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  • tomzarbo
    replied
    Originally posted by Tijmen View Post
    Wow, rear mounting the drivers really makes the baffle look so clean! I think it was worth the effort. Such a shame that these dayton audio drivers are quite a bit more expensive here in Europe.
    Thanks, that's why I did it, for the clean look, but it was just entirely too much work..... on the other hand......

    Originally posted by Kevin K. View Post
    Wow, that looks like it was pretty hairy to do by hand. I'm betting the Walnut baffles will look fantastic after they are finished!
    ...... if I had used a CNC machine to do these baffles, I bet things would have been gone much smoother. With the precision a CNC affords I could even see leaving four blobs of wood there which could later be grooved out with a dremel cut-off wheel for the driver flanges to "Turn into" like screwing in a screw. Then just a few screws to keep things in place would be all you need.

    Really though, this is a crazy amount of work just to get this to fit the space constraints. I went a bit too far I think trying to get everything into the sub-3 Liter space available. The 'public' Bantam MTM's will be an inch or so taller and a few inches wider and not have all these 'too close for comfort' tolerances to worry about.

    I used a 1/2" straight cut bit in the big router to get that material out. Drew the profile of the driver flange on the back and freehanded it in two passes at two depths. Can't see from the pics, but I got most of the dark burn marks out by sanding with medium coarse paper. Just have to wait for the tiny #2 x 1/4" screws to come in so I can get these drivers mounted. I've never need a set of jewelers screwdrivers to put together a speaker before!

    TomZ

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  • biff
    replied
    Tom those rear mounts are def the way to go, so elegant and effective. If you need to do that again on such thick stock you might consider splitting the 7/8 board on the bandsaw into like a 3/8ths thickness cut for the front of the baffle with the roundovers for the drivers, then you can cut the back 1/2" on a scroll or jigsaw for the back part of the baffle, glue them back together and they will look just like yours but be easier. I did that with these, mahogany cut for the face laminated to MDF that was cut out oversize for speaker frames using Davis 16s with the odd frames. But yours are gorgeous.
    Speakers mounted to relatively thin mahogany Baffles mounted to cabinets, laminated to MDF cutout to fit driver frames detail of top, thickness matches original faceplate on LCY ribbons

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  • Kevin K.
    replied
    Wow, that looks like it was pretty hairy to do by hand. I'm betting the Walnut baffles will look fantastic after they are finished!

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  • Tijmen
    replied
    Wow, rear mounting the drivers really makes the baffle look so clean! I think it was worth the effort. Such a shame that these dayton audio drivers are quite a bit more expensive here in Europe.

    Leave a comment:


  • tomzarbo
    replied
    Some progress to report...





    I had to plane this board down a bit as it was rough on one side and had a little twist in it. It's still almost 7/8" thick.

    It's really snug in there. It took me two full half days to get this baffle finished.



    Brazilian Walnut is some hard stuff. My drill press had some trouble drilling this hole, even with a sharp carbide fostner bit doing the cutting. Had to drill out some material so it would keep spinning.





    Looks like everything fit... just barely. It's nice working with hardwood for a change instead of MDF all the time. But this would have been SO much easier if I could have just glued a piece of MDF to the baffle and just front mounted the drivers. Doing it this way added a LOT of complexity.



    As you can see, the stock mounting holes had to go; but I have some tiny screws coming in a few days that will allow me to mount the ND91 securely.

    I'm using Kreg screws to get this together. The holes have enough room for some movement of the baffle pieces.





    I'm getting excited, these are getting pretty close to being ready to finish.

    TomZ

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  • tomzarbo
    replied
    Originally posted by Tijmen View Post
    Hey Tom! Have you had time to work on the cabinets some more? Cant wait to see them completed. Keep up the great work!
    I have only gotten the PR cutouts made, so not much progress. Had a few things to do for work and was a bit sick with a stubborn cold for the past few weeks.

    I have a long weekend, though, so I hope to get them mostly finished, minus the finish.
    Thanks for the interest, I hope they come out well and end up sounding good.

    It feels great to have a bit of energy and desire to do some 'speakering' as well as a few days off... all at the same time!

    Tomz

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  • Tijmen
    replied
    Hey Tom! Have you had time to work on the cabinets some more? Cant wait to see them completed. Keep up the great work!

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  • scottvalentin
    replied
    Look forward to seeing the Walnut baffle!

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  • Kevin K.
    replied
    Wow Tom, those are looking great! The Zebrawood is so rich looking. Glad the router bit and hand router combo worked out for you and I'm betting you'll find more uses for it in the future.

    Leave a comment:


  • tomzarbo
    replied
    Originally posted by ontariomaximus View Post
    These look great! I would consider the removable sealant that comes in a standard caulking tube, and rub a little vaseline on the frame where it meets. For easy future removal. PR systems really need to be sealed up. Someone told me that 20 or 25 years ago, he made a strong case (But apparently is a just a factoid now)
    Thank you, they're shaping up.

