OP
- Thread Starter
- #61
??? That is the 5,400 euro option Erin. Just because you see the template in there, it doesn't mean it is free. You need a specific add-on license to use that.
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Monoprice THX-365IW Review (In-wall Speaker)
- Thread starter amirm
- Start date
This speaker is designed to be mounted in a large baffle; Amir mounted it in a baffle a few inches larger than the speaker itself. Every measurement will show incorrect bass level and a wide variety of diffraction issues which would not be observed when installed as directed. You cannot accurately extrapolate any real world response from this set-up.
The Spinorama in theory shows how a myriad of room effects alter the tonality of the speaker. I don't see why the Spinorama itself couldn't characterize a wall mounted speaker provided you throw out rear wall measurements, but these measurements wouldn't give you that data. These measurements only show what happens when you take a wall mount speaker and measure it without the large baffle it was designed to be installed in.
I assume the Klippel baffle works similarly to the IEC baffle, which has a known dimensions which allow for reasonable half space calculation.
These measurements don't represent the performance of this product accurately; they will have inconsistencies both in bass and treble. The fact that this is a wide-radiating speaker with small driverss exacerbates this fact.
sam_adams
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My new favorite word is pisher. I need to learn more Yiddish
A bit OT, but to broaden your horizons, these two selections are a good start:
https://www.amazon.com/Dictionary-Yiddish-Slang-Idioms/dp/0806503475/
https://www.amazon.com/Dirty-Yiddish-Everyday-Slang-Whats/dp/1612430562/
The second one I think is the best. Learning another language by learning the 'dirty' words first makes it more fun.
sam_adams
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An easy way to measure in-walls is to build a wall. While lumber prices are through the roof, NPI, a half-dozen 2X4s, a 4X8 sheet of 1/2 inch drywall, a 4X8 sheet of OSB, some fiberglass batting and some sweat, and you have a wall analogue to mount speakers in to test. The expensive part is still the license for the software, though...
I think we can make some reasonable assumptions about what we want to see from in-wall speakers. For a speaker like this, you'd want to see smoothly changing directivity with respect to frequency, no major off-axis deviations, along with the regular stuff like reasonably low distortion.
Well, I thought maybe you had it. I do.
OP
- Thread Starter
- #67
That option did not exist when I purchased my system.
OP
- Thread Starter
- #68
If you mean to use it with Klippel NFS, then there are limits to the size of the thing you can put on the stand. A full sheet of OSB and framing would be extremely heavy and impractical for lifting and putting on the stand. Even the one I built is quite heavy.
OP
- Thread Starter
- #70
Actually correlation between my measurements and that of monoprice (likely from THX) are quite good above a few hundred hertz. Theirs is heavily filtered and has large Y axis and despite that, you can see similar features to what I have measured.
As to bass, no one uses these full-range or at least they should not. So how much do we strive to get that right?
sam_adams
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Could the scanner
be placed in front of any baffle? Not having seen it in action—maybe a timelapse video—does the mic move strictly along the orthognal axes or does it described an arc around the DUT?
IMO you have to measure it the way it was released by the manufacturer. If you want to EQ it afterwards that’s fine, of course, but only in addition. I’d endorse using the existing standard baffle size someone posted earlier.
How generous of you.
ASR stands for excellence in measurement, and in most product categories you've provided state of the art measurement and analysis. This particular one does not really meet the standard; it's somewhat revealing if you really know what to look at but I don't think a layperson could use it to decide what to buy.
If I were in your place, I would listen to this speaker in-wall and see how it matches up with the measurements. That's what you do with headphones, another product type with difficult-to-interpret measurements.
In-wall speakers are a fundamentally interesting topology which are capable of avoiding a lot of acoustic issues, so I would personally like to see more discussion on ASR, but I don't know what your priorities are. If you really want to drive traffic, headphones are obviously the way to go....for what it's worth.
If you're looking for interesting non-audiophile products to test, by the way, I would love to see this:
Imagine having one of these going while you prune your tomatoes!
OP
- Thread Starter
- #77
I "have" it. Everything comes in the software install but to use it, you need to a pay license fee. Have you used yours so know that you have that license?
The directivity is wide on this speaker, which is too good to be true. Below 70 degree the sound is always within -6dB below 8k Hz. If it is not measurement defect what makes it has so wide directivity and then suddenly drop?
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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.
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Whoa! Scrolling down to finally see the spinorama after reading the intro was a great surprise. Much better looking than I was honestly expecting.
Yes, I can run it (or I could before I got the beta software). I've got a lot of Klippel licenses. I just don't have the baffle attachment. Right now, my main focus is loudspeakers. I might get the baffle down the line for driver tests if I can ever find the way to fund it but for now my FR measurement method is to use a 23 x 10 foot "baffle" (my garage wall) with inserts placed in to it. And that's free.
Along the same lines, ** even though I know you probably don't plan to do driver testing **, if you plan on getting the baffle, I would only plan on doing it if you are also going to test drivers. If you don't plan on entering that realm, stop reading here. Otherwise, it seems a bit of a "waste" to buy that setup just for a few in-wall speakers now and again. But I'll also add that if you do that then you need to also invest in the LPM and LSI modules because simply having FR for transducers isn't very useful. The LSI module is the big boy... and you'll also want to buy their pro driver stand and the laser. Without looking at the price sheet, I'd guess you're talking probably another $20k USD for the full suite of driver testing gear. And, TBH, it's not something many people care about and is actually more time-consuming than testing loudspeakers on the NFS. Just my two cents.
As I said earlier, personally, I think what you've done here is adequate to give a general idea of the speaker performance. It's not perfect. Ideally the baffle would be much larger. But if you make a generic baffle - a bit larger than the one you've used here - that allows you to insert "blanks" in to them (as many do with drive unit testing), then the baffle diffraction can be modeled as I provided in a previous post. And that baffle will be the same for all tests instead of a different size each time. Easier to make comparisons. And that should at least give folks an idea of the performance of the speaker. It's the best alternative short of going full bore and dropping tens of thousands to measure something you'll probably only measure a few times a year and - honestly - is only academic for the overwhelming majority of people. Again, just my two cents.
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