In-wall Speaker Measurements (Monoprice THX-365IW)

[Bear123]

Picked up 3 of these in the recent sale based on these updated measurements. Got them installed today on my front wall. AT screen going up as soon as I can clear a space to swap the material in my frame. Subjectively, they sound great! I've only listened to them in stereo so far but the imaging is excellent! Used a mattress topper I grabbed at Target for some absorption of high frequency reflections between the speakers and screen.

Are reflections off of the baffle wall created by in wall speakers?

Edit: NVM, with a small search, I see that sound absorption on the baffle wall is to reduce/eliminate surround speaker reflections.

 

[Enchy]

Are reflections off of the baffle wall created by in wall speakers?

Edit: NVM, with a small search, I see that sound absorption on the baffle wall is to reduce/eliminate surround speaker reflections.

It's to absorb reflection between the screen and the in wall speakers, from what I've learned in my research. It's also a THX recommendation.

 

[Bear123]

It's to absorb reflection between the screen and the in wall speakers, from what I've learned in my research. It's also a THX recommendation.

Hmm….well, if it's acoustically transparent…doesn't that imply that sound will travel through the screen somewhat unrestricted i.e. no significant reflections? By the same token, the acoustic transparent nature of the screen *does* allow strong reflections off the front wall from surround speakers, which is why absorption is recommended in your situation. Too lazy to find the link now but seems like it was something from Toole. Regardless, it sounds like it will be beneficial and certainly can't do any harm in any way I can see, and likely didn't cost much.

 

[Enchy]

Hmm….well, if it's acoustically transparent…doesn't that imply that sound will travel through the screen somewhat unrestricted i.e. no significant reflections? By the same token, the acoustic transparent nature of the screen *does* allow strong reflections off the front wall from surround speakers, which is why absorption is recommended in your situation. Too lazy to find the link now but seems like it was something from Toole. Regardless, it sounds like it will be beneficial and certainly can't do any harm in any way I can see, and likely didn't cost much.

Interesting. That does make a lot of sense, more sense than the explanation I was working with. Thanks for the explanation.

Either way, this is the only wall absorption I have in my room (currently). Placing it behind the screen is nice and convenient, and the mattress was $35.

 

[Dal1as]

The recommendation for treating the front wall behind the screen is due to reflections from the rear of the screen. Has nothing to do with surround speakets.

Acoustically transparent screens are not 100% transparent. Far from it.

 

[dasdoing]

here is a meassurement of one of these screens

 

[dasdoing]

and more https://www.reddit.com/r/hometheater/comments/gp6h11

 

[amirm]

The effect of transparent screen depends on how close you put them in front of the speaker and at what angle. The closer and more parallel to the speaker, the worse the effect is.

Here are some measurements I made from different screen material:

The effect was quite audible when distance was short and you kept it parallel to speaker baffle.

 

[Dal1as]

The effect of transparent screen depends on how close you put them in front of the speaker and at what angle. The closer and more parallel to the speaker, the worse the effect is.

Here are some measurements I made from different screen material:

View attachment 172561

The effect was quite audible when distance was short and you kept it parallel to speaker baffle.

Interesting that with the screens in place they actually helped that 120hz dip some. Was the speaker close to a wall by chance? Wondering if the screens helped cancel the front wall reflection a bit.

 

[Enchy]

I used this post as guidance to help pick out a screen material. Bought a few samples to test and ended up liking the Silver Ticket WAB the best. Bonus was that I already had a Silver Ticket screen so I just had to buy new materials. His measurements at 4" for the material I got (grey is 1/48 smoothing blue is psychoacoustic). There's also an interesting table showing db loss at various frequencies.

My screen's about 3" off the speakers.

Question:
I typically gate Audyssey at 500Hz for all my speakers. Would it be advisable to let Audyssey correct the full range for these speakers due to the effect of the screen?

 

[Dal1as]

I used this post as guidance to help pick out a screen material. Bought a few samples to test and ended up liking the Silver Ticket WAB the best. Bonus was that I already had a Silver Ticket screen so I just had to buy new materials. His measurements at 4" for the material I got (grey is 1/48 smoothing blue is psychoacoustic). There's also an interesting table showing db loss at various frequencies.

My screen's about 3" off the speakers.

Question:
I typically gate Audyssey at 500Hz for all my speakers. Would it be advisable to let Audyssey correct the full range for these speakers due to the effect of the screen?

Not sure but this is the reason I will be getting a processor which can do room correction and PEQ at the same time.

As for treating the front wall. It's known to be best practice with theaters. It helps in a couple of areas. The 1st one being to lessen the wall reflection which woes regular speakers especially in the med bass frequencies. The other is to keep reflections from the rear of the screen from causing issues. I would think this is more important for high gain micro-perf screens which have more attenuation. Weaves and spandex (yes spandex) may not need it as much. At least for in walls.

 

[Enchy]

Going to go ahead and enable Audyssey for the full range on these. I don't think I listen loud enough for the +5db boost it's putting on the tweeter to be damaging. I cap the volume on my Denon x3700h at -20db. If I blow a tweet though I'll report back!

I did some A/B testing using both presets last night and they sounded much, much better with Audyssey correcting up to 20khz.

 

[z3roz]

That seems reasonable since the inertia of the bass driver is rather large shoving the wall around instead of creating lovely sound pressure waves, with the tweeter suffering from whatever shenanigans from the bass driver as Doppler shift, due to short wavelength and a “cabinet” that “flaps” around. Then some (resistive) dampening (in-wall) to cancel zeros in the room causing some bass to be “sucked” out.

