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

[SHB]

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.

 

[kemmler3D]

I guess there are some reasonable points here if you define a sub in a certain way, but where in the dictionary does it define a subwoofer's output at a given frequency? To be clear, I personally won't look at a sub that isn't competent at 20hz, but it seems like a lot of people here are happy as long as 40hz is loud.

I think this argument is framed more as a semantic dichotomy type of argument rather than a technical one... The latter being more amenable to productive discussion.

To that end, what are your thoughts on minimum excursion requirements with very large cone area like 18"+?

 

[GD Fan]

Clicked on this thread because I really wanted to see some woofers in a refrigerator. Oh well, disappointed again...

 

[Chrispy]

Clicked on this thread because I really wanted to see some woofers in a refrigerator. Oh well, disappointed again...

Refrigerator sized just doesn't do it?

 

[RexrothPigeon]

scatter dudes the ontology cops are here

 

[SHB]

Optimally, something approaching +/-1” (25mm).

Again, as previously stated, Fs in the mid-teens.

My question is how do you define a subwoofer?

In pro audio, anything with a -10dB spec at 32Hz is a sub. That’s not really a subwoofer.

As a bass player, my 5 string goes down to 30.5Hz (low B). For music to be properly rendered, the sub needs to have a resonant frequency (Fs) around one octave below that to eliminate most of the distortion and group delay.

I have four Rythmik L12 subs. Run wide open, their -3dB point is 12Hz.

My instrument played through my home theater pre with stereo effects upmixed to surround, to me, is almost a religious experience.

 

[Chrispy]

Optimally, something approaching +/-1” (25mm).

Again, as previously stated, Fs in the mid-teens.

My question is how do you define a subwoofer?

In pro audio, anything with a -10dB spec at 32Hz is a sub. That’s not really a subwoofer.

As a bass player, my 5 string goes down to 30.5Hz (low B). For music to be properly rendered, the sub needs to have a resonant frequency (Fs) around one octave below that to eliminate most of the distortion and group delay.

I have four Rythmik L12 subs. Run wide open, their -3dB point is 12Hz.

My instrument played through my home theater pre with stereo effects upmixed to surround, to me, is almost a religious experience.

I like my subs to be capable as low as possible (and use a variety, including diy). Agree generally with what you've mentioned. I do want more than maybe most music provides.....it's good to be capable when the chance comes IMHO.

 

[SHB]

Clicked on this thread because I really wanted to see some woofers in a refrigerator. Oh well, disappointed again...

Sorry, doesn’t seem anyone’s done that yet.

In my book, if it doesn’t also keep my beer cold, what good is it? I’m a big fan of function over form.

 

[SHB]

I like my subs to be capable as low as possible (and use a variety, including diy). Agree generally with what you've mentioned. I do want more than maybe most music provides.....it's good to be capable when the chance comes IMHO.

It’s about moving all of the distortions and non-linearities out of the area where music exists.

Other than some synth heavy recordings and some pipe organs, music doesn’t really go below 30Hz.

The bottom octave of any woofer system is where stuff gets nasty. Move the nasties below 30Hz, they are not going to effect your music listening. It’s the exact same as tweeters where the resonance/break up frequencies are moved above 20kHz so we can’t hear them.

Also, everything I stated is scientifically verified and true.

You mostly agreeing with it is like mostly agreeing that gravity holds us to the surface of the planet.

What ever you don’t agree with about it, you’re wrong.

 

[john61ct]

To me a driver designed to put out its max SPL going down well below 60Hz is a subwoofer.

"trueSub" implies louder and lower.

My choices for 60-200+ Hz are MBM couplers not trueSub.

What OP is talking about, I use BRuTeS (Bone Rattling fUll-size TruE Sub).

Since I am restricted to 12x12" baffle maybe 1.5cuft per unit, I probably need 3-4 each bandpassed not much more than an octave,

to get good SPL out of the full 20-200Hz range.

Might not be everyone's preferred definition but none of us get to just unilaterally impose those on everyone no matter how confidently (arrogantly) we might be shouting.

 

[jhaider]

I have four Rythmik L12 subs. Run wide open, their -3dB point is 12Hz.

How much boost in the amp does it take to get that response? It’s the same issue, only you don’t see it because it’s addressed in the integrated commercial package. Fs of that driver in that box without EQ is probably in the 40ish Hz range. Maybe higher.

Bottom line is bass SPL is simple: piston area plus displacement. Frequency response, as long as the driver has a reasonably linear motor and good thermal management, can be sculpted to taste. Requiring tons of boost at ULF (or to look at it another way, cut at higher frequencies) does not really matter, because ULF sensitivity is determined mostly by cabinet volume and efficiency is higher with a stronger motor anyway.

