Subwoofers Compared

[kach22i]

Soyez le bienvenu a WBF!

For the same total cost, two smaller subwoofers are often better than on large one, if sound quality is what matters most. Let me explain:

The biggest problem for a subwoofer is the room. The room will cause large peaks and dips in the response of even the best subwoofer. You can move the subwoofer or move your listening chair and the peak-and-dip pattern will change, but it will not go away. You can equalize the subwoofer so that its response is smooth in the microphone location, but then the frequency response will actually be worse elsewhere in the room.

However if you add a second subwoofer, and place it in a very different location from the first, you can make a big improvement. Each subwoofer will still produce an ugly peak-and-dip pattern, but they will be DIFFERENT from each other. The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone. And this improved smoothness holds up throughout the room.

Smooth bass is fast bass, because it is the peaks which make bass sound fat and slow. And as a general rule, the more subwoofers intelligently distributed around the room, the more smooth the in-room bass will be.

(I manufacture a subwoofer system that uses four small subs, so I use this idea in my business. I learned it from Earl Geddes.)

So assuming you don't need super-loud and super-deep bass (which are things that one big sub does better than two small ones), you might consider two small subs for better room interaction, because better room interaction results in better bass quality.

A mon avis.

RE: The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone. And this improved smoothness holds up throughout the room.

I'm going to have to take issue with theories over substance as I see it (no offense intended).

The way I see it "the SUM" of these two peeks is processed via a pair of ears and a human brain, and not on a mathematical calculation worksheet and or computer software. Yes I believe in science, but also believe science is always self-correcting it's self in pursuit of the truth.

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

 

[kach22i]

I looked up the KEF Kube and it also doesn't have variable phase control.

On the B&W PV1D. This is in a totally different price point at about $2k. You could get two Rhythmik F12's (with the Aluminum driver) for this price. I looked at the manual for the PV1D and it does seem to have all of the controls necessary. These all seem to be setup in some kind of software on your laptop. I don't know if you could have your laptop conntected and change the settings real time while you listen. If that appeals to you then you could also look SVS Subwoofers which has an app for your phone that you can control from the listening chair.

The other thing is "space". The PV1D is very compact. I don't know how much space you have in the listening area. So perhaps you are looking for something compact. Also, I don't know what you are intention is. If you are wanting extension down to 20Hz I don't think a single PV1D is going to do that. If you are just wanting to supplement the bass from, let's say, 40Hz to 70Hz.

Note that the higher you go in frequency the hard it is to get he subs to integrate with the main speakers. <40Hz is relatively easy, 40-60 Hz getting harder, 60-80Hz Hard to do seamlessly. If you add a crossover to your mains like the JL CR1 it will make integrating them much easier.

Interesting, I recently did an image search on tube/cylindrical and spherical shaped subwoofers and discovered this unit (PV1D).

Bowers & Wilkins PV1D (Matte Black)

Powered subwoofer with digital processing and touch-panel controls

www.crutchfield.com

Two woofers are better than one​

The PV1D is outfitted with not one, but two 8" woofers, which are powered by a built-in 400-watt amp. The cones fire in opposite directions, giving you evenly distributed bass that will fill your room.

Dual drivers firing in opposite directions is similar to my old M&K, and even though it is dual driver it loads the room more like a single point source without the timing errors and phase issues of multiple subwoofer placements.

No way would I spend that kind of money without listening to it first. Back when I purchased my M&K it sounded more musical than a twice as expensive and twice as powerful servo controlled subwoofer in the same room.

Don't get fooled by bombastic power and slam, there is delicacy and nuance in the lower frequencies that some subwoofers are cable of flushing out and not washing over.

 

[sbo6]

I'm going to have to take issue with theories over substance as I see it (no offense intended).

The way I see it "the SUM" of these two peeks is processed via a pair of ears and a human brain, and not on a mathematical calculation worksheet and or computer software. Yes I believe in science, but also believe science is always self-correcting it's self in pursuit of the truth.

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

I can't agree with the statement, "The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone. " as that's not my experience setting up subs many times over, as room dimensions and objects type / positioning throughout rooms are extremely variable. Is there some benefit, yes. Twice?, Rarely.

However, 2 subs do offer the benefit of being able to further tailor the LF response at your sweet spot versus 1, this is a fact. 3 and 4 subs are even better. Also, if integrated properly (not always a trivial task) the ear - brain can't tell the difference especially if you keep the XO frequencies < 80Hz and the slope high, =~24DB / octave.

 

[Robh3606]

The way I see it "the SUM" of these two peeks is processed via a pair of ears and a human brain, and not on a mathematical calculation worksheet and or computer software. Yes I believe in science, but also believe science is always self-correcting it's self in pursuit of the truth.

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

We are all entitled to our opinions

I suggest you read this. I use combinations of single, double, 4 subs. Once set-up correctly you can't hear any of them in any configuration. You are after all in a room and room modes are the dominating feature not the subs.

Rob

 

[kach22i]

We are all entitled to our opinions

I suggest you read this. I use combinations of single, double, 4 subs. Once set-up correctly you can't hear any of them in any configuration. You are after all in a room and room modes are the dominating feature not the subs.

Rob

Thanks Rob, I will look at it later.

Can you tell me if the analysis and conclusions are based on a single listener position, or a wider multi person area?

Hard to tell from the first paragraph where it is headed.

I was only interested in the single person listening position FYI.

I do not have guest over very often, and when I do I give them the good chair.

 

[Robh3606]

Can you tell me if the analysis and conclusions are based on a single listener position, or a wider multi person area?

