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  • dynamo
    started a topic transcenD

    transcenD

    This project has been in the works for a long time. I work slow to begin with and don't have much free time to dedicate to hands on building, but I finally got these done and am happy with the outcome. The design is a relatively small (medium size perhaps) three-way vented floor standing speaker. It uses a Fountek Neocd1.0 ribbon, ScanSpeak 10F/4424G mid, and Dayton RS225-8. The capital "D" on the end of the name is intentional, to pay a personal tribute to what is still one of my favorite commercial speakers I've owned, the EPI A500 (D is roman numeral for 500). They really at this point only have in common with the A500 the fact that they are three-way floorstander. The initial build had cabinet colors that mimic the A500, but the baffle color was changed to black at request for something different (WAF). I will post a pic with the original baffle color.

    Drivers:
    Initially these were going to use a HiVi M8N and Vifa TC9FD18. My inability to get the TC9 and low-mounted M8N to play nice together (sensitivity of a single TC9 was a little too low), forced me to switch drivers. I (am probably the only person here who..) have never used a RS woofer before and was itchy to try one, so I ended up switching woofers in addition to the mid. I already had the baffles done, and finding a driver to do what I needed in the mid and fit the hole was actually quite a challenge, but the 10F worked well. I actually ordered another TC9 pair (because they are probably the biggest bargain in speaker history) and plan to do an MTM with them and the M8N when time permits. All three of the drivers chosen really impressed me. I think the CD1.0 is a bargain at its price for a true ribbon. The 10F is stupid expensive for it's size, but at least it sounds very nice. I am preaching to the choir, but man that RS225 is nice. It looks nice, sounds nice, is built nice, and is super easy to work with for a metal cone driver. You seriously would have to spend at least double to come close to it in most Euro brands. Wish it had a bumped back plate, but I haven't bottomed it yet..

    Cabinet:
    The cabinet was kind of an experiment for me. It is curved and has very thin walls (1/4" only). The idea was to see how well I could do with a thin walled lightweight cab. I used 1/8" hardboard curved around a frame that remained part of the cabinet. The top and bottom cap are standard 1/2" ACX ply and the vertical frame is 3/4" x 1.25" sticks. The cab is then internally cross braced with dowels and more of the sticks. After the first layer of hardboard was adhered, I used a rubberized flooring adhesive (stays pliable) on the surface - all but the edge where real glue was applied, and placed the outer layer of hardboard over it to form a constrained layer. The inside of the walls had cheap ceramic tiles glued to it with construction adhesive and then applied a roll of rubber roofing sealer. The walls were lined with about an inch of fiberglass insulation. The mid chamber is sealed, a 7" x 4"id piece of pvc, stuffed with fiberglass and treated with rope caulk and the aforementioned roll of rubber. I surface mounted the mid and woofer but flush mounted the tweeter. The mid wasn't flushed because I wasn't going to flush the TC9, which had a thinner flange, and the cabinets were done when the new mid was picked. The port consists of a 2" id aeroport flange and just the coupling ring for length. It is very odd to me, but the cabinet is roughly 35L (gross), but DATS shows a lower tuning frequency than the port length would suggest. Perhaps some sort of TL effect occurring? Not sure. The baffle is two layers of 3/4" birch ply, faceted. Like I mentioned before, the baffle was originally stained and body textured black A500 style, but I ended up covering the baffle with gloss black VViVid vinyl. That stuff is amazing. It is so stretchable with just high hair dryer heat. The baffles were done in one piece. They show defects, especially up close, but it isn't the vinyl's fault, I just didn't prep the surface for vinyl application and it is gloss so it shows everything. black wasn't the original baffle color, but I think the look sleek. EDIT 01-03-17: I added the inner flare so the port is both flares back to back.

    Crossover:
    It has a part or two in it.. I will attach the schematic. Crossover points are about 400 and 5k. All filters ended up being third order electrical. I didn't try for any particular filter or slope, this is just what ended up working out. I used Oil caps in the mid and tweeter circuits, only because I wanted to try them. I would have used two ASC caps in the mid section but they appear to have gone NLA so I had to do the Mundorfs. I'm sure Audyn q4 caps would sound fine too, just kind of like playing with different caps. I know I cheaped out on the mid inductor compared to the caps, but it is what I had on hand and is a parallel component. I will say though I am a fan of the steel lam buyout inductors. The oddly placed 1r resistor in series before the mid/high circuits was added after longer listening. The resistors in parallel with the mid and tweeter can be adjusted to suit the listener and environment. I voiced these on a downward tilt (started out relatively flat) because a lot of my music is unfortunately mp3 and or relatively compressed to begin with, and that Fountek driver is a little "honest" for poor recordings. They now sound on the warmer side, but not in a bad way. The impedance measurements are before a couple of minor resistor value changes in the mid and tweeter parallel circuits, but should be close. It is very much an 8 ohm nominal load, but I do prefer the sound on the 4 ohm taps of my 35w tube amp. Edit 01-03-17: Typical for me the longer I listen the more I tinker. The crossover resistors were slightly revised and resistor wattage recommendations were updated after running it through xsim. See the new diagram in post 2. The only thing not noted on there is that if the tweeter is a little hot for you, add a 47r in parallel with the tweeter to bring it down about a db.

