Bedroom speaker build (with renders and questions...)

[John L]

OK, I promised I haven't drifted away into obscurity.

I'll have some progress to update soon but I have a question. (And I promised I searched around first ^_^)

- Where can I find a good looking screw? (don't laugh, I'm serious ^_^)

Also, what size of screw should I be looking at? The driver specs on the PDF are garbled on the mm size of the hole...

I was guessing somewhere in the vicinity of a #6 or #8.

Appreciate all the feedback and help everyone.

You need to be more specific. Are you interested in wood screws, bugle heads, or pan heads? Do you want full thread, or self-tapping?

And what fastener type are you going to use? Will you be using Phillips, hex head, or Robertson/Canadian? Forget the flat driver types, they are so 9/10.

There is a huge difference. Myself, I would recommend using the Robertson tip, which has a square head. It does not strip. As for the head, it depends on whether you want the head to be flush with the surface or not.

Again, I need more information from you.


PS: try this site for retail distribution.

 

[chrisb]

Re: here's a fine Canadian screw....

Robertson screws

been around forever (at least north of the 49th)

A Torx or "hex" head (Allen head), from McMaster and Carr . Can use flat head wood types or socket cap types. Brass sounds better than almost anything else so if available use them if you're serious.

Also check any local boat repair shops...


stew

just be careful not to over tighten brass connectors - at this gauge #6 /#8 or 4mm, they can easily be snapped off by hand, even with precise pilot holes.

don't ask .

 

[planet10]

Myself, I would recommend using the Robertson tip, which has a square head. It does not strip.

Trust me, you can strip a Robertson :^) And once you have rounded off the bit from stripping a couple, it gets quite easy. Fortunately a little box of bits is cheap from the local Home Depot 7-11.

But it is a lot harder than a Philips, which aren't recommended.

We use Robertson as standard, occasionally a hex if we get fancy. (when i ship something with Robertson out of Canada i usually ship a bit too).

dave

 

[John L]

Trust me, you can strip a Robertson :^) And once you have rounded off the bit from stripping a couple, it gets quite easy. Fortunately a little box of bits is cheap from the local Home Depot 7-11.

But it is a lot harder than a Philips, which aren't recommended.

We use Robertson as standard, occasionally a hex if we get fancy. (when i ship something with Robertson out of Canada i usually ship a bit too).

dave

How well I know. Nothing is Kid Proof either.

I forgot to add "under normal circumstances".

That is why it is so important to hold the drill in position for the bit to fit on the screw perpendicular to the plane of the head, or it will quickly round out the edges of the bit. And don't use a smaller bit for a larger opening, as in #1 bit to a #2 screw head.

 

[planet10]

And don't use a smaller bit for a larger opening, as in #1 bit to a #2 screw head

I never did learn the numbers, the sizes are yellow, green, red & black (as are the colours of the corresponding screwdrivers) Red & green are most common.

dave

 

[EEatKSU]

Speaking of screw heads, I use to think that Torx head screws were virtually impossible to strip out... I learned that if you give idiots (and these idiots are even in the college of engineering) torx head screws and a cordless screwgun, they can ruin even Torx head screws.

 

[John L]

I never did learn the numbers, the sizes are yellow, green, red & black (as are the colours of the corresponding screwdrivers) Red & green are most common.

dave

that must be a Canadian thing. South of the border, at least in the south, everything is the same colour. I guess the distributors figure people should be able to tell the difference. Doesn't work all the time, of course, because no one country has a 'lock' on the mechanical morons of this world.

 

[John L]

Speaking of screw heads, I use to think that Torx head screws were virtually impossible to strip out... I learned that if you give idiots (and these idiots are even in the college of engineering) torx head screws and a cordless screwgun, they can ruin even Torx head screws.

One of the Undeniable Truths Of Live: "Nothing is Kid Proof". Kids, even supposedly adult ones, can still 'bugg@r' anything they lay their paws on, and not even break into a sweat over it.

 

[chrisb]

One of the Undeniable Truths Of Live: "Nothing is Kid Proof". Kids, even supposedly adult ones, can still 'bugger-up' anything they lay their paws on, and not even break into a sweat over it.

indeed as any parent can attest "kid proof" is certainly near the top of the oxymoron list

(no political jokes here today)

back to our regularly scheduled programming

I'm personally quite fond of 3 or 4mm threaded insert fitting (NOT t-nuts - another device designed by optimists and cursed by end-users world-wide ), and black anodized button-head hex socket cap screws.

 

[Cal Weldon]

And don't use a smaller bit for a larger opening, as in #1 bit to a #2 screw head.

