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

[nathan]

In any event, I am excited to see testing of speakers in this category and the interest other folks are expressing.

Better in wall speakers aren't just for living rooms where the spouse does't want to see big boxes on the floor. They also enable things in dedicated theaters or listening rooms like the THX Baffle Wall, "solve" SBIR, get "free" added output due to the wall, etc.....and are a staple (albeit in powered form) in some of the best monitoring/mixing rooms.

They won't be everyones choice, nor the best choice in all situations, but they are a great choice when designed and installed well.

--

All this being said, I am surprised just how good this monoprice speaker looks, especially if one takes into account it wasn't really installed as designed and it would be bass managed in a proper installation.

Now I'm wishing I had kept my spare Triad In-Wall Bronze LCR speaker, to share for measurements. I've still got a couple of Triad In Wall Bronze 4 Sats, but those REALLY are small modest speakers which would, at best, be used as surround speakers in a bedroom sized system, so probably not of interest to most people.

 

[Steve Dallas]

These look good enough to mount as surrounds and let Audyssey do its thing. Honestly, that's my only criterion for in-walls: is directivity good enough that room correction can "fix" FR?

 

[nathan]

That's a fair minimum criteria for many applications for sure. That, plus output capability (including distortion) when bass managed, up to the needs of the listening distance, imo, would make an in wall speaker appropriate for many situations.

I hope to be building a new dedicated media room in the next two years, and have planned to use the Revel in wall speakers. (Last room had Triad and while I have no complaints about those, having also lived with "in room" versions of several Triads and several Revels, I'm leaning Revel for the next build.)

This set of tests doesn't make me think "I should place Monoprice higher on my list than Revel" but it does mean there is another choice in this category that needs something "good" at each price level.

 

[radio3]

I actually think the future of hifi may basically be in-wall speakers. With everything going multichannel and people becoming more design conscious, it almost seems like the only way. Remember when only fashionistas bought Apple products and remember when no one gave a damn about sound quality? Now Apple is wealthier than the US government and only weirdo geeks buy PCs and Google phones. Apple Music is lossless, all iPhones do Spatial Audio, Amazon Tidal etc are all streaming 3D.

The days of stereo are basically over and the only way to have 12 speakers etc is going to be in-wall. Real estate prices are insane and the future is minimalism. People don’t want their living rooms piled full of 80s looking black ash boxes. They want 3D sound and Scandinavian/Apple looks — speakers out of sight.

 

[MaxBuck]

only weirdo geeks buy PCs and Google phones.

Hey, now.

 

[radio3]

These look good enough to mount as surrounds and let Audyssey do its thing. Honestly, that's my only criterion for in-walls: is directivity good enough that room correction can "fix" FR?

Arent you only supposed to use room correction for 300Hz and below unless you want it to make your sound worse most of the time? There’s a reason it’s called room correction and not speaker correction.

 

[Steve Dallas]

Arent you only supposed to use room correction for 300Hz and below unless you want it to make your sound worse most of the time? There’s a reason it’s called room correction and not speaker correction.

If you are doing it right, you let measurements be your guide rather than adhering to an arbitrary number. Two to five times Schroeder F for the room is often appropriate. But, I let Audyssey have its way with the surrounds--especially if they are in-walls.

 

[Head_Unit]

the baffle is wider than the frame I built to give it some (small) approximation of it mounting on full wall. Clearly this is a compromise as making this much bigger would make it much heavier and harder to measure.

First off, I think it is GREAT to be measuring in-wall speakers because hey, where else is there any data? And for this category in particular, you have to buy from data because there are basically zero opportunities to listen. Plus it would be SO interesting to see if expensive in-walls can perform well or if the wall cavity kills them.

However, that size baffle doesn't have much to do with a wall. I'd want at least a 4x8 sheet of plywood/sheetrock, or better two side by side"Heavier"? Well probably but measuring in-walls really demands some kind of wall, maybe on caster wheels if need be. Because if one is going to the trouble to measure data for this category, it should have the least qualifiers and problems, otherwise why bother?

And for more verisimilitude, I think I would build an idealized 16" stud bay behind, 2x4 and sheetrock on the back, BUT sealed on all the gaps. This will show resonances which accrue on such installation but without random factors of air leaks. Huh it would also be interesting if the back was removable, to test the effect of putting in fiberglass or foam. (As one test, to see the difference, not every time. And it would be very interesting to run the Klippel on the back, to see how much sound radiates through. I can say it is a LOT with no back box).

Both the gap sealing and the fiberglass/foam can be a kind of best-case target for setups ambitious enough to open up the wall. I think the gap sealing would also help get a cleaner number for the resonance frequency.

