Natalie P Speaker Build

[BlueBeardo]

I've finally convinced the wifey that we need new speakers up front. I currently am using an Onkyo HTIB. Two years ago I replaced the subwoofer with a DIY subwoofer (12" TC Sounds that I'm pretty proud of). Now it is time to replace the left right and center channel.

I think I'm set on doing Natalie P left and right channels. I would like to to do floor standing speakers, but I'm not sure if I should make them ported like opt-e's design or just make them look tall and do the standard design. I figured since I have a decent sub that I should do the latter. Any suggestions?

Also, I'm a little confused on what center channel project to do. I've been reading off and on for a year now, and I thought I remembered seeing a Natalie P design specifically for centers. Is there one or is there a good cc to build? I've seen the Jon Marsh's Modula MTM suggested a few times.

Sorry for the long post. Hopefully this will get the ball rolling.

[---k---]

Ported or sealed is a personal thing. Mine are all sealed since I have a big sub. Some like ported even with a sub. It will depend on whether you want your sub on for music or not. If this is just ht, Ipersonally would go sealed.

As for the center, there is no nat p center. There are several ted that match close enough. Options are: modular mtm, rs 3-way, khancenter, cjd rs mtm. All have pluses and minuses.

Sorry for typos. Aneroid autocorrect is out of control.

[BlueBeardo]

k, you should lay off the Aneroids . Thanks for the help I think I am going to go sealed since this will mostly be for HT and if I listen to music I leave the sub on. I'll to look through the centers again to decide. I'll post some 3D mock ups in a couple of days when I finish them.

[dar47]

I agree, port or sealed is your thing. I'm just finishing up the Modula MTM's for a friend and he choose ported in towers but the bottoms are sealed off with the port in the original configuration behind the tweet. If you can afford I'm a fan of a full 3way centre, just that much better.

[fbov]

+1 on the 3-way CC, but...

The Modula MTM CC is as good as a 2-way CC can be. You still have a choice between 3-way and 2-way, dominated by the same factors as for an L/R pair, but only because this 2-way is designed to cross below the M-M interference frequncy and voiced for the application. That comes at a price in drivers and components, but it fits places where 3-way's don't.

I built a pair of NatP vented towers, a my second pair, unshielded and fabic tweets, are sealed. I used a NatP sideways for several years as my CC and was amazed at the improvement moving to the Modula MTM CC, even though I sit on-axis. It's more than lobing, it's a bias toward dialog reproduction that makes this an excellent CC. Even my wife noticed....

Have fun,
Frank

[subynube]

I have this center channel with the Nat P's as L and R mains.

http://www.zaphaudio.com/ZDT3.5.html

I am quite happy with it and find it to be a pretty good match. Hope this helps.

[BlueBeardo]

Center

I decided to build the Khancenter. I started mocking it up in 3D and noticed that the speaker cutout dimensions don't work out. The RS150 and RS28 top to bottom dimension don't add up. The RS28 is 2-7/16" from the top and 5-1/8" to the RS150. Then the RS150 is 3-3/8" from the bottom. That adds up to 10-15/16". The height of the box is 10-7/8". I know i'm splitting hairs, but I do a lot of 3D design and it bothered me a bit. I was going to make the box 11" tall and keep the 3-3/8" dimension. It will make the center drivers 1/16" further apart. Being that its only 1/16" I didn't see an issue unless anyone else thinks so.

[CWH&R]

Center

I am finishing up on the same center and I made mine 12" tall but keep the same with. Also that center is designed too be put in an entertainment center with a T.V. above it. Make sure too read the complete threat on the build before you decide as this center was built for K's layout.

[BlueBeardo]

I like the look and the design and would like to go with a 3 way design. I will be putting it below a TV, but on top of the entertainment console. Reading though the thread it didn't sound like the design was too restrictive since it was sealed. He just had the height short to fit it in a hole. Should I be worried about it sounding different since I'm not putting it inside a entertainment console? I just wanted to make sure I got the speaker centers right. It sounded important when dealing with the Natalie P's. I wasn't sure if it was here. I mean, we are only talking a 1/16 of an inch.

[CWH&R]

Go to the Garnacha thread and read the last 6 or 8 posts. It talks about what the sound will be like as I am using minr on a stand and up to the back wall for now.

