[emilimo701]

This I hear frequently from dabblers and laymen.

May we start an official thread on quashing these two myths? Let me start:

"15's go deeper than 12's"

I think this myth is due to the fact that sometimes more cone area sometimes does correlate to lower frequency extension. For example, the extra cone area may increase the mass, ultimately lowering its resonant frequency a little bit or alter the Q. But all things being equal, what more cone area does is increase the output ("loudness"/sound pressure). As you increase the cone area, the woofer usually becomes more efficient. Sometimes, a side effect is a higher QTS or lower Fs (or both). But the bottom line is, don't use cone size to judge how low a woofer can reach. Check for known Theile–Small parameters for the best idea of the frequency response of a subwoofer.

"10 inch subs are faster than 12's or 15's" or "10 inch subs are better for SQ"

This sums it up better than I could:

http://www.stereointegrity.com/docs/WooferSpeed.pdf

 

[dougelam]

Why does everyone state that their 10 inch is faster than a 12-15??
The faster it travels back n forth is equivalent to the frequency it produces. The last time I was designing a system I wanted to have the driver that moved slower to produce lower frequencies, the purpose for having a subwoofer. The larger the cone area means more air moving doesn’t it?

I always felt the bigger the hammer

 

[Ludemandan]

Agreed. I've yet to read any science behind the idea of a "slow" speaker. If it's playing at 60 hz, it's oscillating 60 times per second, and presumably the first excursion comes within 1 120th of a second. Even if you were to miss one cycle, I don't think you could hear the difference. If it were truly moving slower throughout all cycles, it would simply reach less excursion and you'd experience that as lower volume.

 

[Zolty]

Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?

 

[jacampb2]

Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?

Kind of-- the more mass the driver's cone has, the slower it is going to be to respond to a change in amplitude or frequency, it will also have more inertia once moving and will be harder to slow down as well, but, as mentioned above, it doesn't make the sound any slower or faster, the speed that the wave cycles is what defines it's frequency.

You can't have one driver playing 45Hz faster than another driver playing 45Hz. It's like saying that when I am driving 70Mph in my car, it is faster than 70Mph in your car.

I think the problem is that music is not just sine wave test tones, it is multiple frequencies riding on top of other frequencies on top of others. So, you have a multiple moves that the driver has to make in microseconds and the more mass it's cone has the less likely it is going to be to be able to respond to every instantaneous change, just like a Semi truck is much harder to stop and reverse than a Ferrari is. This is likely why bigger subs seem to sound less accurate and clear, and smaller subs tend to be more crisp and punchy.

The drivers motor and the amplifier are often overlooked in these discussions. Within limits, the drivers motor should be able to make up for the added mass of the larger cone, but the manufacturers don't always build them like they should, and for the most part, the stronger the motor, the lower the efficiency, so the designers have a lot of trade offs and compromises that have to be made.

The amplifier also plays a role. It will take more power to get that additional mass and/or that more powerful motor moving. Dampening factor also plays a roll in how well the amplifier can control the reactive load.

The root of it is that there is far more at work than just the mass of the cone. And, a "slow" sound is completely different sound from a "fast" sound.

Confused? I hope I didn't do any harm!

Later,
Jason

 

[dark41]

Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?

I'd think this is the proper answer. Larger areas and heavier objects take more to get them moving, and more to stop them once they've started.

I hadn't heard the term "faster" used before. But the term "tighter" sound is what I've often heard others use, and my own ears tend to agree. Its all about "response" time, and response simply has to suffer somewhat with larger cones. The audible difference can be quite noticeable.

That's my preference, tight sound. But to qualify my preference I'm also a bit partial to my 2 x 10" MTX subs (bought in 2002?) - even though they're ancient by today's standards. They may not achieve the low frequencies of larger subs, but they much more resemble the actual sound of a Ludwig bass drum than larger subs do with my classic rock. Having played guitar around these drums for many years, I'm pretty picky about the sound being "right" rather than "more thunderous". If the latter is your preference, the larger subs would probably be more to your liking.

