Composite Nidacore Fearful 15/6/1 Build

[jlepre]

Yeah I know...I still wanna SEE that cab...

 

[BurningSkies]

+1. I love the loadin/loadout but it is getting increasingly irritating keeping the head on the cab and scooting the cab back into position every 10 minutes.

Gb has notation up on his site about additional bracing to help keep small amps on top of fEarful type designs. More bracing on the top panel equals less vibration and less movement.

On the other hand, I bought some velcro straps and velcro from the speakon to the back of my cab...which keeps it in place without making a new project for you.

 

[Robby Hoinsky]

Robby, great to see you over here man! I've been seeing you around for years on DIYMA and have bought some raw drivers from you over there. I wish you all the best in getting into the PA instrument cab game.

Zach

Small world!

I used to post over at DYMA before Ant bought it, now it is too mainstream for my tastes

/end audio snobbery

j/k, I still bump the 12" DIYMA subwoofer that npdang built a few years back. Most symmetrical BL and Kms curves I've seen to date. Great sounding sub, love it. And I'm still using and recommending Second Skin sound deadening in every install. I've got a couple hundred square feet in both of my cars.

Thanks for the kind words, I'm having a ball with these new cabs.

Robby

 

[greenboy]

Gb has notation up on his site about additional bracing to help keep small amps on top of fEarful type designs. More bracing on the top panel equals less vibration and less movement.

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Had to laugh the other day when someone said their 55-pound tube head was vibrating off their 2-driver Emperor cab. There's no excuse for that design/build flaw.

Minis/micros though, are gonna wanna bump around, unless the motor in the cab is just a glorified wind-up toy. Which is a polar opposite of a fully armed Kappalite.

 

[Mr. Pickles]

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Had to laugh the other day when someone said their 55-pound tube head was vibrating off their 2-driver Emperor cab. There's no excuse for that design/build flaw.

Minis/micros though, are gonna wanna bump around, unless the motor in the cab is just a glorified wind-up toy. Which is a polar opposite of a fully armed Kappalite.

I'm sure velcro would be fine for preventing a micro from bumping around of top. One could always add a bracket for a more elegant solution. And with the potential weight savings of this composite material, one could even add on a one or two space rack slot on top as a fEarful amp/cab combo.

 

[greenboy]

Yeah, a Nida-Core build is no different in this respect, than any wood build. There's a certain amount of rigidity that needs to be there to be a great cab. But still, the micros and minis are a special case - just like the things across the room are that are vibrating around on the fireplace mantle when I hit THIS note ; }

 

[deb]

Thanks everyone for the links and suggestions.

I've asked Robby to put an inset top handle/strap similar to what you'd get in Duke's Thunderchild. The rest of the hardware choice will be finalized Sunday.

The next step is for Robby to test the strength of the cured nidacore/PL. If it passes, he'll start gluing the braces and paneling.

 

[Kahooli]

Small world!

j/k, I still bump the 12" DIYMA subwoofer that npdang built a few years back. Most symmetrical BL and Kms curves I've seen to date. Great sounding sub, love it.

Robby

Small world indeed. I left that forum as it became a mainstream crap site, but i still enjoy my two DIYMA REF12s - one in my car in a small sealed, one in my living room in a larger sealed.

 

[Pilot172]

Nothing like a full salvo from the the greatest of ship class...I have a poster of a simular shot. Full salvo actually pushed the ship some 15' in the opposite direction...

Most fEARful builds for the past year have been using the newer recoilless 3015LF drivers.

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[John D]

Judging by the wake in that pic, I'd say more like 50'. Which ship is that?

 

[Bill Whitehurst]

Looks like an Iowa class.
That gives you exactly four choices.

Funny, just a few minutes back I was talking to another bass player
about what I think I may see from a fEarful and we decided that
a hundred pound rack on top of it *might* hold it in place.

 

[BurningSkies]

Looks like an Iowa class.
That gives you exactly four choices.

Funny, just a few minutes back I was talking to another bass player
about what I think I may see from a fEarful and we decided that
a hundred pound rack on top of it *might* hold it in place.

I have 2 fEarfuls, and have used either a 15/6 or a 15/6+15/sub setup for quite a while now, and I don't have any problem with my cab walking away even with a LMII on top. Decent rubber feet make the big difference. Without a composite build, you're looking at 40-55lbs depending upon how its built per cab. You probably don't want to leave anything small sitting on top of the amp or on a nearby surface, though...it will be on the floor after a few moments.

 

[greenboy]

Indeed. The battleship thing is a joke. One with a point. Speakers/drivers don't shoot anything outward - under even brutal use. They vibrate/move back and forth. There is no one force in one direction that would beg to be countered by a reactive force in the opposite direction.

Just make sure the floor doesn't slant. Oops. I'm doing it again.

 

[abarson]

I'm sure velcro would be fine for preventing a micro from bumping around of top. One could always add a bracket for a more elegant solution. And with the potential weight savings of this composite material, one could even add on a one or two space rack slot on top as a fEarful amp/cab combo.

This might be stupid, but then again...
Why not install speaker grill sockets into the top of the cabinet, and affix the pegs to the bottom of your micro amp? There might be just enough latching power to secure the head, yet you'd be able to easily remove it for transport. Velcro seems to have a habit of adhering to stuff that you don't want, like fleece pullovers, etc.

