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-   -   Muffled sound from subwoofer (http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1502852-muffled-sound-subwoofer.html)

smakovits 11-30-2013 08:38 PM

Hey guys, interesting issue creeping up with my subwoofer and I am trying to determine the source, but have no clue where to start.

It is strange, I thought it was only happening with TV from my Dish STB, but tonight I noticed it with a movie form my popcornhour over HDMI. My STB is connected via SPDIF, so the sources are different, but the issue is the same.

I have and SVS PC12-Plus, the thing has been great to date. My receiver is and Onkyo TX-SR805 and I am using sub out as expected, and going to I the the R input on the sub.

In the Onkyo THX Subwoofer is set to no
LPF of LFE is set to 80Hz

beyond that, I have nothing special. The sound I hear is like a muffled/statick like sound from the sub. I never thought much of it till last night I was watching a movie and it sounded sort of like quiet thunder or stadium crowd in the background. The sub still functions normal when there is normal bass to play, it shakes the room, so the sub itself seems fine, so I don't know if it is getting a bad signal or a signal it should not be receiving because like I said, when it comes to the real bass, it plays fine. Is it potentially the Hz setting of the Sub? Is 80Hz right or should this be like 120Hz as I have seen noted elsewhere?

I actually have all my speakers currently set to 80Hz, so maybe I am doing things wrong all around, but first things first is the subwoofer as the added output is annoying as it makes it seem like it is raining in the distance or bombs are exploding over a mountain when that does't fit the scene at all.

Thanks for any help provided.

braveheart123 11-30-2013 11:15 PM

Bypass LPF on the sub amp. Keep it on max available setting on the sub and control bass management from AVR only. Just a thought.

smakovits 12-02-2013 10:52 AM

You have to excuse my ignorance, but how do I bypass the LPF on the SUB amp?

Second, I assume max setting it max volume and then controlling the bass from the AVR refers to the dB level setting, +1, -2, etc.?

eljaycanuck 12-02-2013 11:53 AM

... how do I bypass the LPF on the SUB amp?
The amps on some subwoofers have a "disable" or "bypass" switch for the LPF. If your subwoofer's amp doesn't have one, just max out the LPF (crank the knob fully clockwise). That will effectively disable it.
Second, I assume max setting it max volume and then controlling the bass from the AVR refers to the dB level setting, +1, -2, etc.?
Set the LPF - not the gain ("volume") - on the sub to max.

Set the gain on the sub to around "noon" and calibrate. If the sub's level ("volume") in your AVR's speaker set-up menu is too high, raise the gain on the sub; if it's too low, lower the gain on the sub. Re-calibrate.

Repeat until you have a sub level that is close to the levels of the speakers (erring on the side of a bit lower than the levels of the speakers).

From that point on, adjust the level of the sub in the AVR's speaker set-up menu (not on the sub itself).

Alan P 12-02-2013 11:56 AM

So this was NOT happening before....just started recently? And nothing in your system has changed? Have you tried a different sub cable?

To answer a couple of your questions:

Yes, your crossovers should be set to 80hz (the 120hz you probably saw mentioned is in reference to the "LPF for LFE" setting, something completely different), unless Audyssey set them higher. Never lower a crossover that Audyssey set....however, it is fine to raise them to 80hz if Audyssey sets them lower.

Do not set the gain on your sub to max...you should set it to wherever Audyssey calibrates it closest to 0db...typically this is around 1 o'clock, but can vary greatly from sub to sub.

smakovits 12-02-2013 12:22 PM

I see I have some work to do. I will need to take a closer look at the sub amp, check what options are there. At that point I will go back into the AVR and report my findings.

As far as things changing, the only thing I did recently was change LPF of LFE from 120 to 80Hz. Thought I mentioned it in the OP, but after a quick glance maybe not. I was reading in someone else's post and they mentioned this change. But that was at least 2 months ago so i am surprised I would not have noticed this sooner?

Would it also be suggested to go through an Audyssey calibration again?

Alan P 12-02-2013 03:05 PM

Changing the LPF to 80hz should not cause the symptoms your describing, but you should leave it at 120hz all the same.

If you've made any changes to the sub gain (on the sub), then yes, you need to re-run Audyssey.

braveheart123 12-02-2013 07:13 PM

As far as things changing, the only thing I did recently was change LPF of LFE from 120 to 80Hz.

You have two LPF engaged causing cascading effect, which will yield low bass around the crossover. Keep LPF at max on sub and control bass management from avr only.

smakovits 12-03-2013 08:41 AM

to make life simple, this is the back of my SVS sub amp

Sonic filter is set based on instruction for having none of the port plugs in place.

To confirm, Crossover switch is in the disabled position

The one thing that does appear potentially off is the phase not being at 0...kids... take a look, let me know

Alan P 12-03-2013 09:48 AM

If you have no way to measure your room (REW, OmniMic, etc.) than I would recommend you leave the phase at 0.

JHAz 12-03-2013 10:14 AM

How does it sound on troublesome content with the sub turned off? At 80 Hz, at least to me, the term "muffled" would not apply. You're about a third of an octave above where a lot of engineers/mixers bump up the kick drum for that "hit you in the chest" feeling (60 Hz, although some like 50 Hz). Static/muffling, to me, would be way higher in the frequency range. But of course we're in an arena where individual "definitions" of slippery terms create difficulties in communication.

I do agree that if something seems missing, eliminating double low pass filters could absolutely help.

I suppose another possibility is that you are overloading the input stage of the sub, causing distortion that would indeed get far higher in frequency. If your AVR's sub output is far into the "+" range, turn up the sub's gain control, and recalibrate with a lower AVR output level.

Just a semiuseless WAG . . .

smakovits 12-05-2013 09:49 PM

Ok, so I finally managed to get in the basement again. Seems like the issue is not static, so let's eliminate that from the discussion. Instead it is best described as muffled. Almost like If you are talking and put your hand over your mouth.

So it is like non bass/sub stuff is sent to the sub. I say this because tonight I was watching nhl 2night and the music during highlights was outputting muffled from the sub. Now, if there is something that is real bass, that works fine, the room shakes so in that sense the sub is Ok. Instead it just seems my onkyo is sending stuff to the sub that perhaps it shouldn't? Or is it the sub that should be like I am not playing that...

Now, at the same time this is not the exact same as was during the movie which was more like thunder in the distance, but I think it was similar. The sub outputting something that is not chest pumping bass so instead it just sounds bad. If that makes sense anyway...

Alan P 12-06-2013 08:09 AM

Where are you speaker crossovers set in your AVR? Sounds to me like you have the crossovers set too high.

smakovits 12-06-2013 03:29 PM

If we are talking the same thing, 80hz across the board

Alan P 12-06-2013 04:44 PM

Do you have the sub hooked to the sub out on your AVR?

smakovits 12-06-2013 05:02 PM

Yes. I believe it is called subwoofer preout

smakovits 12-06-2013 07:14 PM

digging around, may have found something. since I did change sub crossover from 120 to 80Hz, and before things were set from Audyssee, since I made this change I didnt re-calibrate so the Onkyo is not filtering correctly. Let me try to switch things back to 120 and see what happens and then report it back .

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