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cloud77

Leads burned up; wtf?!

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So I was coming home from work yesterday and I was bumping at a decent volume.  I started to smell something burning, but it wasn't coil.  I took a reading of the coils from the amp today and wasn't getting the correct nominal.  Took the sub out and read the coils from terminals.  One coil wasn't reading out at all, and the other was reading like 12. Took the coil out and this is what I found:

2014-01-18_14-23-39_147.jpg

2014-01-18_14-23-22_804.jpg

2014-01-18_14-23-00_999.jpg

Recone was done in November or so. This sucks.. =[

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unfortunately I have done that before

 

you clipped the shit out of your amp

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If you're using a typical Korean amp it happens. They don't have the proper output filtering so you can essentially microwave your leads.

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I use a MMATS M3000.1. I thought it might have been due to moisture getting to the sub. Bottom of the motor was a bit frosted.

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I guess I need an alt. like asap. Thought it could wait until spring

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I did this to one of my xcons with an ap3k.  dirty power does bad things.

In no way you can compare my amp to an ap3k

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I did this to one of my xcons with an ap3k.  dirty power does bad things.

In no way you can compare my amp to an ap3k

You should spend more time thinking about my second statement than getting butthurt assuming im comparing your amp to an ap3k.  once again DIRTY POWER DOES BAD THINGS.

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I guess I need an alt. like asap. Thought it could wait until spring

 

And this help furthers my statement......start dropping volts and start sending more dirty power to your subs....and poof

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Hmm maybe this is what happened to the Zcon I sold you.

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Hmm maybe this is what happened to the Zcon I sold you.

I wish it would have been and I would have assumed responsibility. Fact is you are a bad seller and you ripped me off. Why would you even post here.

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I guess I need an alt. like asap. Thought it could wait until spring

 

And this help furthers my statement......start dropping volts and start sending more dirty power to your subs....and poof

I never dropped below 13.5. But that's from my rear batteries. I think using the Vol adjust on my head unit may have had something to do with it.

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This recone didn't have a sewn "pouch" made for the leads like the other I had.

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I never posted a comparison to the coil in the woofer you sold me Bassink but since you asked for it here it is:

2014-01-18_17-01-53_140.jpg

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Left looks like a black anodized coating, right looks like clipping on higher frequency.

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It has nothing to do with clipping. 

 

It has nothing to do with filtering either, the inductance of the voice coil prevents the higher frequencies from ever causing enough current flow to actually heat the leads.  Don't believe me? Calculate the current flow through a 3-4 mh inductor (the voice coil) at the switching frequency of the amp at the maximum rail voltage...  It is no more than a few watts, that doesn't heat up crap...  (an amp that switches at 250K will see a load of 4.7Kohms into a 3mh voice coil at that frequency, this will equal 2 watts if the amplifier put that out at 100 VAC..., harmonics will be even lower)  Hopefully this put the whole "microwave the leads" myth to rest... 

 

It has to do with the lead in your case having a failure in one place and the current is forced to flow through less effective cross-sectional area of conductor, increasing heat.  As heat increases voltage drop and heat increases.  It just keeps getting worse.

 

You have a 3Kw amp, that is what burned up the leads...

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My amp only has an input sensitivity of 2.5v. The headunit is 4.8v preouts. I used a vol adjust option on my JVC headunit to +1 position. Amp never got hot, sub never got hot, just poof.

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I 100% believe you.  I don't think you may have done anything wrong.  Like I said, you have an amp that can produce a 3Kw sine wave, and other waveforms up to possibly 6Kw...  What normally happens is the lead fails in one spot and heat begins to build, it just gets worst from there...  It can be a failure from the way the leads were sewn in/installed to a bad lead material, to over excursion of the sub to simply too much power.  It just happens.  All I am trying to get you to do is look objectively at your situation, and cut through the BS...

 

Everything can be explained through simple circuit analysis, it isn't Voodoo, although some people would have you believe it...

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Thank you.

We'll recone her and put more effort into learning about why this happened and how I can prevent it next time.

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Cool.

 

I just hope everyone now understands how any un-filtered HF output of a class D amp has no effect on leads as long as they are in a circuit that includes a subwoofer voice coil.  It's just the facts...

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It is 100% elaborated in my 1st post.  You have to look into AC circuit theory to go much further.

 

In a nutshell, the voice coil acts as a resistor to current at higher frequencies, at the switching frequencies of class D amplifiers it is so much resistance that virtually no current actually flows...

 

The only way you could burn up the leads from the switching frequencies would be if there was no voice coil in the circuit...  This isn't the case with a subwoofer...  It has a voice coil...

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According to Fi's theory of unfiltered korean amps, you are wrong 98Honda. I could post a video of ice glowing red because it explains it! lmfao

 

PS - You are my new hero

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I have no doubt the unfiltered HF garbage coming out of a class D amp causes issues, mostly distortion...  But in a series circuit that has an inductor (voice coil) with any appreciable amount of inductance anywhere in the circuit, there won't be significant current flow (in the HF range) and therefore heat.

 

Even if the HF is lower, even in the audio spectrum, it will have an insignificant amount of power compared to the intended output of the amplifier...

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