Alpair 10.2 in 8 liter sealed - Too good to be true?

[Richard Ellis]

Originally Posted by chrisb

so how is it on high speed tooling, and what are movement /shrinkage properties like for making a speaker box?

Machine tooling really is the only way to work this stuff. I tried rounding off some corners with a flat rasp....Hah! The stuff just laughed at me. Next I tried a grinding wheel, a benchtop variety, standard type. The wood refused to "remove" itself from the parent material, it just sat there & 'burned'.
Check the properties of the stuff, there are sites which will give you statistics, I believe it is No.2 on the weight rating, a tight grain, a deep gorgeous red, somewhat Walnut type color....but the grain is tighter.
There is an outlet down the street here that is adjacent to a larger "woodstore"......it's almost as if it is the stuff is premium...deserving of its own stores to sell the stuff. A 100mm..X100mm X 2M post runs ya some 90 Pesos, or $20+ USD. I consider that outstanding considering its peers.....seen some Ebony in bulk lately??
I would love for someone outside of my country....that I can communicate with....have me send out a chunk for someone to work on.....Someone with some tooling. Any ideas??

__________________________________________________ _Rick.........

[chrisb]

Originally Posted by buzzforb

The Home Depot' near me carry a very good quality ply that i would put against the baltic birch 5' x 5' I have bought. I have cut up 3 sheets of it in both 1/2" and 3/4", and have yet to find an air pocket. Yet to find anything like it at lowes. the 1/2" is $40 compared to $90-$110 for baltic birch and you get more on top of that. It is not likely that you will build just one pair. I use either 3/4" ply or solid lumber for baffles. FYI, I do not have 1/100th the experience of any of these other guys, but i have yet to hear a significant difference if cabinet is well made and braced.

got a close up picture of laminated "edge grain"?

my situation is somewhat reversed, and of course trade pricing on materials can demonstrate the mark-up / profit margins at retail level - for shop grade 5x5ft 18mm Baltic Birch I'm paying $42, for Murphy Hardwoods 18mm mult-iply 4x8 C2 W1S $84 --very nice stuff, and for some breakouts actually better yield than the 5x5s


as for not hearing the differences that bracing can make - others may well have different anecdotes to share

[chrisb]

Originally Posted by chrisb

got a close up picture of laminated "edge grain"?

my situation is somewhat reversed, and of course trade pricing on materials can demonstrate the mark-up / profit margins at retail level - for shop grade 5x5ft 18mm Baltic Birch I'm paying $42, for Murphy Hardwoods 18mm mult-iply 4x8 C2 W1S $84 --very nice stuff, and for some breakouts actually better yield than the 5x5s


as for not hearing the differences that bracing can make - others may well have different anecdotes to share

quoted with permission from a recent builder of the following enclosures:

Once braced & lined with needled wool the sound is absolutely amazing. A complete reversal from the undamped, unbraced box.

Having one complete and the other unbraced & unlined allows for good comparison though - bass has flattened (reduced a small amount I think) and sound actually seems more extended in the upper registers as well. I'm a low level listener as I'm in an apartment but they leave very little wanting.

These are Eminence 12TAs - it's the "in an apartment" that really got me - best part of 3 4x8 or 4 5x5 sheets in this pair - and I wouldn't even want to think about the cost of veneering.

[buzzforb]

Originally Posted by chrisb

got a close up picture of laminated "edge grain"?

my situation is somewhat reversed, and of course trade pricing on materials can demonstrate the mark-up / profit margins at retail level - for shop grade 5x5ft 18mm Baltic Birch I'm paying $42, for Murphy Hardwoods 18mm mult-iply 4x8 C2 W1S $84 --very nice stuff, and for some breakouts actually better yield than the 5x5s


as for not hearing the differences that bracing can make - others may well have different anecdotes to share

The bracing i am referencing is that which is suggested by Dave in his plans and i completely agree about the benefits. My comment is directed at the idea that we spend a smaller percentage of money achieving 85% of the gain, and a much larger amount dialing in the last 15%.

[JRKO]

As the happy & proud owner of the 12LTA monster above I can confirm each unit is 1.5 2440x1220mm sheets of 18mm 13 layer baltic birch - 75lb per sheet

I think baltic birch is specified as it is almost guaranteed to be voidless and so enables you to build happy in that knowledge. If the structure is riddled with pockets of random sizes between different laminations you could get all sorts of issues, not least the density of your board isn't what was originally specified fo the design.

bracing might stiffen up the cabinet but that is not going to make much difference if each wall is singing its own tune

My motto - 'always follow the maker instructions 100% - who wants 93% of the finished product?'

Originally Posted by buzzforb

My comment is directed at the idea that we spend a smaller percentage of money achieving 85% of the gain, and a much larger amount dialing in the last 15%.

do you mean 85% is the brace & damping and 15% is the cabinet?

[buzzforb]

85 is HD plywood and 15% is BB, at least in my neeck of the woods. As i said i am a rookie an dhav eonly built 6 different enclosures, where Dave,Chris, and Scott hav edone hundreds. Just tried to offer alternative.

[JRKO]

$275 in timber (£59 per sheet x3 inc.VAT) for mine. To save some money I'd have to use 25mm MDF for the same rigidity thats 121lb a sheet. My speakers already weigh over 100lb each with 1.5 sheets of 18mm ply

I think I understand you now.

You'd be hard pressed to work it differently and end up spending a fair amount remedying/correcting - extra bracing etc screwing up the internal volume & air movement etc etc

Dave & Chris' designs are 'whole package' designs. I would feel I had done them (and myself) a disservice if I hadn't followed the design to the letter and at the very least would be wondering what they 'should' sound like

[ODougbo]

25mm (1") is a special order around here ~ can always double layer 12mm (1/2"), which is easy to find. Can go back and lap the material "back over" the ends also.

*25mm ~ oh boy, it's heavy, can only buy 60" wide here also.

[buzzforb]

I am simply talking about using an alternative quality ply vs BB, nothing else. All construction should be to specs.

[JRKO]

I don't think you'll find a lower cost, equal quality ply, even when taking cost effectiveness into account. BB is slow grown, nearly 100% void free, with the highest face quality (mine are A/BB), very high dimensional stability, and i think the most laminations for thickness. How much we are willing to spend on our projects however is a personal matter - and possibly getting it past the other half

I'm in the do it once, do right camp. These may well be my last speaker so I spec'ed it as I wanted. I personally see no point compromising on quality/cost in construction and then trying to make up for it by spending more money & time when it could have been done right first time - that to me is an exercise in futility. But again - How much we are willing to spend on our projects however is a personal matter

Under no circumstances is this to be taken personally - it's my point of view, mine, all mine