DIY Speaker Project PAD

hey now.

as a carpenter (by trade, when it comes to audio i build the boxes, im not a sound engineer) i get so amused by how some speaker boxes are designed.

ive built boxes using lock miter joints, double rabbet joints, drawer lock joints, and glue/staples. there is absolutely no difference in strength (using mdf). now hardwood is a diff story, but we arent taking things with variable tolerances. speakers have a breaking point. most of the time (unless you try to purposely blow the box apart with interntal pressure) its just not happening. where as someone who gets mad and slams a kitchen draw can cause it to break.

maybe because i do this for a living im programmed to think about efficency as well as integrity. for example, im gonna build a speaker box to the best i possibly can and make it the strongest i possibly can, but im not gonna spend however many extra minutes/hours/days on it unless its gonna make a difference. ive heard many speaker designers say that at a certain point, the amount of work that goes into a crossover is not worth it with the results you get- getting minimal advantages for 10x the amount of work..especially when i also like to build furniture and straight razor scales (handles...and ys i shave with them) as well.

now im sure there are "audiological" (its what i call technical audio jargon and other scientific factors that im not even gonna pretend to know) but why not just go overboard where it counts. if you need the utmost structural integrity why not build the inner shell out of cement board? hell you probably wont even need bracing then. why not just use biscuits, or better yet dowels?

im not being confrontational or taking a "the Screw is a matter with you" type of attitude. a friend of mine who just ordered a certain kit was telling me how ridiculous the plans were for the enclosure (this is a guy who works in a shop that has a cnc machine cut everything). i had to see them so he sent them to me and theres all these different angles and routes. none of which makes the enclousre any stronger than just butting the joints and using glue and narrow crown staples (bracing still needs dados imo).

is there some kind of audio science as to how speaker box joinery is decided on? because coming from the wood side of it, im not quite sure the reasoning for some techniques used.

-dave

***ps- if you do all tht fancy pants overboard stuff thats fine. im not attacking you. theres a million ways to skin a cat. my way isnt the only way. and if your learning how to do woodworking i almost encourage you to try out the fancy pants stuff so that way you learn how to do it.

It's more than just integrity of the box, and relates to flexing or vibrations of panels. The smaller an open panel between braces is, the less likely is it to flex, and inherent resonance of the panel will be higher the smaller it gets. This moves the boxy sounds above that of the bass response to not hinder the low end clarity.

There is also the terms of a more resonant internal material to make the cabinets. The stiffer/harder it is, the more resonant it will be- like concrete. This will then involve more extensive methods of damping the internal bouncing waves than for instance- MDF or hardwood.

HDF is an alternative to MDF, but since it is denser- the resonant frequency is less damped and more of an issue. MDF or particleboard remain pretty much the best DIY materials for speaker boxes due to inherent properties of the material.

If you can afford cast phenolic chunks like in the Wilsons, then go for it...
Later,
Wolf

osd1 wrote: im not being confrontational or taking a "the Screw is a matter with you" type of attitude. a friend of mine who just ordered a certain kit was telling me how ridiculous the plans were for the enclosure (this is a guy who works in a shop that has a cnc machine cut everything). i had to see them so he sent them to me and theres all these different angles and routes. none of which makes the enclousre any stronger than just butting the joints and using glue and narrow crown staples (bracing still needs dados imo).

is there some kind of audio science as to how speaker box joinery is decided on? because coming from the wood side of it, im not quite sure the reasoning for some techniques used.

Building a speaker enclosure is not just about making the box strong and making sure it stays together.

Bracing, sometimes to the point of what may look like overkill, is necessary to prevent the panels from resonating. Too much resonance can destroy the accuracy of the speaker in almost every way.

For high end manufacturers, they may use exotic materials to eliminate resonance. But DIY'rs may not have access to exotics, so tons of bracing is the next best thing.

As far as your friend's kit that has all those "different angles and routes", they could be there for other reasons than strength or even bracing. Depending on the kit, they may be part of the design. 1/4 wave or TL designs need a very specific long (compared to the size of the box) and convoluted path. Altering these may ruin the sound of the speaker.

I apologize if I am telling you something you already know.

I use rabbets and dados as much for ease of assembly as I do for strength. It's nice to be able to put the box completely together before the final glue up, and w/ rabbets and dados I can do that w/out it being a sloppy mess. They also make it super easy for bracing placement, I'm not fudging around trying to line up my pieces. I think in the end (depending on the complexity of the cabinet), you get the time spent making those dados and rabbets back in time you save assembling the cabinets, not to mention knowing everything is where it belongs. The extra strength from rabbets and dados is a bonus.

Another really good reason for rabbeting all the outside edges of your panels is that it definitely gives a better seal on the cabinet.

For instance, this is a dry assembly of the Statements I built. Having those rabets and dados makes it go together like pieces of a super easy puzzle.