Dual sub placement - corner + side wall - is this a good idea?

[PHD]

Hi

I know that corner placement will give amplification and excite all possible modes which is sometimes preferred, while subs in side walls will even out the response all across the room. But what if I put one in the front corner and the other in the side wall on the other side, as shown in the illustration I created? Is this a good idea? Could it combine all the advantages?

Thanks

 

[ppataki]

Hi

I know that corner placement will give amplification and excite all possible modes which is sometimes preferred, while subs in side walls will even out the response all across the room. But what if I put one in the front corner and the other in the side wall on the other side, as shown in the illustration I created? Is this a good idea? Could it combine all the advantages?

Thanks

View attachment 392800

Just simply use the Room Sim component in REW and that will show you how this will work in your room

 

[napfkuchen]

Judging from the drawing, there aren't that many other places where the subwoofers could be placed. I would measure the subwoofers individually for each of the available (8 to 10 positions) with the AVR and also take a measurement with REW. For example, in my room it turned out that only one position on about 1/4 of the width of the room gave a good result; in the other positions there were always significantly more cancellations. Placing the subwoofers on opposite walls would have been complicated in terms of cabling, without actually being measurably better.
All of this can be done relatively quickly with a long RCA cable and instead of a potentially inaccurate simulation you get actually usable results.

 

[sigbergaudio]

If you have either automatic or manual EQ available, this is likely to give a more than decent result.

 

[-Matt-]

Especially if you are using MSO or similar then I suspect that diversity in sub positioning and type (and therefore in response) is a good thing.

I.e. If multiple subs have peaks and valleys at different frequencies then they are better able to support each other to create a unified response. Filling in each other's dips.

Conversely, if you rigidly stick to symmetric placement you may end up doubling up on peaks and valleys.

 

[Matt34]

This is what works best in my open concept living room. I have one sub in the front right corner and the other mid wall on the other side. I've tried for symmetry first with both front corners but that results in a nasty 60-70hz dip. Placement options were very limited, but this strategy in combination with smaller subs (kef KF92) gave me the most uniformed in-room bass response.

 

[PHD]

The problem with room sim is that there are way too many variables. What do put in surface obsorption coefficients for a brick walls fromts and sides and a large wooden closed in the back which covers 80% of the back wall?

 

[ppataki]

The problem with room sim is that there are way too many variables. What do put in surface obsorption coefficients for a brick walls fromts and sides and a large wooden closed in the back which covers 80% of the back wall?

View attachment 392819

I always leave those as-is; it will still give you a pretty good approximation

I take two approaches usually:
- if I have many potential placements for the sub(s) I simulate them with REW and then measure those that seemed to be the best - this happens very rarely since we are in a living environment with many obstacles
- if I have only 1 or 2 potential placement options I enter those in REW specifically and see how it looks like and then I measure - usually it ends up being pretty close to what I have seen in REW

Note: if you have an irregular shaped room the sim might not work well; however that also depends on the room; for example my living room has six corners instead of four but still the sim works almost perfectly. You will have to see it for yourself

 

[Oddball]

Think you already got some pretty good advice.

Some additional points to think about - make sure your MLP is not in the middle of the room as that might not work well however you place the subs. Placing one sub behind the sofa (or against the back wall) might also be an option, especially if you are not using identical subs and weaker one might require less distance for the SPL. If equal subs, placing them on the side of the sofa might also work. It is a daunting job to place subs as even a 0.3m movement in placement might get you different results.

This is probably a bad advice on such technical forum, but make sure you like what you hear, despite of the prettiest graphs (obviously with some respect to the graphs and measured outcome). Also, you did not check the box on the sealed room - so is this space open to other rooms/hallways etc.?

 

[Matt34]

The problem with room sim is that there are way too many variables. What do put in surface obsorption coefficients for a brick walls fromts and sides and a large wooden closed in the back which covers 80% of the back wall?

View attachment 392819

Or if your main floor is open to the 2nd floor via an open stairwell and entryway, it makes using the sim very difficult.

 

[jaakkopetteri]

I have a very similar setup and even with MSO there's some tonal variation between seats as you sit closer to the sub on the side wall. If possible, I would place both subs on the front wall, but it's not a big deal (at least with proper DSP capabilities) and your idea might result in better mode handling

 

[ryanosaur]

I took a different approach when I placed my Subs. I didn't want them on the front wall or corner loaded. I did the subwoofer crawl to make certain I found good locations in my room where the bass was solid and used those as locations to place my Subs in-room. A little experimentation resulted in some slight positional EQ, but ultimately the places I chose worked very well. They are asymmetric to both front Speakers and to the MLP.

An important thing to keep in mind is that no two rooms behave the same. Likewise, the room simulators are best if you have a regular closed room... regular shapes don't do well from those I've talked to who use them. For example, I have a high sloping Clerestory ceiling in my room which changes interactions dramatically.

 

[-Matt-]

One thing to possibly listen out for...

When I tried positioning a sub to the side of the MLP I found it easier to localise the sub (easier than when it was at the front of the room or behind).

If you have the same experience and can't reposition you could perhaps experiment with setting a lower crossover for the side sub.

 

[PHD]

OK. I've tried 3 different options by both REW simulation and actually trying them post Audyssey (A1 EVO) calibration. To me the 3rd option where the subs are placed below the side surrounds sounded the best and according to EVO log, the dip removal efficiency was the highest at 97% when fronts were set to large and crossed at 250Hz.

The simulations seem to support this. The difference between corner + side and sides only was subtle. Even the gains were almost identical. Sides did require polarity inversion on both subs while corner+side required polarity inversion on the side sub.


Of course, aesthetically I like the front corners but sonically the sides is best. I assume because the room is very small so It's almost a nearfield placement.

Which simulation results seem best? To me it's the second where both are to the sides of the MLP. But this leaves a clearence of only 1 meter from the sofa....

Thanks.

 

[Flaesh]

Which simulation results seem best?

Eek:

Personally, I prefer

this way, but in a bigger room.