# Giving New meaning to the term "Bookshelf" Speaker (Another Natalie P Thread)



## keelay

Having just finished a set of Parts Express Triunes for a friend, I was hooked. I had been reading about the Natalie P and many positive reviews so I thought I'd give them a try. The main issue is that I had just finished building our entertainment center using a set of Ikea (Billy) bookcase. I had to heavily modify them to get this far ... AND.. my wife really liked it. The only thing she didn't like was the speakers sitting on the shelves. 

So here is the before shot: Family room / Home Theater room (It's a small house) 










The design thread that I used to build these speakers: On/In Wall Natalie P cross over variation Design thread

For Reference here is the Original Natalie P design thread which has baffle step compensation in the crossover


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## keelay

So then here is the plan. I wanted to place the new main speakers vertically, still use the existing bookcase design for the most part, and place the new speakers roughly splitting the room into 1/3's. That makes an ideal placement for mains. I also wanted the speakers to integrate into the existing book case design, which I had to heavily modify to make them look like this in the first place.

So here was my plan:









Split the book case and add a thin book case with a speaker built into the bookshelf.
Here's my original autocad drawing:









So Here is the original Natalie P thread that sold me on the reference design.
And Here is the Natalie P crossover for in/on wall crossover without Baffle Step Compensation. This is the design I implemented.


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## keelay

So here are a bunch of shots of the bookshelf. This was a standard 15 3/4" Billy bookcase from Ikea. I modified the shelves to make the bookcase more narrow. It's actually only 8 3/4" wide now. I added an 3/4" MDF back, and added 3/4" MDF top and bottoms. The front baffle is 1.5" MDF making only the sides particle board (Billy bookcase material). But once I'm finished there will be 1.5" of particle board on each side.









You can see I added lots of bracing. Side to side and front to back


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## keelay

So here 
I added a couple front to back braces. These braces will sit against the baffle once it goes in and reduce baffle resonance. These I went ahead and drilled holes in to reduce reflections from these internal braces.


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## keelay

So here the enclosures are complete with Crossovers installed. I have also provided sound damping in the form of carpet pad for the side walls. and around 2" fiberglass insulation everywhere else.


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## keelay

So here is the baffle construction shots. The baffle is made from sandwiching two 3/4" pieces of MDF. The port tube is integrated onto the front baffle. The Speakers were recessed to be flush mounted.


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## keelay

So here are the boxes put together. I was just finishing painting and installing the drivers. The Port is configured on top since this was the only free space to place it. A little unconvensional. Once I build My Dayton 15" HF subwoofer I plan on sealing the port. Port is tuned to 39 Hz. Internal Volume is 1.4 Cubic Feet.


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## Anthony

Nice build. Keep the pics coming. :T


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## keelay

I have the speakers installed now I just need to take some pictures of them. I don't have the grills completed yet, my wife can't wait till that happens . I will likely have some time this weekend to take a picture of them installed.

- Kyle


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## filtor1

That looks amazing!


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## fbov

In another thread, you linked to the main NatP build thread on HTGuide. I remember your situation and I like the approach you've taken, but, as I may have mentioned, you may not be happy with the results using the stand-alone NatP XO for an in-wall application. You really want this one.
http://www.htguide.com/forum/showthread.php4?t=22626

I made my NatP's as an LCR set with the infamous toppled MTM in the center channel. Understanding the issues that represented, I bought parts for two NatPs and 2.5-way XO, and tried both in the CC. I found that neither design sounded good in the CC, both for the same reason - BSC, baffle step compensation. Like you, I had integrated the CC into the TV stand, effectively making it an in-wall implementation. I switched to this in-wall XO design and it finally sounded right. Apparently, correct levels of BSC was more important to me than the lobing issues of a horizontal MTM. 

So if you used the standalone XO design and find your NatP's a bit boomy, consider using the in-wall XO design. I liked it much better. 

