what is unloading and how does it affect subs

[Typicaljawaiian 3]

hey whats up, I am learning about enclosure design and tuning and was wondering about two terms "imp rise" and "unloading". I breezed through a thread on imp rise and got some very good information. Its the unloading part that im not to clear on. I have a 15" Fi BL Loaded and think that I have damaged it due to unloading (I think). My question is how does it affect the subwoofer, what kind of damage can this do, can a recone kit fix the sub if broken due to unloading.

I was having problems where my sub would cut out then cut back in for some reason as I was playing low frequencies. The amp was not clipping or going into protect as I could see all the LED's while this was happening. So again the sub would kind of fade out at low frequencies then after a while start hitting again.

I was beating on it yesterday and the problem started. I waited till I got home to see if would start playing again and it wouldn't. I just tried before getting online and nothing. I took the sub out of the box and tried each coil seperately still nothing. Anyone have any ideas as to what happened. Can you burn the voice coils or lock them up by unloading the sub? Im totaly lost on this and dont want it to happen again, need to get educated please help!

[altoncustomtech 773]

unloading is what happens when the woofer (in a ported enclosure) plays below the tuning frequency.......... above the tuning frequency the air inside the box is "loading" the cone of the woofer and controlling it's movement much the same as it would in a sealed enclosure..... but when the frequency falls below the tuning frequency of the port the air exchanges at a much more turbulent rate through the port and is no longer controlling the movement of the cone......

This can cause overexcursion where the cone of the woofer can move farther and it's designed to do.... this can lead to ripped spiders and/or surrounds and on some woofers the voice coil itself can smack into the back plate of the motor causing physical damage to the voice coil former.....

all in all its not a good thing to do to any speaker...

[NDMstang65 403]

Clipping LED's are worthless.

Unloading occurs when you play below the tuning frequency of the port of the enclosure. If you do not have the subsonic filter set 2-3Hz below the tuning frequency of the enclosure the amplifier will play full power to the sub. Once you go below the tuning frequency of the enclosure the port no longer resonates and acts as if it were a big open hole in the box...you do not burn coils from this. You break things mechanically when you unload them, you do not burn coils.

Resulting in yanking parts..popping spiders etc.

If you burned the coils and/or tinsels up you are clipping them. Regardless what that little LED says. The only way to know that you are not clipping is via an Oscilloscope.

[altoncustomtech 773]

This brings into light the questions..... what size of enclosure is it in? what is it tuned to? what kind of power are you giving it?

with answers to these questions we can give you a better idea of may have happened..... like Nick said though, if your coils are burnt then the problem was the power it was recieving not the woofer unloading... it sounds to me more like a burnt coil problem giving the fading in and out problem..... but no matter what happened to it, there should be no problem with putting in a recone and getting back up and going again.... just make sure that you make the appropriate changes to keep it from happening again....

Edited November 28, 2009 by Alton

[Typicaljawaiian 3]

This brings into light the questions..... what size of enclosure is it in? what is it tuned to? what kind of power are you giving it?

with answers to these questions we can give you a better idea of may have happened..... like Nick said though, if your coils are burnt then the problem was the power it was recieving not the woofer unloading... it sounds to me more like a burnt coil problem giving the fading in and out problem..... but no matter what happened to it, there should be no problem with putting in a recone and getting back up and going again.... just make sure that you make the appropriate changes to keep it from happening again....

The sub is in a 3.0-3.1 cubic foot enclosure tuned to around 32-33 hz. Im running it of a JL 1000/1. I was playing songs like "soul survivor" Akon and Jeezy.

[altoncustomtech 773]

if you're confident of the specs on that enclosure then you need to take a DMM and check the coils on the sub.....

[NDMstang65 403]

This brings into light the questions..... what size of enclosure is it in? what is it tuned to? what kind of power are you giving it?

with answers to these questions we can give you a better idea of may have happened..... like Nick said though, if your coils are burnt then the problem was the power it was recieving not the woofer unloading... it sounds to me more like a burnt coil problem giving the fading in and out problem..... but no matter what happened to it, there should be no problem with putting in a recone and getting back up and going again.... just make sure that you make the appropriate changes to keep it from happening again....

