ZDT 3.5 Curved Cabinet Build

[Mark_1042]

I’ve got a lot more updates to post. The finishing steps are taking a little longer than I expected, and a couple mishaps along the way sort of slowed things up. I’ll try to bring the thread up to speed.

[Mark_1042]

Drilling Some Holes for the Binding Posts:

After putting on the baffles I had to add the last layer of hardboard to cover up all the seams. Before putting the final layer of hardboard on the back I drilled some holes through into the crossover chamber, since the terminals on the back of the binding posts are too short to make it all the way through. Once I get the veneer on I’ll drill some holes through the veneer and hardboard to install the binding posts. I’ll have to be very accurate because I made the holes in the MDF just large enough for the socket that will be used to tighten down the nuts on the back of the binding posts.

Binding posts are from Parts Express: http://www.parts-express.com/pe/show...umber=091-1150 Great binding posts for the price – nice finish and they accommodate a banana plug, so exactly what I was looking for.






Holes drilled through the MDF:



Now with the hardboard over the top:

[Mark_1042]

After putting the final layer of Masonite/hardboard on the back, it was time to put the final layer on the sides. These panels were a little wider since I had added the extra ¾” baffle to the front, so it meant that the caul which I had made wouldn’t be wide enough (and I actually didn’t figure this out until I was in the middle of clamping down one of the panels :B). As you can see in the pic, the caul doesn’t come all the way to the edge of the speaker:



It really showed me how much the caul helped out. With the caul not coming all the way to the edge, the panel bowed up between the straps. So as a fix I added some clamps between the straps. It worked out pretty well, they came out without any waviness along the front edges.

[Mark_1042]

Here’s some pictures of what the layers looked like before putting the final layer of Masonite over the top. The first picture is a front corner, second is a back corner:

[Mark_1042]

Here’s the two mistakes I had to fix when finishing up the cabs. When I was putting the baffle on one of the speakers I put a clamp in a bad spot and managed to break a glue joint on the back panel. I usually keep the clamps near the shelf braces or use a 2x4 to spread out the pressure, but wasn’t really paying attention here and put a clamp right next to a port hole (opps :B). I carved out some material around the joint so I could get some epoxy in there. The panel was also caved in a little bit, so I had to put a piece of wood inside the speaker to wedge the panel back out while the epoxy cured.





The other mistake was a loose section of hardboard on the final layer. Either I didn’t use enough glue, or didn’t get enough clamping pressure, or maybe a little bit of both. Whatever the case, I could knock on a section of panel and hear the panels slapping together. I thought about leaving it but I think it was bad enough that it needed to be fixed, so I cut out the section and put in a new piece with some epoxy. Using some sandpaper and a plane I was able to smooth it out pretty good, so with the veneer on I don’t think it will be terribly noticeable (if at all).

[Mark_1042]

A couple more tidbits before getting to the veneer, I added the hardboard to the tops and installed some magnetic grill guides:





If your speaker gets a headache, put some ice on it – or some sand… maybe. I didn’t have any bar clamps long enough to attach the tops, so sand bags were the weapon of choice. In this shot I’ve also got the magnets bondo’ed over:

[Mark_1042]

Before I started on the veneer, I did a couple adhesion tests. I thought I’d post the results for anyone who is interested. I’ve laid veneer over Bondo before and got good results, and I’ve seen a lot of other people report good results with it as well, but I wanted to see how strong the bond was so I set up a test piece. This is a layer of hardboard with a layer of Bondo over it, and then another layer of hardboard glued to it with Titebond II. The hardboard and Bondo surfaces were all sanded with 60 grit sand paper prior to gluing. I was actually pretty surprised with how strong the bond was. For a while I thought I wasn’t going to be able to pull them apart with my bare hands, but eventually I found a loose spot and pried them apart from there. You can see that some of the Bondo was still stuck to the glue, so it seems like it got pretty good adhesion. Certainly nothing like a wood-on-wood joint, but much stronger than I had expected:









The other test I did was a piece of veneer, glued down with Titebond II over Loctite 60 Minute Epoxy. I did this test because I wanted to make sure the veneer would stick to the areas that I had repaired with the epoxy. Again, much better results than I had expected. Same as with the Bondo, there was a lot of epoxy that was still stuck to the glue when they were pulled apart. The bond was strong enough that it caused the veneer to separate from the backing when I pulled them apart:

[Mark_1042]

