I will be running two subwoofers off my 4-channel amplifier. The amplifier
is rated 1500W and when the 4-channels are bridged it can deliver 2 x 300W
rms.

I am interested in the sony pentagonal subwoofer.

There are four subwoofers made in this series. I am not sure which is best.

http://www.bsscc.co.za/brandcat.asp?...o=7&ProdType=1

Will it be better to match the subwoofers power rating to the amp's?

Or

Is it better to buy a subwoofer with higher power rating and be sure it
can't be blown.

There is the 300Wrms 10" and 350W rms 12" and then there is the high power
400Wrms 10" and 500Wrms 12"

Which two will run best off my amplifier?

Actualy, your amplifier should be able to provide as much if not more
rms power than the sub can handle. This ensures you can get maximum
volume from the sub without clipping. The only problem with this is, if
you get really overzealous with the volume you will be able to blow your
sub. Althogh clipping will kill a sub whether or not its beyond the
rated limit.

--Jeff

pil wrote:
I will be running two subwoofers off my 4-channel amplifier. The amplifier
is rated 1500W and when the 4-channels are bridged it can deliver 2 x 300W
rms.

I am interested in the sony pentagonal subwoofer.

There are four subwoofers made in this series. I am not sure which is best.

http://www.bsscc.co.za/brandcat.asp?...o=7&ProdType=1

Will it be better to match the subwoofers power rating to the amp's?

Or

Is it better to buy a subwoofer with higher power rating and be sure it
can't be blown.

There is the 300Wrms 10" and 350W rms 12" and then there is the high power
400Wrms 10" and 500Wrms 12"

Which two will run best off my amplifier?

"anon" wrote in message
news
Actualy, your amplifier should be able to provide as much if not more
rms power than the sub can handle. This ensures you can get maximum
volume from the sub without clipping. The only problem with this is, if
you get really overzealous with the volume you will be able to blow your
sub.

All very true.

Althogh clipping will kill a sub whether or not its beyond the
rated limit.

And how do you expect it to do this? Clipping DOES NOT blow subs.

Les
When will this idiotic audio myth ever go away?

On Thu, 5 Aug 2004 00:57:20 -0500, "Les" wrote:


"anon" wrote in message
news
Actualy, your amplifier should be able to provide as much if not more
rms power than the sub can handle. This ensures you can get maximum
volume from the sub without clipping. The only problem with this is, if
you get really overzealous with the volume you will be able to blow your
sub.

All very true.

Althogh clipping will kill a sub whether or not its beyond the
rated limit.

And how do you expect it to do this? Clipping DOES NOT blow subs.

Les
When will this idiotic audio myth ever go away?

It is NOT an audio myth you moron, and if you believe any differently
you deserve all the destroyed drivers you get.

Les
When will this idiotic audio myth ever go away?

Probably never. My recommendations still stands.

--Jeff

Les wrote:
"anon" wrote in message
news
Actualy, your amplifier should be able to provide as much if not more
rms power than the sub can handle. This ensures you can get maximum
volume from the sub without clipping. The only problem with this is, if
you get really overzealous with the volume you will be able to blow your
sub.


All very true.

Althogh clipping will kill a sub whether or not its beyond the

rated limit.


And how do you expect it to do this? Clipping DOES NOT blow subs.

Les
When will this idiotic audio myth ever go away?

"anon" wrote in message
...
Les
When will this idiotic audio myth ever go away?

Probably never.

You are likely right. The problem stems with "experts" who do not
understand, or twist, some basic audio concepts. Then the noobs listen to
the "experts" and the myth perpetuates. But what I would like to know is how
clipping kills subs.

My recommendations still stands.

Half of your recommendation is fine, and I agreed with you. The other half
is bull****. Tell us how clipping will kill your sub? If you stand behind it
then you should be able to tell us how. If you cannot then how do you know
it can?

(The next part is directed at noone imparticular)
To be honest I used to believe the myth too, as I heard it from an "expert".
But once I turned 16 and actually looked at audio and it's concepts it did
not add up. Once you actually analyze what you have been taught you might
actually learn something. Until that time you are merely reciting something
someone else actually learned.

Les

Here goes...

Clipping occurs when the amplifier is no longer able to create an output
waveform which is identical to the input waveform (obviously with an
increase in amplitude) due to a lack of voltage on the rails. When the
amplifier reaches a portion of the wave where this lack of voltage
occurs, a flatspot is formed.