Have fun,
Frank


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## keelay

Thanks for the very thoughtful input. I actually did use the In/On Wall Natalie P Crossover design. I have a link on the first post to both the Original Natalie P site and the On/In Wall crossover variation, but it may not be obvious which one I used. I will fix that. I have everything installed and the In/On Wall Crossover sounds very balanced across the frequency spectrum. There is no boominess. I'm very happy with the choice even though this cost around $50 more in parts than the no BSG Natalie P Xover. I'm thinking of getting some measurement equipment to test these out, but that might take me a while to get.

Thanks,

Kyle


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## Owen Bartley

Very cool project Kyle, great idea. I'm really looking forward to seeing the finished product. Are you still using the CC from your original post, located on top? Any plans for a NatP CC or camouflaging the existing one?


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## keelay

I am still using the same CC from the original post. It is an Infinity Reference that I picked up on craigslist for $20. It isn't quite as good as the Natalie P's but it's decent. I plan to replace the HT in a box surrounds, then the sub and then the Center Channel.

For the Sub I'm going to build a LLT with a Dayton HF 15" sub and a 500W BASH amp from oaudio.
For the surrounds I'm trying out the RB kit from madisound. Just ordered a pair.
I'm still looking for the "perfect" center channel reference design. You know how it goes.


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## fbov

May I then suggest the Modula MTM CC. 
http://htguide.com/forum/showthread.php4?t=11475

Same RS180Ss and designer as the NatPs, but with a $200 Scanspeak tweeter that's so small you can bring the drivers to a 9" spacing on a 9" wide baffle. I can't justify it sonically; I'm still trying to hear the lobing defect, even though I can measure it. But it's the one to make when the time comes. 

Have fun,
Frank


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## keelay

So I took some pictures tonight and am posting them. I haven't started the grills yet. The black circles in each corner of the baffle are carriage bolts that I ground flat. I intend to use magnets on the grills and use these spots as magnetic anchors.

After:









Before: (I thought I'd show them together for comparison)









The sound is better than anything I've heard before. I have relatively untrained ears, but that is changing fast. I spend hours listening to these. I hear new things in tracks that I've never heard before. The same songs have more impact. They really show the difference between a good recording and a mediocre one. You can hear nuances, bit rate differences, in the recording. The imaging a soundstage are impressive. The only bad thing is they really detail points in songs where audio compression has been used. You get so used to the dynamics of the drivers on uncompressed songs and movies that when a compressed song shifts to the chorus and the lead goes from just singing to belting, It sounds a little odd. Almost like someone turned down the volume (exactly what happened in the recording).... mostly because you _expected_ it to be louder.


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## keelay

I have been planning to add a Dayton 15" RSS390HF-4 in a LLT configuration. I originally planned to make the natalie P's sealed. knowing that the Subwoofer will fill the low end better and more accurately than the porting would. I built the ported version knowing that I can seal it. The Q would be less than .7 but not much and I have some volume consuming ideas when I go to seal the ports. I just really wanted to hear how low the ported version can go. It really can go low. You could actually live without a sub for most music. HT you'd want the sub. The Natalie P's can go low and deap.

My cabinets are 1.4 Cubic Feet with the port tuned to 39 Hz. The port on top is because I wanted it as far away from the speakers as possible. The driver placement was intended to place the tweeter as close to ear level as possible while remaining in the space allocated in the bookcase. The tweeter is 42" off the floor.


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## keelay

Here is a little closer up:









Here is a single speaker closeup.


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## Owen Bartley

Kyle, they look awesome, and I'm glad they sound as good as they look. Just a thought... why not leave them ported, especially when you're planning to build a LLT sub, which will play very low, and the speakers should blend nicely around their tuning frequency? Unless you were planning to set them to 'small' and have the sub handle all of the low bass duty. then I guess there's not much point.


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## fbov

First off, my apologies for not remembering (or reading back to see) you'd stated early on that you'd use the in-wall XO design. My comments can only have supported that decision. 

