SevenSixTwo - InDIYana 2018 Coax Design

[KEtheredge87]

Hello again everyone,

More fiddling with XO stuff tonight. I got brave (relatively speaking) by taking out both of the parallel notch filters that I had in the tweeter section, then gave things a listen. It took me a while to recognize it, but there was definitely a noticeable increase in energy at the 5 kHz range. Honestly, I am not sure I heard it during any of the sample tracks I've been using (InDIYana 2017 house mix, if your curious), but I heard it loud and clear during each sine sweep taking frequency response graphs. The attached FRD plots at 0,15,30,45, and 60 degrees bear this out. I also think that leaving the 5 kHz range untouched does a disservice when the 7k-10k range filled in nicely off-axis. Using that notch filter to reign in the 5k range seems to keep everything fairly consistent until 11 kHz and above.

Having said all that about the 5k filter, what I did NOT notice was any meaningful contribution from the second notch filter that was trying to improve the ~11 kHz to 18 kHz range. All the music sounded good to my ears whether that extra notch was included or not. I'm pretty certain I can remove these three components and buy a few more resistors! The attached XO diagram doesn't show it, but several of those resistors will be combinations of series and parallel groups for the power consumption reasons that I've worried about ad nauseum to this point.

I'll take a few more measurements in a couple days when the 5mH inductor and 50ohm resistor groups arrive. Until then I really need to get off my butt and get back to the garage for some more woodworking. That veneer isn't going to install itself on the test cabinet, and I'm pretty sure I've got a few bondo places to clean up first!

I'm not sure I can ever say this enough, but seriously guys... thank you all for following along and providing helpful hints and experience. I'm sure this would be more of a "squawk box" than a legitimate attempt at DIY Hi-Fi without the guidance, and I am very thankful you're all here!

[PWR RYD]

I can definitely see why you need the LCR at 5kHz!

[KEtheredge87]

I can definitely see why you need the LCR at 5kHz!

Yep! Glad my eyes aren't deceiving me there. Even better to hear someone else agree with my assessment. Thanks for the feedback Craig!

[KEtheredge87]

Happy Saturday Everyone!

Today is a conflicted post for me. I finally got around to installing the curly maple veneer wrap on the test cabinet, which has been a long time coming. As the saying "Experience is what you get when you didn't get what you wanted" goes, I got plenty of experience today. I am now experienced enough to know I don't like the way veneer looks if it's only sitting on part of the cabinet. I am also now experienced enough to know that curly maple veneer doesn't always like getting massaged over a 3/4" roundover! I had to pull up the veneer on my first go-round since I didn't get things lined up correctly. That caused me to take even more time to make some repairs to that roundover... at least I got to practice the tomzarbo veneer seaming method twice on this cabinet! Overall I think I need a thinner utility knife blade. The one I used left a clean, if a bit wide seam.

After all this learning I'm also conflicted about how to best proceed with the aesthetics of the cabinet design. I will not wrap the veneer around the other two "real deal" cabinets, but I do intend to have the veneer side panels still. To avoid the appearance of the veneer sitting on top of the cabinet like I created today, I'll set up a router jig to carve out the surface on the side panels so the veneer sits more flush with the cabinet wall. That brings me to the choice of paint color...the painted portions of this cabinet were going to be satin black, but I'm concerned it will be too much black without the veneer wrap. I'll still have the black from the driver cones, so I'll need to make a new paint color choice to regain some visual interest.

This also means I'm not sure about the 1/4" x 1/8" channels I was going to cut on the cabinet to trim the veneer... Honestly, after today's adventure I'm thinking I might want to rip the veneer back off the test cabinet so I can still have 3 total cabinets that have the same visual styling. I imagine that will be a royal PITA.

[jhollander]

Might try something like Dan and Kerry did at CSS

[KEtheredge87]

Might try something like Dan and Kerry did at CSS

Hey John, Thanks for reminding me of that awesome CSS cabinet. The white is a bold and interesting choice for sure. I really liked their design, and I almost felt like I was getting a bit too close to it simply by having the veneered wood panel on the sides of my cabinets. I suppose in speaker design it can be hard to be original sometimes!

[tomzarbo]

Keith, sorry about the issues with the veneer. I didn't remember reading if you used veneer tamer or not, but that can help a bit with flexibility when you're trying to wrap a tight radius. It softens the fibers of the wood and allows them to take the curve (hopefully) without splitting. You probably already knew that, but just in case... I sometimes forget things I already know (knew?).

At any rate, you were very smart to make a 'test' box to try this first on since you knew it would be a challenge, good move there!

I'm just going to spitball a few ideas here not that they'll help....

I wonder if the cabinet could have been left with no routered treatment to the edges, just square corners... the curves will still be there though. Then veneer the parts you want venered. Then apply finish to the veneer, masking off the sides you wanted to paint. Then paint the sides, masking off the veneer. Then apply a thin 'scratch guard' of shelf liner from Wal*Mart or whatever... then apply the corner treatment with your router. Then prime, spray with a contrasting color, or remove the side protection sheets and prime/paint the sides and corner treatments in one shebang. If you use poly for the veneer, you may have to do one last careful 'touch up' on the routed corners, but I wonder if that would work.

I did something similar on a subwoofer I made for my wife's brother, I didn't use an edge treatment, but the line was clean and the process worked very well...


Just an idea for food for thought.