Both as well as comparing predictions in Mathlab to actual results set-up in real room. Worth a look

Rob

 

[kach22i]

I can't agree with the statement, "The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone. " as that's not my experience setting up subs many times over, as room dimensions and objects type / positioning throughout rooms are extremely variable. Is there some benefit, yes. Twice?, Rarely.

However, 2 subs do offer the benefit of being able to further tailor the LF response at your sweet spot versus 1, this is a fact. 3 and 4 subs are even better. Also, if integrated properly (not always a trivial task) the ear - brain can't tell the difference especially if you keep the XO frequencies < 80Hz and the slope high, =~24DB / octave.

Is there a formula that states one subwoofer for every person in the room?

That really sounds like where "sbo6" and "Robh3606" are headed, intentionally or unintentionally.

There is only one sweetspot in the room with Martin Logans (in general), and I listen alone. I'm just fine with one subwoofer. Sometimes less is more.

 

[Robh3606]

Is there a formula that states one subwoofer for every person in the room

The room dimensions the speaker and chosen listening position all are factors to determine what you get. There are no absolute rules and I have never heard of 1 per person. You may get lucky and end up with a spot wide enough to get a couple of chairs with a single sub. That said it is more likely it will be easier using more than one. Hence the multiple suggestion.

With multiple positions I would be way more concerned about the mains set-up and how large their sweet spot is. That above all is going to dictate how feasible it is.

Rob

 

[kach22i]

The room dimensions the speaker and chosen listening position all are factors to determine what you get. There are no absolute rules and I have never heard of 1 per person. You may get lucky and end up with a spot wide enough to get a couple of chairs with a single sub. That said it is more likely it will be easier using more than one. Hence the multiple suggestion.

With multiple positions I would be way more concerned about the mains set-up and how large their sweet spot is. That above all is going to dictate how feasible it is.

Rob

Thank you for the clarification.

I have to think you are right, that with multiple listening locations, multiple subwoofer could be beneficial.

That is unless the entire room is designed as a horn speaker or something crazy like that.

One of the potential downsides in my small room of having the single subwoofer proud of the main speakers is that the single listening position is "near-field" for the bass notes (long waves hardly have time to form), but midfield for the mids and upper frequencies. Is that a potential problem or benefit? Hey it works for me.

I don't recall if I had to flip the phase, but did experiment with it in earlier layouts as I recall.

To be clear, I have not bought a bunch of subwoofers and equipment to find out other options because I got to audio nirvana with the single sub. If you click on my system link in my signature you will see getting a single sub to work before giving up and throwing money at the problem was my goal - and I won.

 

[sbo6]

Is there a formula that states one subwoofer for every person in the room?

That really sounds like where "sbo6" and "Robh3606" are headed, intentionally or unintentionally.

There is only one sweetspot in the room with Martin Logans (in general), and I listen alone. I'm just fine with one subwoofer. Sometimes less is more.

There is not, and that's not how it works. That would imply that 1 sub could fully optimize LF at the sweet spot, which IME is impossible, unless you have a very large and well - acoustically dimensioned room, which pretty much no one does (and even then subs have other benefits). And in that case, you might not need a sub at all if your goal is smoothing out LF modes.

Now, that doesn't mean 1 sub is not better than none. I'd be happy to share graphs before and after.

 

[Holmz]

I'm going to have to take issue with theories over substance as I see it (no offense intended).

The way I see it "the SUM" of these two peeks is processed via a pair of ears and a human brain, and not on a mathematical calculation worksheet and or computer software. Yes I believe in science, but also believe science is always self-correcting it's self in pursuit of the truth.

At 20 Hz the wavelength is >50 feet and at 40Hz >25 feet.
The ears are a half a foot away from each other, so it is effectively the same as a single ear in terms of locating the sound.

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

In one of your earlier posts you mentioned that the sub was only encoded in Mono.
That it sort of at odds with the brain processing 2 sub sources, and also at odds with your single sub approach.

If the response in the room is relatively flat, then one can argue that enough subs are being used.

 

[Duke LeJeune]

I'm going to have to take issue with theories over substance as I see it (no offense intended).

The way I see it "the SUM" of these two peeks is processed via a pair of ears and a human brain, and not on a mathematical calculation worksheet and or computer software. Yes I believe in science, but also believe science is always self-correcting it's self in pursuit of the truth.

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

At bass frequencies, where the ear's time-domain resolution is poor, my understanding is that the in-room frequency response dominates our perception. I'm not saying it's the only thing that matters; I'm saying it's what makes the biggest difference.

My understanding is that the ear/brain system is incapable of separating the multiple bass waves which sum at the listening location, much less discerning whether those combining bass waves originated from different bass sources (different subwoofers).

Imo reasonable minds can disagree, so I'm not expecting you to agree with me.

 

[thedudeabides]

The human brain is going to sense these two sources, sense the confusion they present and reject the inauthenticity of the source(s) - in my opinion.

What factual proof do you have to substantiate how the human brain functions and your resultant opinion? Neuroscience studies? Other related medical documentation?

 

[Duke LeJeune]

@kach22i, here is the full context of one of my statements that you singled out ("The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone"):

"However if you add a second subwoofer, and place it in a very different location from the first, you can make a big improvement. Each subwoofer will still produce an ugly peak-and-dip pattern, but they will be DIFFERENT from each other. The SUM of these two different ugly peak-and-dip patterns will typically be almost twice as smooth as either one alone. And this improved smoothness holds up throughout the room."

The critical stipulation is that the second subwoofer be placed in a VERY DIFFERENT LOCATION from the first. The MORE acoustically similar the two subwoofer locations are, the LESS smoothing will be produced by their summation.

And I probably should have said "The SUM of these two different ugly peak-and-dip patterns can be almost twice as smooth as either one alone."