Never Put Subwoofers In Corners... Even with DSP and Multi-Sub Setups?

[Benedium]

Sure, you’ll usually get a modal peak with the sub in a corner. Parametric EQ can easily fix that – it’s been the go-to remedy on the home theater forums for more than 20 years now. I’ve had corner subs in three different homes, and every one worked great after EQ. My current place, it couldn’t happen, and guess what? Now I have a nasty null. EQ can’t fix that.

Regards,
Wayne A. Pflughaupt

Previously my subwoofer multiEQ/Audyssey curve had a 5db dip between 70-80hz after calibration. My single sub, an svs pb1000 was positioned in front of my couch between center and right speaker.

I decided maybe the couch was the cause of the problem. So I moved the sub to the right/outer side of the right speaker and toed-out about 10degrees angling closer towards the right corner of the wall behind the couch. After re-calibrating audyssey, I find 3x more dips but they are no more than 1.5 db.

Not sure what exactly was happening, but I think it sounds much better and my speakers +subwoofer sound much more controlled and less boomy.

Next I may try moving the subwoofer to the side of the couch like an end table, and point it at the rear wall behind the couch or the right side wall.

 

[sigbergaudio]

I just tried placing my Genelec 7350A in the corner compared to its original location (center, slightly the to the right). The frequency response after GLM correction got slightly better compared to the original location, but the boominess is too strong (in other words, the bass is not tight). So I personally don't recommend it, for music listening at least.

Testing one specific subwoofer in one specific room probably isn't enough to base general advice on. It's perfectly possible to have a subwoofer work well both against wall and against corners. You are likely to get peaks but those can easily be tamed by EQ. You will also get additional room gain, so you may need to reduce the levels of the sub. As every room is different, the specific corner you tried may not be optimal in your room.

 

[zym1010]

Testing one specific subwoofer in one specific room probably isn't enough to base general advice on. It's perfectly possible to have a subwoofer work well both against wall and against corners. You are likely to get peaks but those can easily be tamed by EQ. You will also get additional room gain, so you may need to reduce the levels of the sub. As every room is different, the specific corner you tried may not be optimal in your room.

Sure my experience cannot be generalized.

FYI I did have EQ using Genelec GLM. below are the response curves. The effective curve (green) is quite flat but the overall sound is more muddy. I feel it's probably due to reverberation time which is (in my naive understanding) not fixable by EQ.

 

[sigbergaudio]

Sure my experience cannot be generalized.

FYI I did have EQ using Genelec GLM. below are the response curves. The effective curve (green) is quite flat but the overall sound is more muddy. I feel it's probably due to reverberation time which is (in my naive understanding) not fixable by EQ.

So how did the curve look in your previous position?

 

[zym1010]

So how did the curve look in your previous position?

see the attached. my cross over freq is 85Hz.

 

[sigbergaudio]

Looks relatively similar. I'm not initimately familiar with the GLM, but do you know if this green curve is the ACTUAL frequency response, or if it is a predicted curve? For instance with Audyssey, it shows an "after" curve that isn't actually measured in the room, but just Audysseys prediction. In practice it often looks far better than what reality ends up being in the room. If that is the case for GLM as well, it's hard to interpret the results in either position without doing manual measurements with for instance REW.

 

[zym1010]

Looks relatively similar. I'm not initimately familiar with the GLM, but do you know if this green curve is the ACTUAL frequency response, or if it is a predicted curve? For instance with Audyssey, it shows an "after" curve that isn't actually measured in the room, but just Audysseys prediction. In practice it often looks far better than what reality ends up being in the room. If that is the case for GLM as well, it's hard to interpret the results in either position without doing manual measurements with for instance REW.

Yeah I agree. the green one is the predicted one, not the actual remeasured. https://www.audiosciencereview.com/...-rew-measurements-with-and-without-glm.14518/ discusses about this.

 

[Chromatischism]

For instance with Audyssey, it shows an "after" curve that isn't actually measured in the room, but just Audysseys prediction. In practice it often looks far better than what reality ends up being in the room.

Just for clarity, the after graph in the Audyssey app is the calculated response of the average of the measurements. It is accurate. You need to do an average using the same measurement points to reproduce it in REW. There may also be weighting applied, I'm not sure.

 

[zym1010]

update: realized I made a mistake in my experiment, by putting the subwoofer's reflex port too close to the wall. So my findings might not hold. In any case, I probably won't use the corner setup, as it's too far away from the center and makes too much sound coming from one side (but that's a separate discussion)/

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I just tried placing my Genelec 7350A in the corner compared to its original location (center, slightly the to the right). The frequency response after GLM correction got slightly better compared to the original location, but the boominess is too strong (in other words, the bass is not tight). So I personally don't recommend it, for music listening at least.

@sigbergaudio I updated my post. I just did a quick and informal listening, with the subwoofer still in the corner but with enough clearance for reflex port. The sound is less muddy now. So maybe corner + EQ is fine.

BTW, do you think the corner setup can affect the sound quality by increasing reveberation?

 

[dasdoing]

you guys focus too much on FR. the problem with the corner is the ringing it causes, even after EQ. compare with waterfall plots, not FR.

every "HT-wisdom" has to be taken with a grain of salt for HiFi. the ringing might sound positive for movies for some/most. after all it all about the explosions, not clearing up bass notes.
a perfect example: they will tell you to put even a single sub in a corner. really? the ringing coming from a single corner is very easy to notify. bass is omnidirectional, that doesn't mean you can put it wherever you want, on the contrary...you want to avoid exciting corners unequaly, at least in the horizontal plane

 

[sigbergaudio]

Just for clarity, the after graph in the Audyssey app is the calculated response of the average of the measurements. It is accurate. You need to do an average using the same measurement points to reproduce it in REW. There may also be weighting applied, I'm not sure.

