin off some more
complicated threads. I appreciated the reference to the RANE
article that was mention earlier by someone in this thread. I was
not aware of some of the issues that it addressed.


Search on the internet:
4- What words should I use to find some appropriate technical texts?


Not sure here. You are looking at many different issues when you
start dealing with loudspeakers. E.g., did you know that the 8
ohm rating is only nominal? that actual impeadance can vary from
as low as 4 ohms and go as high as 15,000 ohms depending on the
frequency that the impeadance is being measured at. Some basic
introductory texts on speaker theory might work for you.

Hope this helps some.

- Jeff

"MZ" wrote in
:

If you're in a position to turn the input (or maybe preamp stage)
too far up in a vain quest for extra volume, it may start clipping,
giving the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the
waveform that's the killer, but rather the amount of power being
delivered to the driver. When you just say that square waves blow
tweeters, then this implies that this is true independent of the amount
of power being delivered. This is what feeds the myth that "distortion
blows speakers." Many people, if not most, believe in this myth - that
is, a "distorted" waveform, even when absent a sufficient amount of
power, can blow a speaker. This idea is simply untrue.




I don't recall seeing a spectrum analyzer display of a square wave on the
web so I posted one. I think the point about clipping and tweeter damage
is made quite clear if you look at the jpeg I posted to
alt.binaries.schematics.electronic. The subject is 400hz square wave.
The poor tweeter is expected to reproduce all of those frequencies all at
once with harmonics well beyond it's range. That is just one frequency. I
hate to imagine if one had many frequencies clipping.

r

--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.

"MZ" wrote in
:

If you're in a position to turn the input (or maybe preamp stage)
too far up in a vain quest for extra volume, it may start clipping,
giving the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the
waveform that's the killer, but rather the amount of power being
delivered to the driver. When you just say that square waves blow
tweeters, then this implies that this is true independent of the amount
of power being delivered. This is what feeds the myth that "distortion
blows speakers." Many people, if not most, believe in this myth - that
is, a "distorted" waveform, even when absent a sufficient amount of
power, can blow a speaker. This idea is simply untrue.




I don't recall seeing a spectrum analyzer display of a square wave on the
web so I posted one. I think the point about clipping and tweeter damage
is made quite clear if you look at the jpeg I posted to
alt.binaries.schematics.electronic. The subject is 400hz square wave.
The poor tweeter is expected to reproduce all of those frequencies all at
once with harmonics well beyond it's range. That is just one frequency. I
hate to imagine if one had many frequencies clipping.

r

--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.

"MZ" wrote in
:

If you're in a position to turn the input (or maybe preamp stage)
too far up in a vain quest for extra volume, it may start clipping,
giving the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to.
It's
simply the increased high frequency power content. The distinction is
important.

A squared-off waveform has added hf. Why is one way of describing it
better?

Because it's important to emphasize that it's not the shape of the
waveform that's the killer, but rather the amount of power being
delivered to the driver. When you just say that square waves blow
tweeters, then this implies that this is true independent of the amount
of power being delivered. This is what feeds the myth that "distortion
blows speakers." Many people, if not most, believe in this myth - that
is, a "distorted" waveform, even when absent a sufficient amount of
power, can blow a speaker. This idea is simply untrue.




I don't recall seeing a spectrum analyzer display of a square wave on the
web so I posted one. I think the point about clipping and tweeter damage
is made quite clear if you look at the jpeg I posted to
alt.binaries.schematics.electronic. The subject is 400hz square wave.
The poor tweeter is expected to reproduce all of those frequencies all at
once with harmonics well beyond it's range. That is just one frequency. I
hate to imagine if one had many frequencies clipping.

r

--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.