    Do you mean to apply the sealant between the baffle and the cabinet, and use a little vaseline on the cabinet where they will touch so it doesn't become bonded like glue? I bet that would make a good airtight seal... kind of like making a gasket on mating car engine components. I'm not sure how I would keep it from ooozing all over the finish, though. I had planned on either using craft foam, or some solid neoprene gasket tape if I end up picking some up in time.

    I'm thinking about your statement about PR systems needing to be sealed up well. Every enclosure needs to be properly sealed of course, but I guess you could be right in that they may experience more internal pressure than the average sealed, or even vented enclosure.

    At certain times and at certain frequencies both the driven speaker cone and and PR may be either moving in or moving out concurrently -- creating quite a vacuum or pressure boost inside the cabinet. I suspect when this happens with a PR the pressure is greater than with sealed since there are multiple 'cones' creating the pressure change as opposed to just one with a sealed system. Not sure it would be different than with a vented system, although my little mind thinks it may be so given the increased cone area of multiple PR's over a single vent... Interesting. You've made me think a little bit... I try not to do that on Sunday if i can help it, but I'll forgive you.

    Anyway Dad and I tried a slab of solid 1" thick Walnut in front of these and it looks pretty good, so I'll probably go with that.

    TomZ

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  • ontariomaximus
    replied
    These look great! I would consider the removable sealant that comes in a standard caulking tube, and rub a little vaseline on the frame where it meets. For easy future removal. PR systems really need to be sealed up. Someone told me that 20 or 25 years ago, he made a strong case (But apparently is a just a factoid now)

    Leave a comment:


  • tomzarbo
    replied
    I wanted to share a trick that really helped me with this. It's not often that I find a method that is such a bit improvement, but this is one of those.

    Kevin K. suggested using a small laminate trim bit with an air die grinder of all things... never would have thought of that... but it worked really well. It's so much smaller than even the smallest trim router that it takes trimming veneer to another, much easier level.

    I just used a cheapy HFT die grinder which was less than $20. I think Kevin used a much nicer grinder on his.

    You can check out how he does it at this post: http://techtalk.parts-express.com/fo...44#post1306344



    As you can see in the above pic, there is less than 1/4" of side exposed for a bearing to ride against. I would have never attempted it with a router, but the die grinder, which is much smaller and easier to move did the job fairly easily. This bit has a double bearing for more protection. Yeah, I still could have goofed this up with shaky hands, but using two hands to steady the grinder did the trick. If you find yourself needing to trim up some veneer in a way that you can't just slap a router on it and go, give this a try, it's a REALLY nice way to do it - you'll see once you do it.
    Nice tip Kevin, thanks!





    TomZ

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  • tomzarbo
    replied
    Getting there...

    I used pieces of paper as shims to center the back in the opening, then I marked the holes. I used a 1/4" fostner bit to make a recess for the 1" socket head screws I will use.





    I used a 1/4" bit to make the holes for the baffle attachment screws. I had some Kreg pocket screws which will work well for this as they have a big flat head. The baffle can move a bit without splitting. The speaker is only 4.5" wide, but I took the safe route to avoid any chance of splitting.

    I'm sweating the details a little bit on this....



    Hopefully this looks nice when finished.

    Decided to go with Zebrawood veneer on these. I'll darken these a bit I think, not too much, but those stripes need to be toned down a bit on such a small speaker I think.



    Cabinets with the freshly unclamped bases:



    Closer look at the bases. There is about 1 1/4" of depth in the base for adding crossover bits. Probably not enough room for an I-Core, but most air cores and many sizes of caps will fit under there. See Wolf, I'm thinking! I need every bit of that 3 liters for bass-generating space! There will be a 1/4" thick break between the base and cabinet, that little board is visible on the left speaker base.





    Veneer close-up. Looks pretty dead raw I admit. I did this in one shot - seam at the bottom....one hand holding, the other ironing... pretty exciting!

    Not 100% sure on the baffle material yet. Something that goes well with the Zebrawood, hopefully from my newfound stash of hardwood.

    Hope to have baffles figured out and maybe made by next weekend.

    TomZ


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  • tomzarbo
    replied
    Got a bit more done on these last night... a small bit.





    That's a 1/2" roundover if it's hard to tell, these are pretty small. 10" tall at this point.





    My wife wants walnut on the cabs and cherry for the baffle, but I'm not sure.
    I was actually thinking of white Birch again like the Bantams on the cabinets, and something medium to darker toned for the baffles for some nice contrast.
    Hoping to veneer this weekend... shouldn't take too long, only one seam on the bottom!

    TomZ

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  • Kevin K.
    replied
    Originally posted by tomzarbo View Post

    Mind? It may cause a riot!
    First things first. I need to finish em then I can contemplate the drive. Good luck on your build Tom, looking forward to your results.

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