Chubby, curvy Vifa monitors

[spudfrog]

I've had a set of Vifa drivers sitting around since I retired a rather large set of 1/4 wave pipe speakers last year. I want something to fit up on my wall once I sell off (maybe) the mtms that I have up there now. Or these may go right next to them. Who knows. But anyway...

The woofers are Vifa P17WJs, and the tweeters are Vifa PL27TGs. I really liked these drivers when I had them in use.

I'll probably be using bend threaded rod again with this set. All of that will have to get worked out when I get there. As of right now, I am only building one, so as to make sure there are no issues with the design before cutting up the wood for the second one. I am basically going to be getting all of my projects to the point at which they are ready for paint, as I will be buying a HVLP gun later this week to start doing my own painting (if everything works out well)

Well, here we go with pictures.

I first cut a single template out of 1/2" mdf using the Jasper Jig, then rounding where the two circles meet with the sanding drum. I cut out 7 pieces (one extra) with the jigsaw, drilled 1/8" holes to pin the pieces together, and ran them on the flush trim bit on the table. These cabs will be 6 layers thick.






Double vacuum time




I used the Jasper again cutting out all of the inner circles. I now cut out all of my circles by going 75% of the way through each piece, then cutting with the jigsaw and flush trimming the whole thing. Then I don't have to worry about divots and whatnot when the jasper cuts the center free.










I rounded the outer edges on the top and bottom pieces with a 1" radius. The speakers are flush mounted.

[spudfrog]

The tweeter has the tighetest fit, as I don't want any leaks. I think the tweeter itself its 72mm... the opening is 72.5mm. =P




Ooh la la








I tend to rear-mount drivers more often, so this is my first time chamfering a cutout. I didn't have a 45* bit with a bearing, so I used one of these bits instead. The edge of the chamfer is level with the flange, although it may not look like it in the picture. The bit I used was actually new in the packaging (although it was probably 20+ years old, and it burned up already =P)












I also discovered today that the router table I am working on is older than I am. o_o

[spudfrog]

I decided to try marking the layers as I clamp them without glue. They tend to move a lot with glue on, so I'm thinking this may help out a bit. I also think I may need more of these clamps. I will trimming each layer using the one above it as a template fro the flush trim bit.








I also spent a little time and made some of these for free with some cutouts and drawer liner. Pretty sweet.

[J.R.Freeman]

Wow Spud, looking good! You have some wood working skills! I love the look of the P17's. Dark poly cones look so nice in my opinion - very elegant. Let us know how they turn out!

[rhapsodee]

May i know what is the reason for the rear cutout chamfer? I remember reading something about rear wave edge diffraction?

Nice design and great build! Looking forward to seeing the finished product!!

[J.R.Freeman]

Originally Posted by rhapsodee

May i know what is the reason for the rear cutout chamfer? I remember reading something about rear wave edge diffraction?

Nice design and great build! Looking forward to seeing the finished product!!

Hi rhapsodee,

From what I can gather reading through Zaph's site, driver-board shrouding of the back side of the cone can cause reflections that could result in FR anomalies.


edit: Spud, you were born past 1984? ....I feel old!

[dantheman]

Boy I hate you guys who can make'em look so pretty! Excellent work! Oh, and WOW!

Waiting to see the finished photos,

Dan

[Dr.EM]

Another really tidy and funky looking project! Look forward to seeing how this turns out

[spudfrog]

Originally Posted by J.R.Freeman

Wow Spud, looking good! You have some wood working skills! I love the look of the P17's. Dark poly cones look so nice in my opinion - very elegant. Let us know how they turn out!

I really like them too. They have four tiny points around the dustcap too that I like for some reason. Although I think I could do without the numbers cast into the surround. Or it would at least be nice to have it centered.

Originally Posted by rhapsodee

May i know what is the reason for the rear cutout chamfer? I remember reading something about rear wave edge diffraction?

Nice design and great build! Looking forward to seeing the finished product!!

I was pretty much just following what I had seen before. Probably from going through Zaph's page.

Originally Posted by J.R.Freeman

Hi rhapsodee,

From what I can gather reading through Zaph's site, driver-board shrouding of the back side of the cone can cause reflections that could result in FR anomalies.


edit: Spud, you were born past 1984? ....I feel old!

Well at least now I know why I did it. I think.

Yeah, 1985. I think I qualify as a younster around here. :P



Thanks for the thoughts everybody. I'm really liking how these are turning out myself.

I think now that I have them (it) totally cut out, I will probably pick up another project I had left off to start this one. I think I have about 4 going right now.

[badman]

Welcome aboard, spud. Nice work! I don't think you'll have much cavity resonance, so long as they're well stuffed, but next time, bear in mind- an uninterrupted cylendar is the 2nd worst shape for internal standing waves, after a sphere. With the magnet in the middle it's not as bad, but still not optimal. After the first couple layers, a "wavy" interior pattern would help. I think you'd do very well to stuff the top chamber with normal polyfill and thickly wrap the woofer magnet with batting, so that it goes to about halfway between the walls and the magnet. Get the back end as well. Then leave the area outside of this unstuffed to allow proper evacuation of the backwave/access to the enclosed air.

The work around the mounting is very well done. It's an important feature to prevent the cab from choking the driver, raising Qms and thus Qtc. In 15" subs, not as much of an issue, but for a midwoofer like yours, an important consideration.