[BlueBeardo]

I took a look at it. I didn't realize having something over the top was important. I will be pretty close to the wall. Probably about 5 to 6 inches. Will that solve the problem? Should I shorten it to 12 inches like ---k--- was saying?

[CWH&R]

I can not tell you as I am building this center too match the Garnacha's, CJD is the designer on this project and was going to redesign the X-over for out in the room placement. Hopfully after the holidays are over he will get a chance too come up with something. I will be putting my center on a stand under my 118" screen about a foot from the rear wall, but antil any changes are made it will be up back to the wall as my center is 14" deep and all the walls are 1.5" thick MDF.

[BlueBeardo]

By the way, I'm not sure if it's OK, I haven't seen a lot of it. I will post all the 3D files of the mock ups (drivers, cross over, box design). That way other people can use it. The problem I see is that a lot of people use Sketch up. I use AutoCAD Inventor. I haven't seen a good way to transfer across the two. If anyone is interested I'll post them otherwise I'll stick to pictures.

Here's what I have so far...

Image not available

[CWH&R]

Also I just wanted to let you know so after you build it and it does not sound right that it was designed as too be put in an entertainment center under a T.V. and that was how it was designed.

[dawg1161]

Can I ask what 12" TC Sounds sub you used and what enclosure you built for it ? Thank You...
Any Pics ? I will be building a 12" TC1000 4 ohm dvc model..........

[---k---]

Sorry my measurements didn't add up. I'm a bit of a woodworking hack. By the time I got to the Khancenter, I just went out into the garage and did some cutting without much sketching. The idea is to get the drivers as tight together as possible. Moving around 1/8" isn't going to make any difference. Just get them to look right.

As for positioning, I'm not sure I'm following exactly. I'm reading into in a bit and guessing you got an LCD flat screen that will be behind the front of the center? The khancenter doesn't have to be inside an entertainment center, but removing that big flat surface above or below it will decrease the bass. The closer to the back wall you are the less the effect will be. You can probably switch the 2.7mH woofer inductor from 18ga to either 15ga or 14ga which will increase the bass and compensate.

If CJD doesn't speak up here in a day or so, post this as a separate thread with Khancenter somewhere in the title so it catches his attention. Give a pic of your placement. I'm sure we can make it work.

[BlueBeardo]

My current set up is a 58" plasma mounted on the wall with my entertainment center below it. There is about a 6" gap from the speaker to the wall. I could put it closer if I need to. I could even mount the speaker to the wall if that would help. I can't put it in wall though, it's an outside wall with insulation. It would just be a mess.

Can I ask what 12" TC Sounds sub you used and what enclosure you built for it ? Thank You...
Any Pics ? I will be building a 12" TC1000 4 ohm dvc model..........

I will get some pictures of my sub.

[BlueBeardo]

I've got all three laid out...

Image not available

Just looking for cjd to answer back if I need to make modifications to the crossover of the Khancenter. I will take a picture of where the speakers will be tonight.

[joeybutts]

I love the mock up shots. Nice skills.

Can't wait to hear your impressions!

[BlueBeardo]

Pics of area

Here are two pictures of where the speakers will go. I will be getting rid of the speaker stands since I am building floor standing speakers.

Images not available

[BlueBeardo]

Three questions about the design of the Natalie P's:

1. I was planning on building them sealed but still as towers. I put a divider in the tower to seal the top from the bottom. I put it at 22" from the top to keep it the same as the original design. Will the bottom open cavity affect the performance of the speaker? Should I fill it with anything? I plan on putting the crossover in the bottom half.

2. Is there any benefit with a sealed speaker to to make the speaker cavity bigger or is it minimal in low end gains?

3. It looks like when constructing the boxes, most everyone just uses glue and clamps and no screws. Is this correct?

Here is a pic of the inside of what I was thinking.

Image not available

[JonMarsh]

Three questions about the design of the Natalie P's:

1. I was planning on building them sealed but still as towers. I put a divider in the tower to seal the top from the bottom. I put it at 22" from the top to keep it the same as the original design. Will the bottom open cavity affect the performance of the speaker? Should I fill it with anything? I plan on putting the crossover in the bottom half.

2. Is there any benefit with a sealed speaker to to make the speaker cavity bigger or is it minimal in low end gains?

3. It looks like when constructing the boxes, most everyone just uses glue and clamps and no screws. Is this correct?

Here is a pic of the inside of what I was thinking.

