Magneplanar listening room with the Rooze setup.

Marc Lombardi · Nov 3, 2019

And then ...

A friend asked me to audition a new speaker that he's about to sell. It's totally not what I have ever listened to. From a company that makes studio monitors, it's their first entre into the home market with a small powered speaker ... a little box with a 7" woofer, coaxial AMT tweeter, biamped internally 90/50W. I've listened a few days and they hold their own for their class ($1100/pr). I listened with no EQ or subs, in my well-treated room, with speakers on stands 6' from the front wall and 3' from the side walls. Very nice.

Then just for curiosity ... I took the opportunity to try the Rooze! I put them next to my 3.7's, turned toward the wall, with the tweeter on the same plane. And so it seems the Rooze is not just for planar dipoles! They sounded the same tonally, but the spaciousness of the soundstage made the overall listening experience much improved.

These speakers have high and low trim switches and in the Rooze setup I cut the bass -4db and boosted highs +2db. High end still measures with a rolloff more than in conventional setup, but they still sound good.

Very interesting to compare $1100 to my 3.7's and Nord amp at 6x the price and nearly 7x the power!

josh358 · Nov 3, 2019

Marc Lombardi said:
And then ...

A friend asked me to audition a new speaker that he's about to sell. It's totally not what I have ever listened to. From a company that makes studio monitors, it's their first entre into the home market with a small powered speaker ... a little box with a 7" woofer, coaxial AMT tweeter, biamped internally 90/50W. I've listened a few days and they hold their own for their class ($1100/pr). I listened with no EQ or subs, in my well-treated room, with speakers on stands 6' from the front wall and 3' from the side walls. Very nice.

Then just for curiosity ... I took the opportunity to try the Rooze! I put them next to my 3.7's, turned toward the wall, with the tweeter on the same plane. And so it seems the Rooze is not just for planar dipoles! They sounded the same tonally, but the spaciousness of the soundstage made the overall listening experience much improved.

These speakers have high and low trim switches and in the Rooze setup I cut the bass -4db and boosted highs +2db. High end still measures with a rolloff more than in conventional setup, but they still sound good.

Very interesting to compare $1100 to my 3.7's and Nord amp at 6x the price and nearly 7x the power!

I actually first tried (discovered independently) Rooze using my old Monsoon computer speakers. It was amazing to get that huge soundstage from two tiny panels!

My best guess as to how it works is that it increases the acoustical size of the room since you're listening to the sidewall reflections rather than the speakers. And then the front reflections fill in the center so you don't get a hole in the middle.

Marc Lombardi · Nov 3, 2019

josh358 said:
I actually first tried (discovered independently) Rooze using my old Monsoon computer speakers. It was amazing to get that huge soundstage from two tiny panels!

My best guess as to how it works is that it increases the acoustical size of the room since you're listening to the sidewall reflections rather than the speakers. And then the front reflections fill in the center so you don't get a hole in the middle.

Yes and .... in my room with all the diffusion on the front wall it still works. The diffused front reflections are much later than with the dipoles, because the sound has to bounce around the rest of the room before getting back to the front wall and eventually back to my ear.

A curious thing though ... I put the little speakers right next to the 3.7's so just a little closer to me, same distance from the side wall. Without EQ I measure a significant peak at 40Hz and null at 55Hz with the 3.7's, but no such peak and null with the little speakers. They're pretty flat from 40 to 80.. Left channel plot with Variable Smoothing.

josh358 · Nov 3, 2019

Marc Lombardi said:
Yes and .... in my room with all the diffusion on the front wall it still works. The diffused front reflections are much later than with the dipoles, because the sound has to bounce around the rest of the room before getting back to the front wall and eventually back to my ear.

A curious thing though ... I put the little speakers right next to the 3.7's so just a little closer to me, same distance from the side wall. Without EQ I measure a significant peak at 40Hz and null at 55Hz with the 3.7's, but no such peak and null with the little speakers. They're pretty flat from 40 to 80.. Left channel plot with Variable Smoothing.

