Help with Amplifier

[mtrycrafts]

You can analyze a distorted sine wave as the sum of pure sine waves of fundamental frequency and harmonic frequency components and yes, depending on the particular waveform, that could include d.c. components as well. This is not myth. mtrycrafts, this time it is your turn to browse the web a bit more, try searching Fourier analysis. I think when it comes to this stuff, Mac knows what he's talking about. He has his opinions and I don't always agree with him neither, but he knows his stuff.

I did in fact checked the internet. I posted 4 links.
Why did I include the links if no one bothers to read it!!!


Richard D Pierce Apr 8 1999, 12:00 am show options

Newsgroups: rec.audio.pro, rec.audio.tech, rec.audio.misc, rec.audio.opinion
From: DPie...@world.std.com (Richard D Pierce) - Find messages by this author
Date: 1999/04/08
Subject: Re: Amp Clipping
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In article <7ej551$21...@nonews.col.hp.com>, <R...@nospam.com> wrote:

>: > This is true, because when an amp clips all the power suddenly
>: becomes
>: > high frequency power and overdrives the tweeters, usually.


>When an amp clips, all the power suddenly becomes low frequency power,
>otherwise called "DC". This is what overdrives and burns out speakers.



Wrong, if the amp is clipping symmetrically, there will be no such "DC
component.


> ______ <--DC Component
> / \
> / \
>--/ \ /
> \ /
> \ /
> \_____/


The diagram, as you show, has no real DC component. The existance of a
flat-top waveform does NOT mean a DC componennt

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

 

[mtrycrafts]

Thanks, I think You are right about the DC. the key here is to see how each COMPONENT reacts to the input energy. In this case, because the component can't respond fast enough, it sees the input as DC. My point is, it's all relative.

Hogwash!!!!

In this case the low driver fail because it was way over powered. NO DC!!!


Richard D Pierce Apr 8 1999, 12:00 am show options

Newsgroups: rec.audio.pro, rec.audio.tech, rec.audio.misc, rec.audio.opinion
From: DPie...@world.std.com (Richard D Pierce) - Find messages by this author
Date: 1999/04/08
Subject: Re: Amp Clipping
Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse



In article <7ej551$21...@nonews.col.hp.com>, <R...@nospam.com> wrote:

>: > This is true, because when an amp clips all the power suddenly
>: becomes
>: > high frequency power and overdrives the tweeters, usually.


>When an amp clips, all the power suddenly becomes low frequency power,
>otherwise called "DC". This is what overdrives and burns out speakers.



Wrong, if the amp is clipping symmetrically, there will be no such "DC
component.


> ______ <--DC Component
> / \
> / \
>--/ \ /
> \ /
> \ /
> \_____/


The diagram, as you show, has no real DC component. The existance of a
flat-top waveform does NOT mean a DC componennt

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

 

[mtrycrafts]

.....yet another "sound" argument for big watts.....

Be very careful where you stand as it is in quick sand.

Are you telling me, that a 1000w amp cannot smoke those speakers well before it clips???

Think first, investigate second, then investigate more.

 

[mtrycrafts]

I'm definitely with Mac on this one. Mtry, if you're going to claim "Audio myth" on stuff, I hope that next time you actually understand what you're talking about. Do you have a doctorate in physics? Or for that matter, do you have any education at all in electrical engineering/electromagnetic physics? It seems you do not...

Actually, you should ask the other posters if they have a doctorate in anything, right???
Did you bother to read the 4 links I posted????
Please do so before you jump to conclusions.

As to DC, here is one of the links, please read it all the way through this time. Including the last paragraph about what gets blown when amps clip, from thousands of hard data by the author:


Richard D Pierce Apr 8 1999, 12:00 am show options

Newsgroups: rec.audio.pro, rec.audio.tech, rec.audio.misc, rec.audio.opinion
From: DPie...@world.std.com (Richard D Pierce) - Find messages by this author
Date: 1999/04/08
Subject: Re: Amp Clipping
Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse



In article <7ej551$21...@nonews.col.hp.com>, <R...@nospam.com> wrote:

>: > This is true, because when an amp clips all the power suddenly
>: becomes
>: > high frequency power and overdrives the tweeters, usually.


>When an amp clips, all the power suddenly becomes low frequency power,
>otherwise called "DC". This is what overdrives and burns out speakers.



Wrong, if the amp is clipping symmetrically, there will be no such "DC
component.


> ______ <--DC Component
> / \
> / \
>--/ \ /
> \ /
> \ /
> \_____/


The diagram, as you show, has no real DC component. The existance of a
flat-top waveform does NOT mean a DC componennt

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

 

[jaxvon]

Mtry, are you even reading your own links? According to your information, the tweeter will be unaffected by the DC component due to the high pass filter. What happens to the DC component? Straight to the mid-bass driver.

