Input on bass cab design

[Geoff St. Germaine]

Ok, so I'm looking to construct a bass cabinet that will work with basses with B/F# strings in so far as it has output extending down into the mid 20s (f3 of 23 Hz specifically).

So far, this is what I've worked up:

LF - 2 Eminence LAB12 drivers ported in 7.2 ft^3 tuned to 23 Hz.
MF - Invalid Link Removed 12" midbass (probably sealed but possibly ported).
HF - Invalid Link Removed compression driver on the Invalid Link Removed.

The obvious downfall of the system is the inefficient low frequency drivers. The LAB12s are about 89 dB/1W/1m compared with a typical 18" that is in the mid to high 90s. The reason I'm going with this driver is that I cannot find a 15" or 18" that has similar extension and any that I've found that come close require about twice the volume of two LAB12s. If anyone knows of any drivers that might meet my requirements, I'm all ears. I'm looking for the cab to come in at around 24"x20"x42", or a little bigger than a typical 6x10.

My intention is to cross the LF to the MF at around 150 Hz and the MF to the HF at around 1.6 kHz. I'm probably going to use an active crossover with separate power for each driver.

Anyway, I'm just looking for any and all input, specifically regarding drivers. One thing I'm considering is reducing the size of the midbass as beaming may be a problem with such a large midbass. An 8" or 10" may be more appropriate.

 

[unclejam]

dude check out partsexpress.com [Invalid or Expired Link Removed]

 

[billfitzmaurice]

Ok, so I'm looking to construct a bass cabinet that will work with basses with B/F# strings in so far as it has output extending down into the mid 20s (f3 of 23 Hz specifically).

The bad news is that no driver will deliver high sensitivity with a 23Hz f3 in a reflex alignment. The good news is that a 23 Hz f3 is unnecessary, seach the threads on fundamental versus harmonic content.

 

[Geoff St. Germaine]

Yeah Bill, I've read some threads about harmonic content. I don't see any compelling reason that the fundamental should be simply disregarded for certain notes. I've also had my bass hooked up through my HT setup which measures in room flat to around 15 Hz and low notes sound substantially different which supposedly has frequency response down to 32 Hz. I should really measure it.

I should also just take some measurements off of my basses and run them through some of wavelet analysis programs from my MSc, which will give better time resolution of frequency content of bass signals than the FFT analysis I've seen. In the measurements I've seen the second harmonic of slightly higher magnitude than the fundamental, but I see no reason not to reproduce the fundamental... it's done for most of the notes anyway.

Unclejam, thanks I'll take a look at that driver.

 

[alexclaber]

I think this is an interesting approach to take - however it will be futile if the cab is not loud enough to cope with the environments in which you play.

Based on the specs of the LAB12 that cab will have similar sensitivity to an Acme Low-B2, and due to the extension down to 23Hz similar power handling. This means it will not be a loud cab. I find a single Low-B2 is fine for rehearsals though I prefer two for gigs. Will this dual LAB12 design be loud enough for you?

My gut feeling is that you'd be better served by having four of these woofers, which equates to a HUGE rig!

An alternate approach would be to do some more analysis of your bass signal and find out the precise spectral balance of your low note fundamentals. If you find that the power demand down there is much less than higher up, then maybe you should look into using more efficient drivers in a sealed cab that you can EQ flat to 23Hz. Or maybe one of the BFM horn cabs designed for HT that can be EQ'd flat below 30Hz without over-excursion risk.

For the higher frequencies to save some space/weight and bring more coherency I'd look at some of the coax neo designs. BMS make a very nice 12" neo coax, as do B&C, both of which are plenty loud compared to your subs.

Alex

 

[billfitzmaurice]

I've also had my bass hooked up through my HT setup which measures in room flat to around 15 Hz and low notes sound substantially different which supposedly has frequency response down to 32 Hz. I should really measure it.

If you're comparing the HT to a commercial electric bass cab you do need to measure the bass cab. It may claim response to 32Hz, but the f3 is likely to be a half octave or more higher. The difference you hear is more likely because the HT will actually go flat to 35 Hz, not 15.

 

[greenboy]

The search for this holy grail sure makes the high SPL and low extension claims of most bass cab manufacturers stink of ludicrous, I would imagine ; }

Best you can do easily is to have a crapload of power and another crapload of very inefficient drivers if you truly think you must have 23 Hz. Otherwise, a crapload of power and a crapload of BagEnd ELF/Infra cabs or some Servodrive tech will do the trick.

But if you look at some of the better low-extension subwoofers like BMS's neo 18 or others I think you'll find a compromise that is more practical (f3 at 33 to 38 Hz - you want to be full-on by 46 Hz), with better low extension and excursion capabilities than current bass guitar cabs in a relatively small box, with prodigious power handling and thus SPL available. There are also a couple of nice compromises available in smaller diameters but you'll have to double up the drivers to get that SPL.

 

[greenboy]

BTW, Geoff, I've been doing F#0/E0 for some time now with conventional 34" scale, and with 39.5" Knuckle Quake, and a cab that is full-on by 46 Hz (might need to use a high pass filter) indeed speaks with authority with a tuning that low.

Though it doesn't seem so grand with the typical Reality Distortion Field bass cab that's typically 6 to 10 dB down by that point and more often than not runs out of xmax well before .3 RMS.

