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Discussion Starter #1
Hello,

I have a quick question...Has anyone with an Ultra watched the Hulk? I own the movie and it really is a great movie especially for the LFE. The scene where the Hulk is going through the sounds waves in the university campus and the movie goes into slow motion for a brief few seconds and the bass gets pretty much inaudible, has your Ultra ever over-driven during that particular part? It happened to me. If you have say a BFD, could you prevent this sort of thing from happening or is it just too low for the 20hz tuning? If turn down the gain for this movie then i miss out on all the great bass just for this one scene. Still tweaking this thing and I have it at 82db with Avia / RS meter. I have not found the sweet spot yet, but for the majority of the movies that I own I find I do not have to turn the gain down.
 

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What is the filter set at on the back of sub? How loud do you play it at reference level? The ultra has a subsonic filter on the amp. You want to set it to the same setting as your tuning, so if you are tuned for 20hz, all three ports open, put the filter at 20hz as well, same goes for 15hz with one bung, and 10hz with two bungs.
 

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That is a normal but not good problem with the Hulk and about 4 other BluRay movies There is some very high level subsonic frequencies (below 10Hz) that will over drive almost any sub in that scene and is only if using the uncompressed audio.
It has been commented about many times. Studios need to pay attention to these subsonic frequencies as they do not need to be there at those levels.
 

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That scene you are talking about has a very high level of 12-14hz for a few seconds. One of my personal favorite scenes to demo for people. The Hulk also has a few others with very high levels of content around 10-15hz. Your Ultra should handle it better in 15hz mode.
 

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Discussion Starter #5
Hey Ben,
The filter is set to 20hz on the back and no ports plugged, I know how to tune it with plugs. It is calibrated to 82db with the Avia disc wich would be 85-86db or 75-76db with AVR test tones.

Josh,
I'm gonna try the 15hz tuning again, see how other movies compare between 20 and 15hz. I have tried it in the past but have reverted back to the 20hz.

If tuning to the 15hz I could probably raise the level to 84db with Avia disc to compensate for the few db lost, additionally this setting would protect the sub from overdriving as it is tuned lower. SI this correct? What tune do you guys run your Ultra at?

Thanks for the input.
 

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Consider setting the Room Comp control to Large or Med. Doing this starts to roll off the very lowest potentially damaging frequencies. I keep mine at Large and it's great!


Tim
:drive:
 

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Yeah def want to try and tune it lower, 15hz, 10hz or even sealed may be the best for bass that low. Below the tuning frequency the ported design tends to unload the driver as if it was in "free air" (unenclosed) that is why it is being overdriven. Seems that the SVS subsonic filter is not steep enough to suppress the bass that you are playing. Typically they are 24 or 36db/octave even if you did you may be missing out on that infrasonic bass :). In a room your size you probably get a decent amount of room gain so you may not have to adjust the gain at all when you tune lower. Anyway boosting the gain would just make it not as smooth at your crossover point. The only roll off you would see is going to be starting around 25hz or so if that. Let me know how it works out. I gave my neighbors a break when I sold my pb10, I'll be getting my ultra tomorrow so keep me posted. Oh and by the way from what I researched there is no way to setup a subsonic filter on the BFD1124 and it's -3 is about 4hz.
 

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Discussion Starter #8
"The only roll off you would see is going to be starting around 25hz or so if that"

So Ben,
By this statement, tuned to 15hz, the bass will start to decrease from 25hz and on? Even though the crossover is set to 80hz in AVR? Or is it the other way around?
 

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That is a normal but not good problem with the Hulk and about 4 other BluRay movies There is some very high level subsonic frequencies (below 10Hz) that will over drive almost any sub in that scene and is only if using the uncompressed audio.
It has been commented about many times. Studios need to pay attention to these subsonic frequencies as they do not need to be there at those levels.

Thank you very much!! You have answered the question I have been looking for! This scene made my HSU 3.3 "POP". I has listening to the uncompressed audio track with the THX loudness plus feature (similar to Audyssey's dynamic EQ) on. I was at about -12db and I got a peak of 108db at my 12 foot LP before it happened. I am pretty convinced now that my sub was over driven and not clipped.

BTW, what are the 4 other movies?

Thanks
 

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That scene you are talking about has a very high level of 12-14hz for a few seconds. One of my personal favorite scenes to demo for people. The Hulk also has a few others with very high levels of content around 10-15hz. Your Ultra should handle it better in 15hz mode.

So would my HSU 3.3 handle this scene better with one port blocked "Max Extension"?
 

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I watched it with four 12" THX-12 subwoofers powered by MA-500 mono amps at -14dB and heard distortion for a moment during the scene with the pulsing waves. I think I heard some also during the ending. The bass was loud at -14dB but mostly sounded good. I think I may have had the -10 setting on my FBQ at the time.
 

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If tuning to the 15hz I could probably raise the level to 84db with Avia disc to compensate for the few db lost...

Thanks for the input.
After plugging a port, you want to calibrate to the same level you had before, not higher. You lose a couple of dBs headroom, meaning your *maximum* volume will be lower before overdriving the sub. There is no need to compensate at all volumes.

-Robb
 

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Discussion Starter #13
Thanks Robb.
 

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Yeah take a look at the frequency repsonses for the different tunes on this site under the subwoofer tests for the pb13ultra, above about 25-30hz all the way to over 100hz the output not effected by the tuning frequency. Even at max output, no more than about 1db difference.
 

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20 Hz tune with Room Gain Comp set to Small will handle this scene the best. The RGC to Small will cascade a few 1st order filters above/beyond the normal high pass setting and will roll-off the subwoofer more steeply below system tuning. This will reduce the potential for the woofer to unload on strong infrasonic content.
 

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Discussion Starter #16
I appreciate your advice Ed, thank you. Learning everyday!
 

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Discussion Starter #17
The 13Ultra makes you want to learn more about FR and proper calibration. Before I owned the Ultra I had no idea about FR and sub calibration and all the other variables, i figured you just plug it in and turn it on and turn up the volume...quite the contrary, at least for me. I really appreciate all the input, thank you!
 

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So would my HSU 3.3 handle this scene better with one port blocked "Max Extension"?
Yes. It is very hot and low bass. If it is significantly below the tune and or capabilities of your subwoofer you'll need to be very careful when watching that movie.
 

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So would my HSU 3.3 handle this scene better with one port blocked "Max Extension"?
It's possible. My Epik Castle (tuning is 19hz, according to Chad) also has problems with this scene, and I get audible port noise. The Castle's amp uses a 12dB/octave subsonic filter at right about 20hz. Just for kicks, I purchased a 20hz 12dB/octave subsonic filter to see if it would make a difference. This gave me an effective 24dB/octave roll off and I have to say the scene had no port noise even at very spirited listening levels.

Keep in mind that while plugging a port in your Hsu 3.3 WILL help you achieve lower extension, it also reduces port area by 50%, meaning the subwoofer will be more susceptible to port noise. If my Castle with its 6" port had port noise on that scene, a Hsu 3.3 with a single 4" port will have even more. Still, it's worth a shot, and you might get away with it if you don't listen as loud as I do.
 
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