 

[myyykeym46]

It does seem that a heavier cone would require a higher damping factor amplifier to respond to transients in the same manner as a lighter cone would using a less capable amp. However this also implies that the electromagnetic circuit of the driver is proportionately more capable of transducing the lingering cone motion back into electricity for the amplifier to damp. If the manufacturer is using the exact same motor structure on a 10" and on a 12" or 15", this in an invalid assumption.

This could possibly account for some of the persistent feeling (which I've also experienced btw) that 10s give tighter bass than 15s. If the two drivers had motor structures, cabinets, and amplifiers that were proportional to the mass and surface area of their cones, you would indeed have larger drivers with superb transient performance. For example, in a concert setting you have the chest-pounding punch of the huge-magnet double-18 EAW SB850s driven by Macro Tech amps (which have lots of power and high damping factor to match).

 

[jacampb2]

Another piece of the puzzle could simply be tuning. It could simply be that if the end user is expecting to get the same frequency response from an 18 as from a 10, then that could be the muddy Vs punchy explanation. The place where the additional mass is going to really show is at higher frequencies.

I really believe that if the driver is built correctly, the amplifier is of sufficient power and quality, the crossover points set correctly, and the enclosure is designed correctly that you theoretically should not be able to differentiate based on size alone, with the exception of the frequency response.

Later,
Jason

 

[jmhinkle]

I really believe that if the driver is built correctly, the amplifier is of sufficient power and quality, the crossover points set correctly, and the enclosure is designed correctly that you theoretically should not be able to differentiate based on size alone, with the exception of the frequency response.

Later,
Jason

That's what the physics of it would show. Unfortunately, and to my ears, it's never the case. I don't like 10's because they are always too punchy. I like the sound and feel of a 12. I don't think it's a myth we are discussing here more than a personal taste or description of sound. No matter the set-up, my ears hear and my body feels "deeper" bass from a 12 than a 10. Not saying it is in reality just what I get out of it from listening.

 

[tornaido_3927]

Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?

No!

The enclosure size for the particular driver would have the most bearing on the overshoot/ringing of the driver.

And IIRC after the damping factor of an amp goes above about 50, it really doesn't make much difference how much damping you have, especially in relation to the size of a cone and it's mass.

 

[Z80_Man]

If both subwoofers had equivalent characteristics, the one having the larger cone surface would obviously generate more pressure !

But to achieve this, it should have a more powerful motor too, so the characteristics wouldn't be the same anymore.

Anyway, it won't change the played frequencies.

If we use larger membranes since the eletrodynamic speakers were invented, it's partly because they are unable to produce decent high frequencies because of their mass, so they obvioulsy become more specialized, and partly producing bass frequencies at the same accoustic power than the other frequencies requires much more power (the fact that the human ear is more sensitive in the high medium range also force to play basses louder).

So we must make more powerful motors, so they're even heavier... Pushing a small membrane with a big motor can still be a solution (some recent subwoofers are just pistons with a huge elongation), but if you want to produce a good deal of pressure at that frequency range with a standard and cheap motor (allowing a modest elongation), then having it moving a large membrane does the same thing : moving an important volume of air to achieve the wanted accoustic pressure.

Anyway, the motors have to be big. At low frequencies, the current changes directions so slowly it's almost DC, and the coils have to stand that. Some are even wired with large flat cable.

So finally, the large membrane choice is just a question of efficiency : you have a big fat heavy motor, and you won't certainly spill the power to move a ridiculously tiny membrane, while it's powerful enough to move a large one despite the air resistance to the movement.

It's just a question of getting the most SPL you can with the motor you have.

You can actually get very deep bass with a modest membrane... Unless it has a monstruous elongation, it will just play much less loud when applied the same electrical power.

