Theoretical new bass cab

[dlhughes]

Hypothetical Question:

If there were a bass cab that contained only one 12" driver, was 48" tall, 14" deep, and 18" wide, BUT would make a 60W amp fill up the same space as something of more than twice that power, would that be simply too big to lug around, even if it only weighed about 60 pounds? I know it's a big ol' box, but seriously, it'll make a small amp sound much, much bigger. Flat to below 40 hz, extremely efficient, and with excellent transient response. Note attack happens RIGHT NOW.

What do y'all think? Give me a private shout if you wish.

[iamlowsound]

Originally Posted by dlhughes

Hypothetical Question:

If there were a bass cab that contained only one 12" driver, was 48" tall, 14" deep, and 18" wide, BUT would make a 60W amp fill up the same space as something of more than twice that power, would that be simply too big to lug around, even if it only weighed about 60 pounds? I know it's a big ol' box, but seriously, it'll make a small amp sound much, much bigger. Flat to below 40 hz, extremely efficient, and with excellent transient response. Note attack happens RIGHT NOW.

What do y'all think? Give me a private shout if you wish.

I doubt that you would get much extra sound out of it. In fact, you could get less. There are a ton of calculations that get done for proper enclosure size for rated wattage and individual speakers. I don't think this will work at all.

lowsound

[JohnMCA72]

^^^

I would ask you, what aspects of the design are an advantage for your purpose? What, exactly, are you trying to achieve? What 12" driver are you using, & what properties of it are you trying to modify? What problem(s) do you think this design solves?

[cracker75]

Originally Posted by dlhughes

Hypothetical Question:

If there were a bass cab that contained only one 12" driver, was 48" tall, 14" deep, and 18" wide, BUT would make a 60W amp fill up the same space as something of more than twice that power, would that be simply too big to lug around, even if it only weighed about 60 pounds?

If you're OK with such a huge box for just one driver, you should be looking into folded horn designs like billfitzmaurice has on his site.

I wouldn't want a box that big unless it was truly milking the daylights out the driver in terms of sensitivity.

[rpsands]

Drivers have gotten so cheap for what they are that I'd prefer just more of them in smaller boxes and eq.

[B-string]

I can see where it is coming from? Think the single 15" full bass reflex of "Greatful Dead". The sound is amazing.

[johnk_10]

this is really 'old school' but if it were made like this and used a JBL K120, it would easily handle 150 watts and, be very efficient, and IMO, sound awesome.
(let the flames begin)

[johnk_10]

this is really 'old school' but if it were made like this and used a JBL K120, it would easily handle 150 watts and, be very efficient, and IMO, sound awesome.
(let the flames begin)

[B-string]

Hmmm a classic scoop, I like the full bass reflex better

[JimmyKickButt]

this makes me want to take some sort of sound engineering classes.

[dlhughes]

Originally Posted by iamlowsound

I doubt that you would get much extra sound out of it. In fact, you could get less. There are a ton of calculations that get done for proper enclosure size for rated wattage and individual speakers. I don't think this will work at all.

lowsound

Knowing nothing about the design, I don't think you can say that unequivocally.

[dlhughes]

The design is not a scoop, not a reflex. It's sort of a combination of a tempered quarter-wave pipe (TQWP) and a horn.
I've built one tuned to just below a guitar's low end (about 70 Hz), just to test/prove the idea, and a guitarist friend agrees that it works, very well indeed.
Now, to tune a similar enclosure down to below 40 Hz is the reason for the large size. But then again, there's mostly just air inside, so it's really not heavy.
The idea comes from having heard some TQWP's and being blown away at the sheer volume (and the excellent transient response) from a 6" speaker running on only 5W of amplifier power. Put the same 6" speaker in a ducted-port box and run it on 5W, and it doesn't come close.
Maybe this cab is really just too bulky to haul around a lot. OK, I get that. But for more 'permanent' applications such as churches or 'open mike' clubs where a bass amp is often provided, it just might be the ticket.

[dlhughes]

Oh, BTW....this theoretical cab wouldn't be limited to 1x12 driver. It could contain 2x10's, 4x10's, even 1x15 with a little size adjustment.
The 1x12 configuration is just based on a loose driver I have lying around with which to build a prototype.

[Bassmec]

Originally Posted by johnk_10

this is really 'old school' but if it were made like this and used a JBL K120, it would easily handle 150 watts and, be very efficient, and IMO, sound awesome.
(let the flames begin)

No flaming from me old boy! far from it, the old 4520 design reduced in scale from 15" to match a k120 eh!
That would be awesome and far more efficient than either the original posters infinite baffle design, and a good 3dB louder than a reflex design below 100 hz.
Not an easy cab to scale down and build though, but one of the very best uses for a awesome sounding woofer like the old K/E120.
I still have four of the K series in old concert system floor monitors they are gobsmackingly loud and clear:

The date codes are 1973 and they have been rode hard and put away wet almost every day since, with no issues at all.
Thats Quality!

[billfitzmaurice]

Originally Posted by dlhughes

Flat to below 40 hz, extremely efficient, and with excellent transient response. Note attack happens RIGHT NOW.

What do y'all think? Give me a private shout if you wish.

Flat below 40Hz is of no particular benefit, and being a direct radiator it won't be any more efficient than any other direct radiator.

[rpsands]

IME, the "transient response" thing thrown around about cabs always seems to be more a matter of frequency response than any magical transient attack speed or whatever. Things sound "slow" when they're boomy.

[kesslari]

Are you advertising that you are manufacturing said cabinet, and asking people to PM you about them?

[DukeLeJeune]

Originally Posted by rpsands

IME, the "transient response" thing thrown around about cabs always seems to be more a matter of frequency response than any magical transient attack speed or whatever. Things sound "slow" when they're boomy.

That has been my conclusion as well; the ear has good resolution in the loudness domain (it can hear humps in the response), but poor resolution in the time domain - particularly at low frequencies.

I have built more bad transmission lines (quarter-wave pipes) than you can shake a stick at. Here is one of the problems: At the frequency where the line length equals 1 wavelength, the output from the end of the line emerges 180 degrees out-of-phase with the direct output from the front of the cone. The result is a dip in the frequency response due to cancellation. This dip can be quite large. Look at these frequency response measurements:

http://www.soundstagemagazine.com/measurements/pmc_gb1/

If you are close-miking the woofer cone, this dip won't show up in the measurements but it is definitely there and while not necessarily obvious to the ears (dips are harder to hear than peaks) its effect is certainly audible.

Not to say that a good quarter-wave speaker can't be built, but there are some serious challenges involved and this is just one of them. While solutions exist, predictably they involve tradeoffs.

[James Judson]

Large tends to equal better bass response (look at 60's built Fender or Sunn cabinets with single transducers). More transducers equal better bass response as well (look at anything Bose makes). A small box that is ported right equals better bass response (Bose is another example). There is a lot of math to apply, may take years of study. You can try the trial and error method and hope you accidently stumble on a good design. If I had a transducer lying around I'd look on CL and find an unloaded cabinet (they are cheap without speakers). If I was hell bent on making my own cab I'd copy a design that some jet fuel genious did the math on. Good luck and let us know how it turned out.

[B-string]

Bose is a very bad example The Fender Single Showman 15" cab was the only real light from fender (Helmholtz).