Bigger subs hit lower discussion.

[cotjones 10+ year member]

I remember back in the day on this forum the craze was to flame people who said bigger subs performed the lower frequencies better. But thinking about it now strictly from physics isn't this necessarily true?

Think about it.

lets say we want to assess the performance of a 10 inch vs 18 inch speaker at 30 and then 90 Hz.

If we want the 10" to produce 30Hz loudly the cone has to travel farther to produce the same amount of sound pressure than it would at 90 Hz.

The same can be said of the 18" speaker, except that it is more difficult to achieve higher cone oscillations with a more massive cone. This is just because the more massive the cone is, the more force it takes to move it and thus the more momentum the cone has at the bottom or top of a stroke to be arrested. True?

So this would mean that strictly speaking the larger the cone, the more suited it is to lower frequency (per same material of course.)

This of course doesn't mean 10's are incapable of playing lower frequencies. Just in general, if the building materials are the same, the larger the cone, the more suited to lower frequencies.

True?

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[Kangaroux 5,000+ posts]

The usual argument is that because an 18 has more mass on the softparts (cone, surround, etc.) than a 10 or a 12, it will be able to hit the lows better because more mass = lower resonance frequency (assuming the suspension stays the same). This applies to a free air setup where the operation of a sub is pretty much solely dependent on the specs of it (i.e. Fs). But when you drop a sub in a box you can pretty much make it do whatever you want, and you won't really notice any difference caused by the cone weighing a little more

 

[IonRL205 10+ year member]

You may be able to get louder on the lows with a bigger sub since they can move more air, but that doesn't mean a smaller sub can't get loud on the lows either.

 

[RAM_Designs 5,000+ posts]

Within the same line of woofers, yes, the larger sub will generally be able to play the lower frequencies with more authority compared to the rest of the frequency range. Judging one random 15" sub vs one random 12" sub is pointless without knowing detailed info about each.

 

[cotjones 10+ year member]

The usual argument is that because an 18 has more mass on the softparts (cone, surround, etc.) than a 10 or a 12, it will be able to hit the lows better because more mass = lower resonance frequency (assuming the suspension stays the same). This applies to a free air setup where the operation of a sub is pretty much solely dependent on the specs of it (i.e. Fs). But when you drop a sub in a box you can pretty much make it do whatever you want, and you won't really notice any difference caused by the cone weighing a little more

Yeah that's true, though for the purposes of determining ideal setups, considering that an enclosure is basically a resonance chamber. Doesn't that mean that a more massive (larger surface area) cone is always more inclined to play lower frequencies.

In other words, a box can shift the resonance frequency to equalize response, but this creates a source of inefficiency.

Let me explain my logic here. The way I see it, with a box a and speaker you are basically averaging 2 resonances. In free air, there is only one.

So lets say the resonance of the sub is 40Hz, and the box 50Hz the 2 together would produce peak at 45Hz. But because this isn't the sub's resonance, the possible volume would be higher if the box + sub resonance matched the Sub resonance. True?

 

[Seraphim38 10+ year member]

In truth this a misconception, though it is the common experience in the auto sound marketplace. In larger commercial, professional environments it proves not to be true.

The most successful, best selling, highest output commercial bass guitar amplified cabinet has eight 10" woofers, and will easily overpower a reasonable sized outdoor or indoor large wattage sound system. And I know this because I work for that brand. One might think that 2 18" woofers would out perform 8 10s, but it actually, practically, doesn't work that way.

That said, moving air can be about linear travel and cone area, along with box construction and other factors. More smaller woofers in a proper enclosure can perform as well as a larger woofer in a proper enclosure, but it all comes down to the science and a bunch of details. A larger woofer doesn't automatically result in lower resonant frequecies, but it certainly can seem to be the case in the automotive sound market.

And the mass argument sounds interesting but doesn't prove true when used to its logical ends. One of our brands includes a dual 21 inch subwoofer that takes 4,500 RMS watts continuous to each driver. They are insane. It's not because each woofer weighs a ton; it's a function of the cone area, linear excursion, enclosure design and other variables.

 

[cotjones 10+ year member]

Within the same line of woofers, yes, the larger sub will generally be able to play the lower frequencies with more authority compared to the rest of the frequency range. Judging one random 15" sub vs one random 12" sub is pointless without knowing detailed info about each.

This. I think that's what people assume others are arguing. I'm talking about in the same line in this discussion.

 

[Bettr n' Revrse 5,000+ posts]

Post....

