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Old 23rd July 2013, 07:38 AM   #11
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Quote:
Originally Posted by AndrewR View Post
Just use 18mm Baltic Birch ply. It is probably the best material out there for loudspeakers. It should be readily available, if not then buy from ebay.

Andrew
If only you knew Andrew....
Were I home in Scotland, or back in Romania, there would be no issues, unfortunately I am working in neither.
FleaBay and postal services are on another planet.
Had to hand carry in cables, terminals, speakers, micro amp, dac, etc. just to stay sane, finally cracked and brought the Alpairs. Plywood may well prove to be my next luggage....
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Old 23rd July 2013, 12:46 PM   #12
xrk971 is offline xrk971  United States
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Boblamont,
Wow, it sounds like you are on assignment out in the sticks, literally. At least you have internet access to diyaudio What indiginious materials/building materials/junk is available where you are? If sound quality is more important than looks, as you are at a job site, maybe making something that may look dog ugly, but is cheap and sounds good may be something you can do? When is your next trip back to civilization so you can hand carry some choice construction materials?

If you ever see flat panels of any type of plywood, or better yet, kitchen cabinet door panels, wall panels, drywall, ceiling sound tiles, etc being demo'd from a construction project site.... Those make an excellent back and front baffle for a Cornu BLH Ever think of building a Cornu Spiral horn? Now you can!. I know you are asking for Pensils but those require lots of materials, clamps, a table saw, etc and lots of cutting nice 90 deg corners. May I suggest the Cornu as an alternative? Give it some thought, many folks have been super pleased with the sound and construction can't be simpler. So what you need to bring with you the next time you come home are: hot melt glue gun and lots of glue sticks, a razor, ruler, some old pillow stuffing, some cat 5 wire, a printout of the Cornu plan all folded up, a bottle of pva glue, some wood screws to mount the drivers, wire cutters/strippers, a small keyhole saw for cutting the driver hole, and most importantly, foam core panels pre-cut into 4 in wide strips. This can be very compactly fitted in your suitcase. They can be even cut along the 20 in direction so that they fit in your roller carry-on bag. You may have issues with the razor and saw for carry-on luggage you now have the ingredients for a very nice sounding speaker for your Alpairs that is easy to make and requires only rudimentary tools and supplies, while relying on almost any flat natively available panel for the main baffle and back. I would build the 28 in x 4 in version for the Alpair 7. Trust me, it will sound better than you can imagine. Hope that helps, but that is my 2 cents for your predicament. Good luck!
Regards,
X

Last edited by xrk971; 23rd July 2013 at 12:51 PM.
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Old 23rd July 2013, 01:41 PM   #13
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Not quite out in the sticks, just an artificial environment where the assumed norms do not apply...
The Pensil design is less intrusive than the FH3, so Scott's creation appealed, and I can take the drives when I leave and build either back home. It is just a matter of finding that material which is permitted here, and engineering the solution within that, Chris and Scott's observations have extended the options now.

Have followed the foam-core escapades with some interest, may try it later, but not on this occasion.
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Old 23rd July 2013, 07:21 PM   #14
chrisb is offline chrisb  Canada
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Originally Posted by boblamont View Post
Not quite out in the sticks, just an artificial environment where the assumed norms do not apply...
The Pensil design is less intrusive than the FH3, so Scott's creation appealed, and I can take the drives when I leave and build either back home. It is just a matter of finding that material which is permitted here, and engineering the solution within that, Chris and Scott's observations have extended the options now.

Have followed the foam-core escapades with some interest, may try it later, but not on this occasion.
For the 7.3s you can get away quite nicely with 15mm plywood of decent quality, and even with the smaller drivers, I wouldn't consider the Pensils without some front to back and lateral bracing.
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File Type: jpg 7.3 Penils MarKenT 004.jpg (293.2 KB, 159 views)
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Old 23rd July 2013, 09:32 PM   #15
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Regarding 18mm ply and having read about Bob Brines new 12mm ply M12 MLTL, I built a 12mm version of my 18mm Fe168 MLTL and I hear no difference at all between them, the bracing is the same in both.
My hearing must be shot.

Regards
Bruce
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Old 27th July 2013, 12:32 AM   #16
Eric is offline Eric  United States
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Hey Chris,

Is that your own design for the pencils? I would be interested in some additional details, they look very nice!

Eric
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Old 27th July 2013, 01:18 AM   #17
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I am working on (applying veneer now) a 12mm version of my M10-A10 tweaked to work with the A10P. I here no difference between the thin version and the original built with 18mm material. This is real hardwood Russian birch, not the softwood Chinese knockoff.

IMO 12mm BB/Russian birch is good to ~12" panel widths with only a 12x50mm panel stiffener. I do use window braces around the driver and a 24mm top panel. Gives the whole structure a nice sounding knuckle rap.The long panels of a MLTL don't sound so firm, but once 24mm of type 700 fiberglass lining is applied, the cabinet is sufficiently quiet.

Bob
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Old 27th July 2013, 04:51 AM   #18
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Originally Posted by Eric View Post
Hey Chris,

Is that your own design for the pencils? I would be interested in some additional details, they look very nice!

Eric
See here Eric, think the FH3 is there also.
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Old 27th July 2013, 05:47 AM   #19
chrisb is offline chrisb  Canada
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Originally Posted by Eric View Post
Hey Chris,

Is that your own design for the pencils? I would be interested in some additional details, they look very nice!

Eric

The Pensil design family is by Scott Lindgren - the bracing & aesthetic flourishes in the photoed pair have become a bit of a signature by the Planet10 team.

The "details" are that I built as per the drawing (with extra bracing), chamfered the long front edges, added grilles and a 1" plinth echoing the footprint with a 1/4" recessed spacer to create a shadow reveal line - pretty standard stuff.
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Old 27th July 2013, 07:03 PM   #20
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Originally Posted by chrisb View Post
For the 7.3s you can get away quite nicely with 15mm plywood of decent quality, and even with the smaller drivers, I wouldn't consider the Pensils without some front to back and lateral bracing.
Chris,
Is there any particular reason that these holey plate type braces are better than say hardwood dowels or battens randomly spaced?
I can see that front to back and top to bottom would be firmly linked by this arrangement, but would cross dowels not lock the side panels adequately?
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