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Bass dead-spot in listening position

Rich Marshall

Well-known Member
Hi all.

Recently I moved my gear into what we used to use as the dining room.
The idea was to create a media/cinema room and it works really well with the exception of my bass problem.

The screen, front speakers (kef 1Q5SE) and DIY Monolith sub are positioned in front of a bay window, the sub being directly behind the TV against to the low wall of the bay window itself and the Kef's either side of the tv.

I've gone for a 7.1 setup and wanted my seating position to be away from the rear wall so it's a decent distance from the rear back speakers and level with the rear L&R ones...

This is where the problem arises, if I move 2' closer to the screen the bass from the sub and fronts is full and quite loud, move back closer to the rear wall and it sounds good too - from my seating position it's almost non existant from the sub and/or fronts. It almost sounds out of phase and hollow (it's not out of phase and I have tried switching sub and fronts in all combinations)

I've read a little on the googleweb and understand that the centre of a smallish room is often the worst place to sit due to the wavelength of bass notes:facepalm:

Would adding another identical sub in a different location (not that I have many options here) fix the problem or should I just start from scratch with positioning?

Any advice would be great :lease:
 

Rich Marshall

Well-known Member
Not to scale, the room is 14.5' from bay to back wall and 12' across.
 

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hoppaz

Well-known Member
Have you re done auddessey mic set-up or are you using an eq device like an anti mode?

The old school way of setting up a sub use put it in your listening position and play some bassy material and get on your hands and knees and live about until the bass sounds the best. This is then where your sub should go.
 

Rich Marshall

Well-known Member
Have you re done auddessey mic set-up or are you using an eq device like an anti mode?

The old school way of setting up a sub use put it in your listening position and play some bassy material and get on your hands and knees and live about until the bass sounds the best. This is then where your sub should go.

Hi, thanks for the reply.
Done optimiser on AVR (YPAO) but not tried antimode - I have looked into it a bit but from what I can gather antimode is primarily for flattening peaks in bass rather than fixing phase issues??

I have tried the sub where the coffee table is on the diagram but it sounds worse there.

I was thinking maybe placing the sub back there though and building another identical one for the corner on the other side of the window.

I've also read the crawling theory is false:rolleyes:
 

Member 639844

Former Advertiser
My advice would be simple, get REW and measure whats going on. It will be easy to identify the issue then and decide on how to tackle it.
 

dlg78

Active Member
Hi all.

Recently I moved my gear into what we used to use as the dining room.
The idea was to create a media/cinema room and it works really well with the exception of my bass problem.

The screen, front speakers (kef 1Q5SE) and DIY Monolith sub are positioned in front of a bay window, the sub being directly behind the TV against to the low wall of the bay window itself and the Kef's either side of the tv.

I've gone for a 7.1 setup and wanted my seating position to be away from the rear wall so it's a decent distance from the rear back speakers and level with the rear L&R ones...

This is where the problem arises, if I move 2' closer to the screen the bass from the sub and fronts is full and quite loud, move back closer to the rear wall and it sounds good too - from my seating position it's almost non existant from the sub and/or fronts. It almost sounds out of phase and hollow (it's not out of phase and I have tried switching sub and fronts in all combinations)

I've read a little on the googleweb and understand that the centre of a smallish room is often the worst place to sit due to the wavelength of bass notes:facepalm:

Would adding another identical sub in a different location (not that I have many options here) fix the problem or should I just start from scratch with positioning?

Any advice would be great :lease:

From how I read things you have almost answered your own question.

If you add another sub it seems to me that you will still be getting little benefit from the 1st one, therefore you need to experiment with positioning.

The only messing about I have done is with a REL Storm and I found that it responded to positioning very noticeably in different rooms, from your diagram your room looks square with the sub halfway along one wall, I would be starting with corner placement and working from there, pull the sub out from the corner diagonally and see how it sounds. Then you could try working along one wall - there will be somewhere where it drives the room well.
 

mfife

Active Member
An antinode (bass dead spot) is more a characteristic of the room than anything else. You could try moving the sub around and you may get a change there, but I think in all likelihood you'll just have to bite the bullet and move that sofa closer to the rear wall.
 

Member 639844

Former Advertiser
Would the mere fact a solid mass displacing itself (irrelevant of how fat they are) around a room not have some form of effect Moonfly?

In theory yes but in reality its probably negligible in terms of the crawl method, the room is the biggest influencing factor.
 

JonStatt

Well-known Member
The centre of a rectangular room is, I believe, always an anti-node! I struggle with this in my room, but I just calibrated at the listening point, and it sounds fine there. Just anywhere else in the room the bass is much too heavy. The biggest issue is annoying the neighbours as of course if I wasn't listening in a dead spot, the sub could be a lot lower in output.
 

Member 639844

Former Advertiser
The centre of a rectangular room is, I believe, always an anti-node! I struggle with this in my room, but I just calibrated at the listening point, and it sounds fine there. Just anywhere else in the room the bass is much too heavy. The biggest issue is annoying the neighbours as of course if I wasn't listening in a dead spot, the sub could be a lot lower in output.

this is your biggest issue. The harder you have to push the sub the less headroom it will have and the closer to its distortion zone it will be.
 

DodgeTheViper

Moderator
Rectangular rooms do appear to be a bit of a problem, and mine is also this shape although it does open out at the back into another room. Bass levels appear to be heavier on the outside walls of the room and less so towards the centre. Having said that, mine is at a relatively low gain level on both amp db level, and sub gain level, and sometimes it scares the pants off me. For info my sub is in the centre of the front wall, under the screen.
 

AngelEyes

Distinguished Member
Hi all.

Recently I moved my gear into what we used to use as the dining room.
The idea was to create a media/cinema room and it works really well with the exception of my bass problem.

The screen, front speakers (kef 1Q5SE) and DIY Monolith sub are positioned in front of a bay window, the sub being directly behind the TV against to the low wall of the bay window itself and the Kef's either side of the tv.

I've gone for a 7.1 setup and wanted my seating position to be away from the rear wall so it's a decent distance from the rear back speakers and level with the rear L&R ones...

This is where the problem arises, if I move 2' closer to the screen the bass from the sub and fronts is full and quite loud, move back closer to the rear wall and it sounds good too - from my seating position it's almost non existant from the sub and/or fronts. It almost sounds out of phase and hollow (it's not out of phase and I have tried switching sub and fronts in all combinations)

I've read a little on the googleweb and understand that the centre of a smallish room is often the worst place to sit due to the wavelength of bass notes:facepalm:

Would adding another identical sub in a different location (not that I have many options here) fix the problem or should I just start from scratch with positioning?

Any advice would be great :lease:

The short answer is to move your listening position.

Long answer is to measure your room and then move your listening position. You can't EQ out a Null and adding an additional sub will still require accurate measurement to correctly integrate them both. EQ can be a fantastic tool but it is the last tool you should use once you have optimised the positioning/integration of speakers, subwoofer(s) and yourself.

Adam :)
 

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