Why a pro woofer in a refrigerator sized cabinet is not a subwoofer

[TheKoC]

Ok, here’s the point where people start talking about their subs, what they can’t do, spout nonsense and then it all goes off the tracks.

Bye.

On an unrelated note, the ignore feature is one of the best parts of ASR

 

[voodooless]

Most of this is nonsense to fit your own definition of what a subwoofer is. In the end, the only thing that matters is clean output to a given target frequency in an enclosure of your choosing and if a driver can do that then job done.

And for that, there is loads of evidence that you can use (some) PA drivers for high output, low frequency subbing. In fact, there is more or less a whole website dedicated to it:

Data-Bass: Subwoofer Measurements

data-bass.com

 

[Frank Dernie]

I have four Rythmik L12 subs.

I looked them up.
They "hide" the shortcomings you mention using the servo loop, nothing that small will go that deep without a lot of boosting, so most of what you praise about them is because you haven't understood the physics IMO.

OTOH I do like to have a system capable of a good level down to 20Hz

 

[Redacted]

Surely, much of this is semantics.
Is there an unarguable, numerical definition of "bass"? Why would we care?

To me, my "subs" simply fill in some of the frequency spectrum below that of my modest main speakers, and give more "watts" overall.

I'm noticing "pile-ins" are getting popular on this site too - an external observer might be put off.

 

[Roland68]

A few weeks ago, I posted Understanding subwoofers.

Understanding subwoofers

It seems that most audio fans and reviewers don’t really understand the advantages subwoofers bring to your listening experience other than more low bass. • If you use stereo subs and set your crossover to around 200Hz, you can increase the dynamic range of your system by 6dB or more. If you’re...

www.audiosciencereview.com

Guess I shouldn’t have been surprised that the thing degenerated from an interesting discussion to a miasma of idiocy.

I didn’t go into extreme detail so all kinds of people posted about things that had nothing to do with the original post other than the word, subwoofer.

One particular post, though, stood out to me:

Understanding subwoofers

First off, stereo subs located in the front corners will give you tremendous stereo separation from 200Hz to 20Hz. It would also work for mono with a lower XO point. Having your subs a little wider than your mains will not be audible. We can hear stereo in low bass, but our sensitivity to...

www.audiosciencereview.com

Everything about this is wrong. Since I never went into extreme detail, let me do that now:

• A woofer with a resonant frequency of 36Hz disqualifies it as a subwoofer driver. A genuine subwoofer driver needs an Fs in the teens. A driver with an Fs of 36Hz is by definition a large woofer, not a subwoofer, as its mechanical resonance system is entirely wrong for true subwoofer duty.

• The response rolls off below 110Hz. A driver whose output is already diminishing below 100Hz is not functioning as a subwoofer in any meaningful sense. Its useful operating range is mid-bass, not sub-bass.

• 16dB of EQ boost is required to reach 20Hz. Boost doesn’t create headroom, it consumes it. That much corrective EQ at the bottom of the driver’s range is an immediate indication that the driver fundamentally doesn’t belong there.

• Xmax of 18mm is insufficient below resonance. Excursion requirements increase dramatically as frequency drops below Fs. 18mm gets consumed rapidly, pushing the voice coil out of the gap and destroying linearity at the exact frequencies the EQ boost is demanding maximum output.

• All failure modes are simultaneous and multiplicative. Insufficient Xmax, operation below Fs, and 16dB of boost all converge at the same frequency range. Each alone would be a serious compromise. Together they compound each other into a fundamentally broken system.

• 125dB above 100Hz is irrelevant. That impressive SPL figure exists entirely in the mid-bass range where the driver actually works. It’s being used to sell performance in a frequency range the cabinet isn’t even being asked to reproduce.

• It’s a mid-bass driver in a subwoofer costume. Everything about the driver — its Fs, its natural frequency response, its Xmax, its optimized operating range — describes a high efficiency mid-bass driver for live sound reinforcement. Putting it in a large cabinet and applying heavy EQ doesn’t change what it fundamentally is.

All of this is verifiable. If you don’t agree with it, then you don’t understand it. If you don’t understand it, do the research.

As a joke, I like to say, “It’s science. Just accept it.”

In this case, it’s not a joke. It’s absolutely true.

You have two options:
• You can love it
• You can shove it

Choose wisely.

Whenever something like this comes up, I’m always reminded of the vintage Visaton TL SUB. Both drivers exhibited a steep roll-off below 100 Hz, yet the TL SUB still managed to reach 114 dB at 20 Hz.
Would that, then, qualify as a subwoofer according to your definition?

You state that a driver with a resonance frequency of 36 Hz is unsuitable for use as a subwoofer driver.
Could you please define a specific range—perhaps with a brief explanation—regarding the resonance frequency (Fs) required in the low double-digit range for a subwoofer driver?

 

[Sokel]

Is there an unarguable, numerical definition of "bass"? Why would we care?

I would use REW's frequency bands and call it a day.

 

[Redacted]

But are they not somewhat arbitrary too?
I'm not saying their bands are not perfectly reasonable, and yes, "working definitions" are unavoidable!

At least it's a polite point of view and not a pile-in !