I want to build a "lightweight" 810 bass cabinet (DIY)

[clejw]

I’d like a 810 cabinet – I’m playing in a gigging band and am currently using a cabinet I built myself with a a nice Eminence 15 and two sealed-back 8” PA mids (running it bi-amped with a 1200W PA amp). It’s a single chamber and I used ¾” OSB (like decking for floors), which turned out to be an excellent material. I feel that the varying orientation of the strands makes OSB comparable to marine plywood in limiting panel vibrations, but saves a fair amount of weight and is plenty tough. The cabinet is very lightweight but sounds huge. I just need a higher max SPL…I’m pushing my current cab about as hard as it will go without distortion at most gigs. It performs well, but I want to have SPL in reserve – so I want to go with 8 10’s in a mono setup using the same amp.

Now before everyone jumps in and tells me to get a $400 cab off craigslist cause I’ll save money and it will be better – I have considered that option and it’s still on the table. And we don’t need to turn this into a driver selection discussion; I’m planning to use Eminence B810’s (http://www.parts-express.com/pe/psho...number=290-468). Also, yes, I know how to port it so that it’s properly tuned. Planning on not using a tweeter.

I’m putting this out there to get opinions on construction, particularly the chambers. Ampeg uses 4 with two drivers in each chamber, but most others seem to have two chambers. The chambers are supposed to dampen standing waves, providing for a less muddy or tighter sound. I will line the interior with 2.5” acoustic foam as I did in my current cab (http://www.parts-express.com/pe/psho...number=260-515). Ampeg does not do this.

SO HERE’S MY QUSTION: If I build an 810 with a single chamber, do y’all think my addition of the foam will make up for not having four separate chambers? Should I build two chambers, just to be safe? If I don’t make four chambers, should I add extra bracing to keep down panel vibrations? My goal is to make the cab as light as possible…the Ampeg 810 is something like 170 pounds. I can save a great deal of weight by using OSB and making the cab of a single chamber, but will I build a cabinet that is too muddy?

Covering will be carpet or I was thinking of taking it to a spray-on truck bed liner place – has anyone done this with success? Any other tough coverings that anyone has experience with, like ABS laminate or something?

If anyone is interested, or wants to build a similar cab, here’s a few parts I’m planning on using that I think will be good for an 810:
Custom grill, about 26 x 46 http://www.reliablehardware.com/cust...staggered.aspx
Corner casters: http://www.reliablehardware.com/cornercastertilt.aspx
Handles: http://www.reliablehardware.com/medi...thandle-1.aspx
http://www.reliablehardware.com/medi...andle-1-1.aspx

I appreciate all constructive input or comments! THANKS!!
- Jay

[TylerE]

If you're happy with what you have soundwise, why just build a duplicate of what you already have?

[BassmanPaul]

Plywood is stronger, easier to work with, takes spilled liquids better and is lighter.

Paul

[SC Bassboy]

My SWR Megoliath has two chambers, essentially making it two 4x10's in the same encloser. I think it sounds great. IMHO you should at least go that route to add more bracing and help make the cabinet more stable. My cab weighs about 110lbs. And as for a covering I feel that spray-on bedliner would be an excellent choice.

[mulchor]

An 8-10 with 3/4" OSB is NOT going to be "lightweight."

Aside from that it sounds like a good plan.

If you're into experimentation, you could build with one chamber, then switch to 2 when you find it's too floppy.

[throbgod13]

brace the cab as much as you can.. there's only so much you can do to reduce the overall weight of the cab.. perforated bracing would help.. you could use sheet metal bracing to increase the internal volume, but you'd have to deaden the metal..

use Neo magnet speakers to reduce weight..

other than using different construction techniques, you're going to end up with a large, 100LB+ cab.. there's just no other way around it.. big cabs weigh..

[shadow_FIX]

I used to play through an SWR Workingman's Tower, which is a single chamber 8x10 that weighs 110lbs. It's one of the lightest 8x10's I've come across and it sounded great...so if you're worried about a single chamber, you might look into what they did for that cabinet and maybe do something similar.