I'm sure it CAN be accurate. That it IS accurate, period, especially in the bass region? Not my experience. But I'm sure this will vary based on room etc.

 

[Chromatischism]

I'm sure it CAN be accurate. That it IS accurate, period, especially in the bass region? Not my experience. But I'm sure this will vary based on room etc.

In a video with Phil Jones of Sound United, an Audyssey engineer explained the laser measuring devices used to recreate the exact mic placement to verify post-correction results. He says the after graph is exactly the response you will get. I used to think it was wishful thinking, but his explanation is believable.

 

[sigbergaudio]

@sigbergaudio I updated my post. I just did a quick and informal listening, with the subwoofer still in the corner but with enough clearance for reflex port. The sound is less muddy now. So maybe corner + EQ is fine.

BTW, do you think the corner setup can affect the sound quality by increasing reveberation?

These are very difficult topics to answer in general terms. General advice against walls and corners for subwoofers is in my opinion wrong. We design subwoofers (for music) that are specifically designed to work against a plane in the room (floor or wall), by placing the subwoofer so that the subwoofer driver is ~1-1.5 inches from the floor or wall. This uses the wall (or floor) to its advantage. The plane is pretty much removed from the equation since the reflections are pushed up in frequencies above the frequency response of the subwoofer.

This approach works well even in corners. In my opinion regular subwoofers can be placed in corners as well. But as always with subwoofers, it's a game of trial and error. Saying that subwoofers can work well in the corner isn't the same as saying that everyone must put their subwoofers in corners and that will always be the best position. At least with just one subwoofer, you are likely to get an uneven frequency response unless you have EQ. But the more subwoofers you have, the more likely it is to work well.


On the topic of corner location for subwoofer for music: REL who at least themselves claim to be making subwoofers for music, recommend placement in corners with the subwoofers pointing diagonally into the room.

 

[sigbergaudio]

In a video with Phil Jones of Sound United, an Audyssey engineer explained the laser measuring devices used to recreate the exact mic placement to verify post-correction results. He says the after graph is exactly the response you will get. I used to think it was wishful thinking, but his explanation is believable.

Interesting. I need to try to verify that some day.

 

[RichB]

In a video with Phil Jones of Sound United, an Audyssey engineer explained the laser measuring devices used to recreate the exact mic placement to verify post-correction results. He says the after graph is exactly the response you will get. I used to think it was wishful thinking, but his explanation is believable.

That may well be, but it is the behavior of mics and difficulty in repeating placement that is not trivial. Even then, our ears and brain differ from microphones. I have examined the wildly varying responses found above the room transition frequency that can occur with only inches of mic movement. I now only EQ frequencies that produce stable measurements from the main listening positions.

- Rich

 

[Chromatischism]

I should do my own experiment on this to see if it's strictly an average or if there is any weighting, eg toward position #1. You'll know if there's any "secret sauce" if a strict average doesn't line up. It will have to wait until my system is back together as the ELAC Debut Reference in the living room are borrowing my AVR and amp.

 

[zym1010]

These are very difficult topics to answer in general terms. General advice against walls and corners for subwoofers is in my opinion wrong. We design subwoofers (for music) that are specifically designed to work against a plane in the room (floor or wall), by placing the subwoofer so that the subwoofer driver is ~1-1.5 inches from the floor or wall. This uses the wall (or floor) to its advantage. The plane is pretty much removed from the equation since the reflections are pushed up in frequencies above the frequency response of the subwoofer.

This approach works well even in corners. In my opinion regular subwoofers can be placed in corners as well. But as always with subwoofers, it's a game of trial and error. Saying that subwoofers can work well in the corner isn't the same as saying that everyone must put their subwoofers in corners and that will always be the best position. At least with just one subwoofer, you are likely to get an uneven frequency response unless you have EQ. But the more subwoofers you have, the more likely it is to work well.


On the topic of corner location for subwoofer for music: REL who at least themselves claim to be making subwoofers for music, recommend placement in corners with the subwoofers pointing diagonally into the room.

thx! yeah I guess the rabbit hole for subwoofer tuning is deep... I just tried another configuration, with the sub under and between my legs. It got a flatter response curve after GLM although Genelec recommends putting the sub near wall in general. Given that my ears enjoy all these settings similarly (but I do find that, in this very last setting, the bass volume changed a lot as I changed listening location relative to the subwoofer; it seems that putting subwoofer against wall(s) makes room modes more evenly excited), probably it's time for me to enjoy music for now. When I learn more about room acoustics I will dig more into this hole.

 

[Andysu]

Tried this.
You will likely detect its direction, especially at high SPL. But that's because the harmonics will be audiable, not because you can localise 60hz.

Solution? Use JBL 2242h subs. (Or 3 like me!)

Downside? You'll not be hiding this purchase from the missus...

Here's the port of one of the subs....

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Cheap from ex cinema cheap than fish and chips. JBL 4645C - a homemade 4645 behind the flat screen.

Sooty looks at JBL 4645 wants to climb in though the port like when he was a kitten.

 

[Lbstyling]

Cheap from ex cinema cheap than fish and chips. JBL 4645C - a homemade 4645 behind the flat screen.

View attachment 118206

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Sooty looks at JBL 4645 wants to climb in though the port like when he was a kitten.
View attachment 118212

Now, most importantly.....
I'm trying to guess the film. Stark Trek....hmm.........2? Wrath of Khan?

That's a serious looking setup!

 

[Andysu]

Now, most importantly.....
I'm trying to guess the film. Stark Trek....hmm.........2? Wrath of Khan?

That's a serious looking setup!

Star Trek the motion picture theatrical transferred from laserdisc on DVD-RW for its theatrical Dolby Stereo.