Loud Thwap Sound From Movie

[DavidH]

Quick intro before I start:

AVR: Denon 2313
Fronts: Motion 40's
Center: Motion 30
Sub: Dynamo 500

I recently had my Dynamo 500 sub go out on me after only 8 months of ownership. I worked with Martin Logan and received a new one about two weeks ago. I have been trying to break it in slowly. Some people say you don't have to break in others say yes. I decided to play it safe.

Anyways, the other night my Fiance and I were watching World War Z on blue-ray. During one of the scenes Brad Pitt is in the cockpit of an airplane with another man after an intense moment. The movie had come completely silent when all of the sudden off in the distance an Atom Bomb Mushroom cloud appears and followed by a loud deep Bass Boom from sub and other speakers. As soon as it peaked a loud Thwap sound came from either the sub or fronts. I immediately jumped off the couch towards the sub to check settings. It was only on about 20% power as I have not wanted to crank it yet. I played the same scene the next morning at some lower settings to make sure it wasn't a sound effect from the movie. I did not here the Thwap sound again.

Did I damage my new sub or one of my speakers? I don't hear anything sounding broken but am concerned.

My settings were on the following:

Fronts and Center set to Large. ( Should I place to small?)

Sub LFE was at 100 ( I read some forums and put it at 80)

Default in settings it was at 120.

Volume 70 - 100

Has anyone had this happen before? I am still trying to learn how to setup my system and all of the terms.

Best regards,

David H.

 

[Gordon Gray]

Hi David,

You "bottomed out" your drivers, read max excursion.

You may have damaged them.

One easy way to check is to push in on the center of the cone. If you feel resistance and hear a "scraping" noise, you've blown the driver. Should also be audible when playing bass type material.

If they easily "push in" absent resistance and noise, you got lucky.

GG

 

[DavidH]

Thank you for the response! I really hope I did not damage them, I will check when I get home from work. Should a speaker of that caliber bottom out that easily? It was loud but movie loud not uncomfortable loud.

 

[roberto]

Hola David. There are low frequency transients that could damage a speaker easy. And your system could be set at not so loud volume. You can not tell when this is going to happen. I think that you are safe with the sub, because you played again, and the sub is working. When you have a bad speaker, even the lowest sound level, will tell you that you have a problem. The problem will resonate at certain frequencies that must be present to bring the problem out. Gordon´s instruction is very helpful, also, trust your ears. They will tell you if you have a problem. Happy listening!

 

[JonFo]

...
My settings were on the following:

Fronts and Center set to Large. ( Should I place to small?)

Sub LFE was at 100 ( I read some forums and put it at 80)

Default in settings it was at 120.

Volume 70 - 100

First, I'd recommend setting the speakers (all of them) to 'small' and the crossover for the motion 40's to 60Hz, the rest at 80Hz.

Set SUB LFE (that's the high pass setting on the LFE tracks) to 120.

Run the Audyssey setup following the measurement process.

And don't turn it up so loud

You probably bottomed the sub. Hope no permanent damage was done.

 

[|Tch0rT|]

Do you have a specific time for that scene? At about 1 hour 5 min and 30 sec into WWZ (in Israel) there's a grenade blast that emits a massive bass drop. Just guessing but I'd bet that it dips below 20hz. I'm surprised you didn't mention that scene. The bass was probably below the tuning of the ports for the sub which ported subs do not like at all.

 

[DavidH]

The scene is right after they leave the military base and the zombies are at the cockpit door. Brad Pitt talks to his wife then hangs up and BOOOOOM! I never would have thought a sub that cost $500.00 cant handle that.

I have ran Audyssey before but I did not notice a difference in sound. It turns the Db level down like -9 on all of my speakers including the sub. I may try and call Denon and have them walk me through setting up the system to get its full potential.

I am in process of finishing basement so speakers are in living room for probably the next 5 months or so. The living room is about 20 x 30 with 10 ft. ceilings. It also Opens into the Kitchen. Am I losing sound in such an open room?

Best regards,

David H.

 

[|Tch0rT|]

I found the scene you were referring to. I didn't find it very impressive in the bass department and no loud thump. The scene I mentioned with the grenade at 1 hour 5 min and 30 sec or so is much much more demanding. Have you checked your levels with an SPL meter? Maybe you just had your sub way too loud? Check the levels on the sub itself and on your receiver.

 

[MrBT]

20x30x10ft room size and one 10" subwoofer it's very challenging for such size driver in such large space....

 

[DavidH]

I found the scene you were referring to. I didn't find it very impressive in the bass department and no loud thump. The scene I mentioned with the grenade at 1 hour 5 min and 30 sec or so is much much more demanding. Have you checked your levels with an SPL meter? Maybe you just had your sub way too loud? Check the levels on the sub itself and on your receiver.

My SUB was only set to about 20% on the knob on back. I think having my fronts settings on Large may have been why I had so much bass. The SUB was not turned up high.

I need to play with my receiver as when I purchased everything I just plugged it all in and kept default settings.

Anyone have a system similar to mine? What settings do you use?

Best regards,

David H

 

[Gordon Gray]

I would follow JonFo's suggestion (set speakers to small) and run the audyssey calibration.

That should address the sub volume issue.

 

[MrBT]

I found the scene you were referring to. I didn't find it very impressive in the bass department and no loud thump. The scene I mentioned with the grenade at 1 hour 5 min and 30 sec or so is much much more demanding. Have you checked your levels with an SPL meter? Maybe you just had your sub way too loud? Check the levels on the sub itself and on your receiver.

At 1:05:30 , the scene you are talking about does very bad things to my subs and also may be causing seismic activity in the area.

Volume set to make dialog at 55db(not loud), action scenes peaks at about 75db(also not too loud) but this explosion goes up to 97db!!!!!! (overall volume set not to annoy my wife - not really loud) Now, I have two 12" subs working hard, both manually EQ and measured to achieve flat freq response, small, acoustically treated room. Listening just slightly louder, to make it more realistic I measured peak 108db!!!!

A lot of dynamic range......

 

[|Tch0rT|]

Haha yeah that scene is going to be one of my new surround sound and bass demo scenes for people. It makes my couch massage my back a little LOL. First time I did that scene loud I swear I saw a book shelf shake.

 

[gordonmenninger]

The living room is about 20 x 30 with 10 ft. ceilings. It also Opens into the Kitchen. Am I losing sound in such an open room?

That is your answer right there. That is a 6,000 cubic foot room you are trying to pressurize with a measly 10", 120w sub? No way! You need at least a couple big boy subs in there. The sub you have is for a bedroom but not high quality home theater!