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PostPosted: Wed Mar 22, 2017 2:43 pm 
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For those of you that are interested especially DJ's with their highly compressed music at ear killing sound levels check out the link if you don't want to blow the things up.

http://sound.whsites.net/tweeters.htm


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PostPosted: Wed Mar 22, 2017 4:04 pm 
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His analysis is a bit off the mark. The reason tweeters blow when woofers usually don't is that clipping increases the high frequency power density beyond normal. With a clean signal power density decreases by 3dB with each octave increase in frequency. A tweeter in a 100w system normally will receive 10w or less, so that's all that the voice coil is designed to handle. When clipping causes the high frequency power density to go well above normal that 10w tweeter can receive 20w or more, and that will toast the voice coil. The increase in power density won't bother the 100w woofer, because the maximum level still can't exceed what the amp power rails will allow. If clipping bothered woofers guitar players would have to swap them out nightly, if not between sets.
High levels of compression can make the situation worse, and increase the chances of damaging woofers via long term heat build up. It also will make the sound really bad, as will clipping. There's a simple rule to follow if you don't want to blow drivers: if it sounds bad turn it down.


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PostPosted: Fri Mar 24, 2017 2:36 am 
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Bill Fitzmaurice wrote:
His analysis is a bit off the mark. The reason tweeters blow when woofers usually don't is that clipping increases the high frequency power density beyond normal. With a clean signal power density decreases by 3dB with each octave increase in frequency. A tweeter in a 100w system normally will receive 10w or less, so that's all that the voice coil is designed to handle. When clipping causes the high frequency power density to go well above normal that 10w tweeter can receive 20w or more, and that will toast the voice coil. The increase in power density won't bother the 100w woofer, because the maximum level still can't exceed what the amp power rails will allow. If clipping bothered woofers guitar players would have to swap them out nightly, if not between sets.
High levels of compression can make the situation worse, and increase the chances of damaging woofers via long term heat build up. It also will make the sound really bad, as will clipping. There's a simple rule to follow if you don't want to blow drivers: if it sounds bad turn it down.


Bill I took the liberty of sending your quote to Rod.
Here is his reply.
Mkulu,

Since Bill seems to have glanced at the intro and decided I'm wrong, I have no interest in him or his business.

My tweeter article is the most comprehensive anywhere on the net, but he dismisses it as "off the mark" despite the fact that he's largely wrong.

He simply mindlessly regurgitates the same old explanation that everyone else uses.

If he bothered to read the article, he'd see that I do account for the harmonics (and in far greater detail than anywhere else).

Where is his detailed explanation of the problem? Oh, he hasn't got one, and is only interested in selling speaker plans.

His 'analysis' of guitar player's speakers is utter drivel. A guitar amp that used 100W of speakers for a 100W amp will kill speakers - the speakers should be rated for double the amp power for transistor amps, and about 1.6 times for valve amps.

Cheers, Rod


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PostPosted: Fri Mar 24, 2017 5:35 am 
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Interesting, that he seems to think that a transistor "watt" and a tube/valve "watt" are different...
They aren't. Voltage swing is voltage swing. The type of amplifier is meaningless.

Bill basically repeated one of the points his article makes, with slightly different emphasis. He says Bill is largely wrong, when he himself makes exactly the same point in his article. That is an ignorant excuse for an argument.

I have no dog in the fight... I've never blown a driver, and I hope my streak continues.

When a person begins a counter argument by saying "that's a bit off the mark" and gives a brief explanation, and the response is a childish rant, I question everything the ranter says. If you can't debate like an adult, then don't open your mouth. Don't try to sway an audience by claiming the other guy doesn't know what he's talking about - sway an audience with facts, research, and insight.


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PostPosted: Fri Mar 24, 2017 7:03 am 
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He also seems to not be familiar with one of the most well respected guitar drivers of all time either, the 25 watt Celestion Greenback G12. Anyway, sticks and stones, etc.


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PostPosted: Fri Mar 24, 2017 3:55 pm 
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Bill Fitzmaurice wrote:
The increase in power density won't bother the 100w woofer, because the maximum level still can't exceed what the amp power rails will allow.


