Sub placement theory & simulations

S

Sendu

Audioholic Intern
There's a good article on Audioholics here: Optimum Room Locations for Subwoofers An Analysis.

The author ran simulations on different room sizes, listener positions and sub placements to see what works best. The article concludes with:

The biggest single takeaway from all of this is that rules of thumb about which subwoofer configurations work best are of limited use if you don’t take seating configuration and room dimensions into account. SO, how can this be done? How can these simulation results be of practical use? If you are designing a room and have some latitude as to dimensions, seating and subwoofer configurations, you should be able to look at the data and find a combination which best fits your goals gives the best possible results. If one or two of these variables are fixed, you can make the best selection for the remaining one(s).
The article seems to suggest you can look at the library data to pick out the result relevant to your own situation, but unless I'm being blind the data is no longer available? And the paper costs money to download.

Is there a way to plug your own situation in to these simulation results?

Has anyone done similar studies and simulations with other sub placements? In particular, non-symmetrical positions like 1 sub in a front corner, the other sub 1/4 of the length along the back wall?
 
everettT

everettT

Audioholic Ninja
There's a good article on Audioholics here: Optimum Room Locations for Subwoofers An Analysis.

The author ran simulations on different room sizes, listener positions and sub placements to see what works best. The article concludes with:



The article seems to suggest you can look at the library data to pick out the result relevant to your own situation, but unless I'm being blind the data is no longer available? And the paper costs money to download.

Is there a way to plug your own situation in to these simulation results?

Has anyone done similar studies and simulations with other sub placements? In particular, non-symmetrical positions like 1 sub in a front corner, the other sub 1/4 of the length along the back wall?
You can invest $100 for a measurement microphone and a free copy of REW to run placement simulation for your specific room. Also REW can be used to upload filters for eq to several popular outboard EQs.
 
S

Sendu

Audioholic Intern
You can invest $100 for a measurement microphone and a free copy of REW to run placement simulation for your specific room. Also REW can be used to upload filters for eq to several popular outboard EQs.
Thanks. I don't think you need the mic just to run the simulations? I came across REW simulations after posting my OP and it seems they can be pretty accurate assuming your room is simple and rectangular.

Do REW simulations effectively replace knowledge found in articles like the one I mentioned?
 
j_garcia

j_garcia

Audioholic Jedi
Thanks. I don't think you need the mic just to run the simulations? I came across REW simulations after posting my OP and it seems they can be pretty accurate assuming your room is simple and rectangular.

Do REW simulations effectively replace knowledge found in articles like the one I mentioned?
Best to use all the knowledge available. REW is more tailored to the actual environment, which does make it more accurate, but the "rules of thumb" still apply to all setups as well.
 
everettT

everettT

Audioholic Ninja
Thanks. I don't think you need the mic just to run the simulations? I came across REW simulations after posting my OP and it seems they can be pretty accurate assuming your room is simple and rectangular.

Do REW simulations effectively replace knowledge found in articles like the one I mentioned?
Generic simulations yes. But measurements from your main listening position are invaluable to obtaining the most out of you setup, not just subs. The article you referenced is a little old school (in the manor of outcome, not in results per say) in it dosent take everything in your room into account. Being able to see what is actually happening via measurements is truly the way to go.
 
N

NorCalRP

Full Audioholic
In your other thread about diminishing returns you mentioned a pretty healthy budget. I definitely endorse REW and the MiniDSP U-Mik. If for anything you can do a sub crawl with the mic while running a test tone with the SPL meter. For $400 you could get the MiniDSP DDRC-24. After determining the optimum placement from an output perspective, you could run the Dirac Live to correct your curves.
 
S

Sendu

Audioholic Intern
I have the U-Mik already, and will have everything installed and measured and calibrated by professionals anyway. This is about coming up with places to install electrical sockets and speaker wire outlets prior to room construction.

I've used REW simulator and came up with the following.

Here's my room with just the Front L/R speakers:

Without subs you could EQ that flat down to 20Hz by pulling down to 55dB.

Unless my room is considered sealed, in which case:

Yikes!

The best wall position for 1 sub was mid-rear wall:

Also EQable at 55dB.

Even better was a sort of coffee table position (though this would sort of block the centre speaker, which in my case is positioned on the floor):


This time, the room being sealed doesn't cause problems:


The only 2 sub position I could find that was as good as or better than the above was 2 rear corners. All asymmetric options introduced a lot of seat-to-seat variation.

Still only EQable at 55dB.

Sealed room causes a null at about 25Hz:


I could find no positioning of 4 subs that was as good or better than the above options.

What would you pick amongst these? Does anyone know what kind of room counts as sealed?

What are the implications of pulling down 20dB in order to get flat EQ? Is that just normal, no big problem for your standard AVR (I might be getting one with Dirac Live)? Does it mean your power amps then have to do an extra 20dB of output to get back to normal volume? And does that mean you'd need more powerful amps than you might otherwise have thought?

If my room counts as unsealed, what are the implications of just using my Front L/R for LFE and not having subs at all? (The Martin Logan Vantage 15A's bass reproduction is via active sub-woofers at the bottom of the speaker.)
 
Pogre

Pogre

Audioholic Spartan
The best things I've found to do are the sub crawl to find optimum placement then take measurements from the seating positions to see where your peaks and nulls are. There are some general rules of thumb to follow, but once a room is furnished and things get moved around I would think it changes the response in ways that simulations might have trouble predictiing.
 
ryanosaur

ryanosaur

Audioholic Ninja
The best things I've found to do are the sub crawl to find optimum placement then take measurements from the seating positions to see where your peaks and nulls are. There are some general rules of thumb to follow, but once a room is furnished and things get moved around I would think it changes the response in ways that simulations might have trouble predictiing.
Using the Crawl takes some guess work out. Coupled with measurements, you end up more approaching Geddes technique than the others. I’m still flirting on the boundaries of a full Geddes dive, but it makes the most sense to me, as it allows for you to work with the rooms actual acoustics rather than trying to impose a model upon the room.
 
N

NorCalRP

Full Audioholic
I have the U-Mik already, and will have everything installed and measured and calibrated by professionals anyway. This is about coming up with places to install electrical sockets and speaker wire outlets prior to room construction.
I really enjoy this forum, and have learned pretty much all I know about this hobby from the great members here. It makes perfect sense to me why you're here. With that said, and an aforementioned large budget, and impending help from professionals, why not just place electrical sockets at enough points in your room to accommodate any location, and let the pros do the rest? In a 320 square foot room (I think that's what you mentioned),why not just grab 4 high quality subs and tell your installers to make it happen?
 

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