My NatP's - 1st time DIY, help needed!

[Frank2808]

Hi guys,

After a week or two of reading I've finally decided to begin on my NatP cabinets this weekend. Just a word of warning: I have very limited tools, and no wood working, or electronics experience. I thought that this thread would be a good resource for other complete noobs like myself. I'll be bolding the actual question in each post for easy reference.

My first question:

I plan to build the bookshelf version of the cabinet due to space concerns. The DIY thread uses a prefab cabinet and all of the detailed NatP threads I found depict the tower version. Does anyone have any detailed plans on the bookshelf cabinets? Or know where to get them/make them?

Thanks!!

[Hdale85]

I'm almost posative that the prefab enclosure for the Nat P's is the same as the Modula MTM which is the 1Cu Ft Parts Express enclosure seen here

https://www.parts-express.com/Dayton-Audio-MTM-1.0BK-1.0-ft-MTM-Cabinet-Gloss-Black-302-750?quantity=1

Its either this one or the .75 Cu Ft enclosure....I'd have to look again to be sure.

Edit: Ok I just checked and yes its the 1 Cu Ft enclosure

[ThomasW]

Does anyone have any detailed plans on the bookshelf cabinets? Or know where to get them/make them?

The NatP is exacty the same box as the ModulaMTM

[Frank2808]

Thanks for all the help guys! I've been working hard this weekend modeling the speaker cabinets in Google SketchUp (If you haven't used this program yet, I suggest you take a look. It's already saved me MANY miscut pieces of MDF ) My next question:

What is the radius of the holes that need to be cut for the port in both the brace and rear of the cabinet?

and

What is the radius of the other two holes cut in the brace?

I know it's a 2" port but based on the pictures it looks like both ends require a larger hole.

Thanks!

[Frank2808]

Bump since I posted this on a holiday...

[ThomasW]

This is the last of this kind of question I'm going to answer. This is a DIYourself, not 'get someone else to do it for you' project

http://www.psp-inc.com/psp-inc.com/public_html/instructions.htm

Most people take their measurements from the ports when they receive their parts order.

[JonW]

This is the last of this kind of question I'm going to answer.

Easy, killer. :P


Thomas is right. Don't cut any holes until you have the components in your hands. Driver holes, port holes, etc. You really don't want to be 1/32" too big or too small. Patience, young grasshoppper.

[Frank2808]

Holy cow! I certainly didn't expect that type of response, especially when this forum seemed to be so helpful. I'm definitely not asking someone to do the work for me. I spent the entire weekend reading other posts and trying to model the cabinets in SketchUp. The only measurements I couldn't find was the size of the holes for the port and brace. It makes perfect sense to make the cuts once I receive the components but I was trying to get my model as close to perfect as possible. (Measure twice, cut once). Like I said in my initial post, I have never done any type of woodworking or electronics project so I'm learning all of this for the first time. Please, go easy on me.

[JonW]

Please, go easy on me.

Don't worry. People are super helpful here. And Thomas is tops among them. Heck, just think about that Nat P you're making- Jon designed the thing from scratch (no small effort) just so that folks like yourself could try out some DIY. I don't know much about building speakers, but when I've learned is from a couple books and everyone here being really patient and answering all my newbie questions. The folks here are great.

[Frank2808]

He definitely knows what he's talking about, and I'm grateful that he took the time to design such a great speaker. I just didn't think my question was unreasonable, especially since the measurements I requested are not listed anywhere in this forum (at least I didn't find any) and I prefaced this thread by stating that I had no idea what I was doing.

To this point my biggest woodworking project has been a skateboard ramp that I built 18 years ago.

[JonMarsh]

The Modula MTM is where we hid the juicy details...

The Modula MTM and Natlie P are kissing cousins; actually, they're even closer than that.

Only difference of note is the crossover. So, most of the gory mechnical details were left to the Modula MTM thread, primarily in the very first post which was updated as things went along.

Modula MTM

[Frank2808]

Ah thanks Jon. After reading the Modula MTM thread things seem clearer. I'm going to start cutting this weekend and I'll post my progress on Monday. thanks again!

