Solid Cherry Frugel Horn Mk3 Build

[Bozeman83]

I will be starting my second set of Frugel Horn speakers. I built my first ones from ply wood, this time I will be using solid clear cherry wood. This time I will take lots of pictures of the progress and post them on here. I have already bought the lumber and already own the CHP70 for this build. For anyone who has done this with solid wood, have any advise for dampening. Right now I am going to stay with the same dampening I used in my first set, which was what the build plans had. Any advise on this build would be appreciated.

[chrisb]

no advice, but good luck

[bill_a]

Solid wood - no matter the species - is not a good idea for 6-sided tight-joint boxes, particularly folded horns with the miriad of internal baffles and channels. Either the joints or the material will fail due to expansion and contraction from changes in humidity and the finish, no matter what it is, cannot stop it. This is one of the very first lessons one learns when becoming a woodworker.

Plywood, because of the thin cross-grained laminations does not shrink or expand nearly as much as solid wood. Particle board or MDF that's sealed doesn't either (unsealed, its actually much worse). Thats why most speakers are veneered ply or sealed MDF.

If the thought of learning to do veneer work is too intimidating, just do them out of good birch ply and finish with a good poly finish. IMHO, a good sounding set of fair looking speakers, is a far sight better than a beautiful pair that's going to crack, check or break in a year or two. It's also just a waste of expensive wood.

You are not the first to try it, nor will you be the last. Just a word to the wise from a woodworker with 30+ years of experience.
Bill

[doubtingthomas]

Got to agree with Bill here, I don't think it's completely impossible but the likelyhood of failure is very high, how about making them out of ply or MDF and lining the outside with solid cherry say 10mm thick? It's why no one makes even the most expensive kitchens out of solid wood and solid doors have a floating panel to allow for the inevitable movement, and a proportion of them still fail.

[Bozeman83]

I fully agree that is a high chance of failure, especially if it is not sealed, glued or jointed properly. I just really like solid wood and love working with. The one thing of going for me is I live in Montana where humidity changes are not a huge problem. Stay nice and dry here. The wood was purchased from a small local company that mills and kiln dries there wood in Montana (expect for exotics). So I am not bring in wood that is from a humid area. I will be sealing the the inside of the box, then using dowels and glue to join everything. The outside will also be sealed as well. I have been building furniture, as a hobby, for 15 with my dad and last 5 years I have been building a lot by myself. I fully understand the risk of their being failures. Its going to be fun, because I am going to be putting my wood working stills to the test.

[puppet]

I think you can pull it off.
Couple tips ... maybe you know 'em.

Boards used in a wide panel must be edged slightly concave in the length. When you place them flat, like you'd glue them together, the ends should touch and there should be a space in the center. (1/32" or more) End grain gives up moisture first ... this technique puts the panel into "pre-stress". As the ends give it up, the panel starts to relax. Joints won't check if you've allowed enough at glue-up.

Areas of greatest concern will be:
The side panel bottoms ... so I'd rough cut the shape before glue up and make sure you have the edge spacing machined here in those shorter length pieces.

The top where it meets the side panel. This must float or it'll check here. Top will be joined to baffle and back so no worries about it coming off. I'd use a rabbit/dado combination for the side/top joint (no glue!) Allow for the side to move toward the back under the top piece.

The back will have to have a dado/rabbit joint along its length as well. I'd make the rabbit/dado snug for about 1/2 the length up but the upper half should have a wider dado than rabbit so the side piece can move back and forth without stressing this joint and therefore, the side. Idea is not to trap anything in at least one direction.

Cherry is getting rare and expensive .... don't choke. :P

[mill23bay]

Can some sort of a sealer be used inside? I may fill some voids here and there, good for the corners.
PeterC.

[evanc]

you could build the boxes with solid sides top and bottom with the grain running the same direction all the way around. Wood expands across the grain, not in the long direction. The box will grow from front to back. Then make the front baffle, internal dividers and back from plywood. Seems like this eliminates grain conflicts.

[zman01]

NO expertise here , just a thought - how about you make the insides and bottom panel with plywood and the side and top with real wood? If that would be acceptable as a wood build to you that is...

[Bozeman83]

I currently do have a pair of demo speakers I made from ply wood and thinking about putting a veneer on them, but I am going to be building a full speaker out of solid cherry. I do agree that it's going to be a challenge. I have noticed that cherry has slowly gone up in price. The top of the speaker I do agree could cause some checking and also the front, the front I will be doubling it up so their will be one piece the covers the full front. I might do the same for the top to help with the checking. The side panel with the concave panels is a good idea. I will be sealing the inside, but this is clear cherry so they are no voids, only one piece of lumber has a small knot, but I will be cutting it out.