These flat spots do not cause a problem except for in extreme
circumstances. During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position. A speaker is
cooled by the motion of the cone as it draws and expells air through the
voice coil. Thus you can see that if the duration of this flat spot is
long enough the lack of motion of the speaker will cause heat buildup in
the voice coil which could lead to the speaker blowing.

So yes, clipping can damage a speaker but only under extreme circumstances.

--Jeff

Les wrote:
"anon" wrote in message
...

Les

When will this idiotic audio myth ever go away?

Probably never.


You are likely right. The problem stems with "experts" who do not
understand, or twist, some basic audio concepts. Then the noobs listen to
the "experts" and the myth perpetuates. But what I would like to know is how
clipping kills subs.


My recommendations still stands.


Half of your recommendation is fine, and I agreed with you. The other half
is bull****. Tell us how clipping will kill your sub? If you stand behind it
then you should be able to tell us how. If you cannot then how do you know
it can?

(The next part is directed at noone imparticular)
To be honest I used to believe the myth too, as I heard it from an "expert".
But once I turned 16 and actually looked at audio and it's concepts it did
not add up. Once you actually analyze what you have been taught you might
actually learn something. Until that time you are merely reciting something
someone else actually learned.

Les

On Fri, 06 Aug 2004 03:17:57 GMT, anon wrote:

Here goes...

Clipping occurs when the amplifier is no longer able to create an output
waveform which is identical to the input waveform (obviously with an
increase in amplitude) due to a lack of voltage on the rails. When the
amplifier reaches a portion of the wave where this lack of voltage
occurs, a flatspot is formed.

Ok so far...


These flat spots do not cause a problem except for in extreme
circumstances. During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position.

You're missing the vital point here though.
If you analyse the clipped waveform, the 'sharp' edges contain much higher
frequencies, which will get through the high-pass section of a crossover, and
deliver very high voltage spikes to the tweeters, frying them.



Chris Pollard

--
CG Internet café, Tagum City, Philippines
http://www.cginternet.net

"anon" wrote in message
...
Here goes...

Clipping occurs when the amplifier is no longer able to create an output
waveform which is identical to the input waveform (obviously with an
increase in amplitude) due to a lack of voltage on the rails. When the
amplifier reaches a portion of the wave where this lack of voltage
occurs, a flatspot is formed.

It may be formed, but the speaker doesn't care. As long you don't send it
flying out of it's basket or give it too much power.


These flat spots do not cause a problem except for in extreme
circumstances.

Right, but it is not the "flat spots" it is the fact that under extreme
clipping there is more power being delivered to the driver than before. And
it *could* cause problems, if the amplifiers output power and the drivers
input handling are close, but what blew the speaker was too MUCH power.
Let's say you have a driver with a true handling of 100w and an amp capable
of putting out 100w. If you sent that amp into extreme clipping and you
ended up sending the speaker 140w (close enough number for examples sake)
then over time you would damage the speaker. If you took that same speaker
and fed it 140w from a non-clipped amp you would still damage the driver.
The damage was the same, so did the clipping destroy that speaker? I think
not.

During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position.

This is based on the false assumption that voltage determines the postion.
The voltage does not determine the postion, but rather the acceleration. In
square wave clipping the driver accelerates for 1/2 of the cycle one way
then quickly changes and moves the other way during the other half. A driver
does not stand still. The resulting motion of a square wave vs. a sine wave
are actually quite similar.

A speaker is
cooled by the motion of the cone as it draws and expells air through the
voice coil.

See above. The driver would still keep moving.

Thus you can see that if the duration of this flat spot is
long enough the lack of motion of the speaker will cause heat buildup in
the voice coil which could lead to the speaker blowing.

IF it relied solely on the motion of the cone AND the cone actually stops
(which you can experiement for yourself it never does) the that *could* be
true. But since a driver rarely relies on the motion alone and it never
stops then your example does not add up. You are working from false
assumptions, which make everything after them false.

If your reasoning was true then why doesn't every guitar speaker get damaged
after a few minutes of severely clipping signal?

So yes, clipping can damage a speaker but only under extreme
circumstances.

Nope. Delivering too much power damages a speaker. Clipping can lead to too
much power being applied but nonetheless it was NOT the clipping that does
the damage. It is an important difference to note.

For some further reading check out http://www.rane.com/pdf/note128.pdf

Les

"Phil Kile" wrote in message
Les
When will this idiotic audio myth ever go away?