Bill, could you clarify this for me please.
I only ask because, a common line under "Protecting your Drivers", found in many of your plans, discusses transient output, with a magnitude of x 10 rated power.
I have assumed in the past that the transients are created because that is the power rail capability...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Fri Mar 24, 2017 5:11 pm 
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Grant Bunter wrote:
I have assumed in the past that the transients are created because that is the power rail capability...
When amps are rated it's at a very low THD, which means if it's a well designed amp there's still headroom available in the power rails, and reserve current capacity in the power supply filter caps. I've only blown one driver ever, a 200w EVM 15B that I was testing with a 50w amp. My intent was to put a low voltage signal into it, but I did something wrong, I'm not even sure what, and the voice coil went in about the half of a blink of an eye. It hardly even made a sound when it blew. It certainly didn't get toasted by the 20 volts @ 2.5 amps that you'd think was the maximum that amp could deliver, it was a transient pulse at a much higher voltage and/or current. I thought maybe the amp had blown and taken the driver with it, but the amp was fine. A transient pulse isn't going to be long term, that's why it's called transient, but as this case proved to me it doesn't have to be to kill a driver.


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PostPosted: Sat Mar 25, 2017 4:07 am 
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Bill Fitzmaurice wrote:
Grant Bunter wrote:
I have assumed in the past that the transients are created because that is the power rail capability...
When amps are rated it's at a very low THD, which means if it's a well designed amp there's still headroom available in the power rails, and reserve current capacity in the power supply filter caps. I've only blown one driver ever, a 200w EVM 15B that I was testing with a 50w amp. My intent was to put a low voltage signal into it, but I did something wrong, I'm not even sure what, and the voice coil went in about the half of a blink of an eye. It hardly even made a sound when it blew. It certainly didn't get toasted by the 20 volts @ 2.5 amps that you'd think was the maximum that amp could deliver, it was a transient pulse at a much higher voltage and/or current. I thought maybe the amp had blown and taken the driver with it, but the amp was fine. A transient pulse isn't going to be long term, that's why it's called transient, but as this case proved to me it doesn't have to be to kill a driver.


Ok.
Is there any relationship between power density and transients?

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Sat Mar 25, 2017 8:07 am 
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Grant Bunter wrote:
Is there any relationship between power density and transients?
There is if you have a transient occur in the tweeter pass band that sends it a signal of much higher power than the tweeter voice coil and/or suspension can handle. Say the tweeter is 10 watt capable, which is normal for a 100 watt speaker. A 40 watt transient will destroy the tweeter, yet not be even close to the clean power output capability of a 100 watt amp, let alone what it could provide when clipping. It would be a fairly rare occurrence in normal use. Where it might happen is when a signal cord gets unplugged. What you mainly hear when that happens is low frequencies, so you cringe and pray that you didn't toast a woofer, but if anything's going to be toasted it's probably the tweeter.


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PostPosted: Thu Mar 30, 2017 4:28 am 
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Mkulu wrote:
Bill Fitzmaurice wrote:
His analysis is a bit off the mark. The reason tweeters blow when woofers usually don't is that clipping increases the high frequency power density beyond normal. With a clean signal power density decreases by 3dB with each octave increase in frequency. A tweeter in a 100w system normally will receive 10w or less, so that's all that the voice coil is designed to handle. When clipping causes the high frequency power density to go well above normal that 10w tweeter can receive 20w or more, and that will toast the voice coil. The increase in power density won't bother the 100w woofer, because the maximum level still can't exceed what the amp power rails will allow. If clipping bothered woofers guitar players would have to swap them out nightly, if not between sets.
High levels of compression can make the situation worse, and increase the chances of damaging woofers via long term heat build up. It also will make the sound really bad, as will clipping. There's a simple rule to follow if you don't want to blow drivers: if it sounds bad turn it down.


Bill I took the liberty of sending your quote to Rod.
Here is his reply.
Mkulu,

Since Bill seems to have glanced at the intro and decided I'm wrong, I have no interest in him or his business.

My tweeter article is the most comprehensive anywhere on the net, but he dismisses it as "off the mark" despite the fact that he's largely wrong.

He simply mindlessly regurgitates the same old explanation that everyone else uses.

If he bothered to read the article, he'd see that I do account for the harmonics (and in far greater detail than anywhere else).

Where is his detailed explanation of the problem? Oh, he hasn't got one, and is only interested in selling speaker plans.

His 'analysis' of guitar player's speakers is utter drivel. A guitar amp that used 100W of speakers for a 100W amp will kill speakers - the speakers should be rated for double the amp power for transistor amps, and about 1.6 times for valve amps.

Cheers, Rod


To Bill, Rod and all on the Forum.
My unreserved alpologies for posting Rod's email to me on the forum. I should not have done this.
At the time I had a rush of crazy blood to the head.
Regards
Mkulu


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PostPosted: Thu Mar 30, 2017 7:14 am 
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Not a problem, live and learn. Rod must have some level of interest in either me or my business, as he sent me an email. But the heading of the email read 'Forum nonsense', so I deleted it, unread. I had respect for him on a professional level prior to reading what he sent to you, but that, along with the potential for any respect for him on a personal level, has now been deleted as well. No matter, I suspect we'll both get by.


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