Fact of the matter is, good “pro” woofers make great home subs. You get the best of all worlds: plenty of volume displacement for low-end SPL, stronger and often more linear motors for higher real world efficiency and consistent performance, world class thermal management due to larger diameter voicecoils and cooling systems designed for sustained continuous high power use, and scads of top end headroom for punch and in-room EQ-ability.

 

[SHB]

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.

 

[Chrispy]

It’s about moving all of the distortions and non-linearities out of the area where music exists.

Other than some synth heavy recordings and some pipe organs, music doesn’t really go below 30Hz.

The bottom octave of any woofer system is where stuff gets nasty. Move the nasties below 30Hz, they are not going to effect your music listening. It’s the exact same as tweeters where the resonance/break up frequencies are moved above 20kHz so we can’t hear them.

Also, everything I stated is scientifically verified and true.

You mostly agreeing with it is like mostly agreeing that gravity holds us to the surface of the planet.

What ever you don’t agree with about it, you’re wrong.

Where music exists? WTF is that??

Yes, lower bass is hard.

You still have a high chance of being wrong

 

[RexrothPigeon]

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.

lol bye felicia

 

[Devnull]

How much boost in the amp does it take to get that response? It’s the same issue, only you don’t see it because it’s addressed in the integrated commercial package. Fs of that driver in that box without EQ is probably in the 40ish Hz range. Maybe higher.

Bottom line is bass SPL is simple: piston area plus displacement. Frequency response, as long as the driver has a reasonably linear motor and good thermal management, can be sculpted to taste. Requiring tons of boost at ULF (or to look at it another way, cut at higher frequencies) does not really matter, because ULF sensitivity is determined mostly by cabinet volume and efficiency is higher with a stronger motor anyway.

Fact of the matter is, good “pro” woofers make great home subs. You get the best of all worlds: plenty of volume displacement for low-end SPL, stronger and often more linear motors for higher real world efficiency and consistent performance, world class thermal management due to larger diameter voicecoils and cooling systems designed for sustained continuous high power use, and scads of top end headroom for punch and in-room EQ-ability.

It's sooo boosted. Take a look at the published curves.

Rythmik Audio 12" servo subwoofer • Specifications

And I'd love to know how 18mm is the magic number for a minimum amount of Xmax.

The nice thing about pro sound in the house is knocking it down flat costs literally nothing in power requirements. When you can make 80+dB with 1 watt at 20Hz it really doesn't matter how much it's down power wise from it's published spec.

 

[Vergiliusma]

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.

There are many paths to good bass reproduction, some more subtle than others.

Yours is really a quaint POV, not born out of the practical experience of many in the last few decades. I was there once with that traditional mindset--that's how we were introduced and learned about these things, so I get it.

They don't need to be the size of a refrigerator. Do they have an overdamped response? Sure, and that's not necessarily a bad thing, in fact some prefer it--kinda like a ported version of a sealed rolloff.

If you want to have a serious conversation about it without the tone in your comment I quoted, I'll be happy to oblige.

 

[Sokel]

As a bass player, my 5 string goes down to 30.5Hz (low B). For music to be properly rendered, the sub needs to have a resonant frequency (Fs) around one octave below that to eliminate most of the distortion and group delay.

I have four Rythmik L12 subs. Run wide open, their -3dB point is 12Hz.

My instrument played through my home theater pre with stereo effects upmixed to surround, to me, is almost a religious experience.

As a bass player, you should be the first to know about bass-cabs.
Have a good look at their drivers, most of the famous ones have an Fs in the 30's and 40's.

Plus, they also recommend (the driver's companies) a hi-pass down there at the 30's.

 

[sigbergaudio]

Ok, here’s the point where people start talking about their subs(..)

Isn't that exactly what you are doing?

And I'm not sure I understand your main point of view here. You want 1" of excursion, which I'm not sure your own subwoofer has, but you understand that the 18" with 15mm linear excursion that was mentioned in the other thread will play way louder at any frequency response than the 12" in the Rhythmik, right?

I'm not saying it's an optimal subwoofer driver, but the size of the driver matters quite a bit.

An fs below 20hz is also something that very few drivers have. Somewhere between 20-30hz is pretty common in subwoofer drivers. Go to https://loudspeakerdatabase.com/ and filter on subwoofer drivers to have a look.

 

[levimax]

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.

From the GSG website. There is some nuance to this subject.

 

[3ll3d00d]

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.

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.