on Sale - $55/pr (drivers & XO)

[Soundslike]

Re: on Sale - $55/pr (drivers & XO)

Well, I finished the Duellati set -- I like them a lot. Also finished the Cerberus subwoofer, so now I'm returning to the NTNs and a second Cerberus I'm building for my brother.

The following photo shows the template and router with bushing installed. I attached two strips of wood on the underneath side to center the template on the baffle. Only the top pattern nearest the router, will be used -- the others were unsuccessful efforts. You'll probably notice the notes written on the template -- that became important so I could tell one from another. Only the last one is usable.



This next photo shows the recess cut with the router. You'll probably notice that it's quite a bit deeper than the thickness of the driver frame. Trim pieces will be overlaid over the driver, and I'll add gasket material under the driver. I may regret saying I'm going to trim the drivers, before I actually get it done. No backing out now...

I scribed a circle to locate the through-hole and then cut withing a quarter inch or so of the line with a sabre saw. I used a spindle sander to sand the holes out to the line. A drum sander in a 3/8 corded electric drill, or better yet a drill press, would also work reasonably well. I used this setup (drum sander in a drill) to sand out the reliefs behind the driver.



In this next view, you'll see the baffles after routing. You'll notice that I've opted to put the ports in the baffle, rather than in the back. I did that solely for appearance sake -- hopefully there's no problem identified with a front port, somewhere in this long thread. I thought about reading everything again, just in case Chris has advised against a front port, but that's a pretty daunting task. In the end, I relied on past advice that the only problem with a front port is the possibility of audible chuffing.

I've mounted ports in several different ways on previous builds. On a number of them, I didn't bother with a flare and extended the PVC completely through the MDF. That provides 3/4" of gluing surface all around the PVC, and plenty of strength. I've also rounded over the ports on several builds, with the PVC extended completely through the MDF. I didn't like having to rout the PVC however, so I've switched to the method you see here. I located the port on the inner surface of the baffle, and drilled a 1/8" hole so I'd be able to locate the port from the outer surface. Then I bored a hole with a Forstner bit, from the inside, that matches the outside dimension of the PVC. I bored to a depth of 1/2" and then glued the PVC in with epoxy. I then made reinforcement rings from scrap MDF to compensate for the lost 1/4" of glue surface area. To complete the port, I flipped them over to the outside (after the epoxy dried, of course) and then enlarged the center hole I bored before, to a size large enough (1/2") to allow inserting a flush-trim bit. I then flush-trimmed the MDF to match the inside dimension of the PVC, 1/4" below the surface. I followed that with a round-over bit to create a modest flare. I'll have more tomorrow.

[Herman Trivilino]

Re: on Sale - $55/pr (drivers & XO)

Justin, what did you use for the feet? They look really nice.

[JustinL42]

Re: on Sale - $55/pr (drivers & XO)

brianbunge,

I used 18x14.5x6 external dimensions with 3/8 rabbet joints and 3/4" mdf.

JustinL42

[brianbunge]

Re: on Sale - $55/pr (drivers & XO)

Hi Justin,

Can you tell me what dimensions you ended up building those cabinets?

Thanks!

[JustinL42]

Re: on Sale - $55/pr (drivers & XO)

Here are a couple of pictures of the Ntn's finished.





It was really hot out when we sprayed the black. First two coats were in direct sun about 90 degrees out. We ended up putting a couple more coats on in the shade and the paint flowed much better. It's always dark when we finish so the pictures are not the best.

JustinL42

[XtremeRevolution]

Re: on Sale - $55/pr (drivers & XO)

Sounds like a lot of work. I'm really looking forward to seeing the end result.

[Soundslike]

Re: on Sale - $55/pr (drivers & XO)

I've started on a set of the NTN's. Not much I can add to what has already been said about building these, but I'll post a few things that might be helpful to others who plan to build. Things are going pretty slowly, primarily because I've also got two other projects going -- I'm building a set of Mark65's Duellati, and two Cerberus subwoofers. Both of those builds are, or soon will be, documented elsewhere on this forum.

I decided to build the NTN's after being infected with all the excitement shown by the many builders who had already started their projects. I'm one of those hobbyists on this forum who enjoys the building process, and that makes me want to build everything I see. I became fascinated with the NTN's for several reasons -- I particularly admire high-value designs and this design of Chris' pretty much epitomizes that ideal. I'm really looking forward to auditioning them.

