New AV15 Sneak Peek


  • Member
    JasonA on #236

    John had a couple of prototypes of the upcoming AV15s and sold me one. Being a prototype, it’s slightly different than the production version will be. According to John, the main difference is that mine has an aluminum sleeve over the pole piece vs a copper sleeve that will be used in the production versions. I’ll let John chime in with the specs if he wants – basically this appears to be a souped up version of the older AV15s.

    I snapped a few pics of the driver (which is definitely a beast): http://s117.photobucket.com/albums/o80/jkandreasen/AV15%20Sub/

    The parameters on this driver will let it be used in a variety of applications. I’ll be using mine for HT, so I’m putting it in a ported box. I’m planning on about 6cuft, tuned around 20 Hz. Xmax isn’t exceeded until you get up around 1500W!

    Once the weather shapes up, I’ll get out in the garage and start making some saw dust and update the pics.

    Jason


    Member
    simon5 on #3120

    That’s a nice driver ! Great work, John !


    Member
    jacket_fan on #3121

    So the AV 15s are making a comeback. We look forward to more details.

    Jason,

    How do you plan on forming the curved sides to your box?


    Participant
    stryke on #3122

    I can’t speak for how he will do the curved sides, but I have done similar in the past. Basically cutting the top, bottom, and bracing to the given shape is what you would start with. Then you can do multiple layers of a thinner material built up to make these side panels. Melamine or bending plywood is probably the easiest to bend. You can also bend 1/4″ MDF without too much difficulty. It’s just a process of laminating the layers together as you go. AIT has 4 different types of bending plywood/mdf. http://www.aitwood.com/ They also have up to 96″ Radius quarter rounds. If you are working with an exact radius you can go with one of those. Typically though bending your own and laminating multiple thin layers is much more cost effective and gets the curve you want.

    This should really be a nice looking sub when it is finished. Looking forward to seeing pictures of the build. 🙂

    John


    Member
    Jason on #3123

    Holy cow good thing we got the double wall boxes.. looks like UPS dropped that box a few times…


    Member
    JasonA on #3124

    @stryke wrote:

    I can’t speak for how he will do the curved sides, but I have done similar in the past. Basically cutting the top, bottom, and bracing to the given shape is what you would start with. Then you can do multiple layers of a thinner material built up to make these side panels. Melamine or bending plywood is probably the easiest to bend. You can also bend 1/4″ MDF without too much difficulty. It’s just a process of laminating the layers together as you go.

    …Typically though bending your own and laminating multiple thin layers is much more cost effective and gets the curve you want.

    John

    John is exactly correct on how I’ll be doing this one. I actually stopped by Home Depot today and picked up some 3/4″ material. I had planned on just using MDF, but they had a special buy-out on some nice cabinet grade birch plywood that was about the same price, so I’m going to give that a try. I’m not sure if I’ll use 1/4″ plywood or MDF on the sides (the radius of the sides is something like 32″, so it should be pretty easy to bend). I’ll probably start with 3/4″ for the sides, and if that doesn’t seem like enough, I can add another layer or two. The whole box will be pretty thoroughly braced, so hopefully 3/4″ will be adequate.


    Participant
    stryke on #3125

    @jason wrote:

    Holy cow good thing we got the double wall boxes.. looks like UPS dropped that box a few times…

    Those are just the little love taps UPS gives to all their packages so they feel special. :mrgreen:

    John


    Member
    DAVECS1 on #3126

    Hope you do not mind if I chime in. First off just want to state you guys really know your stuff when it comes to audio. I aspire to be like you guys and know what I am doing some day.

    Anyway, I have noticed in the recent AV mags that I have been getting, that Definitive Technologies is making there speakers with aluminum housings. Some of the models have built in LFE drivers in the bottom half with seperate amplification. My question is: Is aluminum really a viable option for an subwoofer enclosure? If so that would be excellent, cause I am more hand with the alloy than I am with the wood.

    Just for reference, the reason I bring this up, is because of the chat aboout forming the curved sides. When I saw the drawing above I immediately thought about how I could form those bends by running some 3mm 2024 T4 aluminum through a rolling break to achieve those bends, and then use MDF to firm up the panels.


    Member
    JasonA on #3127

    I found a good pic that illustrates how this type of box is constructed:

    This is the basic skeleton that the thinner material is glued/screwed/nailed/clamped to.