Second, I know what you mean about good low end; my sub's been off for 2 months and I can feel things I can't hear with a 2.5 cu ft (70l) box and 33Hz tuning. Same with transients - they deliver a lot of punch when the input asks for it. If I decide to seal them, long term, it'll be by an internal baffle down to 50l. With an F3 point of 40 Hz, and a somewhat larger room than I, you'll integrate with a sub nicely. I have a primary room mode at 40Hz (15' dimension) that really needs bass management to address it properly. 

Nicely done!
Frank


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## keelay

Owen Bartley said:


> Kyle, they look awesome, and I'm glad they sound as good as they look. Just a thought... why not leave them ported, especially when you're planning to build a LLT sub, which will play very low, and the speakers should blend nicely around their tuning frequency? Unless you were planning to set them to 'small' and have the sub handle all of the low bass duty. then I guess there's not much point.


Yeah, I one of the reasons I would seal them is the same reason I would go with an LLT. I'd like to avoid the effects of port coloring in the audible range if possible. I believe I can get a flat response between the Natalie Ps and the Subwoofer. And the OAudio BASH amp has a configurable notch filter which I hope to use to handle room modes.

I wouldn't want to set the natalie ps to small if I went sealed. I would want whatever bass extension is left to blend with the Sub.

Kyle


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## keelay

fbov said:


> May I then suggest the Modula MTM CC.
> http://htguide.com/forum/showthread.php4?t=11475
> 
> Same RS180Ss and designer as the NatPs, but with a $200 Scanspeak tweeter that's so small you can bring the drivers to a 9" spacing on a 9" wide baffle. I can't justify it sonically; I'm still trying to hear the lobing defect, even though I can measure it. But it's the one to make when the time comes.
> 
> Have fun,
> Frank


Yeah I have considered that version. It's a little pricy, but then the CC has got to be good though. One of the other ones I have considered is the mini statement center channel. I like the vertical TM alignment, but couldn't take advantage of the open backed mid. But then again it's pretty pricy(probably pricier) as well. I bet they both sound exceptional though.

- Kyle


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## fbov

I suggested the Modula MTM CC for consistency with the NatP's in driver configuration, size and loudness. Your implementation will fit a larger CC, which opens up the options greatly. Statement/mini statement designs are very well received, but the CC is designed to go with that family's mains. I think there are enough RS-based options to warrant staying in the same driver family. A CC has several requirements, but the most important is to sound like your L and R so objects sound the same when panning across the screen. 

The Modula MTM CC is close to a NatP in some ways, but so are the Modula NeoD CC and Dawaro's 3-way CC. Jon Marsh talks a bit about CC goals and options in the first post of the NeoD thread, but that design is in limbo since the neodymium tweeter was discontinued. 
http://htguide.com/forum/showthread.php4?t=27218
And here's Dawaro's design, using RS225/RS150/RS28A drivers and with 3 XO options.
http://www.htguide.com/forum/showthread.php4?t=15323

Forgot to include the WMTW CC summary thread...
http://www.htguide.com/forum/showthread.php4?t=22393

Again, there are many CC designs available; you want one that can keep up with the NatPs while sounding a lot like them. These fit that bill.

Have fun,
Frank


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## keelay

I thought I'd add a couple of closer up shots:


















Here is the port:


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## keelay

fbov said:


> I suggested the Modula MTM CC for consistency with the NatP's in driver configuration, size and loudness. Your implementation will fit a larger CC, which opens up the options greatly. Statement/mini statement designs are very well received, but the CC is designed to go with that family's mains. I think there are enough RS-based options to warrant staying in the same driver family. A CC has several requirements, but the most important is to sound like your L and R so objects sound the same when panning across the screen.
> 
> The Modula MTM CC is close to a NatP in some ways, but so are the Modula NeoD CC and Dawaro's 3-way CC. Jon Marsh talks a bit about CC goals and options in the first post of the NeoD thread, but that design is in limbo since the neodymium tweeter was discontinued.
> http://htguide.com/forum/showthread.php4?t=27218
> And here's Dawaro's design, using RS225/RS150/RS28A drivers and with 3 XO options.
> http://www.htguide.com/forum/showthread.php4?t=15323
> 
> Forgot to include the WMTW CC summary thread...
> http://www.htguide.com/forum/showthread.php4?t=22393
> 
> Again, there are many CC designs available; you want one that can keep up with the NatPs while sounding a lot like them. These fit that bill.
> 
> Have fun,
> Frank