I know you'll figure out the best solution, looking forward to seeing how it works out for you. I'll learn something I'm sure.
See you in about 4 months for MWAF!

TomZ

[KEtheredge87]

Hi Tom! Thanks for sharing those ideas. I can see how your methods would produce good clean lines there, and the pictures definitely bear that out! I think sometimes I am too fancy for my own good, and I'm always trying to push my own boundaries rather than making the same style of box again and again. The other side of that coin being the "nothing ventured, nothing gained" mindset.

I have seen the veneer softener before. In fact, I did buy a bottle for this project as well. I chose not to use it because I had no issues wrapping straight grain mahogany veneer around my swope towers' 3/4" roundover in the past. I did not anticipate that the curls in curly maple kind of act like rows of armor plates or fish scales, and would pop up in places around the curves. We live and we learn! It might well work with veneer softener in the future though. I've still got about 8'x3' of my veneer sheet left for future projects (and the side panels on these, which I haven't given up on!)

As for the paint scheme... I keep coming back to a classic satin black finish for the painted surfaces. Eastwood sells one they call "Rat Rod Satin" in either 2K spray cans or single stage urethane. I'm inclined to give HVLP spray a try... if I could just decide on what spray gun to use.

So many choices! I hope I get things totally finished in time for InDIYana. If it looks like I'll cut it too close, I'll just bring the raw cabinets with finished XO design. That way I can take my time and do things right with plenty of time before MWAF.

See you then sir!

[KEtheredge87]

Hi Everyone,

After this post, I feel like I should learn to be less dramatic and see things through! I gave things a 3rd and 4th think-through, and decided I had little to lose by proceeding with my test cabinet and making the slot cut. Boy am I glad that I did! Using that 3-wing slot cutter and gigantor bearing to create a 1/4" wide x 1/8" deep slot was just the treatment needed to clean up that veneer edge. Yes, the veneer is still sitting above the rest of the cabinet, but it is now unnoticeable unless you're right up on the speaker AND you're looking for it. I used a climb cut with the router for this, which thankfully was not scary in the least. Taking such a small depth of cut made the work super smooth, without any of that typical "router runaway" that is rightfully concerning.

Boosted by the success of the slot cuts, I went ahead and used my small pilot dado flush trim bit to trim away the veneer inside the driver, terminal cup, and slot port openings. This thing is now looking fantastic once again! For those little areas where the grain popped up around the curve, I will look for some small glue that I can use. I figure a dab will do me, and if I use a strap clamp on those surfaces, it will press everything back into place nicely. Just need to use a glue that won't make an obvious spot where the finish and stain wasn't accepted!

So... having aired my concerns and processed them publicly, I have changed my mind and will proceed with the veneer and cabinet design as-planned. I still intend to paint the non-veneered surfaces with that satin black too! Thanks as usual for following along and providing helpful pushes along the way!

[PWR RYD]

Nice work Keith! I really like how you document your designs/builds with detailed pictures.

[KEtheredge87]

Nice work Keith! I really like how you document your designs/builds with detailed pictures.

Thanks Craig! Its fun to see everyone else share ideas and progress this way, so I like to contribute as well. I can't decide if it's too bad, or probably for the best, that I am limited to 5 picture attachments per post by the forum software. I know Javad loads as many as he wants through Tapatalk, but I cant seem to do that easily from my phone. Trying to type it all up on a virtual keyboard isn't my idea of fun!

[Kevin K.]

This brings back the memories and I feel your pain Keith. Had similar issues with Brian's speakers on the corners. Applied softener to the areas that would go around the radius and that helped but didn't completely resolve the problem. In both our cases, we're wrapping against the grain which inevitably can lead to the tears in the wood. My repair solution was a small corner block that matched the radius. Use Titebond III glue, it's thinner and will get into the grain better. Don't get carried away on the amount of glue or you'll have a nice slick area that wont match the rest of the veneer after dye. Good luck!

[KEtheredge87]

This brings back the memories and I feel your pain Keith. Had similar issues with Brian's speakers on the corners. Applied softener to the areas that would go around the radius and that helped but didn't completely resolve the problem. In both our cases, we're wrapping against the grain which inevitably can lead to the tears in the wood. My repair solution was a small corner block that matched the radius. Use Titebond III glue, it's thinner and will get into the grain better. Don't get carried away on the amount of glue or you'll have a nice slick area that wont match the rest of the veneer after dye. Good luck!
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Hey Kevin, great idea with the matching internal round on the clamping block. I haven't looked into titebond 3 before, but I've been looking for a way to at least try to stain that area properly in spite of the glue. My current plan is looking like I'll use a super small dab of epoxy that's been tinted to match the finish. I've got a bottle of Dark Vintage Maple transtint dye coming that I'll be testing to see if I like that color. Assuming it's a go, I will use that to dye the epoxy before applying it. I'll put a layer of wax paper between the cabinet and whatever clamp setup I end up using just to make sure I don't glue a clamp to the cabinet!

On the other cabinets, you bet I'm gonna use the veneer softener I bought to handle that situation. Lesson learned!

[skatz]

Are all four edges of the baffle rounded? If its just the vertical edges, then rotating your veneer 90 degrees so that the grain is vertical would make it much easier to wrap around those roundovers. If all four are rounded, then orient the grain so that the shorter edges are the ones that get curved across the grain, as Keith mentioned.

[jhollander]

You can't pre-dye then glue? Dye should be heat resistant, not sure about any others.