Is beating Monoprice In-Wall quality for less money possible with DIY? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 12 Old 09-21-2017, 06:43 AM - Thread Starter
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Is beating Monoprice In-Wall quality for less money possible with DIY?

I've finally gotten around to getting serious about getting some sort of speakers into my family room other than what comes out of the TV. Clarity of dialog is #1 issue the wife complains about.
The family room is already severely compromised (wide open floorplan, lots of glass on two of the three walls it does have, and cathedral ceiling), so I was looking at some cheap in-wall speakers, but I'd be mounting them in the slanted ceiling.
I've had great luck with monoprice cables, and have been toying with trying their Alpha In-wall 8in carbon speakers. They run $99 for a pair. I would either be looking for 3 of them or 5 of them to run with my sub.

There never seems to be any threads on DIY in-wall type speakers, so I was wondering if anyone with experience would be able to tell me if I could do better by building my own. One huge, important difference, is if I build my own, I will not be nearly as size limited for the front 3 LCR. I can realistically enclose the "in-wall" speaker with dimensions like 16" x 24" and easily 12" depth and beyond. I would just want to keep the size manageable to keep the WAF in check. I would have less depth to work with if I build 2 rear channels. I've bought and build things from PartsExpress before so building is not outside of my wheel house, I just want to know if I can do better for the few hundred bucks it would cost me to use the Monoprice stuff. If you think I can, I would greatly appreciate some recommendations.

Lastly, what I already have to work with:

Receiver - Denon 4520ci
Sub - Emotiva Ultra 12
Tools - Everything I would need and more.
Materials - Wood and fasteners of all types, metals, magnets, and some stone.

Thanks for any advice in advance.
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post #2 of 12 Old 09-21-2017, 07:11 AM
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controlled directivity speakers will help increase the direct to reflected sound in your room which will increase dialog intelligibility. increasing the level of the center channel will help too. right now you have an echo chamber. adding more speakers to the ceiling is probably going to makes things worse, not better. imho.
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post #3 of 12 Old 09-21-2017, 07:29 AM
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I bet you can't beat $49.5/speaker if you're basing the decision solely on price.
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post #4 of 12 Old 09-21-2017, 03:33 PM
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Most in-wall speakers are meant to fit in a 3.5" deep stud cavity, which is its own limitation, and one that few DIY builds target as a goal. There are plenty of speakers that work in a baffle wall, which basically assumes you have plenty of room behind the wall for the speaker, and just need something that performs when the box is flush with the wall rather than in front.

You could take a design that can use a shallow box and partially recess it into a wall.

But as was said, cost is a thing. DIY is a niche, boutique thing and can never beat the cheapest-Asian-factory-mass-built products at price.
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post #5 of 12 Old 09-21-2017, 04:31 PM
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You should also consider the acoustics. Even the best controlled directivity won't get rid of problems like slap echo. Their main advantage is at reducing early reflections. Highly reflective rooms also suffer from a lot of later reflection problems at and around the listening position.


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post #6 of 12 Old 09-21-2017, 04:44 PM
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I went with the Caliber series (https://www.monoprice.com/product?p_id=6816) and have been pretty happy with them. I couldn't tell you the difference between them and the Alphas other than 1db of sensitivity and 3way vs 2way. Also the Alphas were not available when I bought the Calibers. Maybe you get the price-quality assumption that $20 more = better?

The center channel on either Caliber or Alpha will be a massive step up from your tv. Having a subwoofer, even a 12" (lol AVS...you need need tapped horns and MBMs), will help these speakers tremendously.

I saw a neat trick for sound treatment behind the couch where you back large canvas pictures (of whatever she wants) with acoustic foam to help your wife accept it.
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post #7 of 12 Old 09-21-2017, 06:58 PM
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Quote:
Originally Posted by Mpoes12 View Post
You should also consider the acoustics. Even the best controlled directivity won't get rid of problems like slap echo. Their main advantage is at reducing early reflections. Highly reflective rooms also suffer from a lot of later reflection problems at and around the listening position.


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Does parts express sell drivers that focus on Controlled directivity? I’m looking to created Angled Guided Soundfield in-walls. About a 40 degree angle.

Right now I’m looking at these but I have no idea if they will be “directional”

https://www.parts-express.com/morel-...range--297-024

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2 x Paradigm Prestige 75F's
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Sub 2 x Rythmik LVX12's
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post #8 of 12 Old 09-24-2017, 12:20 PM - Thread Starter
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Well, you guys are echoing what my thoughts are. I cannot really do anything about my room other than curtains and rugs. The advantage I would have, is that putting the speakers into the angle cathedral ceiling is that I would not be limited to drivers that only fit within 3.5" wall spacing. I would not be depth limited on drivers and have the advantage of building appropriately sized boxes for the drivers. So if I can get away with a driver(s)/crossover combination for $50 or less that would out perform the monoprice units, it would likely be worth me trying to take a stab at building my own.
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post #9 of 12 Old 09-24-2017, 09:55 PM
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Quote:
Originally Posted by tjcinnamon View Post
Does parts express sell drivers that focus on Controlled directivity? I’m looking to created Angled Guided Soundfield in-walls. About a 40 degree angle.



