North Creek Cabinet Handbook?/aka cabinet construction

[ThomasW]

Anyone have one of these? Since George stopped selling to DIYers I can't buy one.

So if anyone has one of these, could you/would you briefly paraphase what George says about using the tacky glue?

Thanks,
Thomas

[Mark K]

I have it at home, somewhere...I'll look for it tonight if someone doesn't beat me to it.

[ThomasW]

Thanks I'd appreciate the info... :T

[Habs4life]

"all our cabinet sidewalls are coated with Aleene's soft glue mixed with large crystal playground sand.This mixture forms a counter layer that does not add significant weight to the panel,yet greatly increases it's internal damping".

I believe he later prefered to use drywall compound in place of the sand.


OK here is more"Because of its intimate contact with the cabinet walls,any panel vibration is transferred into the volume of the glop(glue sand mix).We specify large crystal sand as a filler because it's medium density allows the volume of glop to be substantially increased without greatly increasing the effective mass of the panel."

[Mark K]

"all our cabinet sidewalls are coated with Aleene's soft glue mixed with large crystal playground sand.This mixture forms a counter layer that does not add significant weight to the panel,yet greatly increases it's internal damping".I believe he later prefered to use drywall compound in place of the sand.

They used to sell what was essentially white glue (softer than yellow). I know because I bought some to make some sandwich panels. It worked pretty well, but the glue line is hard to hide.

(PS still not home yet)

[Habs4life]

They used to sell what was essentially white glue (softer than yellow). I know because I bought some to make some sandwich panels. It worked pretty well, but the glue line is hard to hide.

(PS still not home yet)

Likewise I purchased some of the Aleene's soft glue at a local craft store to use between panels.

[ThomasW]

Likewise I purchased some of the Aleene's soft glue at a local craft store to use between panels.

That was my basic question, is there any special technique used with the glue, or it is used just like any other wood glue in this situation?

[Habs4life]

That was my basic question, is there any special technique used with the glue, or it is used just like any other wood glue in this situation?

Oh Ok for just laminating panels it would be the same as normal wood glue,no special techniqes needed.He does suggest a composite panel be made of birch ply and MDF.

[ThomasW]

He does suggest a composite panel be made of birch ply and MDF.

Cool that was the plan... :T

[Brian Bunge]

I seem to remember something about spacing braces at unequal intervals to help eliminate standing waves. I have a really old issue of Speaker Builder where a pair of sub/sats were built using North Creek's cabinet recommendations. I want to say vertical braces were placed at something like 2/3 and 3/5 of the cabinet depths.

[Habs4life]

I seem to remember something about spacing braces at unequal intervals to help eliminate standing waves. I have a really old issue of Speaker Builder where a pair of sub/sats were built using North Creek's cabinet recommendations. I want to say vertical braces were placed at something like 2/3 and 3/5 of the cabinet depths.

"If two braces are used ,the correct positions are five-eights and one third the way along.This creates regions of different widths,therefore different resonance frequencies within the panel." He claims birch ply is a better material for bracing than MDF.

[Hank]

Thomas, first, thanks for the question - it motivated me to go through four binders and a stack of papers - catalogs, printouts of HTGuide threads, CES info, technical papers - 7 years worth and a double armload went into the trash can. I know I saved too much, but hey, that comes with the territory.

I retrieved and am looking at the North Creek "Cabinet Handbook" and their "Wiring Guide". First, for FRONT and BACK panels, they use a sandwich of 3/4" MDF for the exterior, glued to 3/4" Baltic Birch plywood interior. They glued the plywood and MDF with "NCMS soft glue", the craft glue, to laminate the panels. They used 3/4" MDF for side, top and bottoms panels. For assembly of panels, they used "hard glue" - carpenter's glue. For "panel damping", they use what they called "Glop", which is NCMS soft glue and pre-mixed drywall compound, one cup of NCMS glue to 1/2 cup of drywall compound. The Glop was spread 1/4" thick on the interior of the cabinet SIDE WALLS ONLY. I actually used the stuff - it takes a couple of days to completely dry, depending on the ambient humidity, and it cracks. I was worried that the stuff would eventually fall of in chunks, especially if a cab received a hard knock, but it never happened. Whatever you use for interior dampening (I'm a fan of the PE vinyl sheet), I think the MDF/Plywood front and rear panel sandwich construction has merit. Another item: they recommend only ply for braces, NOT MDF. Lots of other tips in the little manual.

[ThomasW]

Okay thanks for all the research Hank... :T :B

[CupCak3]

A bit back to the topic of bracing... Does the book talk about (or can anyone comment on) using window bracing as opposed to strips for bracing? I have two big builds coming up and wouldn't mind saving some weight with strip bracing as long as it does not affect performance.

Thanks!

[JoshK]

That glop sounds a lot like something VMPS use to call "soundcoat". I played around in the inside of my VMPS cabinets of yore and it looked something like what I think that would look like.

[ThomasW]

That glop sounds a lot like something VMPS use to call "soundcoat". I played around in the inside of my VMPS cabinets of yore and it looked something like what I think that would look like.

The original Soundcoat was a product sold by the gallon. Fundamentally it's no more than a thick latex paint and sand mixture, so all it does is mass load whatever it's painted on.

A bit back to the topic of bracing... Does the book talk about (or can anyone comment on) using window bracing as opposed to strips for bracing? I have two big builds coming up and wouldn't mind saving some weight with strip bracing as long as it does not affect performance.

Thanks!

Window bracing is the way to go since it locks all the surfaces of of the box together.

[rc white]

bracing

I went into the subject of bracing quite extensively in the design of the loudspeaker system described here..

http://sound.westhost.com/articles/ssl2.htm#s3

What this shows is that most bracing is not nearly stiff enough, and at best only reduces panel vibration amplitude by a few db.

Very stiff bracing has the advantage that it can effectively push the resonant frequencies upwards because it cuts large panels into smaller ones. Smalls data shows that the actual sound pressure in the box drops of as virtually a hyperbolic function of frequency and above 1kHz. it is very small. The advantage of stiff bracing is that halving the area of a given panel multiplies by four its resonant frequency, allowing a typical small satellite with unbraced panels at around 1kHz. to have these pushed up to 4kHz., above most crossover frequencies and very low in amplitude.

Most damping compounds applied to speaker boxes are useless, unless they are applied to thin material, the classic bbc sand loaded bituminous damping by such as Rogers being used over 3/8 inch plywood, any thicker and the damping compound has practically no effect upon the panel q.

Very solid connection at panel edges is also important, the difference between a ridged and non rigidly edge clamped panel is around 3.8 times the amplitude in the middle, some 11db.
rcw

[Habs4life]

That glop sounds a lot like something VMPS use to call "soundcoat".

This sounds like the same as Acoustical Magic that Audio Concepts used to use and sell?It was a special latex paint.

[ThomasW]

This sounds like the same as Acoustical Magic that Audio Concepts used to use and sell?It was a special latex paint.

Yes actually that's what I meant to call it..