Right, but have you noticed how well a red robby (#2) fits a #3 phillips? Very handy in a pinch.

that must be a Canadian thing. South of the border, at least in the south, everything is the same colour.

Even the American tools I own have some indication as to the colour. Even if it's just a small stripe on the handle.
yellow: 0
green: 1
red: 2
black: 3

 

[Nanook]

tools....

I only have Canadian TOOLS , by default, here,spent their whole life here... via legal immigration....

none of my tools have any colour code on them, as I mainly use multi-bit types. As far as a drill and some bits--don't use a drill. Pre drill a hole, lubricate the screw with paraffin, and use either a variable speed drill with a clutch and the torque setting to midpoint. Tighten slowly, if the clutch disengages prior to sinking the screw, increase the torque one step at a time and retry. No broken anything should occur then...

Now if someone manages to "screw things up", it won't be due to not knowing, but rather not being taught.

I only say brass sounds better, because there is a definite difference in my (proudly Canadian)solid wood guitar (LaSiDo Seagull S6, made with real Canadian vintage lumber from our Crown lands and parks that have naturally fallen to the ground no less!) when brass bridge pins are used

stew

 

[Cal Weldon]

Re: tools....

II only say brass sounds better, because

...for the same reason they don't make wind instruments (brass section) from hardened steel.

 

[chirpie]

Once again, you guys are impressive.

Sooo... more details.

I was eyeing using a security hex screw in conjunction with a 1/8" security allen type bit.

Full thread, pan head screw I would think.

How much holding power does a 4" driver need?

Would a screw like this be strong enough to hold a 4" driver in place?

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-840


Fasteners are where I get a little inexperienced. It seems like I would be cutting out a decent amount of my MDF ring to install one and it would be getting pretty close to the inside edge, wouldn't it? (again, I lack experience in this area...) Also some screws (such as the one I linked to) state they don't require a fastener. I assume this means I better not tighten and untighten too often, right? (I'd think I could just fill the hole with wood glue though...)

Thanks everyone!

 

[Cal Weldon]

Those screws are fine but do you need a security screw? That means you have to buy the special bit too.

Yes you can fill a stripped screw hole with wood glue and sawdust combo but most times I would just up it from a #6 to a #8 and be done with it. By the time you have stripped a #6 hole you should be just about finished playing.

 

[chirpie]

Those screws are fine but do you need a security screw? That means you have to buy the special bit too.

Yes you can fill a stripped screw hole with wood glue and sawdust combo but most times I would just up it from a #6 to a #8 and be done with it. By the time you have stripped a #6 hole you should be just about finished playing.

This is where the weird part of me kicks in... I actually like the look of them better. The $3 bit to do the job is worth price. Particularly since I have another application where I think it may come in handy.

Thanks for the tip on the strip out.

I'll order a few extra screws to experiment with first, just to get the hang of it. (and to find the right size drill bill to start the hole...)

 

[John L]

Read John Krutke's page on how he builds speakers. It is quite informative, and he has a fetish for neatness. If you look at his photography, ALL of his furniture, etc, is spotless in his house. I get the impression that he would never think of putting anything in his house if it were not perfect.

Enclosures

All drivers are countersunk, particularly the tweeter. The woofer is also countersunk unless I specify otherwise. About the only time I specify otherwise is when the woofer flange is specifically designed for surface mounting.

All baffles are removable, and fastened with socket head cap screws. Normally I'll use 1/4-20 black anodized, with a metric M6 regualr series washer. Why an M6? Because it's 6.87mm inside diameter fits a 1/4" bolt with less slop. The washer is required so I can make the hole in the baffle a little bigger to allow for slight positioning of the baffle before it's tightened down.

Removable baffles are held in place with corner gussets that hold a Parts Express Hurricane nut. These are like normal T-nuts, but are press-fit rather than having teeth that dig into the back side.

I finish most of my baffles with black Rustoleum texture finish. Before that I'll use sanding sealer on bare MDF, and I'll do about 5 coats of it on the edges with 1 or 2 coats on the face. Sand it all smooth before painting. Depending on how well I seal the edges, I'll likely need two coats of texture finish. Then finally I'll put a single clear coat over that for a for a bit of smoothness that makes wiping dust off easier.

In the case of using a Parts Express pre-fab enclosure, I'll cover the baffles with white "Contact" brand stick-on shelving paper. This will protect it from router base scuffs and scratches. If all goes well, I'll leave this protective paper on and then spray-paint the countersinks so no bare wood shows through the cracks. If all doesn't go well - you might have some chipping, or you might have scratched the baffle anyway, then I'll fill scratches with bondo, sand it a little, and use the baffle painting routine specified above.

