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Old 10-31-2002, 02:08 AM
  #71
apache77
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it tried to jump an increasing gap one time and over excurted, it must have over heated because it would not move any more, (i think it was mud and not distortion thou)
 
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Old 10-31-2002, 09:39 AM
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Quote:
Originally posted by apache77
answer= what the hell is overexcursion?
The overexcursion I was referring to is when the motor is driven beyond it's linear design specs.

A speaker's maximum excursion is listed as "Xmax" on the spec sheet, and is usually listed in mm.

Kinda like "extra stuff" in amps...

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Old 10-31-2002, 12:42 PM
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Originally posted by mcollinstn
There is no gap for the current to jump. In one end of the voicecoil conductor wire, roundy roundy for a handfull of turns, then back out the other end of the conductor. No gap.
Hey apache77...I dug up this page on basic car audio electronics (speaker design), so you can see how a speaker works...you seem to be having trouble grasping the concept...

It also discusses the "electromagnetic gap" you guys seem to be having trouble with...

This page deals with the "stuff" inside amplifiers...

Also, there's a page on "Too Little Power"...that states:

"Too little power will only cause the maximum output level to be low. Abuse and the defective 'wing nut' (an idiot) connected to the volume control blow speakers with low powered amplifiers. If driving a speaker with low power would cause them to fail, speakers would fail every time you lower the volume on the head unit.

Xmax:
By definition it is the peak linear travel of a driver. If you measure the distance that the voice coil can travel in the gap (in one direction) while the number of turns in the gap doesn't change, you have the Xmax. If you go past this point, the actual windings in the voice coil start to leave the gap.

-If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.
-If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).
-If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.
-If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage."

So perhaps we can agree on three things...

1. The clipped signal cannot "weld" a voice coil...only a voice coil overheating can destroy a voice coil.
2. Underdriving properly rated speakers, it is highly unlikely to blow them.
3. It is the wattage from the amp that blows speakers, not distortion.


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Old 10-31-2002, 01:17 PM
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So basically what your saying is that then your pushing a 500watt sub with a 200watt amp with the gain all the way up and the speaker starts to distort and cackle, thats o.k. because a speaker doesn't care about sound quality. So thats less likely to hurt the speaker than when you run a 800 watt amp that is capible of powering the speaker at 1/2 gain with clean signal.
I'm not an electrcal engineer but I know what you read in books isn't allways what really happens, and I have learned from expierience that when your overworking a small amp you loose sound quality and blow speakers. but if you run a bigger amp and turn the gain down it is louder, cleaner and doesn't blow subs. than again I don't really know what I'm talking about at least thats what all the guys at the sound offs used to say right before we'd win.
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Old 10-31-2002, 01:51 PM
  #75
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Sound systems are like high performance engines..... Hold em wide open long enough.... **** will blow!!!!!
 
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Old 10-31-2002, 01:52 PM
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Originally posted by JUST ONCE
So basically what your saying is that then your pushing a 500watt sub with a 200watt amp with the gain all the way up and the speaker starts to distort and cackle, thats o.k. because a speaker doesn't care about sound quality.
Yes. It sounds ugly, but the speaker should last, because it will never exceed it's design spec.

Quote:
Originally posted by JUST ONCE
So thats less likely to hurt the speaker than when you run a 800 watt amp that is capible of powering the speaker at 1/2 gain with clean signal.
No. Both have an upside and downside. A watt is a watt to the speaker.

Quote:
Originally posted by JUST ONCE
...I have learned from expierience that when your overworking a small amp you loose sound quality and blow speakers. but if you run a bigger amp and turn the gain down it is louder, cleaner and doesn't blow subs.
In a perfect world, people would not abuse equipment. But they do. Everyone eventually turns up their stereo...equipment blows.

Now, here's a scenario for you. Let's say you make speakers. We'll call them "Stuff Speakers". As the owner of "Stuff Speakers" your engineers come to you with a new product. On a bench test, this is how the speaker performed:

-music- 100watts- speaker exceeded it's thermal design limits in 1,000 hours
-sine wave- 100 watts- speaker exceeded it's thermal design limits in 3 minutes
-square wave- 100 watts- speaker exceeded it's thermal design limits in 30 seconds

Where do you rate your speaker at?

My point is, speaker ratings are subjective, there is no benchmark from company to company.

