Turn down my subs? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 12 Old 07-14-2017, 12:24 PM - Thread Starter
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Turn down my subs?

I have a room that's dedicated for HT and gaming, with dual SVS PB-12 Plus. The room is about 2800 ft^3. I watch mostly blockbuster-type movies at a volume of around -5 to -8 vs. reference. The subs do great almost all of the time, but about once or twice per movie (like Star Wars or Avengers, etc.) there will be a huge LFE that my subs seem to not handle very well. They're just being over-exerted, I suppose. I want to avoid that happening. I don't want to turn the overall system volume down because I want to keep voices, etc. at the level I like. I just don't want the flapping or distortion or general over-doing-it-ness with the subs. (I don't know the right term.)

I'll go ahead and eliminate one obvious solution: I don't want to buy more or bigger subs. So what should I do? I suppose I can increase the relative levels of all the other speakers, or I can lower the levels of the subs. Or both. If I lower the level of the subs, do I want to do it in the Audyssey menus or on the back of the subs? Or should I do something else? I just want to dial it back enough so that, at my listening volumes, the subs don't go overboard on the craziest LFE scenes.

Thanks in advance for your advice and recommendations!
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post #2 of 12 Old 07-14-2017, 12:41 PM
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Quote:
Originally Posted by HalfaKMan View Post
I have a room that's dedicated for HT and gaming, with dual SVS PB-12 Plus. The room is about 2800 ft^3. I watch mostly blockbuster-type movies at a volume of around -5 to -8 vs. reference. The subs do great almost all of the time, but about once or twice per movie (like Star Wars or Avengers, etc.) there will be a huge LFE that my subs seem to not handle very well. They're just being over-exerted, I suppose. I want to avoid that happening. I don't want to turn the overall system volume down because I want to keep voices, etc. at the level I like. I just don't want the flapping or distortion or general over-doing-it-ness with the subs. (I don't know the right term.)

I'll go ahead and eliminate one obvious solution: I don't want to buy more or bigger subs. So what should I do? I suppose I can increase the relative levels of all the other speakers, or I can lower the levels of the subs. Or both. If I lower the level of the subs, do I want to do it in the Audyssey menus or on the back of the subs? Or should I do something else? I just want to dial it back enough so that, at my listening volumes, the subs don't go overboard on the craziest LFE scenes.

Thanks in advance for your advice and recommendations!
Well according to Audioholics Bassaholics rating, take that for what you will, those are certified for large rooms which they classify as over 3000 cubic feet so room size shouldn't be an issue with 2 of those. I guess what you need to explain is what huge LFE thing your talking about, and what you mean by not handle well.
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post #3 of 12 Old 07-14-2017, 01:52 PM
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What AVR do you have? How are the subs calibrated? Any sub trim added post calibration?
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post #4 of 12 Old 07-14-2017, 01:53 PM - Thread Starter
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Originally Posted by liffie420 View Post
I guess what you need to explain is what huge LFE thing your talking about, and what you mean by not handle well.
One example is this scene in Star Wars:

In that scene, during the initial (very large) explosion, the subs distort, or maybe it's port chuffing, or I don't know what. They don't sound good. It sounds like what you'd expect (or, I guess, what I'd expect) from pushing the subs too hard. The follow-on explosions (after the initial giant one) sound great, clean, etc. But the initial explosion is too much. I don't quite know how to describe it.
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post #5 of 12 Old 07-14-2017, 01:58 PM - Thread Starter
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Originally Posted by basshead81 View Post
What AVR do you have? How are the subs calibrated? Any sub trim added post calibration?
I have a Denon AVR-891: http://downloads.denon.com/documentm...891_lit517.pdf

(I'm happy for you to tell me that I *really* need to upgrade to the 4300!)

My AVR has dual sub outputs, but it's just an internal Y splitter, so they're not calibrated independently. The room is rectangular, and they're at the 1/3 and 2/3 points across the front wall. I have never run any sort of measuring tests or software, etc. I just ran the basic Audyssey that came with my AVR.

I don't have the numbers in front of me, but I followed this forum's lengthy post (commonly cited) to adjust the subs so that Audyssey returns a value of [I can't remember what it's supposed to be--but some particular range]. And then I definitely am not running them hot. I think I might have even turned them down 1 or 2 notches.
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post #6 of 12 Old 07-14-2017, 03:05 PM
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Adjust the subwoofer trim setting in the AVR down until you stop getting funny noises during those scenes. If you still have "enough" bass during everything else, you are done. If you feel like the bass is lacking afterwards, you will have to re-think your stance on getting better/more subs.
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post #7 of 12 Old 07-15-2017, 04:06 PM
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Perhaps you should play with the position of your subs. It's possible, since you have not done any measurements, that they are not playing well together, perhaps even canceling each other out at certain frequencies. Given that these are rated for large rooms, it's more than likely pilot error.