It is NOT an audio myth you moron, and if you believe any differently
you deserve all the destroyed drivers you get.


Then prove me wrong, ****stick. Any idiot (such as yourself) can post a one
sentence reply, but where's the meat? Take a look at my reply to Anon and
dispute it, I dare you too. Then answer me two questions. (Although I doubt
you will be able to even attempt a meaningful reply)

Why don't guitar amps always have blown speakers? They are extremely clipped
all the time.

Why can't you blow a 500W driver using a severely clipped 10W amp?

So, once you can figure out a way to defy physics let me know and I will
take back my statements.

Les

"Christopher Pollard" wrote in

These flat spots do not cause a problem except for in extreme
circumstances. During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position.

You're missing the vital point here though.
If you analyse the clipped waveform, the 'sharp' edges contain much higher
frequencies, which will get through the high-pass section of a crossover,
and
deliver very high voltage spikes to the tweeters, frying them.

Take a look at http://www.rane.com/pdf/note128.pdf
It will explain how you damage those tweets so easily.

Les

I agree with Les. Clipping cannot increase the maximum power output that an
amplifier can deliver. A clipped signal will more likely destroy a sub (IF
THE AMPLIFIER CAN DELIVER ENOUGH POWER) than a normal signal

Clipping cannot miraculously create more power inside the amp. It can only
cause the amplifier to produce its maximum power constantly

"Phil Kile" wrote in message
...
On Thu, 5 Aug 2004 00:57:20 -0500, "Les" wrote:


"anon" wrote in message
news
Actualy, your amplifier should be able to provide as much if not more
rms power than the sub can handle. This ensures you can get maximum
volume from the sub without clipping. The only problem with this is,
if
you get really overzealous with the volume you will be able to blow
your
sub.

All very true.

Althogh clipping will kill a sub whether or not its beyond the
rated limit.

And how do you expect it to do this? Clipping DOES NOT blow subs.

Les
When will this idiotic audio myth ever go away?

It is NOT an audio myth you moron, and if you believe any differently
you deserve all the destroyed drivers you get.

It is NOT an audio myth you moron, and if you believe any differently
you deserve all the destroyed drivers you get.

If 300 watts (clipped) can blow a "500 watt" sub, then it's not really a 500
watt sub, is it?

Here goes...

You stood up to Les. At the very least, it shows you've got some balls.
He's a relentless SOB.

Clipping occurs when the amplifier is no longer able to create an output
waveform which is identical to the input waveform (obviously with an
increase in amplitude) due to a lack of voltage on the rails. When the
amplifier reaches a portion of the wave where this lack of voltage
occurs, a flatspot is formed.

These flat spots do not cause a problem except for in extreme
circumstances. During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position.

I was with you up until this last sentence. The speaker won't stand still.
It will keep moving because the inductance of the coil "rounds" the sharp
edges. Every see a square wave that's low-pass filtered? That's what the
cone motion will look like.

A speaker is
cooled by the motion of the cone as it draws and expells air through the
voice coil.

This is one of the cooling mechanisms, yes. Another cooling mechanism is
that the coil being moved increases the effective surface area of radiation.
In other words, moving a two inch coil one inch in one direction and then
one inch in another direction gives you a total of four inches of cooling
length, thereby doubling its effective surface area. This makes a major
assumption though: it assumes that the coil is spending an equal amount of
time at all positions within those four inches. This is true if it was a
square wave. Under sinusoidal motion, this isn't the case! It would be
concentrated towards the middle. This will DECREASE the effective surface
area of the coil which should actually be detrimental to cooling!

Thus you can see that if the duration of this flat spot is
long enough the lack of motion of the speaker will cause heat buildup in
the voice coil which could lead to the speaker blowing.

But remember. We're talking about tens to hundreds Hertz. That's a lot of
movement in the time it takes to heat up. So even if it did stand still in
spots (which it doesn't), it wouldn't matter. Because it's going to be
moving back and forth 50 times in a second. So what we care about is what's
going on over the course of several seconds or minutes, not milliseconds.

During this flat spot in the waveform, the speaker will
either remain out or in relative to its neutral position.

This is based on the false assumption that voltage determines the postion.
The voltage does not determine the postion, but rather the acceleration.

No, voltage determines position, not acceleration. (actually, that's wrong
too. current determines position - but current is determined by the
voltage, of course)