[Frank2808]

Hello guys! Attached is my first contribution for all those other noobies out there like me. I've spent the past week learning Google SketchUp and then creating a 3d model of the NatP bookshelf enclosure. The attached file contains a model of both the cabinet and the proper cuts to make in a sheet of MDF from Lowe’s. The model allows you to actually fit the pieces together to ensure a proper fit. Please let me know if you find any mistakes.

For those of you who don't use Google SketchUp you can get it here

Thanks!

[ThomasW]

Might be a good idea to post screen shots or exported generic graphic files of your drawings. Doing this means people don't need to install a trial version of a $500 software package to simply look at your drawings.

An excellent freeware program for capturing images in a screen is MWSnap3

[Frank2808]

I don't have a place to host photos but I have uploaded the model into the Google Warehouse. You can view the model here

Google SketchUp is free for personal use. Although it has a few less features then SketchUp Pro (the $500 version) it is more then ample to model most projects.

[soho54]

Don't forget the brace panels. You also might want to double up on the baffle.


EDIT: Is the green panel a brace or second baffle layer?

[soho54]

You also may want to rotate your cuts. Rip instead of crosscut.

[Frank2808]

Thanks for your comments! the green piece is the brace. Are you suggesting that I add a second layer to the front panel?

[seattle_ice]

Thanks for your comments! the green piece is the brace. Are you suggesting that I add a second layer to the front panel?

Yes, he is. If you make the inner piece fit inside the four walls and the outer one the same as the outside of the four walls, you get a very well fitting rabbet joint for free.

[soho54]

Are you suggesting that I add a second layer to the front panel?

Yes, and I agree 100% with seattle_ice's comment about the "rabbet joint." If the green piece is a brace just cut two and mount one to the baffle back before you route out the holes. That way you get a thicker baffle and more surface area for the glue to hold the baffle on to the box.

[ThomasW]

If you add a second layer to the front baffle you'll need to back bevel the area behind the woofers. Otherwise the thick baffle will block the rearwave coming off the back of the cone.

This is a different speaker but it shows back beveling

[soho54]

In your first post you said, "I have very limited tools, and no wood working, or electronics experience." We are assuming you have a router available, with a few straight and chamfer bits. I think you need to give us a tool run down before we give to much advice or things could go bad.

[soho54]

Have you looked at this thread? otp-e

Just shorten the height to your needs and readjust the port. You should be able to pull this off with a skill and jigsaw. The drivers would just be surface mounted.

EDIT: I would probably increase the depth to 12" or 13" myself, for a non-tower.

[Frank2808]

Thanks for all the help thus far! I've tried to stick to the design of the PE 1cu ft. enclosure that the speaker was originally designed for. I'm assuming that you're suggesting a deeper cabinet to add bass? If all goes well, I plan to build a sub as well so that may make up for the lack of low end. My main reasoning around not building a tower is because I want to put these on some bookshelves on either side of my plasma TV (which is hanging on the wall)

Although it's not visible in the picture I posted, I had designed for a rabbet joint to be routed out of the front baffle so I could just as easily create the rabbet by attaching another piece to achieve the same effect as well as add thickness.

As far as tools go, I have a router, table saw, and other tools that I can borrow, however I've never used any of them.

[soho54]

I'm assuming that you're suggesting a deeper cabinet to add bass?

No. The depth would have to be increased to get to the the suggested size of 30 liters net, if you cut it in half to do a bookshelf design. Just my opinion. :B

EDIT: It would be better in the bass department though.

[Frank2808]

The enclosure I pictured is 13.5 inches deep. (based on the PE cabinet I'm using as a model). The PE cabinet has a baffle that is 1" thick. If I add a second piece to the back of my baffle it will be 1 1/2" thick. Will this extra 1/2" affect performance significantly? If so, I could make the cabinet 1/2" deeper to compensate.

[yousuredo2]

1 outer front panel peice of 1/2 or 3/4 mdf full sized
1 inner front panel peice of 1/2 or 3/4 mdf less than full size to fit inside the four walls...