Oh, and if you want to say something else, stop posting the same garbage 5 or more times with a different reply in each one. Use the "edit" function. Your overposting clogs up the forums with fluff. I kindly ask the new guys to not double post their quesetions. I'll kindly ask you do not quintuple post the same e-mail with every response you have to a comment.

 

[mtrycrafts]

Do you even understand the physics behind it?

I guess you don't need to bother to read what the experts are saying???
Speaks volumes.

 

[mtrycrafts]

Mtry, are you even reading your own links? According to your information, the tweeter will be unaffected by the DC component due to the high pass filter. What happens to the DC component? Straight to the mid-bass driver.

Oh, and if you want to say something else, stop posting the same garbage 5 or more times with a different reply in each one. Use the "edit" function. Your overposting clogs up the forums with fluff. I kindly ask the new guys to not double post their quesetions. I'll kindly ask you do not quintuple post the same e-mail with every response you have to a comment.

You guys don't seem to read the links and address it. You force me to post the links and the content. And yes, I did read them and asked you to read the last paragraph:

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency components that suffer the highest incidence of
damage: tweeters.

Please tell me why the tweeters are the ones that blow the most, not the woofers??? Oh, it is not the DC as it is not there, but the tweeter is over powered beyond its limit.

 

[mtrycrafts]

PENG is correct. A clipped signal essentially saturates the output transistors which acts as a switch delivering the DC rail voltage directly to the driver. It may only last a short duration, but it is like putting DC directly to the driver for a short amount of time.

Time to reassess. Peng changed his assessment on this.

 

[mtrycrafts]

.....Mac, you're wasting your time.....you speak from practical experience, he speaks from what others have said....hooray, Mtry can read....I'll take your opinions and reportings every day......

Take his opinions at your own peril.

Maybe you should consult and research the experts on this and everything audio, no??? That takes a bit of reading on your part. It can be learned.

 

[MacManNM]

Hogwash!!!!

In this case the low driver fail because it was way over powered. NO DC!!!


Richard D Pierce Apr 8 1999, 12:00 am show options

Newsgroups: rec.audio.pro, rec.audio.tech, rec.audio.misc, rec.audio.opinion
From: DPie...@world.std.com (Richard D Pierce) - Find messages by this author
Date: 1999/04/08
Subject: Re: Amp Clipping
Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse



In article <7ej551$21...@nonews.col.hp.com>, <R...@nospam.com> wrote:

>: > This is true, because when an amp clips all the power suddenly
>: becomes
>: > high frequency power and overdrives the tweeters, usually.


>When an amp clips, all the power suddenly becomes low frequency power,
>otherwise called "DC". This is what overdrives and burns out speakers.



Wrong, if the amp is clipping symmetrically, there will be no such "DC
component.


> ______ <--DC Component
> / \
> / \
>--/ \ /
> \ /
> \ /
> \_____/


The diagram, as you show, has no real DC component. The existance of a
flat-top waveform does NOT mean a DC componennt

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

Mrty, are you stupid, or is it that you cant read? This is what I have been saying.

This is why the guy's woofers blew, not his tweeters.

 

[MacManNM]

Mrty,
Have you ever had an original thought? Can you think for yourself without trying to quote someone else's work? You have to be the most clueless individual I have ever seen.

 

[PENG]

Precisely what is in that link I posted, by Richard Pierce
[/b]

I read your first link, but did not have time to read the other ones yet When I saw you comments on this d.c.thing, I jumped in because I know d.c. (a component) exists in certain non-sinusoidal waveforms.

People are not really arguing all that much with you about how a tweeter get blown. It has been, at least to me, a technical debate on your point about "there is no d.c.". As to what really cause damage to a tweeter, you could well may be right based on your research so far, and I have never disputed the claim that it is not the clipped output that damages a tweeter. I'll read your other links.

 

[PENG]

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

[/b]

I have never said it was the low frequency signals that damage a tweeter. I was simplying stating the fact that d.c. component do exist, depending on the particular waveform.

 

[PENG]

Further, if your assertion were true, and it is the low frequency signals
that cause the damage, then the damage would occur mostly on woofers when,
in fact, the actual statistics scene in the field are quite the opposite:
it is the high-frequency compoents that suffer the jhighest incidence of
damage: tweeters. If it was low-frequency signals, they would be
effectively blocked by the tweeter crossover, and even the simplest of
two-way systems has a capacitor in series with the wteeter that quite
effectively blocks DC from ever reaching it.


