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Next Project: Arc 40 CBT Array

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  • Kevin K.
    replied
    Originally posted by neildavis View Post
    Wow.

    ​I watched one of the Keele CBT videos in which he pointed out that you can get the same benefits of the curved front baffle from DSP/delay. But he said the electronic version was a lot more complex. After looking at your build, I disagree. It took about 6 beers to build the amps shown below, which have 24 channels of DSP and 20 class-D power amps. Your build looks like it took more than a case of IPA!

    ​Seriously, you have a nice project there, and I hope I can get an electronic delay version going by early next year for comparison. You're right--this is interesting technology and is opening up some exciting new possibilities for more realistic sounding loudspeakers.

    ​I'm sorry to hear about Don's wife and wish them the best.
    Holy cow Neil! If you accomplished that on a 6 pack, imagine what you could do if someone provided a case. Really cool stuff you got going on there and yea it would be awesome to do a comparison between the electronic delay and the curved front baffle delay. Perhaps some day we can arrange it. By the way, not all CBT arrays are this complex. I just have a habit of making my builds this way for some reason. No drama, no fun. Anyway, after these are finished, I'm looking forward to building some simple subwoofers. Surely I wont find a way to over-complicate those.

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  • neildavis
    replied
    Wow.

    ​I watched one of the Keele CBT videos in which he pointed out that you can get the same benefits of the curved front baffle from DSP/delay. But he said the electronic version was a lot more complex. After looking at your build, I disagree. It took about 6 beers to build the amps shown below, which have 24 channels of DSP and 20 class-D power amps. Your build looks like it took more than a case of IPA!

    ​Seriously, you have a nice project there, and I hope I can get an electronic delay version going by early next year for comparison. You're right--this is interesting technology and is opening up some exciting new possibilities for more realistic sounding loudspeakers.

    ​I'm sorry to hear about Don's wife and wish them the best.

    Leave a comment:


  • 6thplanet
    replied
    No doubt man! Those are coming along nicely!

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  • Kevin K.
    replied
    Originally posted by donradick View Post
    Congratulations on the veneer hurdle. Veneer softener is pretty great stuff when you need it.
    Thanks Don. The softener is great stuff. It's a little pricey, but very effective when it comes to getting the veneer to relax. One more baffle to go and then I'll feel like I completely cleared the hurdle.

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  • donradick
    replied
    Congratulations on the veneer hurdle. Veneer softener is pretty great stuff when you need it.

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  • Kevin K.
    replied
    Would like to add a couple of more things to this week's updates. This project is possible in part because of two men, one of whom, Rick Craig, is working with me directly to complete these. The other is the man behind the technology for the CBT arrays, Don Keele. I've had the distinct honor of meeting the man in person and he's about as good a guy as you will ever meet. I'm subscribed to Don's youtube channel because of my interest in the arrays and received a notification about an award he was just given, here is the link for those interested:
    https://www.youtube.com/watch?v=H0QX...em-subs_digest

    I forwarded the link to Rick this weekend and when he replied, stated he'd just spoke with Don earlier in the day about his trip and learned that Don's wife has suffered a stroke. Please keep Don and his wife in your prayers and thoughts.

    Thanks,
    Kevin

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  • Kevin K.
    replied
    Here are this weekends updates. Got the upper back caps and top caps cut and glued to the enclosures. Finished the second harness other than securing it to the enclosure.



    Prior to peeling the paper on the damping and sticking them in place, I epoxied the entire enclosure with hysol 9462. With all of the stress introduced to these panels to conform to shape, figured this would be worth the extra money for peace of mind. This stuff is ridiculously strong. Any of you remember the superglue commercial where they had a guy hanging from a hard hat that was glued to a high rise beam? This is the glue they really used.



    Installed some extra pieces of foam in between the harness and enclosure to make sure we don't get any unwanted rattles. Tom, if you look closely you can see where I added dowels for the baffle alignment, you were right, it gets a little tough to keep everything aligned once you get all that slippery glue in between the panels, especially when you are bowing the panels. Had a hard time with the half scale enclosure so added this to the full scale. It worked great.