[soho54]

The extra .75" will take up about 1-2 liters. Not a big difference, you probably would not be able to tell. Yes, you can extend the back to make up for the lost volume with no ill effects.

[soho54]

What are the outside dimensions of you design? You can't read them in that pic.

[Frank2808]

the 13 1/2" depth is the outside dimension of the cabinet.

Here's a link to the specs of the PE cabinet that I used as a template:

link

[soho54]

So you just copied the PE cab, with no changes other than the 3/4" baffle apposed to the PE 1". I missed that somehow. In that case I would go ahead and double up the baffle, and leave everything else as is. You only lose 1.3 liters compared to the PE cab that way. You want miss it. Remember PE has to consider shipping weight when designing their enclosures, you do not.

[Frank2808]

Awesome! Thanks!

It sounds like after I add the second layer to the baffle my cabinet design will be finalized. Can you recommend a glue to use to stick everything together? I was planning on counter sinking some screws for added stability.

[soho54]

Glue- Titebond I or II
Just FYI, if you are going to use screws and glue, glue and clamp the pieces together first then add the screws with the clamps still on. Once the screws are inplace you can remove the clamps. Screws by themselves do not apply enough pressure for a good glue bond. Trust my years of trying to find an easier way.

EDIT: Note I did not say "many years." :B

[Frank2808]

I placed an order with PE to get the ports and terminals. I'll be heading to Home Depot to buy the glue and MDF on Saturday morning. I should be able to complete both cabinets except for the holes in the baffles this weekend. I'll post pics asap.

Thanks again for all the help! ;x(

[seattle_ice]

There is a trick to using screws with MDF. (Actually - any time you are using screws to clamp with). If anyone knows this already, ignore this info.

What you do is use a countersink to drill the hole initially. Use a #6 countersink for #7 drywall screws. Then you go back and enlarge the through holes on the piece with the countersink by a size or two. That way, the threads are only grabbing the piece underneath, and the head of the screw clamps much more effectively. I would still clamp the pieces together as well as possible first.

[Frank2808]

Wow that's great info!! I'm glad you mentioned that!!

In preparation for my build this weekend, any particular type, size of screws I should use on 3/4" MDF? Also, once everything is dry, should I seal everything up with silicone caulk?

Thanks!!

[seattle_ice]

If the edges of your pieces fit well, the glue should provide an airtight seal. I usually use my finger to form a glue bead after I clamp the pieces and the glue starts squishing out. If you are concerned, it doesn't hurt to caulk it later just to make sure.

I usually use #7 x 1-1/4" coarse thread drywall screws, if I use screws at all.

[soho54]

Any updates?

[Frank2808]

Hey there! I haven't forgotten this project but due to some family matters I was unable to start yet. I have a date with a table saw this Saturday afternoon...

[Frank2808]

Ok I finally gave this project a shot and I'm pretty happy with the results. I don't have the drivers yet so I haven't cut the baffles. There's still a small amount of trimming around the edges to make everything flush.... THANKS to all of you for the help! I'll be finishing up in the next 2 weeks and I'll post more pics when I make progress....


Drawing everything out on the MDF...



I used the port cut to length to figure out where the brace goes. The port is only there for reference, it's not glued in or anything yet...



And the end result with the hole cut for the terminals on the back...

[Exocer]

Thats exciting! looking great so far.

[Frank2808]

Thanks! I was wondering, what is the easiest way to trim the sides to make them completely flush? I know a belt sander is probably the best for small areas but some sides seem to have a little too much overhang to handle with sanding. Is there a special router bit that does the job?

[big_ezy]

Yes there is a special router bit that will handle this assignment. It is called a flush trim bit. It is a straight bit with a bearing at the bottom. HTH

Earl

[ThomasW]

The method Earl posted is significantly better than trying to do this with a belt sander...

[BillPhillips]

I can't imagine a more effective thread to convince me to buy my enclosures from PE

'And, as I have no router, mark out the openings and pay a pro to make the chamfered cuts, etc.