[Mo'Phat]

My thoughts: To reduce the weight, you should consider 1/2" plywood (not OSB, under any circumstances), and internally brace it ala the fEarful cabinets. Strategic 1/2" plywood bracing along the sides, back and baffle, drilled out to skim weight, etc.

Go for plastic corners, plastic handles, and jack plates.

The largest weight savings could be the drivers. Going with neo 10's could save you as much as 25 lbs. Basslites are only about $10 more per driver at PartsExpress, but can probably be found cheaper elsewhere online.

Check out Duratex roll-on truck bed coatings. Good stuff for DIY cabinets.

[Crockettnj]

couple cents to chime in.

1) though you have drivers picked, perhaps consider the superlight but excellent s2010.

2) for a cab that is large, in the 8x10 range, you could save a TON of weight using the foam construction method. There'd be a learning curve, but zack and others on TB have paved much of the way and I have little doubt that a foam noob could get it done. Eliminating THAT much wood would bring this thing into the ultralight range, which is something no one has done yet ( that i ma aware of).

3) the driver chambers will also act as bracing. If you forgo separate chambers, I'd at least make sure to use internal shelves swiss-cheesed with holes to act as a rigid brace (provided you use wood). The 8x10 will have some long dimensions, therefore adequate bracing will be very important. However, one big chamber or 4 smaller 2 driver-chambers or any other iteration will be sonically the same provided: adequate bracing and proper/consistent tuning. It appears you already know this.

Man, I'd seriously reconsider the OSB idea and, with a cab that big, seriously consider the opportunity to go crazy super light.

otherwise just go on craigslist and get one for $400 ;-) (ok, j'k)

either way, good luck and post pics!

[BartmanPDX]

I'd just buy a Bergantino NV610 and be done with it.

[Petebass]

Originally Posted by clejw

SO HERE’S MY QUSTION: If I build an 810 with a single chamber, do y’all think my addition of the foam will make up for not having four separate chambers? Should I build two chambers, just to be safe? If I don’t make four chambers, should I add extra bracing to keep down panel vibrations? My goal is to make the cab as light as possible…the Ampeg 810 is something like 170 pounds. I can save a great deal of weight by using OSB and making the cab of a single chamber, but will I build a cabinet that is too muddy?

Covering will be carpet or I was thinking of taking it to a spray-on truck bed liner place – has anyone done this with success? Any other tough coverings that anyone has experience with, like ABS laminate or something?

Everyone else is making suggestions on saving weight, so I won't.

To address your question, adding a woolly or foam lining to the cab walls will definitely stop standing waves. However in the case of the ampeg 810 cabs, the separate chambers do more than just help with standing waves. Someone already mentioned that act as bracing and that's definitely correct.

There's also the issue of shared chambers where one or more drivers is damaged. The idea on the ampeg cab is that if one driver fails, the worst that cab happen is only one other driver could die with it. The undamaged driver is also now operating in a cabinet that is physically too large, 100% too large in fact, which negatively affects cone excursion. As a result one driver dying usually means the one next to it dies not long after... but you've still got 6 x 10's to "limp home", and all 6 are in theory still operating in the correct enclosure and under, correct conditions, and in isolation from the chamber where all the bad stuff is happening.

Of course, there is always the argument that in an 8x10 enclosure, a bad driver will see the others operating in an enclosure which is too big, but not nearly 100% too big (more like 14%) therefore the collateral damage is reduced.

Given weight minimisation is an important factor in this design, I'd be inclined to go with one chamber for all 8 drivers, but be aware of the consequences if you do notice a bad driver. Turn down immediately and limp home on 7 speakers at a reduced volume .... or you could potentially have to replace all 8.

Oh and as for the truck liner. I have 2 identical cabs, one carpet one covered in rhino truck liner. The one covered in Rhino is 3kg heavier.

[billfitzmaurice]

Originally Posted by Petebass

Given weight minimisation is an important factor in this design, I'd be inclined to go with one chamber for all 8 drivers

If weight is a concern do two 4x10 or four 2x10. The result will be the same.

