What causes the loud shudder sound?

[Sherm]

Guy's I don't know the proper name for it, but I know you have all experienced it.

For instance last night I'm watching the Dark Knight, It was the scene when the helicopter is going between the buildings and all of a sudden my sub makes a loud shudder noice. Is the volume to high? I have noticed this on both my upstairs system and down stairs system.

Does anyone know what causes this ?

[Blu-Dog]

Originally Posted by Sherm

Guy's I don't know the proper name for it, but I know you have all experienced it.

For instance last night I'm watching the Dark Knight, It was the scene when the helicopter is going between the buildings and all of a sudden my sub makes a loud shudder noice. Is the volume to high? I have noticed this on both my upstairs system and down stairs system.

Does anyone know what causes this ?

Yes. It's called "clipping". You can eliminate it by turning down the gain on the sub, or turning down the volume.

There are a few reasons it can happen. Usually, it's because there is not enough power to the driver. When there is a rapid change in the AC cycle at high output, the speaker driver is being pushed back and forth at max extension, for a prolonged period. This takes a lot of power, and the amplifier just runs out of juice.

However, it's still trying to get the message out, so while it's trying to pull the speaker in, it gets the news to push the speaker back out, and it winds up just slapping around aimlessly until it works up enough juice to do the job right.

Also playing a part is the port on ported subwoofers. While great attention is paid to setting port length and circumference by builders, ports are "tuned" to certain frequencies (usually at the optimum frequency of the speaker driver) and sounds that aren't in that sweet spot cause turbulence within the port - creating more pressure on the speaker, pushing back on it when it's trying to extend. This doesn't help any low power situations.

Most folks get mad and say, "I have to get a bigger amp, this is ticking me off", but this may overpower a smaller driver. That's when you get that nasty burning smell.

One other problem: The output signal from the data source. Sometimes source material is just sloppy - one soundtrack may have a bad subwoofer track, another may not. They are also running at different volumes, no two are the same. So the setting on your sub or receiver may be fine for one movie; and may freak out and clip like crazy on another. This is usually not a problem with brute-force gorilla subs, but smaller subs have headaches with this.

Anyway, if you turn it down, it goes away. Multiple subs at lower volume can sound great, without clipping, because when combined they up the sound pressure level without all that clipping nonsense.

Hope this helps...

[aramis109]

Good post, Blu Dog! Layman's terms while still being technical.

[Big Daddy]

Originally Posted by Sherm

Guy's I don't know the proper name for it, but I know you have all experienced it.

For instance last night I'm watching the Dark Knight, It was the scene when the helicopter is going between the buildings and all of a sudden my sub makes a loud shudder noice. Is the volume to high? I have noticed this on both my upstairs system and down stairs system.

Does anyone know what causes this ?

Most probably your subwoofer volume is too high. Have you calibrated your audio properly?

[Bradapalooza]

It's also called bottoming out. So don't become confused when you read something about that

[Sherm]

Thanks guy's

[aramis109]

Yeah, my RM6750 sub did it to me a couple times last week with Meet Dave and Kung Fu Panda.

[Blu-Dog]

Originally Posted by Bradapalooza

It's also called bottoming out. So don't become confused when you read something about that

Actually, when you "bottom out", you hyperextend the driver from too much power. The pole inside the coil is slamming back and forth from being overdriven - smoke, bad smells, panic, and expensive replacements usually follow.

You'll hear this zzzzwwwwooooopppHISSSsssscrackle and then this god-awful stench.

That's bottoming out. Also applies to your wallet after this happens.

[Big Daddy]

Originally Posted by Blu-Dog

Actually, when you "bottom out", you hyperextend the driver from too much power. The pole inside the coil is slamming back and forth from being overdriven - smoke, bad smells, panic, and expensive replacements usually follow.

You'll hear this zzzzwwwwooooopppHISSSsssscrackle and then this god-awful stench.

That's bottoming out. Also applies to your wallet after this happens.

The hell with the wallet. Changing a subwoofer's driver and/or amplifier is a lot of fun. I have done it multiple times and I enjoyed it every time.

[Miller Lite1]

Originally Posted by Blu-Dog

Actually, when you "bottom out", you hyperextend the driver from too much power. The pole inside the coil is slamming back and forth from being overdriven - smoke, bad smells, panic, and expensive replacements usually follow.

You'll hear this zzzzwwwwooooopppHISSSsssscrackle and then this god-awful stench.

That's bottoming out. Also applies to your wallet after this happens.

Once this happens do you have to replace the cone? or just make the adjustmants listed above

[JJ]

Originally Posted by aramis109

Yeah, my RM6750 sub did it to me a couple times last week with Meet Dave and Kung Fu Panda.

I'm guessing during the fight between Tai Lung and Panda at the end? There is some detailed bass in that scene - requires more than a one-note pony.

[aramis109]

Originally Posted by JJxiv1215

I'm guessing during the fight between Tai Lung and Panda at the end? There is some detailed bass in that scene - requires more than a one-note pony.

Yeah. It was this flat "Blaaaaaaaaat" sound that made me go "What the fu...?!"

I always knew the sub wasn't all that great, but between the rest of my setup and the normal listening volume it wasn't much of an issue.

[SRTCraig]

Originally Posted by Big Daddy

The hell with the wallet. Changing a subwoofer's driver and/or amplifier is a lot of fun. I have done it multiple times and I enjoyed it every time.

Ahh yes, i thought i was one of the only ones out there that got a kick out of pulling subs to bits. I'm so bad i even took pictures along the way......

[blu_world]

this happens to me many times and the stupid thing is...

it's a JBL subwoofer!.

[pere]

One solution to all this problems could be to insert an electrònic limiter between the receiver and the sub.
Ajusted properly woun't affect the quality of the sound (the 99% of the time will do nothing) and will avoid the annoying clipping of the sub during this critic time.

[Big Daddy]

In case you blow a driver and need to replace it, read my thread on Repairing & Upgrading Subwoofers. I show with pictures and humor how easy it is to repair your subwoofer or build a new one.

[neos_peace]

I hear that crappy sound a lot on my system can't wait til i get my onkyo recevier and then sell my current sytem and use that money for a bangin new sub.

[Blu-Dog]

Originally Posted by Miller Lite1

Once this happens do you have to replace the cone? or just make the adjustmants listed above

The coil and yoke burn out - you have to replace the whole speaker driver at that point.

It just unbolts, and you put in a new one. It's pretty much impossible to repair one - it's not like reconing the rubber surrounds on a speaker.

[JJ]

Originally Posted by aramis109

Yeah. It was this flat "Blaaaaaaaaat" sound that made me go "What the fu...?!"

I always knew the sub wasn't all that great, but between the rest of my setup and the normal listening volume it wasn't much of an issue.

Yeah - especially when Panda's fat reverberates - the bass notes in that scene is ridiculous - I was like, "Ohhh - so that's what they meant by detailed bass." I bet my father a dollar his Sony sub couldn't do it, he didn't believe me - well, that was an easy dollar,

But on my old Samsung HTiB sub - I used to get CRAZY port chuffing - clipping - it was nuts. When the Death Star would explode my subwoofer would shake itself to bits.

[Miller Lite1]

Originally Posted by Blu-Dog

The coil and yoke burn out - you have to replace the whole speaker driver at that point.

It just unbolts, and you put in a new one. It's pretty much impossible to repair one - it's not like reconing the rubber surrounds on a speaker.

Blu-Dog, thanks!

I think I have smelled this buring typ smell once a couple months ago. If it happens once does the speaker need to be replaced?