Before attaching the veneer, I flattened it out with some Woodcraft veneer softener. It’s the first time I’ve ever used the stuff, it made the veneer a lot easier to work with and was definitely worth the twelve bucks. I used it pretty sparingly, but half of a bottle was enough to flatten out a 4x8 sheet of veneer (already cut up into the sizes I needed). I used a roll of Menard’s construction paper to separate and dry out the veneer sheets, with some weights stacked on top:

[Mark_1042]

Perhaps this is a testament to my sort of unconventional way of doing things, but to attach the veneer I used Titebond II, and used sandbags to hold/clamp the veneer down while the glue cured (and using a layer of scrap hardboard as a seperator between the veneer and the sandbags). I was giving serious consideration to using contact cement because it seemed like it would be the surest method for the curved surfaces; but I still had a decent amount of Titebond II left, and if the sandbags didn’t get the veneer down well enough, with Titebond I figured I could just re-activate the glue with an iron and smooth out any bad spots. One thing I found out is the sooner you re-activate the glue, the better. I think that Titebond says the reactivation has to be done within 12 hours, but I found that within 8 hours seems to be the best. After that I found it to be much more difficult.

Laying veneer seems like such a tedious process, it’s still something that I’m getting used to. After doing it this way I’m thinking that perhaps contact cement would have been the better choice, since I still ended up with a couple (very small) loose spots, but I guess only time will tell.

[Mark_1042]

For trimming around the speaker and port tube rebates I used my specialized veneer trimming bit. Personally, I think this thing works like a dream and I couldn’t imagine doing these speakers without it. The oak veneer is pretty hard and I can trim it with a razor blade going with the grain, but across the grain, forget about it.

I made this from a laminate trim bit, and just cut off the bottom with a diamond Dremmel blade so it can get into more shallow recesses. The rebates for the port tubes on these speakers are less than 1/16” deep, and it still made it in there, so it can definitely make it into some tight spaces. The only drawback is that the bearing wears into the MDF quite a bit, but I didn't find it to be too much of an issue.

[Mark_1042]

After getting off to a fast start the veneering on these is now going pretty slow. On one of the sides some of the veneer is loose where it meets the front edge. To avoid getting glue on the veneer face I think I'm going to wait until after I get some stain and a layer of shellac on it to fix it. I've also got some small loose sections of veneer in the center of some of the panels, so I've been working out a method for fixing those. I think I'm going to cut them open and shoot some glue in with a syringe, but I wanted to make up a test piece and try it first to make sure I don't muck anything up.

[Steve Manning]

After getting off to a fast start the veneering on these is now going pretty slow. On one of the sides some of the veneer is loose where it meets the front edge. To avoid getting glue on the veneer face I think I'm going to wait until after I get some stain and a layer of shellac on it to fix it. I've also got some small loose sections of veneer in the center of some of the panels, so I've been working out a method for fixing those. I think I'm going to cut them open and shoot some glue in with a syringe, but I wanted to make up a test piece and try it first to make sure I don't muck anything up.

I so hate when veneer lifts up ..... I have a few spots on the equipment rack I built a while back that occurred after it was all together and in use for awhile. One of these days I'm sure I'll have it appart for something and will fix it then.

[Mark_1042]

I so hate when veneer lifts up ..... I have a few spots on the equipment rack I built a while back that occurred after it was all together and in use for awhile. One of these days I'm sure I'll have it appart for something and will fix it then.

Yeah, it was driving me nuts on these speakers. Just when I thought I had all of them fixed I'd find another part that was loose. I think I've got all of them fixed now, though. I'm hoping to wrap up the veneering on these this weekend, so I should have some pictures up soon.

[TEK]

How is this going? Did you get it fixed?

[Mark_1042]

How is this going? Did you get it fixed?

The veneer on these is fixed for the most part. There's still a couple loose edges that I was going to leave and fix them once I got some finish on, but I'm planning on just fixing them before finishing and if any excess glue gets on the veneer face I should be able to just sand it off. The speakers are pretty much ready for finishing and have just been sitting aside for a while. I should be stoked about getting them done, but every time I think I'll get a chance to work on them something else seems to pop up (broken washing machine, car maitenance, and some school work). I'm sure I'll be psyched when the time comes to get them done :B, I'm just not too sure when that's going to be. I'm thinking within the next 3 weeks or so.

