Small Sealed 1x12: Best Driver?

Ported and sealed cabinets both have a bit of a different mojo. Though for the same given driver, and bass extension, a sealed cabinet will probably be smaller than a ported one - but the ported can be made to have a lower extension and will have more bass. Not to the extent of one being a subwoofer and the other only being good for mids, but it's a general trend. With that being said, I can see the beta doing well in a reasonably small cabinet - I know there's a ported 212 design on here that uses them, you could just half the size and ports of the thing and make a 112 from there. I believe @kringle77 designed it.

From there, eminence has a legend driver that should do great in a small sealed box, ditto with their bassline 2012. Celestion drivers might also do well, but maybe stick to their bass guitar line.

 

Search Hoffman's Iron Law. If you go with a very small cab you will give up low end. That's non-negotiable, no matter what driver you use. To see what really can be done download WinISD 0.7, learn how to use it. You'll find out, for instance, that a Beta 12 in 1 cu ft sealed has an F3 of 87 Hz, is 10dB down at 60 Hz, and is displacement limited to 115 watts below 100 Hz. That means you can't use EQ to bump up the low end, since 10 dB of boost at 60 Hz increases the power output by a factor of ten. Even if the amp has that much power the driver wouldn't be able to handle it, either mechanically or thermally.

 

IF you want a sealed, 1 cf cab with a 12 inch, the Beta and Basslite are good candidates. They both produce a very similar bass response profile, even to an F3 of 92 Hz. The slow rolloff (12 db/octave) allows an F10 of about 54 Hz. Many bass players would consider that to be fine for a guitar cab. Either of them would handle a light bass boost to add some low end. You're not talking loud or a large venue so they should be fine. However, considering Hoffmans Iron Law, check out this alternative. The B&C 8BG51 (8 inch) in the same 1 cf box, but ported (Fb= 48 Hz): F3 42 Hz, F10=38 Hz. Excursion limited to 140w down to 37 Hz. You get real bass cab performance, but you trade sensitivity (5-6 db) relative to the Beta and Basslite. Since the application only requires low to medium volumes and 100w power handling, this would seem to be an acceptable alternative. All 3 drivers have an upper mid/lower treble presence rise, and are decent full range candidates. Both 12's are excursion limited below 73 Hz at 140w.

 

1 cubic foot for a 12" is extremly small and yes the design intent would be for very tight mid bass. And the small enclosure is for power handling. The resulting high cabinet Qtc would be filtered out with high pass filter.

For full range bass application .8 Qtc for the 12a2 would be around 1.6 to 1.8 cubic feet almost twice as large.

For tradeoff on power handling 1.6 is good volume and wont have to much ripple response. Going smaller will bring up a bass peak and be boomy.

For less ripple just plain old 2 cubic feet will be fine sealed. Treadeoff is less power handling.

A overall good design would also be a 2x12 at 3.4 cubic feet. Which gives good sensitivity. Good power handling. Good ripple response etc etc.

 

You could use the B&C. You would need to make an adapter plate (1/2 inch plywood sized to fit over the baffle board, with a hole for the 8 inch driver) - you might even be able to put the driver and port on the 'plate'. OTOH,if you are pleased with the result you get from the 'Swamp Thang', choosing either of the 12's is a good way forward. For your purposes, the Basslite has a little more upper mids presence and is lighter 4.1 vs 7.5 pounds).

 

The Eminence BP122 is optimized for a sealed box, which makes it unusual in this day, though it can be used in a vented box. Sealed box of about 1 cubic gives an F3 of about 70 Hz. The tradeoff is lower efficiency than a vented-box woofer and less top-end extension. While the top end doesn't have as much energy as the Beta 12 or Basslite 12, its upper-mid peak is arguably in exactly the right spot for electric bass. And, if you ever decide to do an add-on midrange driver, that would be pretty easy because you could let the BP122 just roll off naturally and bring in the mid to fill in the top couple of octaves.

 

Yeah, tradeoffs.

Okay one of the modelling programs I have is the one Eminence sells, so it has pretty accurate information (including curves) for their drivers. Comparing the BP122 with the Basslite 2012, both in a sealed box, both getting the same amount of power, this is what I see:

Below 130 Hz, the BP122 is actually louder. From 130 Hz to 300 Hz, the Basslite is a little bit louder. North of 300 Hz, with the exception of the 1.5 kHz region where the BP122 has its upper-mid peak, the Basslite is a lot louder.

If we factor in the higher power handling of the BP122 (300 watts vs 150 watts), now the BP122 will go significantly louder from about 400 Hz on down, their average is pretty similar from 400 Hz to 2 kHz, and then the Basslite is louder north of 2 kHz.

The Beta 12A2 is a little bit louder than the Basslite up to 2 kHz, and then north of 2 kHz the Basslite is louder.

So in practice I don't think it's the lower efficiency per se that differentiates the BP122 from the Basslite and Beta 12, but rather the tonal balance: The BP122 has the most bottom end, the Beta 12 has the most across the midrange region, and the Basslite has the most top end, but the differences between the latter two are not all that great.

 

Sounds good! Please post your impressions... if the BP122 proves to be a good "convert a 112 close-back guitar cab into a 112 bass cab" woofer, that could be valuable information for a lot of people.

 

Its muddy driver

 

12PR320 by FaitalPRO

 

Is that a new woofer? I don't remember seeing it before. Looks VERY nice!!

 

A 1 cubic foot box for a single 12 is pushing things pretty far - that's smaller than most 112 cabinets you'll find on the market, and even those are compromised in terms of performance - very few bass guitar cabinets you can buy reproduce a low E at anywhere near the same gain as higher notes. With an F3 of 93 Hz, that's (my opinion) an OK guitar cabinet. For bass, you won't get what I'd consider a good combination of low frequency extension and efficiency in that size. You might like it, but it won't exactly boom.

 

That model has been around for a couple of years. Because of its extended range up to 5k you can have a hf unit crossover from there, meaning it can be pushed harder then utilizing it from, say, 3.5k. It also means a cab with no hf unit added will probably sound very full range. Xmax of the woofer is also good... These aren't exactly cheap units however. But yeah. Monstrous specs!

 

I'm intrigued by your idea. If you don't mind, a few questions. Is this an experiment, do you need the cabinet that small for some reason? What kind of amp are you using with it? Do you plan on using it in a band situation? I'd imagine, if you were to play live, you'd probably want two cabs instead of one.