Hard to know what's causing it but I'm thinking that it could be interference between the reflections off the front and side walls, which are out of phase in the 3.7's but not in the dynamics.

Marc Lombardi · Nov 4, 2019

josh358 said:
Hard to know what's causing it but I'm thinking that it could be interference between the reflections off the front and side walls, which are out of phase in the 3.7's but not in the dynamics.

It seems that's the only thing it can be. But I thought speakers are omnidirectional for wavelengths greater than the size of the driver. So the 3.7's would certainly be omni below 100Hz. I've also suspected a tangential or oblique resonance mode is somehow more excited by the 3.7's in this room due to their design and the solid particle board walls and concrete floor.

I'm going to try two things: move the 3.7's away from the wall a foot (still in Rooze configuration) and see what direction the peaks and nulls move; try a pair of small Advents (powered by the same amp as the 3.7's) on the stands where I now have the CX-7 speakers and see if their response is similarly flat.

josh358 · Nov 4, 2019

What you said about wavelength is true for omnidirectional speakers. But in the case of dipoles, the rear wave is out of phase and so still cancels at the sides, maintaining the figure eight dispersion pattern even when the wavelength is larger than the driver. The sound still diffracts around the baffle, but rather than making the speaker omnidirectional, it causes cancellation between the front and back waves, resulting in a 6 dB/octave falloff in amplitude response below the point at which cancellation starts to occur. This has to be corrected with dipole equalization, accomplished acoustically in Maggies, with resonant sections.

Marc Lombardi · Nov 8, 2019

I finally understand Josh ... thanks!

And so it seems inevitable that the Rooze will present this cancellation to the MLP no matter what I do. Fortunately, Dirac is able to compensate quite well and the other benefits are worth the compromise.

I did do some additional tests with no subs or Dirac DRC. I landed with the speakers in a new position, but the cancellation is still there. Some of the peak and null behavior improved somewhat, and I got less comb-ish effect from 200-800Hz, and improved high end response. No doubt positive effects of being further from the side walls.

Attached files show my original baseline Rooze position plus two others (measured from front edge of the speaker at 45deg from side wall) and the final position with Dirac. Shown with Variable smoothing.

Traces top to bottom
Baseline: 1ft from side wall; 7.5ft from front wall
Baseline +1ft: 2ft from side walll 7.5ft from front wall
Baseline +2ft: 3ft from side wall; 7ft from front wall

Final Position with Dirac DRC

Behavior on the left and right continues to be different, with right somewhat more problematic. New position improves the left channel a bit more than the right. Interesting shift of the 160Hz null up to 220Hz at the final position.

Listening ..... the new position changes the soundstage somewhat. It's a bit more forward which is fine, but seems a little more compressed in width. The latter is a compromise ... better with studio recordings than live larger ensemble. Curious to hear withe wife test when she returns this evening. Her perceptions are always interesting.

josh358 · Nov 8, 2019

Marc Lombardi said:
I finally understand Josh ... thanks!

And so it seems inevitable that the Rooze will present this cancellation to the MLP no matter what I do. Fortunately, Dirac is able to compensate quite well and the other benefits are worth the compromise.

I did do some additional tests with no subs or Dirac DRC. I landed with the speakers in a new position, but the cancellation is still there. Some of the peak and null behavior improved somewhat, and I got less comb-ish effect from 200-800Hz, and improved high end response. No doubt positive effects of being further from the side walls.

Attached files show my original baseline Rooze position plus two others (measured from front edge of the speaker at 45deg from side wall) and the final position with Dirac. Shown with Variable smoothing.

Traces top to bottom
Baseline: 1ft from side wall; 7.5ft from front wall
Baseline +1ft: 2ft from side walll 7.5ft from front wall
Baseline +2ft: 3ft from side wall; 7ft from front wall

Final Position with Dirac DRC

Behavior on the left and right continues to be different, with right somewhat more problematic. New position improves the left channel a bit more than the right. Interesting shift of the 160Hz null up to 220Hz at the final position.