So how long does a 100watt speaker last when it gets a 30 watt (30%) clipped signal from music? Probably not very long...speaker companies must balance the design spec with marketing objectives.

To be safe, you're right. Buy the most over-engineered equipment you can, and keep the volume down. However, how many of us can afford a $10K system in our boats that won't hit 100db? Not very realistic.

Like HP breaking drives, the only way to truely guarantee speakers won't blow is to not exceed their thermal limits...how you get there is your choice.

PS- Ever seen the Brahma (1,600 watt RMS handling; 27.32 mm Xmax) in action? Gives the W7 a run for its money...
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Old 10-31-2002, 02:29 PM
  #77
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hey mcollinston, i think he quoted you on the gap thing because i dont think the page he put a link to shows the wire from the amp going to the voice coil so he thinks it magically jumps to the coil.
I will refer back to my earlier post that you (havasu) have never seen the inside of a speaker.

just to let you know, there were things that are wrong on that page and i have emailed the guy that has that page to correct them when he changes them i will let you know.
 
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Old 10-31-2002, 02:49 PM
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Quote:
Originally posted by apache77
I will refer back to my earlier post that you (havasu) have never seen the inside of a speaker.
An I will refer to my earlier post...

Quote:
Originally posted by Havasu Hangin
you seem to be having trouble grasping the concept...
..although I will amend that to read "grasping the concept of anyone else having an opion that differs from yours"...

Well, this world is a much better place because of you and your knowledge...

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Old 10-31-2002, 04:44 PM
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Quote:
Originally posted by BARRY1784
Sound systems are like high performance engines..... Hold em wide open long enough.... **** will blow!!!!!
Tell Em Barry,

Thanks for coming by and looking at my system. Glad to hear it is not as bad as I thought.

Greg Biffle was in the office a few minutes ago and we were talking about you. I ask if he had been invited to your party and he said no. He will be in Homested racing that weekend anyway.

He wants to sell his 353 Formula if you know anyone in the market. He is going to buy a 38 Formula.

Hope you guys did not get too drunk last night

Mark
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Old 10-31-2002, 11:51 PM
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*** I believe you are correct on the V/C resistance, but it's the overexcursion that will decrease resistance, as the current tries to jump the increased gap ***

this statement said nothing about a MAGNETIC gap, it mentioned some kind of GAP that current tries to JUMP. I still say that current does not try to jump any gap in a speaker (unless you feed it 75,000 volts in which case a fat Frankenstein lightning bolt will arc from one speaker wire lug directly to the other, or to ground, or somewhere...).

As far as the magnetic gap, I will certainly agree that when a voice coil passes the boundary of the magnetic gap as pictured in the linked webpage, that the emf which pulls or pushes the speaker is reduced and if severely past the boundary, the force can even reverse - neither of these situations is conducive to faithful sound reproduction.

In Havasu's later post, he clearly stated that a speaker will exceed its thermal limits (fail) sooner when fed a sine wave at "x" watts than when fed music. It will also fail sooner when fed a square wave at "x" watts than when fed a sine wave.

To me this is the same thing as saying that you can blow a speaker through distortion with an amp rated at less than the max wattage of the speaker (which is usually rated with a musical signal at a RMS wattage value).

I STILL say that a 100 watt speaker can be blown (through voicecoil overheating) with a 50 watt amp driven well into distortion.

I STILL say the same 100 watt speaker can be safely driven to a 100 watt level with a big fat clean 500 watt amp and the whole shebang will sit there and play happily for a long long time. I still say this will be true BECAUSE the big fat clean amp is sending a clean unclipped waveform to the speaker and that the speaker can faithfully reproduce this waveform without "stumbling" on itself and choking on spikes in the magnetic field that allow too much current to pass, creating heat.

If I am wrong, I will stupidly and happily continue in my incorrect belief like a moron.

I just keep reading bits and pieces of the reasons WHY I am wrong that continue to support what I am trying to say...

Apache, Havasu - like I said before, I'm not trying to light anyone up - I think this sh!t is fun.

(I also learned from another post that Apaches wonderchick is named Mandy - now I can attach a name to the vision of beauty..)

Not to intentionally stray from the controversial disputes on the operation of a speaker, but who is making the best marine high-efficiency coax 6x9 or 8" speaker right now. Price is an object, but not too much..
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