I'll have some new pics coming soon with some updates. One thing I did find is that the small spots in the middle of the side panels where I thought the veneer was loose, I think its actually the final layer of Masonite which is loose. I'm guessing that not using a proper clamping caul or perhaps some issues with the glue (not enough or perhaps not mixed well enough) is the cause. It kind of sucks because there's not really much I can do now with the veneer on, so I'm just hoping it won't have any noticeable effect on the sound. I thought about dropping the drivers in and "testing" them but if they sound good I'll probably never get them finished. :B

[TEK]

I know excactly what you mean.
Im building a sub - and have assembled it and set it into work while I try to get my hands on some veneer.
It is very easy to just get pleased and let it be there - 3/4 finished.

When it comes to time I have found out that it is quite important not to rush stuff.
At least I'm doing this for fun - remembering that and doing this stuff when I want - and not because i must - seems to be a good rule of thomb...

[Mark_1042]

I know excactly what you mean.
Im building a sub - and have assembled it and set it into work while I try to get my hands on some veneer.
It is very easy to just get pleased and let it be there - 3/4 finished.

When it comes to time I have found out that it is quite important not to rush stuff.
At least I'm doing this for fun - remembering that and doing this stuff when I want - and not because i must - seems to be a good rule of thomb...

Right, I've got a few projects that are about 3/4 finished - sub (needs poly), center (veneer), and speakers.

Like you say - not rushing, I've found, especially with the finishing steps, is a good rule to go by.

[Steve Manning]

You guys sound a lot like me ....... I hate the finishing part of pretty much anything I build, especially when something like the veneer lifting up in the middle of it rears it's nasty head, I feel for you Mark. I just had to deal with some small cracks that showed up in my bubinga trim on my project ..... after 2 coats of finish were already on :x So I've been trying to fix that for the last couple of days, did discover that CA (aka Super Glue) will soak through the finish and into the cracks anyway, hopefully my touch up on the finish will look OK when I'm done. I'm trying TEK's advise and taking it slow which is sometimes difficult when you want to hear the finished product, oh well.

[cjd]

Now you guys know why I like the look of plain birch ply so much!

[Mark_1042]

You guys sound a lot like me ....... I hate the finishing part of pretty much anything I build, especially when something like the veneer lifting up in the middle of it rears it's nasty head, I feel for you Mark. I just had to deal with some small cracks that showed up in my bubinga trim on my project ..... after 2 coats of finish were already on :x So I've been trying to fix that for the last couple of days, did discover that CA (aka Super Glue) will soak through the finish and into the cracks anyway, hopefully my touch up on the finish will look OK when I'm done. I'm trying TEK's advise and taking it slow which is sometimes difficult when you want to hear the finished product, oh well.

Good to know that the gluing part went well, hopefully the finish touch up will go just as well.

[Mark_1042]

Some updates which are long past due. I finished repairing the loose edges on the veneer this weekend. I really like the heavy flake on this veneer, its much more pronounced than it was on the roll which I used for my sub and center. I'm totally stoked about getting these finished - the stain which I got from Sherwin Williams really brings out the flake in the veneer and gives it that sort of "3D effect" when you look at it from certain angles. If all goes well I think the finish is going to look pretty sweet. Now I've just got to cross my fingers, lay out my plan and hope I don't screw anything up :wink:









A picture of the flake on the front:



And on the side:




Rear:

[TEK]

Those are looking really amazing

[Steve Manning]

Very nice job on the veneering Mark ...... those are going to look sweet when the finish is on them!

[Hank]

Good work, Mark!

[Mark_1042]

Thanks guys. I'm hoping to be able to get the finish on within the next 2 weeks, so I'll be biding my time until then.

[Mark_1042]

Thanks guys. I'm hoping to be able to get the finish on within the next 2 weeks, so I'll be biding my time until then.

Did I say the next 2 weeks? ...next 2 months, maybe. :B

Well, I had a couple issues with the finish on these so things are running a little behind. I just started putting a new finish on them this week so with any luck, they'll be done soon.

[Steve Manning]

Did I say the next 2 weeks? ...next 2 months, maybe. :B

Well, I had a couple issues with the finish on these so things are running a little behind. I just started putting a new finish on them this week so with any luck, they'll be done soon.

I can sooooo relate ......... keeping plugging you'll get there ..... at least that's what I'm telling myself

[Mark_1042]

I can sooooo relate ......... keeping plugging you'll get there ..... at least that's what I'm telling myself

Pretty much, I had quite a few setbacks with these during the finishing steps and not much time to work on them, so it took a long time to finish them up.

The finished pictures will be coming shortly, although I'm not sure if they'll measure up to the craftsmanship of the 1071's.

