So I Measured My Room

[Pogre]

I'm still obsessing over the bass response of my towers so I contacted SVS and @Ed Mullen himself replied! He asked for my room dims and a couple of specific sweeps. I just finished up and my quick diagram turned out better than I thought it would.

Anyhoo, I got some some good info and I'm hoping maybe some of the gurus here can help me sleuth it out while I wait for Ed's email reply. So if anyone is stuck at home and knows how to interpret this data I would be greatly appreciative! I have a little bit of flexibility with MLP and the towers, though I can't really pull them forward much further without getting into traffic. If anything else is needed just post and let me know!

Oh, vaulted ceilings too. 8 feet high at the wall then they slope up in the direction of the MLP. I'm not sure at what angle...

 

[ryanosaur]

So the wavelength your null is centered around is roughly 25.5-27.5'. And is obviously most prominent on the right side.
Do you have anything, measurement wise with that speaker that lines up with reflections at the 1/2 or 1/4 wavelength? (Think cone-wall-and-back, for example.)
Have you tried a measurement where you just pull them 1' into the room just to see how the numbers change?

 

[shadyJ]

I wouldn't worry about the bass response of the towers. The reason is there is a very significant room mode null just above 40 Hz, obviously, and there is nothing you can do about it, unless you make a drastic change to your listening position or speaker placement. The rest of the response isn't terrible. Do not try to EQ that null, you will just run the speakers ragged for no real return.

 

[Pogre]

So the wavelength your null is centered around is roughly 25.5-27.5'. And is obviously most prominent on the right side.
Do you have anything, measurement wise with that speaker that lines up with reflections at the 1/2 or 1/4 wavelength? (Think cone-wall-and-back, for example.)
Have you tried a measurement where you just pull them 1' into the room just to see how the numbers change?

They're already 1.5' into the room, measured from the closest corner to the wall at the base of the speakers. From there they slope even further from the wall. I know it doesn't look like it from the images. As for the distances of the speakers from the closest room boundaries you can figure each square on the graph is 1 square foot.

Don't go counting any of the other squares to see if they line up perfect with my measurements tho... lol. When I finished I was off by a couple of squares, but I wrote the actual distances in there.

I wouldn't worry about the bass response of the towers. The reason is there is a very significant room mode null just above 40 Hz, obviously, and there is nothing you can do about it, unless you make a drastic change to your listening position or speaker placement. The rest of the response isn't terrible. Do not try to EQ that null, you will just run the speakers ragged for no real return.

Shady, I have strong compulsive obsessive tendencies and you know this one has been driving me nuts forever. I didn't do all this for eq'ing tho. Possibly 1 or 2 strategically placed room treatments tho? Some positional eq to try and defeat that null? Asymmetry? I dunno. Ain't got nothing better to do right now anyway!

I always appreciate your feedback tho and I don't want you to think I'm just dismissing your solid and most likely correct advice. I'm going at it from a little different angle this time tho and avoiding eq. Plus Ed asked for the stuff and if he's willing to take a look at it for me why not?

*Edit: I should add that Ed has already seen the sweeps. That's when he asked for room dims.

 

[shadyJ]

Shady, I have strong compulsive obsessive tendencies and you know this one has been driving me nuts forever. I didn't do all this for eq'ing tho. Possibly 1 or 2 strategically placed room treatments tho? Some positional eq to try and defeat that null? Asymmetry? I dunno. Ain't got nothing better to do right now anyway!

I always appreciate your feedback tho and I don't want you to think I'm just dismissing your solid and most likely correct advice. I'm going at it from a little different angle this time tho and avoiding eq. Plus Ed asked for the stuff and if he's willing to take a look at it for me why not?

That 40 Hz null is coming from an axial room mode. No room treatment will make a dent in any frequency that deep. EQing doesn't really work here because it is a cancellation effect. The only way to change it is to move the listening position or move the speakers, and even then you are more likely to just shift it to another frequency. I will let my friend Kyle Reese explain the nature of a room mode null:

 

[Pogre]

Ha ha!

You're awesome Shady, lol.

 

[ryanosaur]

That's why I was suggesting retesting the speakers in a different location... just to see how the change popped. If anything, I'd like to see a better L-R match in the FR if possible... Not getting rid of the dip per se, but minimizing the lopsided effect.
This is what I had to deal with to a certain extent in my room... I got 10dB back on a 20dB suckout, which then matched the other side. I called truce after that.

 

[Pogre]

That's why I was suggesting retesting the speakers in a different location... just to see how the change popped. If anything, I'd like to see a better L-R match in the FR if possible... Not getting rid of the dip per se, but minimizing the lopsided effect.
This is what I had to deal with to a certain extent in my room... I got 10dB back on a 20dB suckout, which then matched the other side. I called truce after that.

I might try scooting them out some more just to see what happens. I'm resisting it because I have everything measured pretty precisely and 75 lb speakers... lol.

 

[ryanosaur]

I might try scooting them out some more just to see what happens. I'm resisting it because I have everything measured pretty precisely and 75 lb speakers... lol.

mine are heavier.



You shoulda seen the tape artwork I had on the carpet so I could track the movements.

The things we do for...
...the love of a better curve?