All woofers 7" and under have the inside of the woofer hole chamfered. Depending on the flange, I may just go all the way around the inside or I may "scallop" the inside to allow some meat for screws to fasten into. Depending on how the driver looks, I may choose to bolt it in place using socket head cap screws (normally 1" long #8 or #10) or I just use black wood screws. Using the socket head cap screws requires scallops so there is enough wood to support Hurricane nuts on the back of the baffle.

Enclosures of .375 cu ft or larger have a crossbrace from side to side. Of course if I buy a Parts Express enclosure, it has the crossbrace already in it.

All of my designs call for roundovers on the baffle. 1/2" is the minimum, but 3/4" is better if you have a large shank, variable speed router than can handle it. The roundover is required to help smooth out the diffraction ripple response.

An externally hosted image should be here but it was not working when we last tested it.

 

[Andersonix]

With the speakers being propped up on the stands with a nice gap in between, I think this is a good opportunity to put the port on the underside. I don't especially like looking at the port, and it also doesn't seem like the extra facet on the front adds any function besides styling (plus the port pointing upward will collect more dust than usual).
I also don't think plain rectangular boxes are very interesting. What if instead you slanted the top backward so that you could have the option of turning the speaker upside down where the driver would tilt upward slightly? Of course, the port would need to be mounted in the rear to avoid seeing it.
I would also make the front panel as narrow as possible to take away as much visual 'boxiness' as possible, going slimmer, taller, and deeper, and take advantage of the driver's small size. This will also have the effect of balancing out the relative height of speaker and stand.
It's not too late, is it?

 

[chirpie]

With the speakers being propped up on the stands with a nice gap in between, I think this is a good opportunity to put the port on the underside. I don't especially like looking at the port, and it also doesn't seem like the extra facet on the front adds any function besides styling (plus the port pointing upward will collect more dust than usual).
I also don't think plain rectangular boxes are very interesting. What if instead you slanted the top backward so that you could have the option of turning the speaker upside down where the driver would tilt upward slightly? Of course, the port would need to be mounted in the rear to avoid seeing it.
I would also make the front panel as narrow as possible to take away as much visual 'boxiness' as possible, going slimmer, taller, and deeper, and take advantage of the driver's small size. This will also have the effect of balancing out the relative height of speaker and stand.
It's not too late, is it?

I appreciate the thoughts... I have actually started construction on the speakers with a few changes from the initial design. First and formost, the stands are too damn big. LOL.

The speakers would be less than a foot tall in scale if I made those stands as tall as I initially designed them. (In order to get them at ear level height)

Rear porting wasn't an option due to it's future placement near a wall. I'm not too terribly worried about dust in the port, but I'll see if bottom porting is possible. (I'll need to figure out how to get around my brace...)

Stay tuned! (Get it?.... OK, ok, throw your tomatoes now...)

 

[chirpie]

OK, so they sat mostly unfinished for two months in my furnace room. Finally got a window of time to work on them and hope to finish them up in the coming week or two.

The finishing steps have been real tough. I knew this was going to be the hardest part for me. I'm sure everyone says this but I'll say it anyway...

Man, if I did it again, I could do it in a 1/3 the time, less materials, and do a better job.

But it's been fun. And not fun. And then fun again.

I finally threw the last coat on one of the speakers last night and popped in the port, driver and speaker terminal. (Of course there was the wire soldering step as well, and stuffing the cabinet, and gasket tape...)

I took it to the theater room to test. Yup, pretty inefficient speaker design. LOL. If I was guessing by the SPL of the other bookshelf speakers in there, I'd put it in the 86-88 range. But hey, for a speaker running in mono I was actually very encouraged. It's off axis range is putrid but for a person in the center and one to the left and one to the right, it's laser beam imaging all the way. Vocals sounded very neutral. (Some people might describe it as lean, but I like this sound.)

Bass was so-so (DUH!) but what is there is pleasingly accurate.

The driver sunk more than I wanted it to, so I may remove it and place more gasket padding underneath it so it closer to being flush to the hole. That's probably part of why my off axis is suffering a little. Although the shadows in the pics make it look worse than it really is.

I still need to finish the other speaker. I had a delay in the finishing. Anyone else ever have this happen? I was using automotive spray paint, and had bought 4 cans up to this point with no problem. I bought a fifth and final one, sprayed it on... it looked great. But then it dried. It dried to an almost pink splotch color in comparison to the deep red finish I had seen up to this point. Weird.

It was a can of Deep Canyon Red (T278) from Dupli-Color. So now I'm gonna try my luck and buy another can and see what happens...

Anyway, I still need to attach the plinths but here's a few pics of where we're at now. Is it perfect? Nah. Would it survive a walking by inspection? Probably.

Stay tuned.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.