 

[cotjones 10+ year member]

In truth this a misconception, though it is the common experience in the auto sound marketplace. In larger commercial, professional environments it proves not to be true.
The most successful, best selling, highest output commercial bass guitar amplified cabinet has eight 10" woofers, and will easily overpower a reasonable sized outdoor or indoor large wattage sound system. And I know this because I work for that brand. One might think that 2 18" woofers would out perform 8 10s, but it actually, practically, doesn't work that way.

That said, moving air can be about linear travel and cone area, along with box construction and other factors. More smaller woofers in a proper enclosure can perform as well as a larger woofer in a proper enclosure, but it all comes down to the science and a bunch of details. A larger woofer doesn't automatically result in lower resonant frequecies, but it certainly can seem to be the case in the automotive sound market.

this is what we want to avoid in this discussion. The fact that some 10's that can outperform other 18's is a meaningless comparison. We are talking the same line an tuning.

Another fact, putting an 18 in a box with a 350Hz peak Resonance is likely not going to compare with a 10 tuned to 20Hz if we are comparing them at playing 25Hz. This again is a fudged example. We are speaking of ideals.

 

[cotjones 10+ year member]

Also you are talking about an amp for a bass guitar. Bass guitars produce harmonics in the upper kHz ranges. Thus 18's alone would obviously not be ideal for a bass guitar.

 

[RAM_Designs 5,000+ posts]

This. I think that's what people assume others are arguing. I'm talking about in the same line in this discussion.

Same line, 99% of the time the larger sub will have the ability to have a more exaggerated low-end due to the lower fs. But it's not always the case. If I was going for lots of low-end output, I'd definitely look for larger subs vs smaller ones...just easier to get it done most of the time.

 

[wenn_du_weinst 10+ year member]

a lot of it comes from the early 90's subs where the fs was super high on the smaller diameter subs. Hell the 18's were like 40-50hz on some. If you know what your doing you can over power the FS with the enclosure. The biggest problem is the bandwith becomes small

 

[Seraphim38 10+ year member]

what argument do you want to avoid?

whoever tunes an 18 in a box to 350hz is an idiot. In college logic that is called called a Straw Man Fallacy, which means one tries to argue that an opponents position is incorrect by restating it incorrectly. I did not fudge my examples; they are real life. I was designing boxes over 20 years ago and winning shows with them, and eventually worked my way into employment with industry leading brands who make low frequency audio equipment

I certainly have more important things to do than bicker over meaningless theoretical topics online with someone can't say I have done it. Sorry if that sounds terse, but it's true.

If someone has a real question for a seasoned audio professional, I am all ears.

As i said before, yes, in autosound, you commonly will get more low frequency output from larger woofers in the same line offered from a manufacturer. This doesn't mean that a smaller driver must have a higher resonant frequency, but that it is a common experience in the autosound industry.

 

[T3mpest 10+ year member]

Producing SPL at any frequency is about displacement... For a given SPL you must move a given amount of air. Each time you want to play 1 octave lower, you must displace 4x the amount of air to maintain a given SPL. Meaning if 80hz requires 3liters of air to be displaced every second to reach 110db's, if you want to hit 110db's at 40hz you need to displace 12liters of air, if you want to do it at 20hz you'd need to displace 48 liters. This means smaller subs are limited not in how low they can play, but how low they can play at a given SPL. Even a tweeter can play 30hz if you send it the signal, it's max output before damage may inaudable though.

 

[cotjones 10+ year member]

what argument do you want to avoid?
whoever tunes an 18 in a box to 350hz is an idiot. In college logic that is called called a Straw Man Fallacy, which means one tries to argue that an opponents position is incorrect by restating it incorrectly. I did not fudge my examples; they are real life. I was designing boxes over 20 years ago and winning shows with them, and eventually worked my way into employment with industry leading brands who make low frequency audio equipment

I certainly have more important things to do than bicker over meaningless theoretical topics online with someone can't say I have done it. Sorry if that sounds terse, but it's true.

If someone has a real question for a seasoned audio professional, I am all ears.

The argument we WANT to avoid is a straw man fallacy. You are saying that in a specific instance 8 10's outperform 2 18's. The Outperforming is based on criteria of incorrect comparison. First you are talking about overall performance, not low end extension. I would agree that 10's would make a better setup for a bass Guitar. That's not the argument. The tuning of the box to 350Hz was to illustrate that your argument wasn't really relevant. This thread was created to discuss "meaningless theoretical" topics. If you are incapable of that I'm sorry that you wasted your time posting here.