DIY 3015 Cabinet

[V63]

Another question: in a cab where the grill cloth goes directly on the baffle should I put felt on it to prevent "grill flap"? Do I have to cover the whole thing or just the perimeter? I don't have enough room for any kind of wood spacer.
Thanks again.

 

[beans-on-toast]

I helps to put a padding of some sort under the grille cloth to avoid the flapping that you mentioned. Not all cabs are built this way.

What works well is to use fabric store black felt. Glue it on to the baffle board and use a razor to cut out the felt where the speakers cutouts and ports are. Then mount the grille cloth on top. The felt adds some spongy padding that helps with flapping. Years ago, Ampeg used to use a sponge under the cloth but with time it would disintegrate. It must have been a rubber based product. If you use a little heat with a hair drier or other source, it will shrink the grille cloth tight onto the baffle. This has to be done carefully to ensure that the cloth shrinks evenly. Too much heat and the cloth can melt.

 

[V63]

Thanks beans-on-toast!

I've got some pictures of my woodworking progress.

This is a detail of the rough front corners. I rounded the corners to 3/4" radius back to front and 3/8" on the front and back edges. I've glued in the 3/4 cove pieces I made.

These are the 1/8" trenches that go all around the cabinet for the gold piping thread.

Hole for the SpeakOn jack.

 

[V63]

Checking the baffle gap with the large white piping I'll be using
I've got a whole whack of sanding to do.
I post more picks and info of anyone's interested.

 

[V63]

Does anyone have or know of some sound clips comparing a cabinet without damping and one that has it? How about sound clips of a cabinet that is heavily braced vs. no bracing. I'm trying to get an idea of what to listen to, and shoot for, during this build.

I'd also like to know if putting a nylon stocking over the inside flare of my ports to prevent damping material from entering them would impede their performance.

Thanks very much.

 

[V63]

I understand bracing and damping in theory but I'd just like to know what they "sound" like. I don't want to have take my cab apart eleventy billion times using trial and error if I can help it. It be be nice to know if your cab sounds like "A" then you need more damping, and if sound like "B" them needs less etc.

 

[V63]

I posted this question on a separate thread hoping to get some bites.
Will_33 graciously helped out saying:





As far as "this bracing sounds like this and that bracing sounds like that"or..."this damping sounds like this and that damping sounds like that"...those are individual design specific things and I don't think generalizations can be made.




"You're back to if it sounds good, it is good..which of course, applies in each and every case, regardless if it's studious engineering or pin-tail-on-the-donkey type design.

-looks like its gonna be Pin-The-Tail-On-The-Donkey!

 

[StraightSix]

My understanding, for what it's worth, is to brace as much as you can (within reason) and for damping, start with the cab empty, then add a little and compare...continue to taste.

You will know when you like it best.

 

[seamonkey]

Here's Bill Fitzmaurice suggested bracing

Simple, elegant, works.

 

[V63]

I am recalculating my bracing scheme to have a 3/4" dowel for each dimension. The rest of my bracing volume budget ( no more than 34.18 cubic inches ) will go to bracing the one piece removable back panel.
Using my 3/4" (18mm) baltic birch cut into 1 1/2" strips I plan to cut 1" circles into it 1/4" apart. Is this too small a space between circles?

 

[V63]

Dowels from side to side and top to bottom. Put in a back pillar to attach dowel to the baffle. I'm not sure how well these will hold up. I'll see after the PL dries. They'll make damping more difficult and not sure if they're worth it. I'm becoming a little dishearten with this project. It's becoming more complicated and taking longer then I thought. If it works out and sounds good then I'll be happy. If this thing makes a sound I don't like, which I'm starting to worry about at this point, I'll be very very bummed about the the wasted time and effort, not to mention money.

 

[DukeLeJeune]

View attachment 397460If this thing makes a sound I don't like, which I'm starting to worry about at this point, I'll be very very bummed about the the wasted time and effort, not to mention money.

Assuming you like the native voicing of the 3015, I don't think that's going to happen.

But if it does, figure out why. Don't lose the lesson that your paid for. We learn more from our failures than from our triumphs (that's why I know so much about speaker design!).

And you'll still have a very well-built box that may work great with a different woofer whose native voicing is more to your liking.

 

[V63]

Once again Duke you've really lifted my spirits. You made me remember that I picked this speaker for reasons. I feel better about the cab today. I have had a bad cold the last couple of days and Calgary's weather has been in the -40's C with the wind chill so I think that hasn't helped my optimism and second guessing with this project.

I picked the driver based on is good TS numbers, Johnk_10's build
http://www.talkbass.com/forum/f15/custom-diy-2x15-cab-build-854517/
and this vid from another TB'er


The driver seems to be what I'm looking for.

If the cabinet works out I'll call her "Duke" in your honour for all your help and encouragement. You're a really solid guy.

Sincere thanks once again,
Clayton

 

[Mugre]

The drawing indicates "string tension bolts". Is there a turnbuckle or something similar added for even more bracing?
.

No one answered. Lots of cajones (no giggling, the other word has two "O"s) have something analogous to snare wires across the front panel. The string tension bolts may very well be something to adjust the tension of those wire just like on a snare drum.

Mugre

 

[DukeLeJeune]

If the cabinet works out I'll call her "Duke"

Thanks, but if it's a "her", may I suggest "Duchess"?

And if it doesn't work out, maybe "Dukey"?

By the way, I totally understand that apprehension you mentioned. I still get it almost every time I ship a cab. Does it suck in some way that I either subconsciously overlooked or missed entirely?

 

[V63]

Exactly

 

[V63]

My design was based on my criteria to have the most shallow front-ported cab I could, so I went with a rear-loaded gasket-backed cab. It may have been a really dumb choice. Anyone have any ideas about making sure I get a good seal on the back? My worry about this is making me think about starting again with a front loaded design. My choices also make testing a PITA. Does anyone have any experience with this? (Getting a good seal on a removable screwed-in back)
I could reclaim the extra depth needed for the front of the driver and grill frame of a front-loaded cab by just using straight tubing for the ports instead of the Precision Ports which demand an extra inch of length. Will the gasket tape work or do I ditch the flared ports? I need to know which way to go before I continue with this.
Thanks.

 

[DukeLeJeune]

My design was based on my criteria to have the most shallow front-ported cab I could, so I went with a rear-loaded gasket-backed cab. It may have been a really dumb choice. Anyone have any ideas about making sure I get a good seal on the back?

Gasket tape works fine as long as there are no gaps in it, and don't skimp on the number of screws you use. The screws not only compress the gasket tape, they are also your means of anchoring the back panel rigidly in place. I'd go with #8x32 T-nuts or hurricane nuts and screws with washers under the heads. I'd probably go with one every four inches or less, and in particular you want one in each corner. Imo.

 

[V63]

My buddy whose basement I was building this thing in (thats why it's been taking so long) decided to "help me out" by glueing on the baffle without the speaker. Which is good in a way because I wanted a do-over on this this build anyway. I'll do a front loaded cab this time.

My question now, which I may start a new thread on, is: if I don't what a rear ported cab, nor see the ports, and I want the cabinet to be as shallow as possible, is putting the ports on the bottom the best way to go?
Are there any problems or quirks associated with this type of porting?
How high off the floor does it need to be so as not to restrict air flow?

Thanks

 

[bgavin]

The least amount of impact on location is the front slot port.
It is also the most difficult to tune.
Multiple build iterations, or a removable slot scheme is required.
There are formulas that will get you pretty close.

Reference the fEarful series for the visual.