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Discussion Starter · #1 ·
I was watching a movie (Valkyrie-single disc edition) and the subwoofer made a noise on a certain passage, Not the battle scene at the beginning, which came through lifelike loud and clear, but the part where the allies are bombing the city (off screen) but there is a a bunch of booming sounds including one which knocked the the plaster of the ceiling in Staffenburg's house, the subwoofer made a Blowing sound (fluupt) I didn't hear the driver clack against the magnet so It wasn't being over-driven.


The same thing happed on Hot fuzz, which I think is way over-modulated anyway.


The day after tommorow and the watchmen and the new fast and furious was fine and noise free along with War.


I watched Death race at almost full volume and no noise, except room rattles.
 

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What sub do you have? Your excursion of the driver increases slowly the further down you go in frequency starting a little over twice the tuning. Right before tuning the excursion decreases and at tuning frequency its barely moving. Without a high pass filter the driver unloads after that and that increases the excursion hugely. This could be mechanical noise that your are hearing, but you would hear th woofer moving.


Port air velocity increases the further down in frequency you go. Once again, about twice the tuning frequency is where the port starts kicking in. Above that, other than possible resonances, the box and woofer act like a sealed enclosure, ie no port noises. You probably hit something with extreme low frequencies at high levels. That will make your port sing horribly, like a 1st grade chorus.


That gets back to what sub do you have? Something like the svs ultras at their lowest tuning frequency (10 hz) only has one small port to push a lot of air through. Throw something like the Irene scene in there with only one port and you are almost sure to get some port noise. Unplug one more port and you have twice the space for airflow, there decreasing the overall velocity, but still moving the same air.
 

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Discussion Starter · #3 ·
The sub I have is an Insignia NSHT51, I managed to move the sub not to long ago and turn down the gain which helped a lot more than I thought it would Brandonnash.


I am starting to think DD (dolby digital) has a higher distortion rate in the LFE than a DTS track, seince I tried a more agressive DTS movie (Armageddon Criterion collection edition) and got no noise, even at the volume I watched to Valkyrie.


I even tested it with Sunshine, which is another Intense bass movie, and Jumper, which has a similar bass to Valkyrie throughout the movie and no noise, with the changes I made. I replayed the scene from Valkyrie also and I don't hear that sound anymore.
 

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Quote:
Originally Posted by Raymond Leggs /forum/post/16994456


The sub I have is an Insignia NSHT51, I managed to move the sub not to long ago and turn down the gain which helped a lot more than I thought it would Brandonnash.


I am starting to think DD (dolby digital) has a higher distortion rate in the LFE than a DTS track, seince I tried a more agressive DTS movie (Armageddon Criterion collection edition) and got no noise, even at the volume I watched to Valkyrie.


I even tested it with Sunshine, which is another Intense bass movie, and Jumper, which has a similar bass to Valkyrie throughout the movie and no noise, with the changes I made. I replayed the scene from Valkyrie also and I don't hear that sound anymore.

It has nothing to do with whether the coding is DD or DTS. The factors that come into play are the levels and the frequencies of the material. Just because one movie has bass that is as intense as another, whther you get port noise depends on what frequency most of the bass energy is at. Frequencies that are close to or at port tuning ar most likely to cause port noise.
 
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