I really like the Dayton RS WMTW Center. I also like the Mini Statement Center as well. I know the Tweeter isn't available anymore and the voicing probably doesn't match my natalie p's, but that titanium Tang Band Mid does get very good reviews. I don't know if my wife would ever go for anything that large though. The unfortunate side affect of that vertical alignment is the tall Center height. With the woofers on the sides it just imposes more. I'm just wondering if an Encore or Modula MT on end or even on its side wouldn't do the trick without the visual "impact" of these hefty designs.


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## fbov

It all depends how loud you play. Even a pair of RS150's won't keep up with the NatPs, so the Encore is at a disadvantage, and a single RS180 in the Modula MT is similarly handicapped. CCs are not filler loudspeakers, as surrounds usually are. They carry the majority of the HT program and it'll be obvious if it can't keep up at high volumes. If you don't play loud, it's not an issue. 

With apologies for not noticing earlier, I will mention is that your NatPs are recessed, not flush mounted. In a standalone design, you'd bevel or round the baffle between the RS180s to improve tweeter performance. In your case, you might want to consider spacing them out to match the side walls. The effect will be subtle but this is one area where some DIYers have documented a distinct change in response as a result of optimized baffle edges. 

As always, YMMV,
Frank


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## SturmMD

Just saw this thread - it's a treat to see the whole process at one time instead of waiting. The bookshelf setup looks perfect. So how much are you charging for the kit.


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## keelay

fbov said:


> It all depends how loud you play. Even a pair of RS150's won't keep up with the NatPs, so the Encore is at a disadvantage, and a single RS180 in the Modula MT is similarly handicapped. CCs are not filler loudspeakers, as surrounds usually are. They carry the majority of the HT program and it'll be obvious if it can't keep up at high volumes. If you don't play loud, it's not an issue.
> 
> With apologies for not noticing earlier, I will mention is that your NatPs are recessed, not flush mounted. In a standalone design, you'd bevel or round the baffle between the RS180s to improve tweeter performance. In your case, you might want to consider spacing them out to match the side walls. The effect will be subtle but this is one area where some DIYers have documented a distinct change in response as a result of optimized baffle edges.
> 
> As always, YMMV,
> Frank


Would you help me clarify your suggestion?

I think I understand what you are saying. But I'm not sure. Are you saying that the drivers should be flush mounted to the baffle? If that is the case, the drivers are within < 1/16" recess of the front baffle. My rabbet cuts were slightly deep. I've been thinking about fixing this. It wouldn't be too hard. I don't think this is what you are saying though. I think you are saying that the side walls (the white part) juts out 1/2" into the room out from the baffle. You're suggesting that the drivers be extended to be at least flush with the front edge of the outer sidewall. Is that what you are saying?

Thanks,

Kyle


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## keelay

SturmMD said:


> Just saw this thread - it's a treat to see the whole process at one time instead of waiting. The bookshelf setup looks perfect. So how much are you charging for the kit.


Thanks man. It was a fun project and I think integrated well. I usually prefer to take all the pictures and then just post the whole project at once. I might be missing out on some good feedback along the way, but it just seems simpler to do it all at once. 

I know you are kidding about "the kit" but I'll give some info anyways:

The bookcase is your run of the mill IKEA BILLY bookcase. Of course for my application, I made the shelf more narrow but you wouldn't have to. Especially considering this is the on/in wall crossover for the Natalie P. The extra baffle width wouldn't hurt a thing.

There is a bill of material from parts express to order the parts for the Natalie P Drivers and crossover components. 


