Standing Waves and AVR Bass Management

[niceshoes]

I have a problem with standing waves creating patchy bass in my large room.

Setup is a Marantz SR-6007 with B&W CM8 and an SVS SB-12.

I'm aware of the usual fixes for standing waves: 2 subs, acoustic treatment, speaker placement etc. Let's say I've exhausted all of those options.

If I go to receiver settings to change my main speakers to "Large" and set the bass management to Sub + Mains, will the 3 combined sources of bass reduce standing waves in the same way as having 2 subs?

Edit: couldn't decide if this was an AVR, subwoofer our loudspeaker question. I went with loudspeaker in the end

 

[agarwalro]

The CM8 have a low F3 of 69Hz. You're not gaining much output in the bass range and will reduce overall headroom in the amp. Since the option is available, you can try it as a stop gap. You already know the cure .

 

[WaynePflughaupt]

I'm aware of the usual fixes for standing waves: 2 subs, acoustic treatment, speaker placement etc. Let's say I've exhausted all of those options.

In that case you have a couple left: subwoofer placement as determined by room measurements, and parametric EQ to smooth out the sub’s response. As hundreds if not of HT buffs frequenting the audio forums can attest, it works great.

Regards,
Wayne A. Pflughaupt

 

[niceshoes]

I don't see that eq can help? I mean all other things being constant a 30hz tone from a particular point in the room is going to reflect in a given manner. I can't tell eq to change the way the sound waves are being reflected.

Unfortunately moving the sub isn't an option.

Anyway I was really wanting to know if the floorstanders can be "subbed" for a 2nd sub (awesome pun intended)

 

[agarwalro]

I understand the improvement, in headroom and seat to seat uniformity, facilitated by corner loaded multiple subs. Yet the modal ringing ringing aspect is completely ignored. What happened to getting a RT60 into the 200-300ms range?

 

[niceshoes]

How am I supposed to reduce the rt60 without adding acoustic treatment?

In case it wasn't clear in the OP, I'm not able to introduce acoustic treatment, move the gear around or add new gear.

I just want to know to what extent its theoretically possible for the 5" woofers in my tower speakers to cancel out standing waves from my 12" sub. I mean, it seems to me like it could work, but if it was a decent solution why don't I hear about more people doing it?

 

[herbu]

I'm not able to introduce acoustic treatment, move the gear around or add new gear. I just want to know to what extent its theoretically possible for the 5" woofers in my tower speakers to cancel out standing waves from my 12" sub.

Agarwalro already pointed out the problem w/ your particular setup. I think it is your answer. If your mains cannot produce the same frequencies as your sub, they cannot help w/ standing waves. If you get some mains that are full range, then yes they can. What am I missing here?

It sounds like you can't replace or move any equipment, and can't do any room treatments. So you're asking what you should hear? Why not try it and see what you do hear?

 

[Swerd]

I don't see that eq can help? I mean all other things being constant a 30hz tone from a particular point in the room is going to reflect in a given manner. I can't tell eq to change the way the sound waves are being reflected.

EQ helps when you identify the frequency of the prominently loud standing bass wave(s) in your room. You then suppress it/them with a narrow notch filter to lower that peak a similar level as the rest of the bass. Finally adjust the sub woofer volume. You'll probably have to raise it some.

Use the EQ to suppress offending standing peaks, but don't use it to raise standing valleys. Leave them alone. It works surprisingly well.

 

[highfigh]

I'm aware of the usual fixes for standing waves: 2 subs, acoustic treatment, speaker placement etc. Let's say I've exhausted all of those options.

If you have exhausted those options and you still have these problems, you need to find something that's more effective- I know these can be limited, but they are the best ways to cure this. Equalization isn't the way to solve it.