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[will33]

This might be stupid, but then again...
Why not install speaker grill sockets into the top of the cabinet, and affix the pegs to the bottom of your micro amp? There might be just enough latching power to secure the head, yet you'd be able to easily remove it for transport. Velcro seems to have a habit of adhering to stuff that you don't want, like fleece pullovers, etc.

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Now that might work, assuming you use the same amp all the time. Of course you could get more of them and position them for different amps, etc. I'm getting curious as to how all this vibration would affect the lifespan of these little micros, internal parts, etc. May still want to put a piece of foam or something between the amp and cab although something that weighs 3 or 4 lbs. may not stay there either. There is a solution here somewhere.

 

[greenboy]

This vibration thing is getting out of hand. Properly built, there's no more vibration potential on top of one of these cabs than there is with any other box with a 3015LF in it. Less, in fact, because hardly anyone braces in 3/4" construction which means less local panel area damping. The real issue is that micro heads are so light.

As far as solutions, once you have a top handle it's easy to do a cradle or wrap around thingie using neoprene and velcro or whatever - with actual shock damping courtesy of the neoprene (ever seen the thicker cloth-covered neoprene mousepads?). Or adapt the micro-heads carry cases to stay in place.

Gotta say though: bass players have really turned obsessive these days, always wanting specialized systems for each and every thing. Sometimes simpler is better and not following trends blindly has its upside. I still prefer handles on sides balanced so that one-handed carries are comfortable yet two handed carries are at a non-knee banging height that doesn't stress the back because close-to-chest clutch is easy. That's great for large distances and now both one and two-handed carries are accomodated.

It also allows quick-tighten nylon straps or bungies to do their easy magic in battening down a head, with some closed cell foam or neoprene cut to footprint dimensions in between.

 

[BurningSkies]

This vibration thing is getting out of hand. Properly built, there's no more vibration potential on top of one of these cabs than there is with any other box with a 3015LF in it. Less, in fact, because hardly anyone braces in 3/4" construction which means less local panel area damping. The real issue is that micro heads are so light.

As far as solutions, once you have a top handle it's easy to do a cradle or wrap around thingie using neoprene and velcro or whatever - with actual shock damping courtesy of the neoprene (ever seen the thicker cloth-covered neoprene mousepads?). Or adapt the micro-heads carry cases to stay in place.

Gotta say though: bass players have really turned obsessive these days, always wanting specialized systems for each and every thing. Sometimes simpler is better and not following trends blindly has its upside. I still prefer handles on sides balanced so that one-handed carries are comfortable yet two handed carries are at a non-knee banging height that doesn't stress the back because close-to-chest clutch is easy. That's great for large distances and now both one and two-handed carries are accomodated.

It also allows quick-tighten nylon straps or bungies to do their easy magic in battening down a head, with some closed cell foam or neoprene cut to footprint dimensions in between.

Agreed. A while back, in one of the early fEarful threads people brainstormed a variety of different 'head-restraint-devices' all of which were entirely unnecessary. I run a velcro strap from the speakon connector at my amp back down to the connector on my cab back. Done. Cost about 50 cents, and sets up in moments. Many times I don't use it and my head still doesn't rattle off to far, mostly because the speakon is heavy enough to keep it in place.

Apparently people around here need a different 'head restraining device'

 

[will33]

Ahh, keep the micro in it's padded case....duh.

Good bracing = no vibration of course, but I'm curious if these amps are so light, they'd have the "vibrating the beer glass off the table" affect. That would be the sound waves doing the vibrating and not the actual cab top.

Of course, I don't have a micro, or a flimsy cab to try it.

 

[DukeLeJeune]

I've asked Robby to put an inset top handle/strap similar to what you'd get in Duke's Thunderchild.

Shouldn't be too hard; the handle is inset by two thickness of 1/2" plywood in my design. So you have a "spacer" board in between the top of the cabinet and the board that the handle is mounted to. The cutout is 9" by 5", and the outer dimensons for my spacer board as well as the board the handle is mounted to are 10" by 6" (which may or may not translate over to the Nidacore). I think this is a big enough cutout to give adequate clearance for large hands. One possible theoretical side benefit is that you get some extra bracing of the top of the cab along the way, so it's less likely to vibrate the amp off. Again, I don't know whether that's a consideration with Nidacore.

Mounting the handle requires a bit of attention to get adequate clearance underneath for the fingers, but if you go too far in that direction you'll end up with the handle sticking up too high and interfering with the amp. If you end up short on finger clearance, this can be remedied by building up the clearance with some rubber-backed washers.

One final calculation that should be made before finalizing the design and cutting material is the balance point; with this ultralight cab, the woofer's magnet will be a very significant factor (the crossover inductors are also pretty heavy). Might end up having to run the top handle sideways or something so that it ends up roughly centered over the balance point.

 

[markkoelsch]

I am reading this, and I have a slight concern. Being polypropolene I think epoxy is not the correct thing to use in bonding it. I beleive you need a polyster resin...not epoxy. That being said, and having done some composites before I have a couple other thoughts. First, when making the fillets on the inside joints one might wish to consider an amendment to the resin. Something like a chopped carbon fiber, chopped glass, or kevlar pulp. Most resins by themselves are brittle, and addign an amendment to them toughens them significantly.

Secondly, I am surpised that he did not consider using a nomex cored fiberglass panel. Epoxy will adhere to this, and epoxy is generally better than polyester resin in temrs of strength.