I estimate that the two speakers including the bookcases, components, drivers, wire, MDF etc. cost me around $600.


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## fbov

keelay said:


> Would you help me clarify your suggestion?
> ...
> I think you are saying that the side walls (the white part) juts out 1/2" into the room out from the baffle. You're suggesting that the drivers be extended to be at least flush with the front edge of the outer sidewall. Is that what you are saying?
> 
> Thanks,
> 
> Kyle


Exactly, but moreso the baffle than the drivers, per se. 

Think of a tweeter in free space. The diaphram oscillates in and out, producing a roughly hemispherical wavefront. The only thing that affects the wavefront radiating from the driven element is the edge of the tweeter face. 

Now, flush mount it on a large baffle.The edge of the tweeter face is now flush with the baffle, and has no effect. It's the edge of the baffle that can affect the wavefront. An in-wall design, this edge is many wavelengths away, and looks more like a room boundary than a baffle boundary. 

Finally, make the baffle smaller, say 9" wide. Now the baffle edges are fractions of an audible wavelength away, and have a marked affect on the wavefront at audible frequencies. The desire to make the transition gradual, over a range of frequencies, and thus less severe, explains the use of large radius roundover or bevel edges around a tweeter. 

In your case, there's a low wall at the edge, and one would expect a peak/null in frequency response at frequencies that are 1/4, 3/4, 5/4, etc. wave distance from tweeter to edge. You get a little more linear distortion. It's not a huge effect, but its one of the things that a perfectionist might address, and the proven designs are intended to be as good as humanly possible. Some go so far as to surround the tweeters with wool felt to further modify this transistion. 

In your case, it's a choice between the low wall at 9" and a sharp edge 1.5" farther out on each side. You're too far along to change the edge profile without major surgery, and with recessed shelves, it'll look a bit odd if the baffle were flush with the vertical edges, but not the horizontal edges. You have a very elegant installation as it sits, I should probably have kept my mouth shut... sorry!

Frank


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## keelay

fbov said:


> Exactly, but moreso the baffle than the drivers, per se.
> 
> Think of a tweeter in free space. The diaphram oscillates in and out, producing a roughly hemispherical wavefront. The only thing that affects the wavefront radiating from the driven element is the edge of the tweeter face.
> 
> Now, flush mount it on a large baffle.The edge of the tweeter face is now flush with the baffle, and has no effect. It's the edge of the baffle that can affect the wavefront. An in-wall design, this edge is many wavelengths away, and looks more like a room boundary than a baffle boundary.
> 
> Finally, make the baffle smaller, say 9" wide. Now the baffle edges are fractions of an audible wavelength away, and have a marked affect on the wavefront at audible frequencies. The desire to make the transition gradual, over a range of frequencies, and thus less severe, explains the use of large radius roundover or bevel edges around a tweeter.
> 
> In your case, there's a low wall at the edge, and one would expect a peak/null in frequency response at frequencies that are 1/4, 3/4, 5/4, etc. wave distance from tweeter to edge. You get a little more linear distortion. It's not a huge effect, but its one of the things that a perfectionist might address, and the proven designs are intended to be as good as humanly possible. Some go so far as to surround the tweeters with wool felt to further modify this transistion.
> 
> In your case, it's a choice between the low wall at 9" and a sharp edge 1.5" farther out on each side. You're too far along to change the edge profile without major surgery, and with recessed shelves, it'll look a bit odd if the baffle were flush with the vertical edges, but not the horizontal edges. You have a very elegant installation as it sits, I should probably have kept my mouth shut... sorry!
> 
> Frank


Thanks for the clarification. I do appreciate you're input. I have been aware of the possibility of diffraction effects due to the square edges of white bookcase edges. I'm glad you mentioned it. Too often I see threads with finished designs where people for reasons of being polite don't raise significant design issues. Very often its because the design is finished and most posters have a general sense that the builder would like to come away feeling praised for their work and rewarded for sharing. I guess I've been an engineer long enough to get used to a "peer review" process where every piece of works goes through an honest critique by other engineers. So I say lay it on me. :yes: I'd like to learn from this experience. 