    Member
    Rene on #3128

    On these speakers I did, I used 1/8th MDF and just layered it with glue and a lot of brads to hold it in place. and between each layer I gave it a good run over with a very hot Iron I use strictly for veneer work. turned out really well in the end. But for a sub i’d use 1/4″ MDF, 3/4″ brad nails along the bracing and good dose of tight bond between each sheet. And go no less than an inch thick. you might have to throw some weight around when flexing the 1/4″.. but i doubt it for the curve you’re going for.

    ohh! and the most important tip i can give you. OVER size your sheets by at LEAST an inch each way! once all the glue has cured. you can just use a flush trip bit to get rid of the overhang.
    and watch your fingers please, even with the 1/8th I pinched my finger between the sheets when pressing one down… ouch..a lot

    [attachment=0:o44h7lqd]Speaker10 copy.jpg[/attachment:o44h7lqd]


    Participant
    stryke on #3129

    @davecs1 wrote:

    Hope you do not mind if I chime in. First off just want to state you guys really know your stuff when it comes to audio. I aspire to be like you guys and know what I am doing some day.

    Anyway, I have noticed in the recent AV mags that I have been getting, that Definitive Technologies is making there speakers with aluminum housings. Some of the models have built in LFE drivers in the bottom half with seperate amplification. My question is: Is aluminum really a viable option for an subwoofer enclosure? If so that would be excellent, cause I am more hand with the alloy than I am with the wood.

    Just for reference, the reason I bring this up, is because of the chat aboout forming the curved sides. When I saw the drawing above I immediately thought about how I could form those bends by running some 3mm 2024 T4 aluminum through a rolling break to achieve those bends, and then use MDF to firm up the panels.

    Hi Dave,

    Krell has been doing an aluminum cabinet for years. The problem with aluminum is that while it is very strong, it’s not well damped and resonates easily. It needs to get quite thick with lots of bracing so you push any resonance out of the audible range. The Krell Master Reference sub uses 1″ thick aluminum. Yes, EXPENSIVE to build and weighs in at 437lbs. http://www.krellonline.com/krell_component.php?id=4&page=MRS

    There are quite a few cabinets out there now that are made from an extruded aluminum. With the extrusion you can add a lot of strength and rigidity vs just a few flat pieces. One thing you could try would be to build 2 layers of thinner aluminum with say 3/4″ to 1″ space between and some ribs to connect between the two. Then get some heavy pour foam, 10lb, 15lb or 20lb per cubic foot variety to fill the space between. This would get you a lot of structural strength and great damping also. http://www.smooth-on.com/foams.htm We use this stuff.

    There is also a company that makes solid aluminum speaker cabinets… I’ve talked to him before, but I can’t find the website right now.

    John


    Participant
    stryke on #3130

    @rene wrote:

    [attachment=0:1i0n3n9n]Speaker10 copy.jpg[/attachment:1i0n3n9n]

    Just wanted to say I like the work there. Which woods are those that you used?

    John


    Member
    JasonA on #3131

    I managed to squeeze in a couple of hours in the garage tonight and I got a few pieces machined. I started with the top/bottom and the two main horizontal braces. These are the curved pieces. I picked up a little used Ryobi band saw last week, which worked really well to cut the curves. As you can see in this picture, I used some of the Super 77 spray adhesive to attach a full-scale print of the brace onto the plywood, and then cut to about 1/16″ from the line.

    After I cut the first brace, I used it as a template to trace the outline onto the remaining pieces, which I rough cut on the bandsaw. Then I attacked the piece with the template with my belt sander to get it right down to the line and to get a nice smooth edge. I then used that piece as a template for the others, using a router and template bit. I made sure to mark the edges (one line on one side, and two lines on the opposite side) to make sure I kept them all oriented the same way. They came out fairly symmetrical, so it may not have been completely necessary…

    The notches in either end of the braces are to accomodate the driver and amp cutouts. Those along with the internal cutouts on the braces will have to be finished up with a router and a straight edge.

    Here’s the pile I ended the night with. Pretty decent progress for the first day.


    Member
    DAVECS1 on #3132

    That Krell sub is rediculous! I do like the foam inbetween the aluminum sheets idea. I think you could really damp out any extraneous noise. Not to mentioned a completely polished aluminum sub with black laquer end cabs would be amazing looking.

    Back to the post at hand. First off I would like to say that is some nice work cutting out the patterns. Is that all router? So are the curved side to help eliminate standing wave or is it pure asthetics? Either way. I think that will be a nice piece. In my coffin looking sub I used the mini looking anechoic chamber foam to glue to the walls, in hopes of stifling some standing waves. I am currently contemplating using some polyfill, to see if that will help the sub more easily produce higher output.


    Member
    Rene on #3133

    John, I used Zebra wood and Paduk on those. I’m actually looking for another excuse to use paduk again. it’s a great wood to work with.

    Rene

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