 

[greenboy]

I'll second Alex's suggestion of BMS coaxes for mids and highs. They make excellent 15, 12, and 8 inch Neo coaxes with elliptical 80x60 waveguides for superior phase and polar response - you can actually get a good match with non-coax versions if you want to double up mid drivers for more SPL.

 

[unclejam]

Invalid Link Removed

4 of those and find or build a 8x10 or6x10 with a spl of 108db/m/w

 

[Geoff St. Germaine]

Thanks for the input guys. I wouldn't be surprised if the Eden I have that is spec'd to 32Hz is -10 dB there.

The labhorn has had my attention for a while. While loud, I believe that they are something like 15 dB down @ 30 Hz from the measurements I've seen.

The inefficiency of the LAB12s in a bass reflex cabinet may just be too limiting. I figure that with power compression they'd only be capable of 112-116 dB peak.

If I relax my requirements to 30 Hz it opens this up to a lot more drivers and a lot more sensitivity.

Thanks for the heads up on that BMS 18" greenboy, that may be a better way to go.

Thanks for all the input from everyone.

 

[JustdaBassPlaya]

Just get a Fi car audio btl 18" that has an xmax like 16 mm and use it, its geared slightly toward SQ, but I certainly one of the most Spl capable 18 inch subs, goes down under 20hz too. Who cares if its a car sub. Put it in a 6 cube enclosure, port tuned to 30 hz and come back to us with your review.

nevermind about the btl, get the Q series for the best sound qualtiy and a 27 mm xmax!!!!!! The other Fi series are more geared to SPL. And only 310 bucks for an 18 like that

 

[greenboy]

The Eden reality distortion field is very strong - I wouldn't be surprised if it was more than 10 dB down at that figure ; }

Anyway, with the 4-ohm (or 8) neo BMS 18n850 you can get great low extension in a 3.5-4 cubic foot box, and probably more SPL per pound in that band than anywhere else unless you want to go a lot bigger.

 

[knuckle_head]

Is this a reference or performance rig?

If it is something you want to hear/record with I can recommend a decent 15 that will get you pretty close to 20 Hz, has decent xmax, and can be pulled off in a fairly small cab.

the Dayton Titanic 15" sub

I have the Mk II loaded into a cab Link Removed that I am really pleased with. The Mk III looks as though they have improved the design a might. I would not recommend this cab for stadium stage monitoring, but it can handle alot of juice and the lower SPL can be made up for by its power handling.

Alex and greenboy's suggestions are awesome - the BMS stuff is some of the best I've seen on spec. As soon as I can come by a OSX-friendly modeler I will be running new cab designs. The answer is out there.

As to the harmonic content of where you are headed, you will benefit to a degree from inferior string design. The F# alternatives currently available in particular are looser than I care to see, and what this offers up is a bit more emphasis on the fundamental as harmonic content goes. You may be able to go a bit further than true specs suggest you will get.

 

[greenboy]

Hey Knuck,

Why not run WinISD Pro on the Mac via Windows emulation?

 

[Geoff St. Germaine]

Hey Knuck,

Why not run WinISD Pro on the Mac via Windows emulation?

That's what I do.

 

[Geoff St. Germaine]

Just get a Fi car audio btl 18" that has an xmax like 16 mm and use it, its geared slightly toward SQ, but I certainly one of the most Spl capable 18 inch subs, goes down under 20hz too. Who cares if its a car sub. Put it in a 6 cube enclosure, port tuned to 30 hz and come back to us with your review.

nevermind about the btl, get the Q series for the best sound qualtiy and a 27 mm xmax!!!!!! The other Fi series are more geared to SPL. And only 310 bucks for an 18 like that

Interesting. That driver has pretty high efficiency for a car/home sub driver.

 

[Geoff St. Germaine]

Is this a reference or performance rig?

If it is something you want to hear/record with I can recommend a decent 15 that will get you pretty close to 20 Hz, has decent xmax, and can be pulled off in a fairly small cab.

the Dayton Titanic 15" sub

I have the Mk II loaded into a cab Link Removed that I am really pleased with. The Mk III looks as though they have improved the design a might. I would not recommend this cab for stadium stage monitoring, but it can handle alot of juice and the lower SPL can be made up for by its power handling.

Alex and greenboy's suggestions are awesome - the BMS stuff is some of the best I've seen on spec. As soon as I can come by a OSX-friendly modeler I will be running new cab designs. The answer is out there.

As to the harmonic content of where you are headed, you will benefit to a degree from inferior string design. The F# alternatives currently available in particular are looser than I care to see, and what this offers up is a bit more emphasis on the fundamental as harmonic content goes. You may be able to go a bit further than true specs suggest you will get.

I'm kind of looking for a rig that can do a little of both, though I would say that I'm not really looking for a straight up sound reinforcement cab here.

 

[billfitzmaurice]

Thanks for the input guys. I wouldn't be surprised if the Eden I have that is spec'd to 32Hz is -10 dB there.

-20dB is more likely.

 

[knuckle_head]

I'm kind of looking for a rig that can do a little of both, though I would say that I'm not really looking for a straight up sound reinforcement cab here.

With a program rating of 800 watts at 4 ohms I am betting the Dayton Titanic will keep up with most full range options even given its sub-92 dB SPL. I have been pleased with mine, but I have to admit to not having gigged with it.

Free air resonance below 20 Hz is a nice perk, and I like that it has an xmax of more than 20mm.

SR is about the only place to get the straight dope - and even in that arena there are very few options when trying to go this low.