    Outcome:
    Well, I can't judge my own design, but will say I am very happy with them. Pics to come. Thanks for looking!
    Last edited by dynamo; 01-03-2017, 08:23 PM. Reason: I changed a few things about the design

  • Millstonemike
    replied
    Originally posted by Kevin K. View Post
    Appreciate your insight and explanations. I'm thinking a 60 tooth ripping blade might cut it pretty smooth and may be less likely to try to jerk it during the cuts. After MWAF, I might play around with this some. Thanks Dynamo.
    I use a 40 tooth blade on my miter and table saws. With PVC, the slower the feed, the smoother the cut (I guess that's true with wood etc. as well)

    Leave a comment:


  • dynamo
    replied
    I only had a very light coat of wiped on poly, I would recommend some sort of sealer, the trade off I found is with it more porous it was more easily placed and pulled off if I goofed, as well as bubbles easily breathed out; where as it does not stick nearly as good as it would to a smooth sealed surface but would undoubtedly be harder to work with. Your call I guess. I would do two coats of gloss poly sanded if I was to do it again.

    Since it sat now for a little while, the vinyl has shrunk and shows a little wood at the very edges, and has a couple small ripples at the complex corners. I think the shrinkage and ripples would be minimized greatly if the surface was sealed better for better adhesion.

    So I guess make sure you allow for shrinkage. If I had wrapped the baffles before I glued them on it would have been perfect because I could have wrapped around the back of the panel and the shrinkage would not have shown and pulled actually even tighter. I will try that on the next baffle. Any little spec of sawdust on the surface really telegraphs too, which I found the hard way and had to peel it off the first time to fix. Heat seems to be the magic trick for this stuff both for adhesive activation and nice compound stretchability.

    Let me know how it turns out and what you think of it. Mine isn't perfect but the flaws are my fault and I'm still really happy with it.

    Leave a comment:


  • ani_101
    replied
    Bought some vivid vinyl based on your experience, will see how it goes. Did you seal the wood before putting on the vinyl? Would a few coats of sanding sealer work better on the wood for the vinyl?

    Leave a comment:


  • dynamo
    replied
    Thanks guys, I really appreciate the comments

    Leave a comment:


  • gdmoore28
    replied
    Having built some curvy cabs, I know what a real pain they can be to construct. Your idea of using the PVC pipe for the back cap is a really ingenious move. Got to file that one for future use!

    GeeDeeEmm

    Leave a comment:


  • chrisn
    replied
    Looks Good! I agree with you on the fresh cuts, they even smell good sometimes

    Leave a comment:


  • dynamo
    replied
    Thanks for the kind words, definitely appreciate it! My enclosures are usually ok looking from listening distance but I don't have the fine finishing skills like a lot of the guys here to make them perfect up close. The facets and curved enclosure were both new things for me and there were plenty of learning moments for me. It really surprised me that it pinched like that, didn't expect that at all.

    Leave a comment:


  • 6thplanet
    replied
    Good job man! You pulled off a really nice enclosure with the facets and curved sides. As for cutting PVC pipe lengthwise, your spot on with it wanting to spring back together and pinch the blade, been there, done that! Like you said with a little planning ahead it'll be fine.

    Leave a comment:


  • dynamo
    replied
    No problem at all; Look forward to seeing how it works out for you.

    Leave a comment:


  • Kevin K.
    replied
    Appreciate your insight and explanations. I'm thinking a 60 tooth ripping blade might cut it pretty smooth and may be less likely to try to jerk it during the cuts. After MWAF, I might play around with this some. Thanks Dynamo.

    Leave a comment:


  • dynamo
    replied
    No worries at all, glad to talk about it. I just used a plain Jane harbor freight ripping blade because that is what was in there, but I wonder if a finer tooth count would be better. It worked fine though for me.

    Leave a comment:


  • Kevin K.
    replied
    Everything you said about the cut makes sense. Did you use a special blade on the table saw or was it just a standard ripping blade? Not trying to derail your thread, but this part of your build has my interest peaked. I had a project in mind some time back that used a piece of PVC like this but couldn't get up the nerve to try the cut on the tablesaw. After seeing what you have done, might go back and pursue it further. Thanks.

    Leave a comment:


  • dynamo
    replied
    Originally posted by Kevin K. View Post
    Nice! Not to disagree with the Mrs.'s, the original baffles looked pretty good also. Looking forward to the build pics.
    That vvivid vinyl is pretty nice. It didn't stick real hard to the wood like I'm sure it would to something non-porous so I'm thinking that if I ever wanted to go back to the wood it would probably release without leaving a bunch of gunk. The possibility of going back to the wood was part of the reason I opted for a sticker finish instead of paint. Oh and it was way easier too..

    Leave a comment:


  • dynamo
    replied
    Thanks, actually the pvc wasn't bad to rip. I was a little worried about how it would go. I just drew a line lengthwise down the pipe by laying it down and laying a 2x2 along it as a guide for my sharpie. The table saw I used had a fence that was short which worked good because then I just pushed the pipe along the fence keeping the line lined up with the top edge of the fence. Then I put the pipe on one of the top or bottom pieces and determined how far around the arc to cut the other side of the piece, lined that mark with the blade and made a new line with the marker using the fence as a straightedge and the just kept it lined up with the fence when I went. Hopefully that makes sense. It wasn't that bad I just probably can't describe it well.

    One thing I found after ruining my first attempt is that as you get twoard the end of the cut it starts to pinch hard and causes your piece to narrow at the end from grinding on the side of the blade. I just ended up sticking a piece of scrap wood in each end to keep it from pinching. It isn't a perfect cut but definitely close enough to fill with joint compound or bondo.

    Leave a comment:

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