A different approach which I used was to take out a ceiling tile and make a wooden baffle. I moved all the cabinets far enough out so that the floor bounce was the first reflection. Using MLSSA with the microphone at 1m, with 8'≈2.43m I then got 3.86m distance before the floor reflection hit the microphone. So that's lets see, speed of sound at 343m/s, 3.86m/(343m/s)=11mS if I did that right. Which equates to valid data every 90 Hz? Ugh it's too early in the morning, something seems a bit off, I don't think I was getting quite that much resolution.

 

[gauthamv77]

This is a review and detailed measurements of the Monoprice THX-365IW THX Ultra certified, 3-way in-wall speaker. It was kindly purchased new by a member and drop shipped to me for testing. It costs US $400 from the company direct.

This is the first in-wall speaker we are measuring so I had to go through some prep to test it. Between the owner and I, we decided to build a back box using 2x4 American studs. The THX-365IW is made to hold on to drywall or plywood so I built the latter from scraps I had in my woodshop:

View attachment 137272

As you can see, the baffle is wider than the frame I built to give it some (small) approximation of it mounting on full wall. Clearly this is a compromise as making this much bigger would make it much heavier and harder to measure. I chose to not seal the back box enclosure as in typical application of it just mounted to a well, it enjoys a very large space behind it. I figured allowing leakage would reduce the back pressure on the driver. Good or bad decision? I let you all comment. I confirmed during testing that copious amount of air was leaking around the 2x4 framing.

In addition, I made the executive decision to use the metal, magnetically attached grill as I doubt anyone would use such with exposed drivers. Speaking of which, this is a 3-way design with dual woofers:

View attachment 137273

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 1000 measurement which resulted in error rate of less than 1% below 10 kHz. Above that error shot through the roof so that area of the response is likely not reliable.

Reference axis was the tweeter center. I also tested it with mid-range being such but it did not make much of a difference.

Monoprice THX-365IW Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 137274

The graph is pretty unsettling at first blush. The low frequency variations though I believe due to leaky back box. Actual response in room will be different both because of that and room variations. Its level is higher than the rest of the response. Company produces its own measurements which we can compare:

View attachment 137275

Alas, they don't list any conditions as to how the test was done. The low frequency response is indicated as "near-field" which tells me is not anechoic. There is decent correlation between theirs and mine in higher frequencies including the bump around 3.5 kHz and peaking at the end.

We can look at my near-field measurements for how the crossover responds (these were done WITHOUT the grill):

View attachment 137277

Overall integration of drivers seems fine to me. The main issue I see is the non-flat response of the tweeter.

Back to our spin data, my measurements are 360 degrees so we have our usual graphs even though some of it such as rear wall reflections are not appropriate here:

View attachment 137278

If we took that out, the tilt would be less. The same applies to predicted in-room response:

View attachment 137279

This looks good to me.

Impedance graph shows the issues in bass with respect to enclosure leakage:

View attachment 137280

Ignoring that, I am surprised at the very low impedance of just 2.9 ohm. I compared that to the company measurements and it matches. So whatever amp you are going to use these is going to work hard as far as current delivery and may even shut down if you use these as your fronts in home theater application.

Distortion graphs look good considering the vagaries of the backbox I built:

View attachment 137281

View attachment 137282

Beamwidth seems to be nice as delivered by the mid-range and some of the tweeter:

View attachment 137283

I don't have an explanation for heavy beaming of the tweeter above 10 kHz other than it being impacted by measurement error. Anyone has other ideas?

Note that anything past 90 degrees is of no consequence in real use which is also noted in the directivity graphs:

View attachment 137284

Figuring out what is going on in the vertical directivity plot would probably takes weeks of research.

View attachment 137285

I did not have time to listen to the thing. I got bruised up building the box in my unfinished wood shop so decided to just publish the measurements.

Conclusions
There are a ton of factors here relative to how we are testing and how the speaker will be used. If we take the approximation as presented, performance seems reasonable. Most in-wall speakers are built to a price and have horrible performance. Such doesn't seem to be the case here.

I am open to suggestions of how to vary or improve the setup for future testing. In-wall speakers are a huge category and would be good to have a standardized method of testing them that is reasonable, defensible and not very time consuming to build.

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As always, questions, comments, recommendations, etc. are welcome.

Getting killed around the house with various chores. The stupid dryer decided to break its own trim mount resulting in two hours of cursing to remove the trim, glue it back up to assemble later. By then it was hot but I had no choice to go in the yard and deal with all the damage done to our corn plants by rabbit or some other animal. The darn think ate the stock right at the ground and left 99% of the plant to die. Noticed racoons are going after our prized cherries so have to go out now at 8:30 pm and harvest what I can before they eat them all tonight!!!