Shopping list (gym plates for some mass):
View attachment 141971
In-wall Dampening (3M bitumen):
View attachment 141972

And some braces

(Yes, I’m the worlds worst and bodgiest speaker designer)

I’m sure a well-designed mechanical all-pass filter with a nice Q factor for that critically damped step response would sort out most of that in a hurry? An Atkinson-style accelerometer would sort that out in a hurry?

In walls are slick and discreet. I can imagine that in a competently executed setup, the lovey sounds just appears out of nowhere.

I'm new here and an idiot when it comes to all this jazz you all are laying down, but, the drivers are mounted to a fairly acoustically inert baffle, not directly to the wall. The back wave in such a large cavity would no more affect the tweeter than a normal floor stander or bookshelf. Those tweeters aren't normally isolated from the back waves, at least in the speakers I've owned.

The 365's tweeters look like they are somewhat shielded by any back waves via the crossover PCB anyways.

I'm going to get the newly released 465IWs and use them as LCRs in a 2x6 wall with 703 insulation behind them and no other voodoo. Hopefully it's an enjoyable endeavor.

 

[Dal1as]

I'm new here and an idiot when it comes to all this jazz you all are laying down, but, the drivers are mounted to a fairly acoustically inert baffle, not directly to the wall. The back wave in such a large cavity would no more affect the tweeter than a normal floor stander or bookshelf. Those tweeters aren't normally isolated from the back waves, at least in the speakers I've owned.

The 365's tweeters look like they are somewhat shielded by any back waves via the crossover PCB anyways.

I'm going to get the newly released 465IWs and use them as LCRs in a 2x6 wall with 703 insulation behind them and no other voodoo. Hopefully it's an enjoyable endeavor.

Nice. Please provide an update on those 465s. Probably what I'm going to use too although in a treated baffle wall.

 

[danzilla31]

I'm new here and an idiot when it comes to all this jazz you all are laying down, but, the drivers are mounted to a fairly acoustically inert baffle, not directly to the wall. The back wave in such a large cavity would no more affect the tweeter than a normal floor stander or bookshelf. Those tweeters aren't normally isolated from the back waves, at least in the speakers I've owned.

The 365's tweeters look like they are somewhat shielded by any back waves via the crossover PCB anyways.

I'm going to get the newly released 465IWs and use them as LCRs in a 2x6 wall with 703 insulation behind them and no other voodoo. Hopefully it's an enjoyable endeavor.

Those 465IWs are the new big boys right? I believe they are 9 inches deep from the specs I wonder if they built them to be put into a baffle wall? Not sure how many walls could handle those

 

[Dal1as]

Those 465IWs are the new big boys right? I believe they are 9 inches deep from the specs I wonder if they built them to be put into a baffle wall? Not sure how many walls could handle those

Yes they are. The Monoprice website might be wrong about the depth as I have seen that with new products before. They don't look any deeper than the 365s which will fit in a regular wall. Or, and I did hear someone mention that they will be providing backboxes soon. Maybe that depth measurement takes that into account. Doesn't matter in my case but could with others.

 

[danzilla31]

Yes they are. The Monoprice website might be wrong about the depth as I have seen that with new products before. They don't look any deeper than the 365s which will fit in a regular wall. Or, and I did hear someone mention that they will be providing backboxes soon. Maybe that depth measurement takes that into account. Doesn't matter in my case but could with others.

Hey heads up I spoke to Monolith guy on AVS and he said it was indeed an error they are only 3.6 or 3.7 inches deep. That's great news because I'm really interested in these as well

 

[russelms]

I used this post as guidance to help pick out a screen material. Bought a few samples to test and ended up liking the Silver Ticket WAB the best. Bonus was that I already had a Silver Ticket screen so I just had to buy new materials. His measurements at 4" for the material I got (grey is 1/48 smoothing blue is psychoacoustic). There's also an interesting table showing db loss at various frequencies.

My screen's about 3" off the speakers.

Question:
I typically gate Audyssey at 500Hz for all my speakers. Would it be advisable to let Audyssey correct the full range for these speakers due to the effect of the screen?

Thank you for pointing us to that review site. I have had both Silverticket WAB and now WVS screen with the 365IW behind it roughly 3" with no treatments. I now will aim to install some mineral wool 2 or 3" material around the speakers. I'll measure before and after with REW once I get around to doing it.

Question how far apart from the edge of the 365IW should the 3" mineral wool be placed to not negatively impact dispersion?

 

[Enchy]

Thank you for pointing us to that review site. I have had both Silverticket WAB and now WVS screen with the 365IW behind it roughly 3" with no treatments. I now will aim to install some mineral wool 2 or 3" material around the speakers. I'll measure before and after with REW once I get around to doing it.

Question how far apart from the edge of the 365IW should the 3" mineral wool be placed to not negatively impact dispersion?

I have mine just barely overhanging the baffle. Basically just covering the area where the screws are. Not sure if this is good or bad, but I haven't (subjectively) noticed any issues with dispersion for my L or R speakers. My foam is pretty thin though, about 1.75"

 

[TrexWasabi]

Have any of you installed the 465IW speakers? If so, could you post a brief review - perhaps in a new thread? Thanks.
BTW, if you installed them, which speaker are you using as a center?