In my case I think you ended up getting right to one of the trade offs most of us married folk have to make is that the wife has to be happy with it. The baffle is recessed so that I have room to place a grill over the speakers. The Grill is going to be ever so slightly recessed as well. I'm going to have to live with the trade off for now.

I would love to design a home theater room where every element starts from a performance design constraint first and then an aesthetics second. I get the sense that many of us DIYer would lean heavily that way. Not that all aesthetic decisions have a negative effect on performance. That is part of the fun of DIY is finding those positive aesthetic decisions that also have a positive affect on performance. That is the sweet spot!

In my case I agree that the recessed baffles with square edges that does have some negative performance consequences. That one I'll have to wonder about. I will probably at some point try taping up some felt to do some temporary testing to assess the diffraction affects.


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## fbov

If you're making grills, I'd suggest using quarter round stock, with the flat sides toward the lip and the baffle. That would provide a radiused inner edge for smoother diffraction. 

And as an engineer, I appreciate you understand the sense of my comments. In that context, I no longer feel bad about telling you that NatPs are designed for the tweeters to be inboard - you have L and R switched...
http://www.htguide.com/forum/showpost.php4?p=319693&postcount=462
But I suspect this is a really fine point!

Have fun,
Frank


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## keelay

fbov said:


> If you're making grills, I'd suggest using quarter round stock, with the flat sides toward the lip and the baffle. That would provide a radiused inner edge for smoother diffraction.
> 
> And as an engineer, I appreciate you understand the sense of my comments. In that context, I no longer feel bad about telling you that NatPs are designed for the tweeters to be inboard - you have L and R switched...
> http://www.htguide.com/forum/showpost.php4?p=319693&postcount=462
> But I suspect this is a really fine point!
> 
> Have fun,
> Frank


Thanks again for the input. All input is welcome. 

I was planning to do pretty much exactly that with the grill covers. I likely will use HDF and do my own rounding on the inside edge. Square outer edge like you said. 

Now that you mention it I don't know what gave me the idea that the tweeter should be on the outside. I read the entire Natalie P (HT Guide) thread and saw both setups featured in the various image postings. I guess I just assumed it could go either way. 

If I decide to swap them it will take an hour or two to unscrew the bookcases, move and rewire. Probably not hard enough to keep curiosity from getting the best of me. 

-------------------------

Update: It looks like the tweeter inward/outward question has been answered. 

Kyle


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## windforce2009

I really like your idea of building the speakers into the bookcase. It gives a really nice finished look. Have you considered also building a subwoofer in as well?


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## keelay

windforce2009 said:


> I really like your idea of building the speakers into the bookcase. It gives a really nice finished look. Have you considered also building a subwoofer in as well?



Thanks for the compliment. I like your idea. A Subwoofer could be really cool looking as well especially if you left if exposed. One of the Dayton Reference subs would go very nicely. Unfortunately, I know my wife would never go for it. She says the room already screams bachelor pad. I have been planning to building a large (12CF) box into the ceiling with a white cloth grill cover to "blend in" to the ceiling before my wife and I got the itch to move. So we've started looking and I'm not going to put any permanent fixtures in a house until we settle into a new space. But I do really really really want to add a sub.

Kyle


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## cjbrownco

I know this thread is super old but I can't figure out how to PM keelay. I have been thinking about building some Nat P's into a new entertainment center and it looks like your avitar shows that maybe you have changed your Nat P's to stand alone instead of flush mount. If that is the case I am wondering if maybe the flush mount didn't sound as well to you? Thank you for any info you may have


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## cjbrownco

Sorry, just realized that the speaker in your avitar is actually a Triune:duh:Anyway, I still would like to know if you are still liking the sound of your Nat P's flush mounted if you are still on this forum. If anybody else has flush mounted Natalie P's please let me know you like the sound.


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