fEARful™ Part Ten (10)

[PhiDeck]

3506string:
Murphy's Law guarantees that, at the worst possible time, something will get hooked on the protruding screws that mount the cabinet's feet. I suggest they be flush with the T-nuts.

 

[tom-g]

How important is using gasket tape on the mid speaker... I kind of had a brain fart when ordering that stuff, and only ordered enough for the 3015lf... If it's essential, what are some alternatives that can be bought at a place like autozone, wal-mart, or menards?

The 3015lf comes with a gasket. At least mine did.

 

[Mjury02]

I was under the impression that using gasket tape on the 3015lf was a good idea, even though there is a gasket already in place, but I could be mistaken. If anyone could let me know for sure what is the best way to go about mounting that, it be greatly appreciated.

 

[tom-g]

I didn't use any additional gasket tape (on the 3015lf). My 15/6 works fine.

 

[JEDI BASS]

Jeez! I'm currently building my own bass.... just bought 2 Carvin LD1503s to downsize my gigging rig to something manageable (and mucho killah)..... and now I've subscribed to this thread!

Yep, I'll soon be building my own cabs..... and loving it!

Greenboy, you rule!

 

[lelandcrooks]

Leland,
If you're following this thread:
I just noticed that you have the 15/6 flatpacks listed on your site. Any idea when you'll have the 12/6 flatpacks ready?

Next week. I didn't get quite as far as anticipated this last weekend. I did get 80% of the way there. But does anybody ever get everything done they plan for in the anticipated time?

I know for DIY home improvement, my rule of thumb is double the estimated time, add 10%.

 

[Sundogue]

Next week. I didn't get quite as far as anticipated this last weekend. I did get 80% of the way there. But does anybody ever get everything done they plan for in the anticipated time?

I know for DIY home improvement, my rule of thumb is double the estimated time, add 10%.

Hey Leland, I'm about set to order some things from you like the 3015LF and the crossover. It mentions that the crossover is on two boards and that you have to drill mounting holes on the PCB boards. I've only seen crossovers mounted on a single board. I'm assuming the PCB boards don't have the circuitry running inside the boards themselves? If it were I wouldn't want to drill through circuitry accidentally.

Do you have any photos of completed crossovers? I'm trying to wrap my brain around how it gets mounted/connected and photos would help (not like you don't have enough to do already ).

 

[Foz]

FWIW I haven't been using extra gasket material on the 3015LF's seems to work fine - have found it is needed for the mids, horns, jack plates - basically everything else that doesn't already have a nice thick pad on the backside. The chamber gets pressurized - it will leak if it can - and leaks will squeak and whistle.

a moving cabinet indicates asymmetrical forces

There is no such thing as symmetrical forces and even if there were they wouldn't exist in a bass cab. The forces and mass distributions related to a bass cab are far from poised/counterpoised in balance and no wood box, regardless of thickness or bracing scheme, is immune to non-trivial vibration at the energy levels under discussion. When you drive a 3015LF series fEarful to its excursion limits these forces add up to about 1 horsepower [+/-750 watts/joules] reciprocating a linear motor in a +/- 20 kilogram box at frequencies as low a a few dozen cycles per second.

1 horsepower is a lot - that's like 4 reindeer or 1.5 zebras or one of these:

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If dedicated to lifting a +/-45 lbs. cab this is enough energy to raise the cab over 10 feet up in the air every second. Only a tiny fraction of this energy need be lost to to self vibration [versus vibrating the air in the room] to make the box slowly wiggle across the floor.

Put the cab on a non-resilient surface, hit it hard, and absent significant weight on top and/or squishy feet - it moves. This does not mean the cab is not reasonably braced - it means you need squishier feet or a nice soft pad or a bikini clad assistant to sit on your cab.

 

[3506string]

3506string:
Murphy's Law guarantees that, at the worst possible time, something will get hooked on the protruding screws that mount the cabinet's feet. I suggest they be flush with the T-nuts.

Thanks for the heads up. I was planning on pulling out the dremel and cut off wheel and taking those down at least the fronts. I don't like the look of them sticking up like that.

 

[mikeddd]

Thanks for the heads up. I was planning on pulling out the dremel and cut off wheel and taking those down at least the fronts. I don't like the look of them sticking up like that.

They look fantastic! About the wheel bolts; why don't you just buy shorter bolts? Home Depot/Lowes definitely has'em. I like the handles. Haven't seen those before. Where'd you get the grills?