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Hi ,
I'm looking to set up a 7.2.4 in a 3800 cubic feet room. Plan on using Denon AVR 4700. I have the Emotiva XPA 7 amp. Can I use the THX 365 in walls for all of my 7 speakers? I was looking into the THX 465 for the LCR. However, I'm not sure if I need 4 woofers in the LCRs if I'm going to use 2 dedicated sub-woofers? I would like to stay with monolith for budget and timbre matching

 

[nathan]

THX 365 in walls for all of my 7 speakers

Thats probably what I would do.

I was looking into the THX 465 for the LCR

Wait, I thought you were looking into the 365 in walls for ALL seven speakers, but now you are looking into the 465 in walls for three of the seven? Okay, those are not a bad choice, and if you are sitting more than 4 or 5 meters from the front speakers then the larger speakers up front may help you get the volume you seek.

You don't mention how far you sit from your LCR, so it's a bit of guess work.

Don't forget to budget for two monolith subs, and to take the time to set them up well.

 

[gauthamv77]

Hi Nathan,
Thank you. RIght I would prefer the 465 for the LCR and the 365 for the surrounds . First row ( main seating ) would be 16 feet from the screen and second row 22 feet . The 465 are out of stock till July. I'm building my basement and plan to complete by June end. Hence the question if I can get by with the 365. What other in wall speakers ( 1000$ budget) do you all suggest for a room 3800 cubic feet and seating distance as mentioned above?
Prefer to stay will monolith for timbre matching

 

[gauthamv77]

Sorry to clarify 1000$ per speaker for the LCR .

 

[nathan]

Hi Nathan,
Thank you. RIght I would prefer the 465 for the LCR and the 365 for the surrounds . First row ( main seating ) would be 16 feet from the screen and second row 22 feet . The 465 are out of stock till July. I'm building my basement and plan to complete by June end. Hence the question if I can get by with the 365. What other in wall speakers ( 1000$ budget) do you all suggest for a room 3800 cubic feet and seating distance as mentioned above?
Prefer to stay will monolith for timbre matching

I would wait for the larger ones even though they won’t be ready for a few weeks after your target.

Ps sometimes monoprice gets stuff in early so if you order now you might get a pleasant surprise.

 

[gauthamv77]

Great. Thanks. Will do.

 

[wolffan]

I am interested in mounting this 365iw speaker under my TV (rotated 90 deg). I understand the horizontal dispersion wouldn't be great in this orientation. If I fabricated a replacement front panel and rotated the tweeter/mid sub-assembly, would this work well? Or, is there something in the electronics/crossovers that would keep this from being optimized?

Alternatively, I would buy the 365C center and mount it inside the wall (flush with wall). But, it would be more elegant to use a speaker designed for in-wall mounting.

 

[rvsixer]

Or, is there something in the electronics/crossovers that would keep this from being optimized?

Yes on both changing the in wall's driver layout without addressing the crossover, or putting a speaker not designed for in-wall use inside a wall. Why not simply use one of the two matched Monoprice THX in-walls designed for center use?

 

[wolffan]

Yes on both changing the in wall's driver layout without addressing the crossover, or putting a speaker not designed for in-wall use inside a wall. Why not simply use one of the two matched Monoprice THX in-walls designed for center use?

Which matched in-walls are you referring to? I only know of the THX-LCR and the THX-365iw. I could use the THX-LCR (https://www.monoprice.com/product?p_id=34366), but it is so tall that I would have to raise my TV to an undesirable height to accommodate.

 

[rvsixer]

Which matched in-walls are you referring to? I only know of the THX-LCR and the THX-365iw.

https://downloads.monoprice.com/files/images/34368_13.jpg

The other THX in-wall center is not a 3-way, but my money would be on a purpose designed/response matched 2-way being better than a hacked/untested 3-way.
Assuming your listening window is narrow enough to accommodate the inherent limitations of most any non-coax horizontal center.

 

[wolffan]

https://downloads.monoprice.com/files/images/34368_13.jpg

The other THX in-wall center is not a 3-way, but my money would be on a purpose designed/response matched 2-way being better than a hacked/untested 3-way.

Got it, thank you. Do you think this 2-way model would work equally well in vertical and horizontal orientations? I assume this because it doesn't have the tweeter/midrange combo that imparts some directionality. I'm asking because I could use this for L, R, and center if it works in both orientations.

 

[clipghost]

Got it, thank you. Do you think this 2-way model would work equally well in vertical and horizontal orientations? I assume this because it doesn't have the tweeter/midrange combo that imparts some directionality. I'm asking because I could use this for L, R, and center if it works in both orientations.

Any updates on what you decided to go with? In similar situation. So if you were doing the Monoprice THX-365IW for Left and Right + surrounds, would you recommend lets say the THX-265IW as a center? Or no because it is a 2-way. Trying to find a center that is IN-WALL to compliment the 365IW other than the THX-LCR which is different size, is beginning to be a headache. Could you do another brands center? Or bad idea since won't be timbre matched?

Thanks!