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Discussion Starter #1 (Edited)
Hi All,

Have been busy with our current room for a couple of years now but keep bumping into some issues which I don't know how to (if even possible) solve;

At the listening spot there are some major dips/nulls in bass response.
Below graphs are the result of just the main speakers, no subs playing, no crossover active, receiver is set to pure direct.
aejd.jpg

5iy7r.jpg

View attachment 51257

Guaranteed this is mainly caused by the room and the used materials. Starting with the room build, I did not put enough attention in room acoustics (major mistake, I know :) ).
- The room is about 6 x 4,20 m. Height is 240cm
- Half of the room (front part) is drywall with rockwool and concrete ceiling.
- The other half (rear part) is brick wall with drywall ceiling (no isolation behind that as far as I know).
- The rear wall is glass/wood entrance to the garden.

To give an impression:

6ie8.jpg

img5710jq.jpg

In each rear corner I placed 2 GIK 244 panels behind each other, this helps a little bit in bass response.

My own thoughts on treatment, have been super chucks and rear wall absobtion. Practically these are not really possible.
Super chunks should be placed in every corner and the only corner I might be able to use, is the one where the receiver is placed.
Treating the rear wall is not an option (I think) because this is a walk-through to the garden. Also WAF could be a thingy.:D

What would ceiling treatment do, and what are the options?
Maybe something I did not think of?

These treatments are mainly for stereo as low bass response for movies is quite OK because of the use of 2 subwoofers.
Main thing I miss in stereo is slam bass (e.g. kick drum). What I am missing because of the dip between 80 and say 120Hz I don't know.
Reverb in the higher areas is quite ok, so extra dampening there should be reduced to a minimum.

To complete things, below the response of both fronts in combination with the subs. No eq is used.

frontssubsnoeq.jpg

watervalall.jpg

Thnx in advance for thinking with me:)
 

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Treatments targeting the low frequencies will primarily improve ringing; they won’t necessarily give drastic improvements to frequency response, at least not as drastic as your top two graphs require. Furthermore, improvements in ringing below (IIR) ~60 Hz requires lots of really big traps. Your waterfall actually looks pretty good in the ringing department.

As such you probably need to look elsewhere to solve your low-end response problems. However, you didn’t give us enough information to go on. For instance, your “left” and “right” graphs: Are those main speakers only, or were the subs running? If the former, there doesn’t appear to be any crossover in place on the main channels to roll out the bass response. This could be a big part of the problem, if you’re running full-range mains with subwoofers.




Regards,
Wayne


 

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Discussion Starter #4
Thank you for your reply Wayne.

The left and right graphs, are just the main speakers. The receiver (Onkyo NR808) is on "pure direct" mode, which disables the low level subwoofer output. The subwoofers are not connected through high level.
In this setting, stereo music is always played. I prefer it above the stereo setting, gives a nicer and wider picture, less "flat".
Tried plugging the bass ports of the main speakers, but this did not bring big improvements, so I consider this the finetuning area.

The purple graph is both the fronts playing with both the subs using bass management --> crossover 70Hz.

Should you need any more info, please let me know.

Ringing indeed is quite OK. Lowering it, would be a bonus but surely not a necessity.
Huge traps indeed are a bit of a problem, superchucks in the rear corners could be a "last resort", but I would only consider them if it would really do any good.
The peaks can be flattened with dsp (e.g. minidsp between receiver and power amp or EQ on Foobar), the nulls/dips are the challenge.

Connecting the subs high level might be a way to compensate here and there. Getting the most out of the mains however, has the preference. But it could be that I am demanding too much of the current room/setup within the possibilities :).

As said, the main goal is to improve stereo. I am quite happy with the surround picture, the ideal sweat spot for correct bass response is a bit small, but I can live with that as I am mostly the only one noticing:rofl2:
 

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Thank you for your reply Wayne.

The left and right graphs, are just the main speakers. The receiver (Onkyo NR808) is on "pure direct" mode, which disables the low level subwoofer output. The subwoofers are not connected through high level.
In this setting, stereo music is always played. I prefer it above the stereo setting, gives a nicer and wider picture, less "flat".
Thanks for the info, Ralph. Your left and right graphs certainly give credence to one of the oft-stated benefits of subwoofers, that the speaker locations that get the best imaging are often not the best for bass response. As long as you listen in the “pure direct” mode I don’t really see that there is much you can do to improve bass response. Those graphs are even beyond equalizing.

The combined graph looks pretty good, but you could probably see some improvements by relocating the subs to corners and then equalizing them. I’ve never gotten anything but abysmal response with center-of-wall placement.

Regards,
Wayne

 

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Discussion Starter #6
Yep, bass response is a pain in the :).

Subwoofer placement at this moment, is as ideal as it is going to get. The nulls of the SVS are compensated by a BK xxls400 in the rear left corner. Only there the response does not extend well under 30Hz, that is what the SVS on the side wall is for :D.
Both subs are matched in phase with the mains.
 

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Well Ralph, the good news is that your room LOOKS great! :)

Unfortunately I don't have much to add beyond the things already discussed. Are your mains ideally located for imaging now? You might be able to improve things by moving them around, but it seems like you might have them in that spot for a reason already. Same for the subs, even moving them a few feet along the wall might help if possible.
 

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Discussion Starter #8
Thank you for the compliment Owen.

For movies I am already quite happy. A small improvement in the ringing would be nice, but I can live with the current situation.
As you already thought, the fronts now are on the location for the best image. Moving them improves bass response, but the spacious picture collapes.

Tried to add one of the subs a couple of weeks ago, but the high level cable picked up too much interference of some other cables (I think).
Going to rewire the whole lot in the coming weeks and also place the equipment behind the projection wall. So during that proces I will also try to fix the overspeak.
After that, new listening and new measurements, cause the equipment is now in the left corner and who knows if that might have an influence on the acoustics as well.
 
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