Image not available

No need to fill the bottom- but don't make it a partly open cavity in to the room, as it can resonate. Close it off.

If you make the main box of a sealed speaker bigger, it will tune the Fs lower, but will also lower the Q. Idea Q range is from about 0.7 (butter worth maximally flat) down to 0.5 (critical damped, -6 dB at fs). Use unibox if you want to consider tradeoffs. If you're using a sub, it's all pretty moot. If just sealed box, the ideal thing is to place the cabinets in the room relative to boundaries so that the boundary boost occurs in a complementary fashion to the roll off. There are reference threads describing that here.

NO screws- just glue and clamps. Glue is stronger than MDF.

~jon

[BlueBeardo]

I'm going to build the cross over tonight. What kind of wire and gauge is recommended? I have some 16 AWG and 14 AWG speaker wire that I can use. I was planning on one of those to go from the speakers to the crossover. I wasn't sure if that was ok to use in the crossover. It seemed a little much. I was thinking just regular 16 AWG wire.

Also, I was going to hot glue the components to peg board and zip tie the large components. Does anyone have any issues in the long run with components falling apart when done like this?

[BOBinGA]

16 ga. wire is just fine for the internal wiring. Save the 14 ga. for the amp to speaker connection. its the resistance of long runs of wire to worry about and three feet from crossover to speaker is practically nothing. However, twenty feet from amp to speaker could possibly cause enough resistance to change the Q of the speaker ever so slightly, so use the fat stuff here.

I've hot glued and tied components and have not had any problems. Put the crossover together and shake it real hard to see if anything comes loose. If not, put it in the speaker. One word of warning: some resistors can get hot under very high power play, especially any woofer and mid resistors. Consider mounting them slightly raised from the crossover board so they have adequate cooling. But then again, I have mine mounted right on the surface of the crossover board and haven't had problems.

-Bob

[BlueBeardo]

Couple questions about the speaker fill:
1. Since the speakers are sealed do I need insulation on the walls or just use poly-fill or do I use both.
2. Is egg crate OK to put on the walls of the speakers?
3. What should I use to seal the inner corners of the speakers? I heard some sealants can be harsh to the speakers. Or should I just run wood glue along the edges?
4. Do I need to cover the cross over or do anything special with it once it is in the speaker?

[---k---]

I usually put insulation or foam on the walls and then stuff as needed. But lots of people just stuff.

Lots of opinions on whether egg crate is good or not. I've heard good speakers that use egg crate. I've also read many people say it is worthless. Probably the truth is somewhere in between and it depends on the implementation. Zaph's has some info on what he does here: http://www.zaphaudio.com/mantras.html

If you did a good job building the boxes, no need to seal the corners. I've read the vapors from Silicone can cause problems, but don't know. I sealed my subs way back when, but I haven't any since. Usually I just make sure I have good cuts and smear the glue oversqueeze all along the joint.

I don't do anything special to cover my crossovers. Just velcro them in. But there are some remote corners of the internet where people do put them in special boxes to prevent sound waves from hitting the crossover pieces and causing micro vibrations that will affect the sound. Any truth? I don't worry about it.

[JonMarsh]

Couple questions about the speaker fill:
1. Since the speakers are sealed do I need insulation on the walls or just use poly-fill or do I use both.
2. Is egg crate OK to put on the walls of the speakers?
3. What should I use to seal the inner corners of the speakers? I heard some sealants can be harsh to the speakers. Or should I just run wood glue along the edges?
4. Do I need to cover the cross over or do anything special with it once it is in the speaker?

Some suggestions from the designer- take with a grain or two of salt, we're not talking critical issues here:

1. For the original mass loaded foam was used for the walls. Having trouble remembering the brand name- was used on the Ardents and some other projects, too.
2. Second preference is heavy felt- 3/4". At the enclosure walls, the gaming material must be designed for high pressure and low velocity. Within the enclosure, the other way around.
3. Wood glue is fine- Titebond, or Marine epoxy. My favorite SERIOUS adhesive! I stay away from the 5 minute stuff, for the obvious reasons- no working time, and not very strong/stable when set compared with long setting time epoxy. Epoxy will be better at filling cracks than Titebond.
4. Nothing special needed; they don't need to be covered up.

[BlueBeardo]

Here are some progress pictures. I had a pretty productive weekend.

