Material for BD15 bass enclosure... Bert (Off Topic)

by BobW @, Wednesday, January 18, 2006, 22:52 (4382 days ago)

I am planning to use a sandwich of 3/4 + 1/2 inch Baltic Birch plywood to get to the specified 32mm which is just not an option here in America. A vacuum press would be used to make the sandwich and at 1500 lbs/sq. ft. that ought to do the job. I am NOT a fan of particle board.

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Material for BD15 bass enclosure... Bert

by Bert @, Thursday, January 19, 2006, 09:01 (4382 days ago) @ BobW

Hi Bob,

I am planning to use a sandwich of 3/4 + 1/2 inch Baltic Birch plywood to
get to the specified 32mm which is just not an option here in America. A
vacuum press would be used to make the sandwich and at 1500 lbs/sq. ft.
that ought to do the job. I am NOT a fan of particle board.

The suggested wall thickness is needed for the suggested particle board. If you use other materials then things in the design change. If you would like to use different material then the only importance is the internal volume and the port dimensions which should be the same as on the drawings.

For the rest I do not know the real effect caused by the other materials used.

Ciao,

Bert

--
BD-Design - Only the Best!

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Material for BD15 bass enclosure... Bert

by BobW @, Thursday, January 19, 2006, 13:32 (4382 days ago) @ Bert

I think the only difference would be that the birch ply would be more rigid that particle board... and heavier.... I'll have to hire a couple of illegal's form Central America to carry them up from my garage! I don't know the situation there but here almost all physical labor, etc. jobs are done by illegal immigrants... they wait on street corners and in Home Depot parking lots for day labor jobs. OK with me since Americans will not do these jobs any longer.

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Material for BD15 bass enclosure... Bert

by GC, Thursday, January 19, 2006, 14:59 (4382 days ago) @ BobW

I think the only difference would be that the birch ply would be more rigid
that particle board... and heavier....

Hi Bob

I have buildt many cabinets over time in different materials.

A simple test is to hold the board in free air and knock on it. You will then hear the sound caracter it will apply to the sound of your speakers.:wink:

BR
GC

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Material for BD15 bass enclosure... Bert

by Bert @, Thursday, January 19, 2006, 15:09 (4382 days ago) @ BobW

Hi Bob,

I like the sound of the particle board as used with the Reference bass enclosures. The enclosure is tuned with that material plus the dampingmaterial and used bracing to something I like to hear.

Feel free to use anything else though, that's what we as DIY-ers usually prefer to do... :smile:

Ciao,

Bert

--
BD-Design - Only the Best!

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"Particle bd' or MDF

by BobW @, Thursday, January 19, 2006, 20:25 (4382 days ago) @ Bert

Particle board here is usually very cheap stuff made from sawdust and some kind of resin while MDF or medium density fiberboard is made from finer material and resin and is smoother and denser. Which are you refering to since sometimes they are used interchangeably, Mostly what I call PB is used in cheap furniture that always sags and for cheap kitchen counters with some kind of plastic laminate... it swells when it gets wet.

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"Particle bd' or MDF

by Bert @, Thursday, January 19, 2006, 23:30 (4381 days ago) @ BobW

Hi Bob,

Mostly what I call PB is used in cheap furniture that always sags and for cheap kitchen counters with some kind of plastic laminate... it swells when it gets wet.

Yep, that is the stuff but then without the plastic laminate. The dense outside and the relative loose inside of these panels absorb energy which is good. The speed of sound in these panels is also different keeping "noise" inside the enclosure and less audible for the "outside" world. These panels have a low Q.

MDF, high undampened Q, is my least favourite material in terms of sound, you can always hear that an enclosure is built from that material giving an artificial sound. Perfect for finishing, cutting and painting though which is probably the reason why most loudspeaker manufacturers use it. It's cheap and less labour intensive giving it's wrongly accepted popularity in the common world.

Ciao,

Bert

--
BD-Design - Only the Best!

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"Particle bd' or MDF

by GC, Friday, January 20, 2006, 06:29 (4381 days ago) @ Bert

Yep, that is the stuff but then without the plastic laminate. The dense
outside and the relative loose inside of these panels absorb energy which
is good. The speed of sound in these panels is also different keeping
"noise" inside the enclosure and less audible for the "outside" world.
These panels have a low Q.

I'm also a great fan of the PB. The knock test shows a nice pattern of dampening qualities and what is left sounds very musical.
The choise of materials for all parts involved in a speaker system is critical. That goes from the cabinet to both the diaphragmes, voice coil forms, voice coil conductors, spiders, surrounds etc. etc.
All swinging parts contributes to the overall sound in a positive or negative way.:smile:

But not only PB is excellent for cabinets. Also plywood of different wood sorts. Birch as one of my favourits. A compromise between the hardwood sandwich board and the soft wood sandwich board.
Also newer materials as very light weighted composit boards, such as the materials choosen for the ORIS SWING, exels extremely good musicalities. It keeps unwanted sound trapped and what is left sings like Marial Callas.:ok:


MDF, high undampened Q, is my least favourite material in terms of sound,
you can always hear that an enclosure is built from that material giving
an artificial sound. Perfect for finishing, cutting and painting though
which is probably the reason why most loudspeaker manufacturers use it.
It's cheap and less labour intensive giving it's wrongly accepted
popularity in the common world.

No wonder this material never were the choise of any instrument builders.:naughty:


BR
GC

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"Particle bd' or MDF

by rodneyAB, Friday, January 20, 2006, 10:06 (4381 days ago) @ BobW

Particle board here is usually very cheap stuff made from particles of wood. I think the MDF is the pressurized sawdust.

Particle board is the good stuff from home Depot. half inch and quarter inch thick sheets, about two sheets of each IIRC. I did laminate a birch or maple multiply sheet on the face where the BD 15 sits, but if I were to do it again, I'd stick to PARTICLE Board throughout. it actually looks good with several coats of semigloss varathane.
yeh I hate that filthy ParTicle Board when it is used inappropriatly for cheap kitchen cabinets and poorly implemented counter tops...this is part of the modern american way tho...use the cheapest material..use the fewest fasteners...throw out any sense of traditional craftsmenship...and try to make huge profit...:sad:
Bert's use of particle board for the BD 15 is an appropriate use in this application, and the resultant cabinet, if well made by the DIYer, will provide good BASS :grin: :grin: :grin:
rodney

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"Particle bd' or MDF

by BobW @, Friday, January 20, 2006, 15:53 (4381 days ago) @ rodneyAB

Thanks to all for the input. PB it is! Laminate the sheets to the specified 32mm. How ever I will veneer the cab. Raw PB would never pass the WAF (Wife Acceptance Factor) here; I'm surprised she did not object to the horns.. just a "where would they go?" to which I replied "over there".

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