Its Back!

[DavidH]

So,

I have posted on the forums before about a Loud Thaw sound coming from my Sub (Dynamo 500) http://www.martinloganowners.com/forum/showthread.php?15070-Loud-Thwap-Sound-From-Movie I calibrated the system using Audessy and tweaked a few settings here and there. All of my movies were sounding fantastic, I was surprised at how good calibrations could make the speakers sound.

Then Pacific Rim came out, one of my favorite movies of the year so I had to pick it up on blue-ray. http://www.blu-ray.com/movies/Pacific-Rim-Blu-ray/72628/#Review

First off this movie is fantastic for pushing some BASS! Friday night me and some friends had the grill going some beer and turned on Pacific Rim. I unlocked the speakers to go from 70-100 volume to 80-100. We watched the movie on 75 volume. It sounded fantastic. Then the crackling thwap sound came back. Crazy thing is, it was not during the most bass heavy moments. Only happened about twice. My friend who is very tech savvy and an audiophile said he has never herd that sound from a sub before. He was wondering if it was receiver sending some static that built up?

So I am back again for advice from pros. What could this be? I am on my second Dynamo 500 and not sure if its the sub or receiver connection?

 

[gordonmenninger]

The Dynamo sub is a pretty low end sub fyi with only a 120W amp and 10" driver probably not capable of handling reference levels of blu-rays with tons of bass. What you are haring is the sub bottoming out due to design limitations. You kind of get what you pay for especially with subs.

 

[Gordon Gray]

Agree with Gordon.

Static buildup? Highly unlikely.

Be careful. You may not be so lucky next time and will be forced to replace drivers due to too much volume.

 

[soundacct]

Perhaps the movie soundtrack contains subsonic information, and the sub is just trying to reproduce the signal it is being fed?

In that case, you'd be able to rewind the movie and reproduce the effect. Also you'd see the woofer move (a lot) while the noise happens, but you'd hear little or no bass.

This happened to me often, back when I used to think that rap was music...but I digress.

But I have to agree with both Gordon's here, that would be a pretty strange symptom of a failing amp. I can't imagine the receiver being at fault (static, as in static electricity?, or as in audible static like a radio station not tuned in properly?), and what you're describing sounds a lot like the sub just "bottoming out" because trying to play bass too low, too loud.

As a personal preference for home theater, I couldn't recommend any 10" single driver sub because I just don't think they can produce enough low, loud bass - not without ridiculous amounts of power and/or huge / complicated enclosures, that is.