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Discussion Starter #1
I built my first DIY sub over a year ago now I think and it is still running strong. When I did the model it showed that the XMAX was exceeded bigtime under 17Hz but that has not happened. My A500 amp has no high pass filter and I play HT stuff all the time.


What have you guys done to blow drivers?
 

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Discussion Starter #3
I dunno why the red went away. You can still see the graph though.

The XMAX is 9mm but the XMECH is 27mm I think. I model for 380 watts which is what the A500 has been tested to put out under normal conditions.

 

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Discussion Starter #5
yeah it is. Have you ever blown a driver?

I don't get it I am really speaking generally here.
 

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Discussion Starter #7
It is wired in series but the driver has dual 4 ohm coils. The WinISD file assumes parallel wiring.
 

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Discussion Starter #9
No it is dual 4 ohm coils. 2/8 wiring means it can be wired for 2 or 8 ohms.


How does that change xmax? Does series give you more xmax compared with parallel? Does not seem likely.
 

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I think 400 watts is 400 watts. No matter how much resistance the VC has.
Consider what you just said...

Solving 400W = V**2 / 8 ohms gives V = about 57 Volts
Solving P = I * V gives I = about 7 amps


Solving 400W = V**2 / 2 ohms gives V = about 28 Volts
Solving P = I * V gives I = about 14 amps



Now, assuming your amp can deliver the current, which 400W is more likely to reach xmax? Which produces the greater field in the voice coil, 7 amps or 14 amps?


Of course,the assumption about the amp being able to deliver the current is not trivial. Which condition will land the amp on my service bench sooner?
 

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Discussion Starter #14
electric field is based on voltage and amps. A coulomb can be defined using both. Why are you only looking at the amps?
 

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Because it is the current that matters when creating a magnetic field in a coil. You can have all the voltage that you want, but the current will define the field.
 

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I've blown a few drivers in my younger and dumber days. :rolleyesno:


Fred,
The modeling predictions are just that and assume that things are staying perfectly linear. It usually takes quite a bit more juice than predicted to mechanically damage a driver. At the edges of things the amp will be running out of gas, the drivers motor force is dropping off, the suspension is tightening up, the port may be compressing, the vc's are probably heated up enough to change the response slightly, thermal compression may have set it and a whole host of other issues. Not to mention that your electronics chain, everything from the disc player, to the receiver, to the amplifier, is combining to roll off the extreme <10hz response too. All of that together means that you may not have any danger at all with no dedicated HPF in your set-up. That SS SPL170 was a beefy car sub in it's day and was built to take quite a bit of abuse. I'm not surprised that it is unphased by 380w HPF'd, or not. It wouldn't hurt to add one though.
 

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You can damage a speaker by under powering it as well, distortion can cause all sorts of issues. How much wattage is the KLH rated for and what is the frequency responce?
 

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Thats fine, the amp is well suited for that driver however it is very possible to blow the sub with that amp if your feed it material with lots of subsonic frequencies. As long as you have the receivers crossover set properly Just keep it low and you will be fine.
 
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