    Next up was the part that had me sweating bullets all weekend. Attaching the baffles without splitting the veneer. Decided to kind of pretreat the baffles so to say. Applied veneer softener with a piece of cotton cloth and pre-shaped the baffles. Every couple of hours I would apply another light coat of the softener and add a little more to the bend. Seems to have worked, no unwanted cracks or splits after installation.







    That's it for this weekend fellas. Will try to get the second enclosure caught up to the first one this week and then get started on the last of the outer panels this next weekend.

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  • Derekj
    replied
    Nice project! I really like those SB drivers - good bang for the buck.

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  • Kevin K.
    replied
    Originally posted by Wolf View Post
    I just squeeze them tighter with needle-nose pliers, BUT, I'm not installing that many drivers in a cab like you are.
    Good info there, Kev!
    Wolf
    That's the way I've always done it in the past Ben but like you said, there are a few more drivers involved here and I was worried about the hand cramps.

    Originally posted by greywarden View Post
    woooooooooow what a cool build, really love the shape and the veneer as well.
    Thank you Sir!

    Originally posted by lowpolyjoe View Post
    AWESOME build. I stumbled across Karelian Birch a few years ago. absolutely love it. i thought it contrasted well with bubinga. my finish was shellac plus a little furniture wax.

    can't wait to see more of your project
    Thanks Joe, your cabinets are stunning. Love Bubinga but just couldn't swallow the cost for that on my project and decided on Sapele. It won't be as striking but the contrast should still be nice.



    Stay tuned fellas, these should start to come together in the next few weeks or so.


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  • lowpolyjoe
    replied
    AWESOME build. I stumbled across Karelian Birch a few years ago. absolutely love it. i thought it contrasted well with bubinga. my finish was shellac plus a little furniture wax.

    can't wait to see more of your project

    Leave a comment:


  • greywarden
    replied
    woooooooooow what a cool build, really love the shape and the veneer as well.

    Leave a comment:


  • Wolf
    replied
    I just squeeze them tighter with needle-nose pliers, BUT, I'm not installing that many drivers in a cab like you are.
    Good info there, Kev!
    Wolf

    Leave a comment:


  • Kevin K.
    replied
    I want to preface this next thing with the fact that I love PE and all they do for us. But, sometimes they just don't have everything you need and you need an alternative source. PE carries crimp on terminals, but they don't carry all of them needed to do the job right. Through research, I have discovered you typically have two different thicknesses of terminals on the drivers, they are referred to as .5 or .8mm terminals. We are not talking about the width here (.110, .187, .250 being the most common), but the thickness. A cheap set of dial calipers will help you figure out which ones you need. If your calipers only measure in inches, the .5mm will be somewhere around .020, and the .8mm will be around .032. Here's a PDF explaining the differences for those who have ever wondered why some of the terminals would push on and still feel loose while others fit just right.

    http://www.ferrulesdirect.com/pdf/Sp...Difference.pdf

    Found this source online and they carry about every type of crimp on terminal you can imagine. Prices are very reasonable. Hopefully, PE doesn't view this as me trying to re-direct business somewhere else. They just need to carry all of the ones we need and I will gladly buy em from them.

    As luck would have it, I needed the .5mm terminals for my tweeters and the .8mm terminals for the mids. Ended up buying a bag of 100 of each of the sizes needed. Gonna need most of them for the arrays and will have a little stock left over for future builds.

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  • r-carpenter
    replied
    Originally posted by Kevin K. View Post

    Spectacular looking Roman. Thanks for the advice. I sprayed lacquer on the Archers but the Texas heat was wreaking havoc on the finish, had a lot of orange peel. Tried a retarder but not much improvement. It's starting to cool off a little down here now, so could probably get away with it in the evenings or early mornings.
    Thanks guys.
    In TX I would probably look in to classic marine varnish. It likes heat and cures well. Can be buffed up to a high gloss.

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  • Kevin K.
    replied
    Thought I would share a couple of other things some of the builders may find helpful. I needed angles on the damping foam for my arrays and trying to cut the angles with a razor knife just wasn't working out. Found the best way to cut these was on a band saw. I realize not everyone has a band saw, but if you do, a 14 tooth per inch blade is the way to go. Cuts the foam very clean.



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