My NTN's will be finished in high-gloss piano-like black. I will also recess the drivers and will make trim pieces for the ND's to cover the thin metal frame. Why, you might logically ask? I'm tempted to borrow a quote from the famous mountain-climber George Mallory who, when asked why he wanted to climb Mt. Everest, responded, "Because it's there." That's a big part of it, I guess. I figured it couldn't be too difficult and started to scheme about how I'd make a template to use with a router bushing to duplicate the outer shape of the driver, and I liked the challenge it presented. It was tougher than I thought -- more about that later.

I followed my usual process of cutting the necessary panels from a large sheet of MDF -- first cutting pieces to a manageable size with a circular saw and panel guide, and then squaring them up to final dimensions on a table saw. I won't bore everyone with the details -- most already know how it's done -- but for anyone who's curious, the process is described in more detail in the build-strings that can be reached by clicking on the links below my signature.

I decided to follow Chris' advice and utilize dadoed joints. In fact, I've used that joint on the two other builds I mentioned above. I've used bu**t joints, both with and without screws, and biscuit joinery on previous builds and I'd say the dadoed joints are easily the best method. You end up with easier assembly, and a more accurate result. I used an adjustable dado blade to cut the dadoes, but it can also be done with a standard blade on a table saw. There are a few things you have to keep in mind however -- I'll describe the process in my Duellati build since whatever I write at the end of this very long string, isn't likely to be very visible. But, I should caution anyone who decides to use the dado joint to be sure to dry-fit the panels together before starting assembly. You need to know which panel goes where, and where to spread glue, before starting or you're likely to end up with a gooey mess.

I used the standard dimensions, if there is any such thing with this design. One of the appealing aspects of this design is the variety of different over-all shapes used by different builders, but I opted to go with the 28" by 6" by 9-1/2" dimensions.

I mentioned above that I will flush-mount the drivers. It turned out to be quite a challenge to come up with a pattern I could use with a router fitted with a bushing guide. I tried a variety of different methods but the shape is fairly complex and any small measurement or cutting error will ruin the effort. One of the first things I tried was to draft the shape in a CAD program, and then transfer the resulting dimensions to a piece of 1/4" Masonite (hardboard). Unfortunately, the data sheet for the driver only provides a few dimensions, so you're left to derive your own dimensions by measuring. To duplicate the shape, you'll need to know the radius of the arcs that form the mounting tabs, and where to place the center of that arc. Get the arc wrong, and the angled sides won't be correct. You also have to determine where the straight lines intersect the arcs on both ends. Also not easy to do. I tried a variety of different methods, but wasn't happy with the result.

I finally achieved a satisfactory result using the following process.

Select a piece of 1/4" hardboard and sand it smooth, if necessary. If time permits, apply a coat of something like varnish, lacquer, or shellac, to bind the surface better. A rough surface will cause you to draw jerky, irregular lines. If the surface is the least bit flaky, small bits will come off while you are shaping the pattern, leaving you to guess where to cut.

Draw a perfect square (I used 6" X 6"), and lay out diagonal lines corner to corner.

Find the center using the diagonal lines and draw arcs in the four corners to designate the outermost point of the mounting tabs (the outermost point, not the shape).

Draw arcs at 0, 90, 180, and 270 degrees to define the outer edges of the driver's primary shape.

draw a circle for a cutout the size you will use on the baffle (I used 3-3/4"). Cut the hole.

Place the driver in the hole and align the mounting holes with the diagonal lines. Be precise. Mark the locations of mounting holes on the pattern.

Drill the mounting holes, and attach the driver to the pattern.

Use a utility knife to trim away any gasket material that may be protruding form beneath the driver frame.

Using a fine-point pen, carefully trace the outline of the driver frame being careful to keep the pen at the same angle all the way around. This line won't be used, but you may find it helpful later on.

With the driver still mounted on the pattern, draw the outline of the enlarged shape (to account for the difference between the pattern and where the router will actually cut - in my case, 3/32") all the way around. I find the best method is to make a spacer that can be placed against the driver frame. The spacer will allow you to consistently make accurate parallel lines and marks to designate the tops of the arcs. At this point, you should be sure to check the arcs defining the primary shape at 0, 90, 180, and 270 degrees.

Two tough tasks remain -- drawing the arcs that define the top of the mounting tabs, and determining where the straight lines begin and end, and where the various arcs begin. I'm pretty sure a student of geometry could tell us how to find the radius and center points of the arcs, but I was left to experimentation. I cut a variety of arcs from thin non-corrugated cardboard, until I found the necessary size. Once the arc radius was determined, I used a compass and the intersection of the diagonal lines and the outer marks drawn earlier, as a pivot point from which to mark the center for the tab arc radius.

