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Old 5th November 2006, 01:53 PM   #11
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Most of the newer quality car subwoofers that use a short coil also have a very long long magnetic gap to reduce distortion. The short coil is never really out of the gap...

Here is a very good explanation of short coil long gap technology...


http://www.hometoys.com/htinews/jun0...hiel/thiel.htm
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Old 5th November 2006, 02:11 PM   #12
BHTX is offline BHTX  United States
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Quote:
Originally posted by burnedfingers
These power figures are for 1K sine wave.

After looking at the web page I can tell you that these wouldn't be considered for any large format commercial system at all. They might work for light DJ work.
Just for the record, after looking up the info on that page myself, I absolutely agree. ..Just didn't go back and delete my careless assumption like I should have.

If a dual 2 ohm woofer were connected paralell to that particular amplifier and either played at fairly high volume for an extended period of time, or just having the amp throw massive amounts of unecessary power at it for some unjustified reason...then yes, I suppose it's likely that something bad could very well happen to the amplifier itself. Otherwise, I just can't see it happening, unless another unknown variable was the culprit (defect within the amplifier).

*shrug* Who knows?
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Old 5th November 2006, 03:45 PM   #13
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I suppose one other possibility is that a cheap woofer might not have a bumped backplate, so if fed far too much power it would ram itself into the backplate and could severly short the coil. However, the woofer would be scrap after this occured.
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Old 6th November 2006, 08:16 AM   #14
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I always try to use 10x margin so if I build or modify a solid state amp to handle 0.4 ohms I should be able to use a big 4 ohm car audio subwoofer right?

Since I don't very much about these things I depend on the information given to me and I have had no reason to doubt my friends knowledge before.

Thank you all for your help and ideas.
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Old 6th November 2006, 08:39 AM   #15
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Yes an amp designed to handle 0.4 ohms will laugh at 4 ohm speakers all day long. However, it would also be the size of a small engine, need an inductrial power feed, cost a fortune and require 'difficult' construction techniques and parts.

What I'm trying to say is there is no need. If you take into account the reactive nature and design properly for the rated impedance it should be fine.
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Old 6th November 2006, 08:56 AM   #16
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It is a well known fact that car audio and home/pro audio products cannot coexist!!!! They despise each other so much that often one will commit suicide just to spite the other and leave it useless.

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Old 6th November 2006, 09:52 AM   #17
sss is offline sss  Israel
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all inductive loads return energy back to the amp .
some amps even got protection diodes across the output stage for that purpose.
bigger speakers=more energy
car speakers not only blow "home amps" , they blow car amps also ...
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Old 6th November 2006, 12:35 PM   #18
AndrewT is offline AndrewT  Scotland
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Hi all,
are posts 16 & 17 a wind up?
The authors cannot seriously expect us to believe that nonsense.
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Old 6th November 2006, 12:39 PM   #19
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I was of course joking.

I'm not so sure sss was.
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Old 6th November 2006, 12:51 PM   #20
ilimzn is offline ilimzn  Croatia
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Quote:
Originally posted by sss
all inductive loads return energy back to the amp .
some amps even got protection diodes across the output stage for that purpose.
Wrong, the diodes are not there for that purpose. Under normal operating conditions they never conduct, regardless of impedance. The amplifier output stage is responsible for returning inductive current to the power supplies under normal conditions, which is why reactive loads increase power dissipation in the output stage.
The diodes are there to prevent the inductive load producing 'flyback' pulses that can be signifficantly higher than the power rail voltage (even several hundred V is not uncommon) when the output stage is cut off mid cycle due to protection activation. Many amps actually don't have these diodes when they should - resulting in output stage destruction by their own output stage protection circuits being activated in the presence of an inductive load!
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