[Mark_1042]

I'll try to keep up the same level of detail I started the thread with - maybe it will help build the suspense a little bit.

Here's some pics of drilling the holes for the binding posts into the crossover chamber. I had already drilled larger holes through the MDF earlier, so these holes only had to go through the veneer and a layer of masonite. I used a Harbor Frieght drill guide to keep the holes straight, and drilled the holes before sanding/putting on the finish, just in case the base of the drill guide left any scratches on the veneer.

The drill guide is a great tool if you don't have a drill press or have a project that won't fit on a drill press. I've actually never seen one before but saw it recommended in one of the tool threads on this forum. The Harbor Freight model has a little bit of play in it so the holes it drills aren't perfectly straight, but for me its better than doing it without one. For brass inserts something a little more accurate might be better, but for wood screws it seems to work well. The Rockler version also might be a litte more precise:



Holes drilled and testing the fit of the binding posts. Before sanding and finishing, I also drilled the holes to mount the drivers.

[Steve Manning]

Pretty much, I had quite a few setbacks with these during the finishing steps and not much time to work on them, so it took a long time to finish them up.

The finished pictures will be coming shortly, although I'm not sure if they'll measure up to the craftsmanship of the 1071's.

I'm betting they look great, especially seeing what you've posted to this point, the veneer is looking very nice.

[Mark_1042]

Here we are with the finish on and the drivers being installed. Probably a rookie mistake, but my driver cutouts were a little deeper than they needed to be, so I made some gaskets to get them to flush out with the front of the baffle. For the woofers I made gaskets out of some left over vinyl damping material, which turned out to be the perfect thickness. For the mids, I just used a layer of black construction paper. Not the most glamorous solution, but it did the trick.

I think the reason that the woofer cutouts were too deep was because of the way I measured the flange thickness - I just put a caliper over the flange and the factory gasket and sqeezed as hard as I could, and it must not have compressed the gasket as much as when the speakers were mounted. (the factory gasket probably compresses to almost zero thickness when the speakers are mounted, so isn't even worth including in the measurement) I'm not sure why the mid recesses were too deep, probably just an error in measurement.

In the first picture here you can see the warm orange "glow" that I was looking for. This finish is almost a perfect match to my TV stand and oak end tables, but I made a couple errors in the application that I'll get to later.





To secure the tweeter, I just applied some silicone caulk around the flange. To mount the mids and woofers, I used Special drywall screws, which were the perfect size for the countersinks on the midrange:

[Mark_1042]

I'm betting they look great, especially seeing what you've posted to this point, the veneer is looking very nice.

Thanks Steve, I am happy with the way they came out. Just some of those small errors that are hard for the builder to ignore (a couple streaks in the finish), but I'm hoping they'll become less of an issue over time, and for most people will go unnoticed.

[Mark_1042]

Last but not least, installing the port tubes and binding posts. Another thanks to Jason (a.k.a. oneplustwo) here for the advice - he built these same speakers and said that he didn't get any port noise using a single flange tube. I think a double flange is recommended for this driver and cabinet size, but I wanted to avoid the additional time and cost, so just stuck with the single flange tubes that come with the Parts Express kit.

IIRC, by my measurement I would have had to cut about 1/8" off of these tubes to meet Zaph's specification for 40Hz tuning exactly, but to avoid the extra hassle I just left them as is. I laid a bead of (clear drying) caulk around the flange and cutout to seal around the tubes, and wiped off the excess:





The crossover chamber was pretty tight, so soldering the wires to the back of the binding posts was a bit of a chore. They didn't come out looking the most professional, but I got a good connection and they should hold. The binding posts aren't installed here, but this is a pic of the crossover chamber and binding posts holes:

[Mark_1042]

I'll try to get some better pictures of the pair up later, but for now here are some pics of a finished speaker with the grille off:

[Mark_1042]

And with the grilles on:







And the completed system (except for the subwoofer). The center channel (which pulls out of the cabinet under the TV) still needs to be veneered and finished:

[Steve Manning]

Those turned out great Mark:T I really like the clean look with you using the magnets for the grills. So inquiring minds want to know, how do they sound?