 

[AVUser001]

They're already 1.5' into the room, measured from the closest corner to the wall at the base of the speakers. From there they slope even further from the wall. I know it doesn't look like it from the images. As for the distances of the speakers from the closest room boundaries you can figure each square on the graph is 1 square foot.

Don't go counting any of the other squares to see if they line up perfect with my measurements tho... lol. When I finished I was off by a couple of squares, but I wrote the actual distances in there.

Shady, I have strong compulsive obsessive tendencies and you know this one has been driving me nuts forever. I didn't do all this for eq'ing tho. Possibly 1 or 2 strategically placed room treatments tho? Some positional eq to try and defeat that null? Asymmetry? I dunno. Ain't got nothing better to do right now anyway!

I always appreciate your feedback tho and I don't want you to think I'm just dismissing your solid and most likely correct advice. I'm going at it from a little different angle this time tho and avoiding eq. Plus Ed asked for the stuff and if he's willing to take a look at it for me why not?

*Edit: I should add that Ed has already seen the sweeps. That's when he asked for room dims.

Not sure if this will help with the bass null/suckout at 40+hz..but I'd try a couple of things..
- intentional asymmetric placement of the right speaker...if the null is due to boundary interference, try moving it forward away from the wall first..,and if it doesnt help , as well closer to the wall(see what happens..maybe opens up addl choice for treating the boost)
- try absorbing or diffusing the reflection from the rear wall first and front wall ..maybe throw a wall rug and see if it changes anyting
- move listening position away from rear wall

 

[William Lemmerhirt]

POOOOOOOGRAAAAAYYYYY!!!!!!!!!(still can’t help that)

You didn’t measure the closet.....
Start over.

 

[Pogre]

Not sure if this will help with the bass null/suckout at 40+hz..but I'd try a couple of things..
- intentional asymmetric placement of the right speaker...if the null is due to boundary interference, try moving it forward away from the wall first..,and if it doesnt help , as well closer to the wall(see what happens..maybe opens up addl choice for treating the boost)
- try absorbing or diffusing the reflection from the rear wall first and front wall ..maybe throw a wall rug and see if it changes anyting
- move listening position away from rear wall

There's about 18' between the MLP and the rear wall. I can't get it much further...

It's actually pretty damned good if you stand back at the rear wall. There is room behind the MLP tho. For my most recent calibration I pushed it quite a bit closer and I think it made it worse. Maybe this weekend I'll shove everything as far back as I can and see what I get.

I can play around with some asymmetrical configurations too. I just can't stand the thought of my triangle not being symmetrical, but it's time to let it go and experiment a little more outside the box. I'll shoot for this weekend, if not sometime this week. Might not be a bad idea to buy a roll or 2 of masking tape while I'm at it.

 

[afterlife2]

Stop it(kindly) dude. That why you have a sub. I know boredom is syncing in, but the sub is there for a reason. Listen to Ed and Shady both good guys.

 

[Pogre]

Stop it(kindly) dude. That why you have a sub. I know boredom is syncing in, but the sub is there for a reason. Listen to Ed and Shady both good guys.

*Pogre crawls toward his Umik like a junkie who just found a fix*

 

[KEW]

You've gotten several worthwhile suggestions here, but for right now, I'd just stick until you hear back from Ed!
Like you say, if he is willing too go through the details with you, see what he has to offer before convoluting things! He has a level of expertise worth letting it play out following his lead!
Most likely he will confirm what ShadyJ said, but there is also an outside chance that he might see/do something a little different, and that is where things can get exciting!

 

[AVUser001]

There's about 18' between the MLP and the rear wall. I can't get it much further...

It's actually pretty damned good if you stand back at the rear wall. There is room behind the MLP tho. For my most recent calibration I pushed it quite a bit closer and I think it made it worse. Maybe this weekend I'll shove everything as far back as I can and see what I get.

I can play around with some asymmetrical configurations too. I just can't stand the thought of my triangle not being symmetrical, but it's time to let it go and experiment a little more outside the box. I'll shoot for this weekend, if not sometime this week. Might not be a bad idea to buy a roll or 2 of masking tape while I'm at it.

Didnt realize you were 18ft away from rear wall ! Maybe move back a little, looks like you're sitting in the null where there's cancellation . Shady's right about no EQ, here.

Ed is a great guy, curious what he'd recommend.

Meanwhile, Just noticed you have two subs already in the front...I'd try moving the 2nd sub forward to somewhere middle of the room(sidewall) and see if that helps eliminate standing wave null at your listening position (getting them in phase, negating the null).

Interesting thread - eager to see what comes out of it!

 

[Pogre]

Just to reiterate- this is all totally superfluous and I know it is. I've got it really good with my subs on and a high-ish crossover. Everything measures and sounds great. I'm just ocd'ing on my towers when I play them without the subs.

I know I'm spinning some wheels here, but this is me when I get bored. I was pleasantly surprised when Ed replied to me so I figured why not? I've already learned little bit from this exercise so far, so I'm not coming out empty handed.

 

[panteragstk]

I'm just ocd'ing on my towers when I play them without the subs.

I've figured out a perfect solution to your issue.

Stop listening without the subs.

You're welcome.