Once the outline was defined, I cut most of the center out with a sabre-saw, and sanded/filed to the final shape. I'm fortunate to have a spindle sander, simple sanding drums could be used effectively.

At this point, I should admit that it took repeated attempts to arrive at a usable process. Looking around at discarded pieces of hardboard and MDF littering the shop area, I find evidence of at least six attempts.





This initial post has turned out to be a lot longer than I had planned, in light of the reality that there won't be much interest. But once I waded into the narrative, I was faced with either discarding much of what I'd written in favor of something simpler, or finishing what I'd started. With my generation (don't ask) the choice is clear. Still, I can provide more detail if anyone wants it. I'll be back later with a few more photos -- right now, I'm going to make some sawdust...

[brianbunge]

Re: on Sale - $55/pr (drivers & XO)

My dad and I are each building a pair of the ntn's in 40"H tower form. He'll be building the cabinets probably tomorrow and I'll head over there one weekend soon to route all the driver holes. I'm not sure how we will finish each of them. I have several sheets of veneer but they've been in storage for a while so I'm not sure what kind of shape they're in. I'm also contemplating painting my pair but I'm not sure just how yet.

[Chris Roemer]

Re: on Sale - $55/pr (drivers & XO)

cwad8505,

Thanks man. The brackets are pretty nice and surprisingly well constructed. I'm still digging your towers too. If you ever get any really hi-res pictures of them I would love to see them. That orange is really bold!

Chris Roemer,

I got a text from my dad the other night telling me how fantastic they sound. Between the new speakers and him recently getting hearing aids he has really been rediscovering his love of music. I even got a text from my mom saying she enjoyed them as well. Thanks again for hatching out this design. You have created a monster of a thread of people who have built them. Partsexpress really should showcase these and then put the nd105s on sale again.
---------------------------------------------------------------------------------------

Also if anyone else has experience with the dta-100 vs the Lepai. I have both now and I think the Lepai sounds better than the dta-100. Wishing I hadn't forked over the $99.00 for the dayton now. I really like having the bass and treble adjustment and the tone defeat on the lepai, plus it worked great out of the box and I haven't noticed any dimming of the lights when the 'bass beats hit' like extreme did. On a side note it was kind of funny that the lepai came with a Vonage branded power supply.

JustinL42

You're entirely welcome, I'm glad your parents are enjoying them.

Chris

[JustinL42]

Re: on Sale - $55/pr (drivers & XO)

cwad8505,

Thanks man. The brackets are pretty nice and surprisingly well constructed. I'm still digging your towers too. If you ever get any really hi-res pictures of them I would love to see them. That orange is really bold!

Chris Roemer,

I got a text from my dad the other night telling me how fantastic they sound. Between the new speakers and him recently getting hearing aids he has really been rediscovering his love of music. I even got a text from my mom saying she enjoyed them as well. Thanks again for hatching out this design. You have created a monster of a thread of people who have built them. Partsexpress really should showcase these and then put the nd105s on sale again.
---------------------------------------------------------------------------------------

Also if anyone else has experience with the dta-100 vs the Lepai. I have both now and I think the Lepai sounds better than the dta-100. Wishing I hadn't forked over the $99.00 for the dayton now. I really like having the bass and treble adjustment and the tone defeat on the lepai, plus it worked great out of the box and I haven't noticed any dimming of the lights when the 'bass beats hit' like extreme did. On a side note it was kind of funny that the lepai came with a Vonage branded power supply.

JustinL42

[cwad8505]

Re: on Sale - $55/pr (drivers & XO)

Wow...nice progress...those pinpoint mounts are the cat's meow, aren't they? Nice work, Chris W.

[JustinL42]

Re: on Sale - $55/pr (drivers & XO)

Greywarden,

That's pretty good! He's going to add white screens to them so the name is fitting!

JustinL42

[fastbike1]

Re: on Sale - $55/pr (drivers & XO)

That's good! Brightens up a Monday morning.

Incog-Neos?

:D

[greywarden]

Re: on Sale - $55/pr (drivers & XO)

Incog-Neos?

:D

[Chris Roemer]

Re: on Sale - $55/pr (drivers & XO)

Chris,

I figured you would like the white ones. I've seen your picture gallery! He got the brackets on amazon, they are pretty well made. They only had black so we sprayed them the same color as the speakers on all exposed parts. They clamp down really well and then it's also screwed to the bottom of the cabinet. We may have to modify the bracket to allow the speakers to angle down more to the listening area. I wish they didn't have to be so high up but the glass really rules out anything lower.

JustinL42

I've heard in-ceiling surrounds. I'm sure they'll be fine.

Chris