--
| **** Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPie...@world.std.com |

[/b]

I am not arguing, and I have never said it is the low frequencies that damage a tweeter. I was simplying stating the fact that d.c. component do exist, depending on the particular waveform. I did say Mac knew his stuff. He mentioned something to the effect that a clipped signal has higher rms....output/...energy..... (sorry Mac I am not quoting word for word) and that makes sense to me because a "flat top" signal (just an example) will have many high frequency sine wave (harmonics) in it. That's pretty much all I was trying to say in my posts.

 

[j_garcia]

Whichever speaker went blew because it received more power than it was rated for, period, not because the amp clipped.

I think sometimes you guys just like to argue pedantic details. The amp clipping caused a spike in the amount of power sent to the driver. Yes, it was too much power that caused the actual damage, but that spike in power was because the amp could not provide enough power to adequately drive the speaker.

THIS came out of your articles:

Wherever possible, amplifiers should never be allowed to clip - this much is well known to anyone who is interested in quality reproduction. That it very likely will happen at some point is also accepted - parties in particular being the worst offenders. For those who use relatively small (i.e. low powered) amplifiers as a matter of course, the risk is greater, although the DC voltages so created are also reduced because of the lower overall supply voltage.

For those who prefer valve (tube) amplifiers, they are only partially immune from this problem. Since transformers cannot pass DC by their very nature, the DC cannot get to the voicecoil. There is still the real risk that distortion will increase dramatically if an asymmetrical waveform causes amp clipping, since it is now the output transformer that takes the burden of the DC ... this may cause core saturation. The problem will be worse with push-pull amplifiers, and their distortion could easily rise to the levels commonly found in single-ended designs.

To what extent have the effects described here influenced reviewers (who typically never use any instrumentation, and usually never know if the amp under test is clipping or not)? I have no idea, but it is not unreasonable to assume that some degree of clipping must be experienced from time to time, and that will affect the outcome of a subjective test ... but with absolutely no technical detail to indicate the actual cause of the problem should it exist. Reviewer-speak will obfuscate the real issue(s), and the lack of instrumentation leaves us in the dark.

Finally, it must be pointed out that this shows that clipping with real-world (speech or music) signals creates not only the harmonics that have been described in innumerable web pages, but also generates a subsonic signal that is potentially very damaging to drivers, but is never mentioned. This signal has the capability to cause driver damage at worst, or unwanted cone modulation and additional loudspeaker distortion at best - neither can be considered a desirable outcome.

The moral of the story is to avoid clipping at all times - even momentary (supposedly inaudible) clipping will generate an unwanted low frequency or subsonic signal whose frequency will be completely unrelated to anything in the programme material.

 

[MacManNM]

Look the guy just likes to argue, he will argue about anything. You say its tan, he'll say its earth tone. It doesn't matter who is right, with him, arguments with him are living creatures, constantly changing. See when he's wrong he picks on some other part of your statement, it's like an ant moving a mountian, one grain at a time. I dont know, maybe his mother didn't hold him enough

 

[mtrycrafts]

I think sometimes you guys just like to argue pedantic details. The amp clipping caused a spike in the amount of power sent to the driver. Yes, it was too much power that caused the actual damage, but that spike in power was because the amp could not provide enough power to adequately drive the speaker.

THIS came out of your articles:

Are you telling me then that a 1000watt amp will not blow a speaker??? LOL.

At clipping, the power increases rapidly up to 2X. If it is beyond the speakers capacity, it smokes, period.

Please call Chris Russell at Bryston. Posted his number above. Power what kills the speaker.
The article states, don't clip because of the excess power increase, period.

 

[mtrycrafts]

Mrty, are you stupid, or is it that you cant read? This is what I have been saying.

This is why the guy's woofers blew, not his tweeters.

Call Bryston for answers, period. Chris Russel will starigten you out. NO DC!!! TOO Much power

 

[mtrycrafts]

I have never said it was the low frequency signals that damage a tweeter. I was simplying stating the fact that d.c. component do exist, depending on the particular waveform.

The author has a qualifier:
if your assertion were true,

for argument sake. But, talking further with the chief amp designer, Chris Russell, at Bryston, the input signal to the amp itself must have a DC component first, however, many amps have a DC blocker. Power beyond the speakers capability is what blows speakers.

 

[j_garcia]

Power beyond the speakers capability is what blows speakers.

I don't think anyone is questioning that fact. It's HOW that power is generated that seems to be at issue, and I don't see why it needs to become such a long, drawn out, semi-redundant discussion about small details that really mean quite little to most people.