The sub is in a 3.0-3.1 cubic foot enclosure tuned to around 32-33 hz. Im running it of a JL 1000/1. I was playing songs like "soul survivor" Akon and Jeezy.

If you blew a BL on a 1000 watt amp it's without a doubt the gains, tuning, "SUPER BASS" setting on the head unit and the loose nut behind the knobs

Speakers are stupid...they do exactly what you tell them to do

[Typicaljawaiian 3]

Had the gain set to a little more than half, subsonic filter between 25 & 30 hz, bass boost on head unit was at 1 out of 5, bass knob was like half way up (maybe a little more). So from what you are saying, more than likely my settings are way off. Maybe I should also tune lower? An upgrade to a bigger amp for louder bass? Maybe even think of a sealed enclosure for daily. would a box tuning of 25hz sound decent?

[altoncustomtech 773]

Had the gain set to a little more than half, subsonic filter between 25 & 30 hz, bass boost on head unit was at 1 out of 5, bass knob was like half way up (maybe a little more). So from what you are saying, more than likely my settings are way off. Maybe I should also tune lower? An upgrade to a bigger amp for louder bass? Maybe even think of a sealed enclosure for daily. would a box tuning of 25hz sound decent?

most likely the enclosure is just fine, it's tuned to the Fi recommended specs..... you should set your gains and subsonic with 0db reference test tones and a DMM to get the settings much closer.... and don't use the BASS BOOST on the head unit or the amp.... those are settings befit for failure..... what was your sub wired to? 4, 2, or 1 ohms??

[Typicaljawaiian 3]

Had the gain set to a little more than half, subsonic filter between 25 & 30 hz, bass boost on head unit was at 1 out of 5, bass knob was like half way up (maybe a little more). So from what you are saying, more than likely my settings are way off. Maybe I should also tune lower? An upgrade to a bigger amp for louder bass? Maybe even think of a sealed enclosure for daily. would a box tuning of 25hz sound decent?

most likely the enclosure is just fine, it's tuned to the Fi recommended specs..... you should set your gains and subsonic with 0db reference test tones and a DMM to get the settings much closer.... and don't use the BASS BOOST on the head unit or the amp.... those are settings befit for failure..... what was your sub wired to? 4, 2, or 1 ohms??

The sub was dual 2 wired to 4 ohm. I think it was also a loose nut behind the knobs!

[altoncustomtech 773]

The sub was dual 2 wired to 4 ohm. I think it was also a loose nut behind the knobs!

lol..... damn them loose nuts.... although when it comes to high powered car audio i think just about every one of them has nut that's at least slightly loose.... lol

@ 4 ohms on that 1000/1 using test tones you'll be looking for around 63 volts with the DMM.... make sure its a True RMS meter too...

[kryptonitewhite 1]

This brings into light the questions..... what size of enclosure is it in? what is it tuned to? what kind of power are you giving it?

with answers to these questions we can give you a better idea of may have happened..... like Nick said though, if your coils are burnt then the problem was the power it was recieving not the woofer unloading... it sounds to me more like a burnt coil problem giving the fading in and out problem..... but no matter what happened to it, there should be no problem with putting in a recone and getting back up and going again.... just make sure that you make the appropriate changes to keep it from happening again....

The sub is in a 3.0-3.1 cubic foot enclosure tuned to around 32-33 hz. Im running it of a JL 1000/1. I was playing songs like "soul survivor" Akon and Jeezy.

soul survivor peaks right around your tuning...perfect match

[Huricaine 0]

Ever think that maybe his electric is weak?

[Duran 387]

Ever think that maybe his electric is weak?

Ever think this is a 10 month old thread?

He has a completely different setup now.

[Randal Johnson 544]

[SpeakerBoy 64]

[ssh 924]

Don't bring up old threads...

[Dictator1992 6]

sealed box's have no tuning!!!