 

[lelandcrooks]

Hey Leland, I'm about set to order some things from you like the 3015LF and the crossover. It mentions that the crossover is on two boards and that you have to drill mounting holes on the PCB boards. I've only seen crossovers mounted on a single board. I'm assuming the PCB boards don't have the circuitry running inside the boards themselves? If it were I wouldn't want to drill through circuitry accidentally.

Do you have any photos of completed crossovers? I'm trying to wrap my brain around how it gets mounted/connected and photos would help (not like you don't have enough to do already ).

You can pretty much drill them however it's needed. The circuit paths are very basic on the boards. I send pics whenever somebody buys the boards unassembled. The low pass is easy, just 2 holes for the cap wires. The midrange depending on the model requires quite a bit of modification, including scribing a line through the copper.

 

[lelandcrooks]

I'll also mention right now that corners with the wrong radius from Parts Express are often thinner different plastic as well, and can become the source of hard-to-locate buzzing on some notes. It's partly because they don't flush down as well to the round-over, and partly because they are flimsier.

They're nowhere near as good as the Penns. I switched away several years ago.

 

[Mjury02]

For the handles on the box I built, I just made a jig, and only went as deep as the handles needed to go, basically trying to prevent any air leaks. I'm using the spring loaded handles btw. Does anyone forsee this being a problem? There is about one ply thick left, and I plan to silicone the handle to the back of the wood to prevent any buzz or rattle.

 

[BurningSkies]

For the handles on the box I built, I just made a jig, and only went as deep as the handles needed to go, basically trying to prevent any air leaks. I'm using the spring loaded handles btw. Does anyone forsee this being a problem? There is about one ply thick left, and I plan to silicone the handle to the back of the wood to prevent any buzz or rattle.

No but you should think of installing some 'backing' plywood on the inside of the cab anyway, just so you can use longer mounting screws.

 

[ian_s]

Leland, are the Penn corners paintable?

 

[3506string]

Why are you calling them "nearfuls"? I do note that you have too wide a spacing between waveguide and mid driver and was wondering about that but...

Well this started out as a 2 x 3015 non LF build. Then due to vehicle space constraints I decided that I wouldn't be able to build a cab with decent volume. So I decided on the 3012ho. Then I realized I had enough room to build around the medium vented 3012lf. So I started planning around that. It wasn't until I had my panels cut that I realized my plans were only an inch or so off from the spec'd 12/6/1 and sub. By this time I was quite frustrated but decided to go ahead with the build as planned or I would have had to buy and recut two new sheets of the ply.

But anyways these are a bit smaller they are 23x16x16". I also used dowel rod bracing.

 

[3506string]

They look fantastic! About the wheel bolts; why don't you just buy shorter bolts? Home Depot/Lowes definitely has'em. I like the handles. Haven't seen those before. Where'd you get the grills?

I got the handles from ebay and the grills from partsexpress.

The rest of the info on the build.

All panels are 1/2" baltic birch except the baffle which are 3/4" birch.

I used 1" poplar dowels for opposing panel bracing.

Drivers are 3012LF, Eighteen sound 6ND410, Eminence ASD1001 and Dayton H07E waveguide

Only crossover component is duke's HPF.

Speakon inputs. 2 pole for the sub and 4 for the 12/6/1

Using a crown XTI2000 to Bi-amp.

Primed boxes with cheap flat black home depot latex and coated with duratex dried in my DIY tent oven.

Right now I just have a LR8 at 650hz making sure everything is functioning and that there are no leaks. Hopefully later today I will get to spend some time working out the crossovers. I can already tell I am going to have too much fun playing around with and making presets in band manager for the xti.

 

[mikeddd]

Thanks for the source on the handles. They are pretty cool looking. I didn't know PE sold expanded metal grills. Cool. They are becoming more of a "one stop shop" than they already are. So, you're using dowels for bracing...I thought they weren't necessary when following the bracing scheme for the plans? I read that yours are a bit undersize...but are you using the recommended bracing? If not, that explains the dowels.

 

[Sigurd]

I'm at a little bit of a loss right now. You guys are walking cabs across the floor?! Why am I not getting that kind of low end and volume? I guess I have yet to experience that. I'm still getting a chuffing sound out of the port, particularly on the low E. The B is nice, but doesn't contain the destructive power that's being talked about.

Settings are: bass volume and three-band are maxed, blend is in the middle. From there, I set the amp gain until the low B string won't light up the clip light, then master volume to taste. Am I still just EQing wrong?

 

[Sigurd]

Thanks. I know it's impossible to diagnose things like this over the internet.