How do I know if I need a sub woofer?

@soix, +1

@lanx0003, I think you need to wind you neck in, you do not know what you are talking about.

@OP, it's simple. All rooms regardless of size or shape need subs. It's not a case of it depends on the room, depends on your speakers or depends on what you listen to.

All rooms will have modes which means you have problems. This is an anavoidable scientific fact. Anyone who doubts this needs to do their homework.

What can be done? Well lots. Install some room treament. Have a look @tcutter's room as a fine example. Even with the extensive treatment seen in the photos and the admirably smooth response including envious RT60 performance subs will be needed. I say again subs will be needed. 

There is no other way to avoid peaks and nulls. If you are serious about your sound you should embrace measurement and fix the fixable problems. Most people now know about REW the free download so spend the equivalent of a dinner for 2 and grab yourself a mic.

The subs should not be ported nor have passive radiators. Get sealed subs and insist on having variable phase to make dial-in easier. REL subs do not have variable phase only 0-180 phase flip which renders them very difficult to locate and properly dial-in. If people have 0-180 phase flippers I often turn down the job. 

One of my subs is a REL and I have hauled this thing all over the room and finally found a spot that works reasonably well. Now add to that ports which are additional bass sources that resonate at only one frequency and can't be tuned and you are adding problem upon problem.

Somebody here said their sub is too slow! No such thing as a slow, boomy or one-note-bass sub. It's your room acoustics and poorly set up sub/s  If there are peaks 20dB louder than the average SPL then it will obviously take much longer to decay and guess what? You get to hear the complaints mentioned above.

It is simple guys, try reading stuff by Welti, Dr. Earl Geddes who wrote his thesis on this very topic and Toole, though I don't agree with everything Toole says. Avoid mindless ill informed posts from the likes of lanx and his ilk if you wanna move forward.    

lol

How do you know when you need a subwoofer?

After due diligence, including without limitation:

• Optimizing speaker placement for bass response to avoid reinforcement and cancellation effects and achieving as flat frequency response as possible. 
• Tanking room frequency measurements if possible to assist in room treatment.  
• Placing diffusers, absorbers, and bass traps and validating improvements by taking measurements again. 
• Using speaker decoupling devices (stands, platforms, footers). 
• Developing an understanding of how acoustic bass sounds (organ, percussion, string, and wind instruments) in both large and small venues.   Focus not only on bass detail, but on timbre, micro and macro dynamics, and how staging and imaging develops.  
• Identifying reference recordings to test your system.  

After due diligence, if you are left wanting for more low bass detail, more accurate timbre, more dynamic impact, better reproduction of bass micro dynamics, or more precise imaging and staging, you need a subwoofer.  If you believe you system sounds like live, acoustic bass response as it is, you do not need a subwoofer.  This is strictly subjective and based on your own perception.   There is only one axiom, if your speakers only go to 30-35hz +/- 3db, a subwoofer will open up the sound stage.   All other bass SQ attributes are subjective and you need to determine the benefit /cost ratio yourself   

​​​​​​​

How do you know when you need a subwoofer?

After due diligence, including without limitation:

• Optimizing speaker placement for bass response to avoid reinforcement and cancellation effects and achieving as flat frequency response as possible. 
• Tanking room frequency measurements if possible to assist in room treatment.  
• Placing diffusers, absorbers, and bass traps and validating improvements by taking measurements again. 
• Using speaker decoupling devices (stands, platforms, footers). 
• Developing an understanding of how acoustic bass sounds (organ, percussion, string, and wind instruments) in both large and small venues.   Focus not only on bass detail, but on timbre, micro and macro dynamics, and how staging and imaging develops.  
• Identifying reference recordings to test your system.  

After due diligence, if you are left wanting for more low bass detail, more accurate timbre, more dynamic impact, better reproduction of bass micro dynamics, or more precise imaging and staging, you need a subwoofer.  If you believe you system sounds like live, acoustic bass response as it is, you do not need a subwoofer.  This is strictly subjective and based on your own perception.   There is only one axiom, if your speakers only go to 30-35hz +/- 3db, a subwoofer will open up the sound stage.   All other bass SQ attributes are subjective and you need to determine the benefit /cost ratio yourself   

​​​​​​​

How do you know when you need a subwoofer?

After due diligence, including without limitation:

• Optimizing speaker placement for bass response to avoid reinforcement and cancellation effects and achieving as flat frequency response as possible. 
• Tanking room frequency measurements if possible to assist in room treatment.  
• Placing diffusers, absorbers, and bass traps and validating improvements by taking measurements again. 
• Using speaker decoupling devices (stands, platforms, footers). 
• Developing an understanding of how acoustic bass sounds (organ, percussion, string, and wind instruments) in both large and small venues.   Focus not only on bass detail, but on timbre, micro and macro dynamics, and how staging and imaging develops.  
• Identifying reference recordings to test your system.  

After due diligence, if you are left wanting for more low bass detail, more accurate timbre, more dynamic impact, better reproduction of bass micro dynamics, or more precise imaging and staging, you need a subwoofer.  If you believe you system sounds like live, acoustic bass response as it is, you do not need a subwoofer.  This is strictly subjective and based on your own perception.   There is only one axiom, if your speakers only go to 30-35hz +/- 3db, a subwoofer will open up the sound stage.   All other bass SQ attributes are subjective and you need to determine the benefit /cost ratio yourself   

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