Speaker mounted in free-standing panel as baffle?

[sumitagarwal]

I've been struggling to figure out how best to incorporate a 15 degree toe in for adding "wings" to my existing wall as a baffle wall for my theater, and ultimately found myself thinking: why not just put the speakers in a free-standing acoustic panel as a baffle instead?

I'm looking at this 4" free-standing "bass trap": https://www.gikacoustics.com/product/freestand-bass-trap/

Speakers are Genelec AIW26, a sealed 4" deep in-wall speaker that is front-ported.

Also, how about bolting two tension rods on either side of an acoustic board so that the whole thing could be arbitrarily moved around but still securely braced against both floor and ceiling for stability. And hopefully the internal springs would naturally impart some level of isolation too?

I'm looking at things like these:

RoomDividersNow 120 in. - 150 in. Premium Tension Curtain Rod in Silver PTROD-SLVR150N - The Home Depot

RoomDividersNow is the premier supplier of spring loaded tension rods on the market today. Considered to be the strongest tension rods available, RoomDividersNow has worked tirelessly to evolve and perfect

www.homedepot.com

Ratcheting Cargo Bar

Amazing deals on this Ratcheting Cargo Bar at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[alex-z]

A 2x4ft acoustic panel may not provide enough baffle surface to achieve the full bass loading that in-wall speakers expect.

Additionally, isolation mounting can backfire. The isolated panels can resonate at higher frequencies than a larger rigid structure would. Even coming from Genelec, I would not assume they are fully inert speakers.

I would build the wings as a false wall structure, braced every 12-18", with 3.5" fibreglass in the cavity.

 

[sumitagarwal]

I'm now looking into mounting my speakers into tension rods and actually attaching a baffle surface to it.

This looks interesting and should clamp strong enough to create a rigid structure? And it's also interesting that it allows for tilting in case the speakers need to be tilted downwards to the listening area:

https://www.amazon.com/Support-Adjustable-Telescopic-Extends-Supports/dp/B09PDXS53Z/ref=asc_df_B09PDXS53Z/?tag=hyprod-20&linkCode=df0&hvadid=564699464532&hvpos=&hvnetw=g&hvrand=12274089446946446431&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004354&hvtargid=pla-1644354248823&psc=1

 

[sumitagarwal]

A 2x4ft acoustic panel may not provide enough baffle surface to achieve the full bass loading that in-wall speakers expect.

Additionally, isolation mounting can backfire. The isolated panels can resonate at higher frequencies than a larger rigid structure would. Even coming from Genelec, I would not assume they are fully inert speakers.

I would build the wings as a false wall structure, braced every 12-18", with 3.5" fibreglass in the cavity.

Not exactly the same question, but I had asked Genelec about mounting the speakers *onto* the wall instead of *inside* the wall, and I got this interesting response:

You can expect very similar results. The monitors can be installed directly on the wall because their reflex ports are on the front side of the speaker. Therefore the reflections from back wall will be minimal.

If you are able to install the AIW on the wall reliably then I don't see any problems in doing so.

 

[Speaker_tweaker]

Better just to mount it in the wall and forget about the toe in. The baffle edge diffraction will likely cause more issues than not having toe in.

 

[Godataloss]

Why not mount them in the wall at 15 degrees?

 

[sumitagarwal]

Why not mount them in the wall at 15 degrees?

Are you saying have the speakers either protruding from the wall at 15 degrees, or recessed into the wall at 15 degrees? I think in both cases the issue is diffraction, maybe some other things too?

 

[Godataloss]

Are you saying have the speakers either protruding from the wall at 15 degrees, or recessed into the wall at 15 degrees? I think in both cases the issue is diffraction, maybe some other things too?

I'd have them protrude. You could bevel the whole wall out if you are that worried about diffraction. Dry wall is exceedingly cheap and easy to work with.

 

[alex-z]

Not exactly the same question, but I had asked Genelec about mounting the speakers *onto* the wall instead of *inside* the wall, and I got this interesting response:

You can expect very similar results. The monitors can be installed directly on the wall because their reflex ports are on the front side of the speaker. Therefore the reflections from back wall will be minimal.

If you are able to install the AIW on the wall reliably then I don't see any problems in doing so.

TBH that doesn't make much sense. With on-wall mounting, you have to deal with diffraction, as sound leaves each edge of the baffle and strikes the wall the speaker is mounted against.

The front porting of the design has nothing to do with this, it just means that the port response isn't compromised by placement unlike a rear ported speaker.

If you want wall mounted speakers with a 15 degree toe-in, the only sensible approach is toe-in the wall itself, as seen here:

Q. Should monitors be near the rear wall?

Most of the advice I’ve seen about speaker placement suggests keeping them well away from the walls, but I was recently advised to place my monitor loudspeakers directly against the back wall...

www.soundonsound.com

This is a fairly popular approach with studios, because while diffraction can be mitigated with EQ, the time domain effects never go away completely. And the hollow cavity created by angling the walls can be filled with absorption material, creating a non-visible bass trap.

 

[sumitagarwal]

TBH that doesn't make much sense. With on-wall mounting, you have to deal with diffraction, as sound leaves each edge of the baffle and strikes the wall the speaker is mounted against.

The front porting of the design has nothing to do with this, it just means that the port response isn't compromised by placement unlike a rear ported speaker.

If you want wall mounted speakers with a 15 degree toe-in, the only sensible approach is toe-in the wall itself, as seen here:

Q. Should monitors be near the rear wall?

Most of the advice I’ve seen about speaker placement suggests keeping them well away from the walls, but I was recently advised to place my monitor loudspeakers directly against the back wall...

www.soundonsound.com

This is a fairly popular approach with studios, because while diffraction can be mitigated with EQ, the time domain effects never go away completely. And the hollow cavity created by angling the walls can be filled with absorption material, creating a non-visible bass trap.

