FT1600 with plywood ?

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I've bought Bob's plans and have ordered parts. Nice complete package BTW for anyone considering it.

Being this would be my first build...I'm not sure if I'm competent enough to do the veneering required to make them look as nice as he does.

I'm thinking of building them with decent grade plywood and the hardibacker instead of MDF and staining the plywood. I would get solid Oak for a full front baffle.

Anybody build his plans using ply instead of MDF? How do they sound?

Thanks
 
Not that I have an answer to your question but if building out of plywood is not an option, what other options for the mdf enclosures could one use other than veneer? I am thinking of building these speakers and was looking at different coatings or textures to apply rather than just plain old gloss paint.
 
The MDF/HardiBacker sandwich is a design feature of the FT-1600, and all of my floorstanders for that matter. However, there is no reason that you can't use Baltic Birch or Appleply. The thing is, I haven't done any experimenting with plywood, so I don't know if you will get any objectionable ringing. My guess is that with the Hardibacker glued down with Liquid Nails, probably not.

If you do not veneer the cabinet with a single piece of veneer as per instructions, you will need to solve the problem of what to do with the raw edge of the MDF/plywood/whatever. The craftsman approach is to use pre-veneered sheet goods -- both MDF and decent cabinet grade plywood should be available in larger markets, and then glue a matching strip of wood to the edge of the front panel. You can then do the round-over on the wood strip. It does take a bit of skill to make the joints between the wood strip and the sheet goods without objectionable gaps.

Painting is always an option, but it takes more time and effort to do a decent paint job then it does to veneer. That's why I don't offer a paint finish. I can't afford the time at my price point. Also, if you are considering a piano finish, remember you will need commercial grade spray equipment and a dedicated spray booth. You can't do a piano finish out of a rattle can.

Bob
 
>>> You can't do a piano finish out of a rattle can.

I will never forget my efforts to get a piano black finish many years ago. I primed the boxes white, put my first coat of black spray, then another a few hours later... than another few coats the next day... then the next... next... next... the paint began to build up and look terrible. There were always dull spots. Eventually, i threw the cabinets away.

Now i just use black wood paint from home depot and my cabinets look black and shiny but not like a piano finish.

Godzilla
 
FWIW, my own FE167E MLTLs, which are quite similar to Bob's FT1600s in several areas, are built from BB ply. It's just a case of working with your chosen material.

BB plywood is considerably stiffer than MDF, and while it resonates, this tends to be at a frequency above the main passband of the cabinet. So, when working with it, the object is to keep those resonances up high, above the point where they'd be an issue. Basically, this is the opposite approach to using the denser, but less-stiff MDF, where you're looking to push panel resonance down, below the passband of the cabinet. Both methods have their advantages; my preference is for the former approach, while I know Bob favours the latter. IMO, neither is really 'better' -they're just different & which you favour is about personal preference rather than superiority.

I've got two left thumbs on a good day, and no facilities at all, so my mate Ed very kindly built my enclosures (because I wanted a pair of attractive cabinets for a change, and he's a bit handy at the old woodworking) -they're in the picture below, sans drivers, next to his own Vofo folded TQWTs. In construction terms, the front-panel is doubled, all vertical panels are end lap jointed (I believe that's the correct term), leaving only a 5mm vertical band of exposed ply edge down the back of the enclosure. The front & upper ply edges are concealed by 3/4in pine quadrants. Panel resonance is a non-issue -the ply isn't adding anything of its own to the proceedings.
 

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Bob Brines said:
Yes. This is exactly the technique I was recommending if you want to use pre-veneered flat goods. Remember, though, if you choose a dark stain rather than just a clear finish, the wood strips must be the same species as the panels or the color will not match.

Bob


So you just turn that into a "detail feature" :angel:


Very pretty boxes Scott - kudos to Ed
 
Thanks all...

I have been giving alot of thought to how edge will look and how stain will take.

Bob, If I replace your baffle with a piece of solid wood that was cut 1 1/2" wider , I could cover that raw edge. And, you're right about the stain, would be difficult to get a match if material is different.

I got speakers in last night and rest of parts will be here today, so I need to get on it. Like most newbs, I have been suffering from info overload. Took a couple weeks of reading and searching and I have least figured out what I want to build and where I will place them.

I have always heard that "procrastination is the key to flexibility" but at some point you just have to do it and see how they turn out.
 
repeddler said:
Thanks all...

I have been giving alot of thought to how edge will look and how stain will take.

Bob, If I replace your baffle with a piece of solid wood that was cut 1 1/2" wider , I could cover that raw edge. And, you're right about the stain, would be difficult to get a match if material is different.

Even with mass damping panels, you'd want to take precautions joining a single plank of solid wood the dimensions of the FT1600 front baffle to a plywood or MDF shell.

Depending on the color of stain, you could easily disguise minor variations between solid and preveneered sheet goods of same species. The solid material will most likely have a different grain pattern and density, and if you're planting the front baffle of a shell of preveneered ply/mdf, there will be the exposed end grain at the top of the baffle to contend with. That's where you'll likely have the biggest contrast of color. Treating the entire cabinet with a pre-conditioning sealer would help mitigate that.

these big boys are cherry veneer on the cases, with a combination of cherry and black walnut solid edge fills - with a dark port stain, the difference is not that noticable

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As I alluded earlier, another approach is to use entirely different species for the case and front baffle or solid radiused edges, and highlight the color difference as a feature.

these are simple clear coat (sprayed NC lacquer)

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That solid front panel would be 41.5"x10.5" and constrained top and bottom. I wouldn't try it. If you must, I'd build the box as designed with MDF/plywood and float the solid wood panel with liquid nails or something like that. As Chris noted, you will still have end grain at the top -- right at eye level.

Bob
 
Assuming what? BB plywood? If using BB ply, I wouldn't use anything at all. With the bracing Bob's put into the FT1600 its resonances will be above the main passband of the cabinet, and therefore innocuous, with the added bonus of rapid decay time. Adding heavy damping like Hardibacker, which is ideal when working with MDF due to its different properties, will drag panel resonance back down, but you'd also in the process loose almost all the inherent material benefits of working with BB ply in the first place.

A slight downside is that Bob will have taken the thickness of the Hardibacker into account in the Vb calculation for the enclosure; however, you'll likely just get a touch more gain, so I can't see it being a terrible issue.
 
Indeed I do take the thickness of the HardiBacker into consideration. If you go with BB without the HB (as Scottmoose notes, leave it out!), you can either reduce the width and depth by 1/2" or accept a bit more gain at the bottom (may boom) and a bit more distortion 80-100Hz. You can also shorten the port tube a bit to bring the tuning back to the original. High quality playtime here!

Let me know what you decide and how it turns out.

Bob
 
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