Bass disappears when I sit down

[statikcat]

Hey everyone. Feel free to merge this with another thread if needed.

I have an Acoustic Audio Sub12 and am having a weird issue in my new apt that I did not have in my old apt. When I stand up in my listening position I hear lots of sub.. when I sit down it drops dramatically! I always thought of sub placement as helping on the horizontal axis. Is there anything special you can do to correct verticle issues? I have never had this kind of issue with a sub before.

The sub is about 12-14 inches from the wall and not near any corners. Like a lot of HT the sub is about 8 feet in front of me and to the left about 2 feet. The tv stand is to it's right and floorstanding speaker to it's left. The front positioning is the same as my old apt. It is sitting on carpet and I have been thinking about getting a platform for the sub.

Any suggestions?

[Aerodude73]

Originally Posted by statikcat

Hey everyone. Feel free to merge this with another thread if needed.

I have an Acoustic Audio Sub12 and am having a weird issue in my new apt that I did not have in my old apt. When I stand up in my listening position I hear lots of sub.. when I sit down it drops dramatically! I always thought of sub placement as helping on the horizontal axis. Is there anything special you can do to correct verticle issues? I have never had this kind of issue with a sub before.

The sub is about 12-14 inches from the wall and not near any corners. Like a lot of HT the sub is about 8 feet in front of me and to the left about 2 feet. The tv stand is to it's right and floorstanding speaker to it's left. The front positioning is the same as my old apt. It is sitting on carpet and I have been thinking about getting a platform for the sub.

Any suggestions?

Maybe you might want to try moving it a couple feet either way, or to the other side and see if the problem persists. Or you could get the Subdude here. I just did and though I haven't given it a proper workout (testing of certain Blurays with Known great LFE content---Transformers, TDK, Incredible Hulk, U-571, etc)., just normal TV viewing so far, I have already noticed better sounding, cleaner sound from my main sub.

[aramis109]

BD has posted some links and high-tech mumbo-jumbo that I don't understand, but basically yes, placement can help on the vertical axis as well. Try putting it on a chair or something raised up a couple of feet and see if it changes. Also, just try moving the placement around. Sounds like you're getting some standing waves that are cancelling each other out.

[Grevlin]

I bet Big Daddy and others will get in on this one. I just got the AA HDSub-12, and the only way I could escape the bass would be to leave my house

In my experienced noob-state, I would say maybe move it over near the corner and ABSOLUTELY put it on a DIY riser or similar.

I'm thinking it has to do with your room shape and placement of the sub. (The waves and all that...)

Edit - Aramis types faster

[statikcat]

Yeah I have tried moving it a little but do not have a lot of room to dramatically move it's position at the moment plus .. I would need a longer sub cable.

Actually, now that I think about it.. there is a 40 inch foot tall counter (bar attachment on kitchen) to my left so that might be what is causing phasing issues. No idea why I did not think of that before . I will have to get an extension for my sub and try and place it on the other side of my stand and see if that helps. I also have a smaller second sub I want to experiment with. I Guess I will just have to tamper more with placement I just never came across verticle issues. Oh well time to do some moving tonight. I would take pics of the room but since I just moved it is still messy

[VinnAY]

I have two subs one 12 at the front between my stand and the floor standing speaker array, and an 8" centered behind my couch. I didn't feel that I was getting the heavy bass I should have with that setup so I moved the 8" to the back corner and it really livened things up alot.
The old addage that you can place a sub anywhere because those freq's are nondirectional really doesn't apply as best I can tell LOL

[statikcat]

Good to hear.. I have some space behind my couch that I was thinking about testing my extra 8" sub at as well. Hopefullly someone's bedroom is not on the other side of that wall

[mgrimsley]

dont sit down !

[Grevlin]

Or make the sub stand up

[statikcat]

Originally Posted by mgrimsley

dont sit down !

Ha! Should I put my couch on a raiser .. or get a really comfy bar stool??

[Mike2060]

This is a placement issue. The bass waves at your sitting location must be canceling each other out. You should move the sub to a diff. location.

[HAMP]

I know you said you have a short cord, but can you put the sub at the sitting position and then do the crawl method.
Doing this you should be able to find the best placment for the sub.

[Yeha-Noha]

Does your monoblock or plate amp powering your sub have a variable phase control between 0 and 180 degrees? If so, you might give that adjustment a try.