Images not available

[---k---]

Your progress looks good, but you should chamfer the back side of your mid and woofer cutouts. Without, there can be a few wiggles in the frequency response. Since the boxes are built, I suggest a wood rasp. I've done it, a rasp will chew through the MDF quickly. This almost always should always be down with double thick baffles and depending on the drivers even with single thick baffles.

[JonMarsh]

Your progress looks good, but you should chamfer the back side of your mid and woofer cutouts. Without, there can be a few wiggles in the frequency response. Since the boxes are built, I suggest a wood rasp. I've done it, a rasp will chew through the MDF quickly. This almost always should always be down with double thick baffles and depending on the drivers even with single thick baffles.

+100%

[BlueBeardo]

Thanks for the tip!. I'll make sure to do that. I seem to have skipped that step.
Any suggestions on how big to make the chamfer? 1/2", 3/8"....? Looking at the Natalie p thread it looks to be about 3/8".

[---k---]

It looks like you have a double thick baffle on your center. I would do that one as big as possible, especially on the mid. On the NatP, it looks like you use a single thickness. If so, you're probably safe following Jon's lead with the 3/8".

I went even further with my center, using a big panel bit. You can sort-of see it here, but it the plywood makes it deceiving.



The key is, stick the driver in the hole. Just as much air move off the back of the driver as the cone moves in as moves off the front when the cone moves out. You want to make sure the air can move in and around the frame easily. The driver needs to "breath". When you stick the RS150 in that hole, you'll likely not be able to see the frame vents from the top or side. Keep rasping until it looks right!

[BlueBeardo]

On the Khancenter, how should I pass wires through the speaker walls (within the speaker from crossover to crossover, not out the back). Do I just drill a hole and pass the wire through and then seal up around the wire or do I need to use binding posts?

[---k---]

Just drill a small hole and then seal it up. I've seen people do binding posts, but that is crazy, imho.

[BlueBeardo]

Good, I wasn't looking forward to paying another $12.00 to ship a $2.00 part from PE.

[BlueBeardo]

I'm still haven't quite decided what to do on damping inside the speakers. Reading through Zaph audio's article that ---k--- suggested, it seams like he just recommends stuffing for sealed enclosures. However, a lot of you are recommending padding. I was thinking about using 1/2" carpet padding around the entire box with it double up on the speaker wall. Then stuff the speaker with pillow fiber. Any thoughts? Would insulation be better, or is this a preference thing?

Also, how "full" do I want to pack the fiber-fill in?

[BlueBeardo]

---k--- looking at one of your pictures it looks like more or less just set some stuffing in. Not really any packing. Does that sound right?

[BlueBeardo]

On the Khancenter wiring diagram. When the speaker has a plus on the picture, does that mean the top wire coming into the picture diagram is the positive lead and vice versa when it has a picture has a minus. Also, on the source, how do I know which side is positive and which is negative to connect to the terminals.

[joeybutts]

On the Khancenter wiring diagram. When the speaker has a plus on the picture, does that mean the top wire coming into the picture diagram is the positive lead and vice versa when it has a picture has a minus. Also, on the source, how do I know which side is positive and which is negative to connect to the terminals.

You got it right. Plus means it is in phase, ie positive input to positive terminal.

Positive input/source is the up line from the circle.

[---k---]

---k--- looking at one of your pictures it looks like more or less just set some stuffing in. Not really any packing. Does that sound right?

That is correct. My boxes are oversized to begin with, so they don't really need extra stuffing to increase the volume. I also used high quality foam and insulation on the walls to arrest the soundwaves. So, depending on how your filler varies from mine, you may or may not need to experiment with adding a fist full or so... season to taste.

[BlueBeardo]

I clamped the backs on and wired up the speakers to make sure everything is working. All is well. Now I just need to glue the back on and paint it.

The center channel is giant! It's great. That is my old center channel cowering in the corner of my stand. I expected to wake up this morning to find that the Khancenter had swallowed it whole.

Image not available

[---k---]

Looking good. :T

[wkhanna]

V nice!
You’re gonna love em! :W

[joeybutts]

Paint me jealous. And your speakers.:P or how ever you are finishing them!

[BlueBeardo]

What's the preference for sealing the edges of the mdf (seems to be highly debated)? I was going to use bondo to seal the edges and fix any imperfections on the box. I would rather not use spackle because it is rather brittle. I plan on spray painting it with Krylon primer then Krylon satin black after doing the prep work. Any suggestions that might make life easier?