Thanks for the link! Good read, and especially interesting the idea that as you move the speaker closer to the wall (and eventually into it) you move the problems up in frequency until you reach frequencies where they are more easily dealt with.

Since these speakers are less than 4" deep I was actually thinking one benefit of mounting them onto the wall instead of in the wall is it will allow me some depth for acoustic treatments until I end up flush with the speaker face. I was thinking of 2 layers of 2" duct liner, something along these lines. Of course this illustration doesn't address the toe-in of that left speaker.

 

[Eulipian]

TBH that doesn't make much sense. With on-wall mounting, you have to deal with diffraction, as sound leaves each edge of the baffle and strikes the wall the speaker is mounted against.

The front porting of the design has nothing to do with this, it just means that the port response isn't compromised by placement unlike a rear ported speaker.

If you want wall mounted speakers with a 15 degree toe-in, the only sensible approach is toe-in the wall itself, as seen here:

Q. Should monitors be near the rear wall?

Most of the advice I’ve seen about speaker placement suggests keeping them well away from the walls, but I was recently advised to place my monitor loudspeakers directly against the back wall...

www.soundonsound.com

This is a fairly popular approach with studios, because while diffraction can be mitigated with EQ, the time domain effects never go away completely. And the hollow cavity created by angling the walls can be filled with absorption material, creating a non-visible bass trap.

Not directly pertinent, but fellow Canukistan resident woodworker and designer John Heisz has spent the past year experimenting with room treatments, speaker construction, including open baffles, and related topics like resonance and damping materials. I don't know if his audio science is sound, but it's an interesting project to watch. The open baffle model he comes up with has (I believe) a 15 degree or so deflection wing.

 

[alex-z]

Thanks for the link! Good read, and especially interesting the idea that as you move the speaker closer to the wall (and eventually into it) you move the problems up in frequency until you reach frequencies where they are more easily dealt with.

Since these speakers are less than 4" deep I was actually thinking one benefit of mounting them onto the wall instead of in the wall is it will allow me some depth for acoustic treatments until I end up flush with the speaker face. I was thinking of 2 layers of 2" duct liner, something along these lines. Of course this illustration doesn't address the toe-in of that left speaker.

The front wall is the one that needs the least acoustic treatment IMO, the ceiling and side walls contribute most of the reflections, both for 2 channel music and home theatre. Why waste 4" absorbing baffle diffraction when you could flush mount and not experience it at all?

The only channels actually pointed directly at your front wall will be the rear surrounds, which are only present in a 7.x setup, and are among the least used channels in a surround mix.

 

[Chromatischism]

The front wall is the one that needs the least acoustic treatment IMO

Not if you're trying to eliminate bass SBIR with the front speakers. Your speakers radiate at 360° up to 300-1000 Hz depending on the speaker.

 

[sumitagarwal]

I'm also hoping that the 4" of duct liner across the front wall will work as a bit of a bass trap. As I understand it the wide length and tall height of it will allow it to absorb lower than 4" normally would.

EDIT TO ADD: Would it work to put a thin wood veneer (what Grimani calls thin wood "door toppers" or something) to work as a bass-absorbing diaphragm either in between the two 2" layers of duct liner or on the face of the 4" duct liner stack?

 

[sumitagarwal]

Mocking up a test in the living room since the theater is under construction and full of dust.

The rods may not have the most rigidity, but the speakers will be pressed against a solid wall with duct liner on all sides.

 

[Chromatischism]

I think that speaker will have an F3 of like, 200 Hz

 

[sumitagarwal]

I think that speaker will have an F3 of like, 200 Hz

Picture the same thing but with the rear flush against gypsum board and the surrounding embedded in duct liner.

Genelec told me to expect similar performance to the 8050B, which Amir reviewed here: https://www.audiosciencereview.com/...ds/genelec-8050b-review-studio-monitor.20542/ Of course take that with a very large grain of salt.

Based on that that would be an F3 near 80Hz? I'm not so smart with graphs.

The room will have 3 subwoofers worth of bass reinforcement.

 

[mhardy6647]

For far, far more than you ever wanted to know/read re: open baffle loudspeakers, click the link below.

Open Baffle Epiphany!

So its -25 Celcius and the car wont start so of course I started messing around with my gear and came up with what I can only call an epiphany! I took a pair of Foster (Fostex) FE103 alnicos with Planet-10-HIFI phase plugs that I had lying around and decided to cut up a left over cardboard...

audiokarma.org

 

[sumitagarwal]

For far, far more than you ever wanted to know/read re: open baffle loudspeakers, click the link below.

Open Baffle Epiphany!

So its -25 Celcius and the car wont start so of course I started messing around with my gear and came up with what I can only call an epiphany! I took a pair of Foster (Fostex) FE103 alnicos with Planet-10-HIFI phase plugs that I had lying around and decided to cut up a left over cardboard...

audiokarma.org

Hah, I'll read that one day. For a time I was considering open baffle speakers and subs, particularly JBL's Synthesis line, but now that I've got all these Genelec speakers and HSU subs I'm going to stay the course for at least V 1.0 of this theater...

 

[mhardy6647]

I've played around with open baffles in the past and even acquired a bevy of OB-friendly drivers (i.e., woofers or extended range drivers with fairly high Qts).
Nothing ever made me think, yeah, this is what I'm looking for.