Not here in Greece. Here we are getting them mostly in multiples of 10mms, designated by Φ. For example Φ10, Φ20, Φ70 and so on. And this is outer diameter, so I will have to calibrate the length for the thickness of the tube as well.
Thanks for the link Dave. I think I m ready to go on with my build now. I will calculate the actual piece sizes later today and post them if anyone cares to double check
It s just that this month has to pass before I start... too many payments for now... no money to spare...
Thanks for the link Dave. I think I m ready to go on with my build now. I will calculate the actual piece sizes later today and post them if anyone cares to double check
It s just that this month has to pass before I start... too many payments for now... no money to spare...
I faced the same problem here in Lebanon when looking for quality ply.
I ended up experimenting with high quality marine ply, and these had near zero voids. the downside was the black veneer they had.
This was before I finally was able to source high quality ply, after a 4 month search.
After building the same enclosure out of MDF and Plywood, I personally vote against MDF.
It does make a substantial difference in sound especially that you're trying to push big bass out of your enclosures.
They are also very nasty to work with due to the dust they give off and they tend not to glue as good as plywood.
Regards
I ended up experimenting with high quality marine ply, and these had near zero voids. the downside was the black veneer they had.
This was before I finally was able to source high quality ply, after a 4 month search.
After building the same enclosure out of MDF and Plywood, I personally vote against MDF.
It does make a substantial difference in sound especially that you're trying to push big bass out of your enclosures.
They are also very nasty to work with due to the dust they give off and they tend not to glue as good as plywood.
Regards
Yeah, marine grade use to be no void, but no longer available AFAIK in my locale, though it's been posted that it's still available in some countries. Otherwise, from a stiffness POV, ~1.125" thick MDF has as much as 19 mm BB or Apple ply. One still needs to brace it for high power apps though, same as plywood, so larger cabs quickly become unacceptably heavy and of course there's the health issue.
One option is to build/brace the cab out of a decent grade of 12 mm plywood and 'skin' it with 15-19 mm MDF to get a good compromise between stiffness, damping. This also allows an easy way to 'flush'/flared 'inset' mount the driver.
GM
One option is to build/brace the cab out of a decent grade of 12 mm plywood and 'skin' it with 15-19 mm MDF to get a good compromise between stiffness, damping. This also allows an easy way to 'flush'/flared 'inset' mount the driver.
GM
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To have the same stiffness as good ply, MDF needs to be considerably thicker than good ply. All that extra mass brings its own set of issues, but it is a good 1st approximation.
dave
I managed to find some decent looking 19mm marine grade ply.
It has 11 layers, but it also has some inlay patches on its surface, probably replacing knobs, indicating that wood selection is rather poor. I cannot see any voids on the "endgrain" though. Just some scuffs or marks, probably from small wood knobs again.
The alternative is some 5 layer stuff from the local Home-Depot-Style store, which clearly has many visible voids on its ends. I used that to make a flexy style rack a few years back. Its surface layers are pretty thin too. Hardly sandable. Kind of ridiculous. It goes up to 40mm though...
Anyway... I think I will stick to ply, and try to find some better quality
It has 11 layers, but it also has some inlay patches on its surface, probably replacing knobs, indicating that wood selection is rather poor. I cannot see any voids on the "endgrain" though. Just some scuffs or marks, probably from small wood knobs again.
The alternative is some 5 layer stuff from the local Home-Depot-Style store, which clearly has many visible voids on its ends. I used that to make a flexy style rack a few years back. Its surface layers are pretty thin too. Hardly sandable. Kind of ridiculous. It goes up to 40mm though...
Anyway... I think I will stick to ply, and try to find some better quality
Indicating that it is shop grade. The little footballs are there so that the ply has no voids. It does not significantly affect the structural properties, just the cosmetic ones. All the BB that we have used comes with patches, the architectural grades are more expensive, and only guarantees that the outer plies don't have patches.