Listening ..... the new position changes the soundstage somewhat. It's a bit more forward which is fine, but seems a little more compressed in width. The latter is a compromise ... better with studio recordings than live larger ensemble. Curious to hear withe wife test when she returns this evening. Her perceptions are always interesting.

Reminds me that when I tried it, the only recordings that didn't work were those Beatles recordings that are mixed hard left and right! Without something in the other channel, the sound moved way forward to where the sidewall reflection was.

Marc Lombardi · Nov 8, 2019

josh358 said:
Reminds me that when I tried it, the only recordings that didn't work were those Beatles recordings that are mixed hard left and right! Without something in the other channel, the sound moved way forward to where the sidewall reflection was.

Friend of mine brought over the 5.1 mix of Abbey Road last week .... yeah we noticed that.

josh358 · Nov 9, 2019

Did you notice it on anything else?

Marc Lombardi · Nov 9, 2019

josh358 said:
Did you notice it on anything else?

Older jazz studio recordings, like Herbie Hancock Maiden Voyage ... drums all the way to the right. It happens on enough recordings that I do believe certain mixes exacerbate the issue of holes on one side or the other or the center. Not as much of an issue with conventional setup. But still .... we like the Rooze better overall.

josh358 · Nov 10, 2019

I wonder if a bit of left-right mixing as in headphone listening would solve the problem.

Marc Lombardi · Nov 10, 2019

josh358 said:
I wonder if a bit of left-right mixing as in headphone listening would solve the problem.

Yes I think it would, I should mention, when evaluating and fine tuning the speaker position - and commenting on what I hear - I'm listening in 2.1 stereo. If I use PLIIx Music or dts Neo:6 Music the image fills in nicely and benefits from the center channel. As I've had a really good implementation the past couple months though, I've found that most 2-channel sounds really good in 2.1 ... much better than ever before. So I often listen that way rather than using a surround mode as in the past. The Rooze - more often than not - results in the enveloping soundstage previously unheard in 2-channel.

josh358 · Nov 14, 2019

Marc Lombardi said:
Yes I think it would, I should mention, when evaluating and fine tuning the speaker position - and commenting on what I hear - I'm listening in 2.1 stereo. If I use PLIIx Music or dts Neo:6 Music the image fills in nicely and benefits from the center channel. As I've had a really good implementation the past couple months though, I've found that most 2-channel sounds really good in 2.1 ... much better than ever before. So I often listen that way rather than using a surround mode as in the past. The Rooze - more often than not - results in the enveloping soundstage previously unheard in 2-channel.

I very much like three channel. It gives the image a solidity that the two-channel phantom image can never have.

Kakkadu · Jan 10, 2020

Very interesting, I'm surprised I didn't think of this option before

Are those diffusors made out of wood or foam? Very nice measurements although variable smoothing doesn't reveal much.

Marc Lombardi · Jan 10, 2020

Kakkadu said:
Very interesting, I'm surprised I didn't think of this option before
Are those diffusors made out of wood or foam? Very nice measurements although variable smoothing doesn't reveal much.

Thanks Kakkadu! Others went around on this many years ago and I just found the threads about 8 months ago. The diffusors are Vicoustic Multifusors made of EPS (expanded polystyrene foam). As they are made the surface is smooth and solid and takes water based paint well without absorbing too much.

Here's a frequency amplitude response plot with 1/24 octave smoothing.

Kakkadu · Jun 28, 2020

josh358 said:
Hard to know what's causing it but I'm thinking that it could be interference between the reflections off the front and side walls, which are out of phase in the 3.7's but not in the dynamics.

A dipole produces a null at lower frequencies 90° off axis so in a Rooze setup this might become a problem.

/edit: I noticed that this issue was already discussed... Very impressive measurements Marc.

Magneplanar listening room with the Rooze setup.

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