Right now I’m looking at these but I have no idea if they will be “directional”



https://www.parts-express.com/morel-...range--297-024

Controlled directivity just refers to a speaker that seeks to manage the radiation patter of the speaker. Most direct radiators become more directional at higher frequencies and do so in an undesirable way. You want a speakers output to lower as you move off axis and to do so smoothly. A normal speaker will Lower as it should but it will vary with frequency causing very directional highs and often a hole in the midrange.

A point source speaker that concentrically mounts the tweeter has some qualities of a CD speaker but typically a speaker cone is not an ideal waveguide for a tweeter. They can often have very compromised performance. While I've seen some really excellent examples I've never seen one that could better a good waveguide.

Parts express sells lots of speakers that can be used to create a controlled directivity speaker. The waveguides and compression drivers will do that down to about 1-2khz and then you just need to find a midbass that has a similar shift in its directivity so you can match directivity between the tweeter and midbass. This is not trivial and requires careful measurements and careful crossover design.


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post #10 of 12 Old 09-24-2017, 09:58 PM
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Quote:
Originally Posted by PCMusicGuy View Post
Well, you guys are echoing what my thoughts are. I cannot really do anything about my room other than curtains and rugs. The advantage I would have, is that putting the speakers into the angle cathedral ceiling is that I would not be limited to drivers that only fit within 3.5" wall spacing. I would not be depth limited on drivers and have the advantage of building appropriately sized boxes for the drivers. So if I can get away with a driver(s)/crossover combination for $50 or less that would out perform the monoprice units, it would likely be worth me trying to take a stab at building my own.

While you can probably build something decent sounding for $50 I do have to ask if you have any speaker design experience. The crossover is one of the most important parts and if you haven't designed one before, I'd suggest going with a kit or established design. Parts express has the Cnote kit which I think is actually quite nice for $100 a pair.

https://www.parts-express.com/c-note...nets--300-7140


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post #11 of 12 Old 09-25-2017, 08:26 AM
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Quote:
Originally Posted by Mpoes12 View Post
Controlled directivity just refers to a speaker that seeks to manage the radiation patter of the speaker. Most direct radiators become more directional at higher frequencies and do so in an undesirable way. You want a speakers output to lower as you move off axis and to do so smoothly. A normal speaker will Lower as it should but it will vary with frequency causing very directional highs and often a hole in the midrange.

A point source speaker that concentrically mounts the tweeter has some qualities of a CD speaker but typically a speaker cone is not an ideal waveguide for a tweeter. They can often have very compromised performance. While I've seen some really excellent examples I've never seen one that could better a good waveguide.

Parts express sells lots of speakers that can be used to create a controlled directivity speaker. The waveguides and compression drivers will do that down to about 1-2khz and then you just need to find a midbass that has a similar shift in its directivity so you can match directivity between the tweeter and midbass. This is not trivial and requires careful measurements and careful crossover design.


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They would not have full range that could achieve this? What would be an example of a mid-bass driver that has a shift in directivity

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post #12 of 12 Old 09-25-2017, 05:35 PM
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Is beating Monoprice In-Wall quality for less money possible with DIY?

Quote:
Originally Posted by tjcinnamon View Post
They would not have full range that could achieve this? What would be an example of a mid-bass driver that has a shift in directivity

There are no full range drivers that fully meet the criteria for Cd. Controlled directivity is admittedly a concept without a definition. Constant directivity has a definition and I use the term controlled directivity to refer to a looser interpretation of constant directivity. Per the original patent, 6db down angle at 90 degrees. That means that the response falls by 6 dbs at 90 degree angle (45 from center). That the transition is smooth and the roll off is flat. For lots of reasons this would not be possible for a full range driver. Some are better than others but most become very directional (narrow beam width) at higher frequencies.

As for a midbass that meets the criteria, it's more about matching a speaker to the waveguide. All drivers become more directional at higher frequencies. Many people think that the reason to have large midbass drivers is for loud midbass. That's a bonus but it's not the primary reason with waveguide speakers that seek CD behavior. Instead it is that the larger midbass drivers roll off their response at off-axis angles at a point that matches a typical CD crossover point. This directivity matching at the crossover point is something the designer does. Generally, as a rule, a waveguide that is about 15" wide matches the directivity of a 12" to possibly 15" driver. They typically allow a crossover point between 1khz and 1.2khz (maybe up to 1.5khz) with a good match in the directivity. All drivers have more omnidirectional radiation over a 180 degree plane as frequencies get lower. The point of this shift depends on the cone diameter. Since our goal is -6db at 90 degrees over the widest possibly frequency range, that means you need larger midbass drivers to shift the point where the speakers radiation pattern narrows to a lower frequency range.

This is why 12" -18" midbass drivers are used on CD speakers, they have optimal radiation patterns to shift the radiation pattern control down lower allowing for a very flat directivity index. A perfect speaker would have a flat directivity index down to be rooms Schroeder frequency. Once you get down that low two mechanisms work to make bass non-directional in a room (both in perception and propagation) so there is no point in shifting it lower.

There's your primer on Cd speakers. I know I didn't recommend specific speakers but that's because there are too many choices. While true Cd behavior largely requires the use of a waveguide for high frequencies, any woofer can work you just have to work within its limits.


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