If that doesn't work, then it does look like you'll have to find the best placement for the sub as others have suggested.

[Big Daddy]

Originally Posted by statikcat

Hey everyone. Feel free to merge this with another thread if needed.

I have an Acoustic Audio Sub12 and am having a weird issue in my new apt that I did not have in my old apt. When I stand up in my listening position I hear lots of sub.. when I sit down it drops dramatically! I always thought of sub placement as helping on the horizontal axis. Is there anything special you can do to correct verticle issues? I have never had this kind of issue with a sub before.

The sub is about 12-14 inches from the wall and not near any corners. Like a lot of HT the sub is about 8 feet in front of me and to the left about 2 feet. The tv stand is to it's right and floorstanding speaker to it's left. The front positioning is the same as my old apt. It is sitting on carpet and I have been thinking about getting a platform for the sub.

Any suggestions?

The long wavelengths of bass frequencies interact with the walls, ceiling, and floor and create standing waves and room modes. There are three types of modes. The strongest of these modes are the horizontal (wave interaction with side walls) and vertical (wave interaction between floor and ceiling) axial modes.

As a result of these standing waves, you get high pressure and low pressure locations in the room. If your subwoofer is placed in a high pressure location, you will hear too much bass, perhaps not a very good thing. If the subwoofer is placed in a low pressure zone, you will hear no bass or very poor bass. For the same reason, if your seat is in a high pressure zone, you will hear loud and tiring bass. If your seat is in a low pressure zone, you will hear very poor bass. The worst location for your subwoofer or your seat is in the middle of the room. Cubic rooms and square rooms are the worst type of room for bass frequencies.

Normally, when you move your subwoofer around in a room, you deal with the horizontal axial modes. The best location for a sub is in a conrner about a couple of feet away from the walls. If the sub is too close to the walls, it may become too boomy and tiring.

The only way you can deal with vertical axial mode is to raise the subwoofer or hang it from the ceiling. The other option is to use a very high chair. To be practical, you have two options:

1. Move your seat and subwoofer around to get the best bass sound possible.
2. Build a riser and lift your subwoofer about 1 ft to 2ft. Instructions are in the Repairing & Upgrading Subwoofers thread. Go to Post #2 and scroll about 1/3 down.

[statikcat]

Thanks big daddy it is good to know that increasing the height of the sub can help with verticle issues. I moved the sub to the other side of my stand and it helped a lot but I still want to construct or buy some kind of 6-12" raiser and I think it will sound pretty solid.

[Fors*]

Originally Posted by statikcat

Thanks big daddy it is good to know that increasing the height of the sub can help with verticle issues. I moved the sub to the other side of my stand and it helped a lot but I still want to construct or buy some kind of 6-12" raiser and I think it will sound pretty solid.

Risers are easy to build, as you can check out BD's sticky here...

https://forum.blu-ray.com/showthread.php?t=74527

I built my own based on his recommendations and it improved the sound (pictures in my gallery) that I now get from my sub. Not a bad idea either to think of a 2nd sub if you are having any " LFE voids" issues in the room, to balance out the lower db's.

[Grevlin]

For those afraid of hammers, you could:

Buy a cheap black ottoman

Cut out the bottom fabric with a kitchen knife (most are hollow, don't get the storage type)

Stuff with polyfill or some insulation from lowe's/home depot (or even an old pillow)

Set your sub on top - Done, that will get you about 14-18" rise, a bass trap, and even a little isolation most likely.

[Grevlin]

<------------ My label changed



Sorry Been stuck on the computer for two weeks because of a knee surgery.

[Aerodude73]

Originally Posted by Grevlin

For those afraid of hammers, you could:

Buy a cheap black ottoman

Cut out the bottom fabric with a kitchen knife (most are hollow, don't get the storage type)

Stuff with polyfill or some insulation from lowe's/home depot (or even an old pillow)

Set your sub on top - Done, that will get you about 14-18" rise, a bass trap, and even a little isolation most likely.

CLASSIC! - Excellent fairly cheap solution Aramis. (Polyfill pillow from Walmart, $3+ & Up!)

[jomari]

aside from building risers, and addressing the axial modes of the room, id also suggest to find out why we have the issue as well.

big daddy has posted numerous stickies, as a great reference point, and has also 'worded' them as plain as possible, which isnt easy, and underappreciated.

here is the
guide to subwoofer placement

standing waves