[Mark_1042]

Thanks Steve, I was going to wait a little while to post my thoughts, but I think I've spent enough time with them already... I had the center channel running for a while now, and have had the towers hooked up for about 2 weeks now. Great speakers all around, but they probably won't be the last speakers I build (not like the first set ever is for any of us )

The first thing that really caught my attention was the clarity and realism of percussion instruments. Snare drums sound crisp and life-like. Like others who have built these speakers, I also think that they image well - very good placement and seperation of instruments. But I think the biggest strength of these speakers lies in female vocals, in my opinion they are nothing short of spectacular. I don't normally listen to female vocalists, but these speakers got me to dig out some CD's/music that I rarely listen to. Taylor Swift's first album sounds amazing, it sounds like she is right in the room - and the same with the Band Perry's "If I Die Young." I don't think I've ever cranked up Taylor Swift before :B, but I think even people who aren't fans would find it hard to stop listening. Even at high volume the vocals are crystal clear.

As for weaknesses, if I had to point out one flaw I think that at times they have a tendency to sound a bit unnatural, and perhaps a little lacking in the "warmth" which I think is more common with paper cone speakers - but it is something which seems to be more apparent when watching TV and using them as HT speakers, and it seems to be less noticeable when watching blu-ray's so perhaps its an issue with the source. Either way, I think these speakers are great for watching movies and very detailed. Also I should probably note a couple things here: I modified the baffle dimensions of the center channel so it would fit below my TV, I'm not sure how big of an effect that might have. Also my center channel placement probably isn't optimal, but after experimenting a little bit I don't thing reflections off of the cabinet doors are an issue. And, I didn't use any roundovers on my baffle corners - so there were a couple design changes I made that one might want to keep in mind.

But overall, I am satisfied with these speakers and I think they are great speakers. Contrary to other reviews, I don't find them to be lacking in the bass department. I also haven't auditioned very many Hi-Fi speakers, so I don't have much to compare them to. They definitely blow the Polk RTi-A7's which I had out of the water. The best speakers I can compare them to is a pair of B&W 683's which I auditioned, and I'm not sure if they top the 683's because I didn't spend much time with them, but I think they definitely come close.

[sdl2112]

Mark, Flawless...you did a really nice job on the whole speaker. You nailed the veneering and finish :T

[Mark_1042]

Mark, Flawless...you did a really nice job on the whole speaker. You nailed the veneering and finish :T

Thanks sdl, that really means a lot. I don't think I could have gotten a better match on the color so things went great there. I did end up with a couple streaks in the finish but I'll try to resist the urge to point them out when people are over, and just wait to see if anyone notices (nobody has noticed yet).

If any readers are wondering these speakers sound great with most rock and country music (which is what I listen to most of the time). I had thought HiFi speakers might be a little too detailed for the type of music I listen to, but for the most part they sound great, with the exception of some songs which I'm assuming are just poorly recorded. Classical and instrumental music sounds phenomenal. :T

[wkhanna]

Those are V nice.
Difficult to distinguish from a Hi-End retail cabinet.
Enjoy!

[Ntruder]

Trimming Off Excess Material:

After all the panels were on, I trimmed off the overhanging material. This was covered in one of the recent build threads, but the overhang on the front/back edges can be trimmed off using a straight cut bit. I used double sided tape to position a strip of 1”X2” on the front and back panels, and this allowed me to come down on the overhang with a 1/2” straight cut bit. For the extra material on the top/bottom edges, a flush trim bit can be used. I don’t have any picture of these steps, but I’ll try to get some and add them later.

Can you try and explain this process a little more? I'm not following, and am trying to figure out how this is done

[Mark_1042]

Can you try and explain this process a little more? I'm not following, and am trying to figure out how this is done

Hi Ntruder,

I borrowed a picture from another build to show you what I mean. In the picture below he's stacked up two pieces of MDF to put his router on - this gets the router elevated so you can plunge down on the overhanging material (or come across it) with the end of the bit. In the pic below a flush trim bit is being used - this is the safest way to do it because it keeps you from plowing the bit into the MDF that the router is resting on and gives you much better control, but you can also just use a straight cut bit which is what I did.



I used the method shown above to trim the overhanging material on the front/back edges. For example, to trim off the extra material on the corner where the side meets the baffle, stack the MDF on the baffle face and come down on the overhang with the end of the bit. I should also note that you don't really want to try to get it flush as it's fairly easy to take too much off - just get it close and use a sander to bring it flush.

Hope that helps.

[Mark_1042]

Those are V nice.
Difficult to distinguish from a Hi-End retail cabinet.
Enjoy!

Thanks for the compliments wkhanna, very much appreciated.

[Hank]

Great job, Mark! I hope they "warm" up a bit for you over time. Actually, my experience is that paper cone drivers sound warmer than metal cones.