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Author Topic: $4,000 Budget Recommendations  (Read 6680 times)

Nathan Lehouillier

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Paging Roy
« Reply #10 on: February 13, 2006, 09:07:38 pm »

I would like to know more about how you "toast" sub's
with HF? I do prefer LF out of my sub's but can't quite
figure out how you could kill an sub with HF.
Thanks,
Nathan Lehouillier
Kick Drum Sound & Lighting
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Andy Peters

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Re: Paging Roy
« Reply #11 on: February 13, 2006, 11:15:12 pm »

Nathan Lehouillier wrote on Mon, 13 February 2006 19:07

I would like to know more about how you "toast" sub's
with HF? I do prefer LF out of my sub's but can't quite
figure out how you could kill an sub with HF.


Well, think about this.  The voice coil has some impedance.  Put some HF into the speaker, and even though the speaker doesn't do a very good job of reproducing HF, you're still dissipating that power in the voice coil.  Put in enough power, and ... you burn out the voice coil.

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Nathan Lehouillier

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Re: Paging Andy
« Reply #12 on: February 14, 2006, 10:36:02 pm »

Andy,
Joking a side It's not like your going to boost 10K
60 db to try to flatten out your all purpose 18"
My point was more that it's misleading to tell
someone that you sub's will burn up if they see HF.
I have no technical data to prove that 400w of hf will heat
a coil more or less than 400w of LF but I would like to see
someone come up with that.
Possibly the decrease in excursion by 50%
per octave leads speakers with active cooling solution's
Heatwick/ventedgap to the failure point??
I do believe it is or was Turbo Sound that has/had there hi mid speakers naturally roll off with no low pass on that pass band.
I would think this would lead to "toasting" the drivers?
From what I have experienced the directivity of frequency's above a 1/4 wave length of the cone's diameter become more of a concern than over heating.
And I am sorry for hi jacking this post I just though this could use alittle clearing up.
Respectfully,
Nathan Lehouillier
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John Roberts {JR}

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Re: Paging Andy
« Reply #13 on: February 15, 2006, 12:12:37 am »

Nathan Lehouillier wrote on Tue, 14 February 2006 21:36

Andy,
Joking a side It's not like your going to boost 10K
60 db to try to flatten out your all purpose 18"
My point was more that it's misleading to tell
someone that you sub's will burn up if they see HF.
I have no technical data to prove that 400w of hf will heat
a coil more or less than 400w of LF but I would like to see
someone come up with that.
Possibly the decrease in excursion by 50%
per octave leads speakers with active cooling solution's
Heatwick/ventedgap to the failure point??
I do believe it is or was Turbo Sound that has/had there hi mid speakers naturally roll off with no low pass on that pass band.
I would think this would lead to "toasting" the drivers?
From what I have experienced the directivity of frequency's above a 1/4 wave length of the cone's diameter become more of a concern than over heating.
And I am sorry for hi jacking this post I just though this could use alittle clearing up.
Respectfully,
Nathan Lehouillier



I believe the proper perspective on this is that all of the energy applied to the voice coil contributes to it's heat load whether it makes sound or not. While the LF driver is not likely to fail just because some mid or high frequency gets in, if it's on the edge of overheating adding some more out of band energy doesn't help matters, not to mention making the amp work harder for no benefit.

JR
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Nathan Lehouillier

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Thanks
« Reply #14 on: February 16, 2006, 09:50:05 am »

Agreed,

Power applied is power applied.
Thanks,
Nathan Lehouillier
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Andy Peters

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Re: Paging Andy
« Reply #15 on: February 16, 2006, 12:57:31 pm »

Nathan Lehouillier wrote on Tue, 14 February 2006 20:36

Joking a side It's not like your going to boost 10K
60 db to try to flatten out your all purpose 18"


Not joking either, but I have seen attempts to "improve" HF response in 2" compression drivers by boosting HF (over and above any CD horn boost).  No extra output, but early amp clipping and more heat dissipated in the driver.

Quote:

My point was more that it's misleading to tell
someone that you sub's will burn up if they see HF.


Well, I did say, "put in enough power." Smile

-a
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Nathan Lehouillier

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Re: Paging Andy
« Reply #16 on: February 16, 2006, 01:55:59 pm »

I see were you are coming from.
Thanks,
Nathan Lehouillier
KDS&L
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Roy Richards NRBC Media

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Re: Paging Roy
« Reply #17 on: February 16, 2006, 05:27:23 pm »

Quote:

My point was more that it's misleading to tell
someone that you sub's will burn up if they see HF.

I have repaired a few of those Yamaha 18 subs that did indeed burn up while being fed without a crossover. The heat dissipation is significantly reduced as the frequency is increased. It was the same in all of them, the voice coil had melted near the middle of the winding, indicating a heat issue. While the amp feeding the speakers was matched to the speaker wattage, the coils still burnt up. After showing the users how to feed the subs with a low pass filter, they have not had any more meltdowns.

Just my experience with the Yamaha subs, sorry if you felt it was mis-leading.
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John Roberts {JR}

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Re: Paging Roy
« Reply #18 on: February 16, 2006, 09:13:07 pm »

Roy Richards  NRBC Media wrote on Thu, 16 February 2006 16:27

 

My point was more that it's misleading to tell
someone that you sub's will burn up if they see HF.

I have repaired a few of those Yamaha 18 subs that did indeed burn up while being fed without a crossover. The heat dissipation is significantly reduced as the frequency is increased. It was the same in all of them, the voice coil had melted near the middle of the winding, indicating a heat issue. While the amp feeding the speakers was matched to the speaker wattage, the coils still burnt up. After showing the users how to feed the subs with a low pass filter, they have not had any more meltdowns.

Just my experience with the Yamaha subs, sorry if you felt it was mis-leading.



By all means, it's good practice to bandpass any multi-amped speaker. FWIW with subs don't disregard the lower skirt too. Pumping in LF energy below what the box can handle will do nothing good and can cause mechanical issues as well adding to thermal load.

JR
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