Are the speakers running crossed over or are you using both the mains and subs to produce bass? Then you have 4 sources to interact and perhaps badly ...

Are you running with a bass enhanced mode on the receiver? Turn it off, as that will artificially enhance certain frequencies and contribute to the problem.

Are you running them hot? After Audyssey set them up did you bump their output in the receiver or by turning the gain up on the back of the subs?

To get the best out of your subs and your room, consider investing in room tuning tools, such as REW, or at least a dB meter, so you know what is going on (can't fix what you don't understand). That is a hell of a lot cheaper than buying new subs. Besides, if you clean up the set-up of your current subs and still want more, you can always buy more subs then.

Last edited by RayGuy; 07-15-2017 at 04:15 PM.
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post #8 of 12 Old 07-15-2017, 04:18 PM - Thread Starter
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Thanks RayGuy. I might check out REW one day. I've peeked before, and it looks excessively complicated, though I know people here say it's not.

Yes, of course the subs are crossed over. No, there's no bass enhancement mode on. No, I'm not running them hot. Rather, I had turned them down a bit. And based on Alan's recommendation, today I turned them down a bit more in the receiver.
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post #9 of 12 Old 07-15-2017, 04:38 PM
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Originally Posted by HalfaKMan View Post
Thanks RayGuy. I might check out REW one day. I've peeked before, and it looks excessively complicated, though I know people here say it's not.

Yes, of course the subs are crossed over. No, there's no bass enhancement mode on. No, I'm not running them hot. Rather, I had turned them down a bit. And based on Alan's recommendation, today I turned them down a bit more in the receiver.
All good news. I would still look at sub positioning as a possible issue. Perhaps run one in the front of the room and one in the back? Does your receiver allow you to separately tune two subs?

If REW looks excessively complicated, a dB meter, graph paper, and a test tone CD are a very easy and intuitive way to accomplish the same thing (well, not exactly the same, but some info is better than no info).

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post #10 of 12 Old 07-15-2017, 05:02 PM - Thread Starter
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Originally Posted by RayGuy View Post
Does your receiver allow you to separately tune two subs?
It does not. Thanks again for the input. I might try playing around with sub positioning, but since I can't separately tune them, I haven't done so. My next AVR will have that feature, and we'll go from there!
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post #11 of 12 Old 07-15-2017, 05:23 PM
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Originally Posted by HalfaKMan View Post
It does not. Thanks again for the input. I might try playing around with sub positioning, but since I can't separately tune them, I haven't done so. My next AVR will have that feature, and we'll go from there!
Hi,

You have already gotten some good suggestions, but I thought I might add to the discussion. First, no AVR you buy is going to EQ the subs separately. XT-32 with SubEQ, for instance, is only going to allow separate SPL and distance settings for dual subs. They will still be EQed as one. The .1 LFE channel is a single channel and that is the way that all AVR's are supposed to work.

The suggestion to try different room placements is a good one. Audyssey is doing what it can, but the better condition you present it with, the better job it can do. There are two other things you can try. One involves Audyssey, and the other involves your subs. First, with respect to Audyssey, you can try either turning off DEQ, or using an RLO setting to mitigate it's effects, because it is boosting your subs by 2.2db for every 5db you are below Reference. At -15 MV, for instance, DEQ adds 6.6db of sub boost. As you experiment with the RLO settings, you might find a sweet spot that let's you enjoy the content you want without the port chuffing. And, you can change RLO settings on the fly, during a movie.

The other thing you can do is to use the 20Hz port mode on your Pluses. Doing so will necessitate re-running Audyssey, and this isn't something that you can easily change back-and-forth. But, it will probably eliminate the port chuffing entirely, while still giving you good bass down to about 20Hz. If you do it, don't forget to change the DSP setting in the subs as well as with the port plugs.

That gives you two measures you can use--one more permanent in nature, and the other transient, depending on the particular material you are watching.

Regards,
Mike
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post #12 of 12 Old 07-15-2017, 05:46 PM - Thread Starter
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Originally Posted by mthomas47 View Post
First, with respect to Audyssey, you can try either turning off DEQ ... The other thing you can do is to use the 20Hz port mode on your Pluses.
Thank you, Mike. I do have Dynamic EQ off, and I am running them in 20 Hz mode.

FWIW, I re-ran the Star Wars scene mentioned in my earlier post about 8 times, with each time me adjusting my sub speaker level in the AVR. Before the adjustment, it was at -6.0. I first turned the sub level down to about -10.0, and that clearly "solved" my issue, but at the expense of sub output. I also tried -4.0, just to replicate my issue and try to confirm what I was hearing. I then tried all sorts of different levels from -6.0 to -8.0, and I ended up at -7.0. At that level, the subs are sounding great... plenty of low end but the huge explosion scene wasn't causing distortion (or what I perceived as distortion) anymore.

I may yet play with positioning, but only if I decide to dive into REW, etc.

Thanks again (to all of you) for the helpful input.
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