fEARful cabinet build

Volitions Advocate

Hero Member
Hi Guys,

I've probably posted 5 different threads in this forum trying to come to some idea of what I want in a new rig.  After much waffling and trying new things I've settled on the Positive Grid Bias amp head in a rackmount.  I've played with their software and the thing is pretty fantastic.  I should be receiving my pre-order sometime around the end of this month.

I wasn't sure if I wanted to buy an ugly Yorkville speaker or something else with a flat response to run through my modeller.  I can load impulse responses of speaker cabinets so it's pretty versatile if I get a nice full range speaker, but it needs to be good, and look good.

Some searches in TalkBass, and even a post or two here pointed me to greenboy.us and his fEARful cabinets.

The deal is. Greenboy made these designs, they are his trademark, but he has released the plans for free as long as you do not use them for commercial purposes.  If you follow the builds exactly you should have an amazing quality product.  A fellow nearby saw me asking questions on the forum and offered to let me try out his cabinet and it sounds pretty amazing.

Originally designed for Bass guitar and some keyboards, they have a homemade crossover design for adding in the tweeter that makes it a nice 3-way setup that is supposed to sound something like a nearfield reference monitor, which would be perfect for me.  The positive grid amp comes with a 600W amp built into it, which should be plenty for running this thing and any instrument I want through it, whether guitar, bass, or synth.

I was originally going to build a 12/6, but it would be too narrow for a nice square look with a rack amp sitting on top, so I went with the 12/6 cube (designed to stack with a 15 inch sub design) since it will be the same width as a rackmount case.  I was going to extend the sides above the top of the cabinet and mount my amp in there like a combo, but I changed my mind and I am building it to greenboy's specs, and I will build a nice rack case for my amp later to match it.

Anyay, here is how It's coming along.  I already have the speakers, but I'm waiting for the crossover components and the horn for my tweeter to come in the mail.

Check it out so far:





Dry fit: Top is about 1/16" too wide. I'll have to shave it, it will be the last piece I glue in after finishing the insides.



If this is as good as I hope it will be, my tube amp will be up for sale on reverb.  Hopefully somebody in the U.S. is looking for a deal on exchange and is dumb young enough to want a 100 W head.  :laughing11:

Here is a link to my build thread on the greenboy forums.  You'll have to register if you want to see it over there.  If you're interested in these cabinets at all this is the place to be.  But I'll update it here as well.
Took the clamps off.  Top fits like a glove, will glue that in later.

Once the handles get here I"ll figure out the best place for them.



Test fit the speakers.  the 12 still doesn't quite fit. I'll have to sand out the hole just a little. I don't want to make it too big!

I'm using the Art Department's shop at the university.  I'm a masters student in the Music department, so I can keep my WIP stuff in my own office and out of everyone else's way when I'm not working on it.
Advoc said:
I'm using the Art Department's shop at the university.  I'm a masters student in the Music department, so I can keep my WIP stuff in my own office and out of everyone else's way when I'm not working on it.
Man o man, that's one sweet arrangement.  I've never considered building my own amp.  I'm waiting for approval on the greenboy site, you've piqued my interest.
Does anybody here know where to get things like inductors and giant capacitors?

I ordered parts for my crossover, but they gave me the wrong values for my woofer crossover.  They shipped me the parts for a 15 inch when i'm running a 12 inch.
(I got a 2.7 mH inductor and a 40uf capacitor instead of a 3.3 mH inductor and a 33uf capacitor, which is what I need)

I have no idea where to find these components, especially in Canada.  The electronics hobby stores don't have anything that big, and the industrial stores don't have anything that small.  Tayda and Mouser don't seem to carry them either.
The guy already sent me the replacements free of charge.  Those prices is are pretty crazy for wire coils.  Living in Canada sucks sometimes.
Advoc said:
Those prices is are pretty crazy for wire coils.  Living in Canada sucks sometimes.


a 3mH inductor from Q components is $12.95 CAN.  A similar one from parts express is $18.10 USD.  Don't see how ether of these are terribly expensive or how the Canadian one is more...
The one I need is $38!

I paid he USD equivalent of that for the entire kit from speakerhardware.

It's all good though, This thing will be done soon. Hopefully just in time for my amp to arrive.
IF you're really gonna be feeding it 600W I'd strongly consider biamping. No point is getting a running start only to throw it all away as heat.
It's the design that hundreds of people have sworn by.  It's all on the website.


The amp that's coming is 600 watts, so...  Biamping isn't really feasible without spending a bunch of extra money.

It works guys.  I've seen / heard it myself.  It's impressive.
From the website:

Properly applied over-damping allows one to use beefier components while still keeping the build simple, the parts count low, and weight manageable. In the case of the fEARful, this is a better choice than using more components but of lesser power handling - both in terms of longevity and performance.
Moving along!

I decided to go ahead and glue the cabinet top on, This should be easy enough with the woofer opening in the baffle.  I have the outside all sanded and squared up.  Once I take the clamps off tomorrow I"ll get the top sanded down nicely and then round the edges to 1/2" roundover for the corners.

Then some bright red vinyl for the cabinet and I'm still mulling over the grille.  I kind of love these LINK, but they don't make a 6" version, and it doesn't offer much protection to the cone.  I might make something myself that is similar.

Crossovers done.  I just have to add the Lpad to the Hi Pass.

Had I known these were so easy I would have skipped the kits and PCBs and just got the components.  Especially since I'm using an Alphalite 6A, the mid board is mostly unused and just jumpered. (you can use an 18 Sound mid driver that requires a different crossover with all the big resistors on the board, but I stuck with all Eminence)
Long overdue update.  Been a busy holiday season.  Hard to find time to get the hobby stuff done.

I have sanded the box down and rounded the corners with a 1/2" roundover bit.  It worked alright and the corners fit really nicely with the vinyl on.  I thought I'd have to take a rasp to the corners because they didn't quite fit over the bare wood.  The vinyl made it perfect though.

I picked up the vinyl covering from a local fabric store.  The stuff isn't super durable, but it's the right colour to match my amp's logo.  I'll just have to be careful with it.
This is my first attempt at doing a wrap like this and I think I did OK.  Not really super great, but it works and I have no bubbles or runs or anything.  Just need to trim up some mitres and such.
I tried really hard to make sure it went on square when measured against the factory edge of the fabric, but I wasn't perfect which I think accounts for the mis match on the back.  It'll be covered up by a large patch though, once I trim them flat.  I wont do that until I have the jackplate figured out and the hole for it cut out.

I still have the grill standoff pieces to paint black and PL/Bradnail onto the baffle.  I just have a plan piece of expanded metal for the grille, I think it will look just fine.  I like this chrome/red/black combination.  Something a bit different than just straight black.

I have eggcrate foam for the interior, and my crossovers are ready to go, and I have speaker wire.  Ages ago I needed 2 speaker cables for a PA system in a rehearsal space, so I bought a 50', cut it in half, and used banana clips at the cut end for 2 cables.  THey aren't being used anymore, so I figure I'll cut my speaker cable out of that cable for use inside the cabinet.

I have literally everything I need to finish except the rear jackplate.  I'm goign to hit up one of the local live sound companies to see if they have any spare parts.  Otherwise I've already designed one myself for 3D printing with ABS or PETG, which should be strong enough as long as I get a good gasket around it.  We'll see.










On the right track...  But it wobbles a bit.  Not sure why I'm not perfectly square, but a small shim under one of the rubber feet should fix it.