I used ¾” OSB (like decking for floors), which turned out to be an excellent material.

OSB is the worst possible material to build speakers from, with the exception of paper mache. 1/2" plywood properly braced is far better, yet lighter.

[johnk_10]

i'm thinking about making a super lightweight 8x10 too. i would be making it exactly like an ampeg straightback (w four chambers) and i'd be using foam core/fiberglass construction, with herculiner instead of tolex. i would either use eight 2510's, s2010's or b108's.
i'm pretty sure that if i go with 8 neo's it'll weigh 1/3 as much or less than a an actual ampeg.

[Petebass]

Originally Posted by johnk_10

i'm thinking about making a super lightweight 8x10 too. i would be making it exactly like an ampeg straightback (w four chambers) and i'd be using foam core/fiberglass construction, with herculiner instead of tolex. i would either use eight 2510's, s2010's or b108's.
i'm pretty sure that if i go with 8 neo's it'll weigh 1/3 as much or less than a an actual ampeg.

We'll have to start a "Composite cab" club here soon. Good to see

[Sundogue]

Make two chambers, only make two vertical 410's as most of the weakness in the panels runs top to bottom, not side to side.

In the pic below the divider running down the middle would be one solid piece...

O l O
O l O
O l O
O l O

This will also minimize the need to use more bracing.

And definitely use 1/2" ply (or try the foam option for the heck of it). 1/2" ply properly braced is stronger than 3/4". Do not use 3/4" anything, much less OSB.

And go neo.

Be sure to post pics.

[bgmww]

the Eminence B810 were built to be used on sealed cabs. If you are planning to add ports to the cab, you probably won´t be getting the best out of those speakers. Just consider to make it sealed.

i´d say.. you want it lightweight ? That´s relative... So.. i think you better take steroids, do an extensive liftweight training at the gym during a year... and then build the cab woth the proper materials.. It´ll be light for you after training hard at the gym. :P

[rpsands]

Skip the 8x10 and build a vertical 4x10. It'll be damn near as loud and do the same work. Use Arauco 15/32 ply from Lowes

Use better drivers, and you'll also be much happier. BeachAudio and SpeakerHardware both have Basslite S2010s for the price of those Legends.

The massive sensitivity advantage (2db+) will make a 4x10 as loud as an 8x10 with the Legends. And you shave 12lbs (3lbs per driver) for a 4x10 and 24lbs for an 8x10.

[Mr. Foxen]

Originally Posted by Petebass

There's also the issue of shared chambers where one or more drivers is damaged. The idea on the ampeg cab is that if one driver fails, the worst that cab happen is only one other driver could die with it. The undamaged driver is also now operating in a cabinet that is physically too large, 100% too large in fact, which negatively affects cone excursion. As a result one driver dying usually means the one next to it dies not long after... but you've still got 6 x 10's to "limp home", and all 6 are in theory still operating in the correct enclosure and under, correct conditions, and in isolation from the chamber where all the bad stuff is happening.

Of course, there is always the argument that in an 8x10 enclosure, a bad driver will see the others operating in an enclosure which is too big, but not nearly 100% too big (more like 14%) therefore the collateral damage is reduced.

The dead driver thing isn't just because of the bigger space, the dead driver acts as a passive radiator, sucking in and out opposite the live one, which unloads it even more.

[clejw]

woops, i meant 1/2 OSB, not 3/4. my current cab is made from 1/2 OSB and it works great. i hear everyone dissing OSB really, really bad, but no one every gives any reasons. OSB is NOT particle board, it doesn't soak up liquid and is pretty tough. and 1/2 OSB is lighter than 1/2 marine birch plywood. i understand that cheap 1/2 ply can have voids which can buzz, although i've never experienced this. my first cab build was a 115 and i used 1/2 ply. it turned out nice too.

So WHAT'S THE DEAL about why OSB is bad?

[clejw]

and thanks for the suggestion on foam core / fiberglass. i'll have to research that one. i have no experience working with syntheti materials or where to even get them. also, would the thing just shatter if it was dropped? or is it pretty tough?