11 plies is pretty good (official BB would have 13 plies/18mm, the Murphy ply we use now has 15 plies/18.5mm)
dave
what type of finish had you intended for these?
I'd be inclined to go with the "marine" ply - a properly patched not on the face veneers is generally not some to worry about, and darker patches on cross grain plies can be indication of unpatched structurally sound knots (which would be expected to be filled by glue during the lay-up process) or mineral stains in veneer sheets as they're rotary lathe cut from the log.
Also be aware that when it comes time to cutting parts, the "nominal" thickness is just that - whether expressed in metric or imperial. For example the difference between '3/4" ' BB and the Murphy Multi-ply I use is as much as 1mm from the nominal .75" / 19.05mm.
Most of the time that's hardly an issue, but make sure to allow for it in the cutting plan, and measure something like the Met from the inside out - otherwise internal parts (braces, bottom plate, etc) could end up just small enough to not fit if cut to "exact size" without dry-fitting.
I'd be inclined to go with the "marine" ply - a properly patched not on the face veneers is generally not some to worry about, and darker patches on cross grain plies can be indication of unpatched structurally sound knots (which would be expected to be filled by glue during the lay-up process) or mineral stains in veneer sheets as they're rotary lathe cut from the log.
Also be aware that when it comes time to cutting parts, the "nominal" thickness is just that - whether expressed in metric or imperial. For example the difference between '3/4" ' BB and the Murphy Multi-ply I use is as much as 1mm from the nominal .75" / 19.05mm.
Most of the time that's hardly an issue, but make sure to allow for it in the cutting plan, and measure something like the Met from the inside out - otherwise internal parts (braces, bottom plate, etc) could end up just small enough to not fit if cut to "exact size" without dry-fitting.
For finish I am planning on some veneer anyway, so I do not worry about patches or other surface issues.
About the nominal sizes, I plan to cut front and bottom a bit bigger and then flush trim them with the router. Only the side walls and the brace will be cut to width. So even if the thickness is a bit less, I would only have to trim the front and the back a bit to keep the inner volume as required. Now if it is thicker... we ll see I will probably handle it by rounding the corners with the router or something. I will measure before cutting the front and back panels just in case
The trickiest should be the top and bottom panels which will require a precise angle cut with the scroll saw (Miter saw will not be able to cut the entire front face length). For the top, I might glue it like that (90 degs cut) and then trim the excess with a japanese thin blade for a nice flush surface.
About the nominal sizes, I plan to cut front and bottom a bit bigger and then flush trim them with the router. Only the side walls and the brace will be cut to width. So even if the thickness is a bit less, I would only have to trim the front and the back a bit to keep the inner volume as required. Now if it is thicker... we ll see
I will probably handle it by rounding the corners with the router or something. I will measure before cutting the front and back panels just in case The trickiest should be the top and bottom panels which will require a precise angle cut with the scroll saw (Miter saw will not be able to cut the entire front face length). For the top, I might glue it like that (90 degs cut) and then trim the excess with a japanese thin blade for a nice flush surface.
By the way, you think it is worth flush mounting the FF225? The metal ridge is about 6mm high, but the weird shape makes it a bit tricky to route with a plain circle pivot jig. I guess I can do it as a circle that fits the entire driver and then use some wood putty or something to fill in the gap before the veneer is glued on top of it. Oh veneer will most likely be synthetic 0.5mm for the first trial.
You think it would be worth the effort or should I just mount it on the surface and not worry too much about it?
You think it would be worth the effort or should I just mount it on the surface and not worry too much about it?
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Even though I tend to flush mount drivers in all my builds for aesthetic reasons, I'd be inclined to agree with IG81 on the FF & FE series with the stamped basket frames - they are actually quite well engineered. Now thicker cast frames such as F120A, FX120 and any of the Mark Audio drivers and most dome tweeters with none tapered flanges should be flush mounted.