A famous example was the Focal Utopia 27WX 11" subwoofer : it gave ultra deep bass, much deeper than the 13" (the one I own) and 15" ones... But it's efficiency was also much lower. It was still a perfect choice for an SQ setup.

 

[Zolty]

I hadn't heard the term "faster" used before. But the term "tighter" sound is what I've often heard others use, and my own ears tend to agree.

I'll remember that - "tighter" not "faster", learning all my life and will still die supid
The other thing - cone material, it also does make a difference in punchiness - see paper vs. kevlar etc.

Regarding the frequency response - of course if signal is let's say 60Hz, then no matter what the cone size is, it should still be played as 60Hz, but.....
In real music we do not get such clean frequencies - there is always a bunch of them. Being absolute green in theory of speakers I just think the larger cone the lower frequency it can play (assuming proper installation etc) - so we can hear frequencies which are below "capabilities" of the smaller cones thus "deeper" bass. Should there be no difference we all could use tweeters as subs

 

[Z80_Man]

Focal actually made 5" real subwoofers, and they were rather efficient (of course, depending on the enclosure).

SPL was unsurprizingly not huge, of course. They were often used by pairs, or even more. Their main quality was the rather small load volume needed. Of course, their price was a problem too if you wanted to multiply them !

 

[Sawzall]

Cone material is just as important a factor as motor or size. A stiff cone more resembles the perfect piston. In the best of worlds, you would have a perfectly stiff cone that had zero mass - which of course is impossible.

A general rule: Any general rule that is one sentence long is wrong. There is almost always many more factors to consider - and in this case, there is a reason that a good spec sheet has more than just the T/S - those are just the beginning of what you need to know to design a good speaker system. But its a lot easier to sell "these are the biggest drivers that will fit in the box."

 

[PaulD]

I thought this thread was going to be about dispelling the myth yet most of the posts seem to AGREE with the premise (that larger speakers are "slower")

 

[Zolty]

Myth Not Busted !?!?

 

[raamaudio]

I have built mostly sealed 10 and sometime 12" systems and have to agree, at least nearly all the time, the tens are "quicker" sounding, really punchier is more accurate, but a very stiffly coned but low weight 12 can sound that way as well.

But, my favorite sounding subs of all time were even larger and not overly high in output but played with enough authority for real music in an incredible, world championship winning, car with ID horns and Big mid bass drivers. IB is the best I have ever heard but have never owned the right vehicle to do it in, until now.

The Studevette we are building over the next few years will have, hopefully, at IDW subs, at least 2 of them, IB install, they are quite hard to find. If not able to then probably ID15's as I run two in my home system in a huge (63.5x39x34") double chambered horn loaded enclosure and they sound great paired with the Egarhorns, modified 10 watt tube amp and Oppo BDP83SE Blu Ray player with quad 24bit DAC outputs on each stereo channel. I have 1kw running now, it works better with 2kw to the subs Those IDs are quite musical and do not weigh a ton which I need to avoid since the target weight of the car is less than 3k lbs, with a cage, race seats, fire system, etc....

Anyway, back to the topic, I love a lot of bass but not enough to blow out the windows and it must be very very accurate, a properly built system will do it with whatever size you pick, with the right gear and install, power, etc.......but easier with smaller subs, just add more until it is loud enough for you

Rick

 

[chad]

This can easily be solved with testing say, a 10" driver and a 18" driver with the center of the VC's on the same plane.

I can assure you that the impulse arrival time will be tits on, the same. Thus negating one driver being slower than the other.

 

[ChrisB]

What size sub will allow me to feel those low notes when reproducing Toccata & Fugue in D minor from Don Dorsey's Bachbusters? A sealed 10 with a predicted F3 response of 57 Hz or a ported 15" sub with a predicted F3 of 15 Hz?

 

[el_chupo_]

If a 40z tone is a 40hz tone on a 10, and the 15 is slower, then it would be a 37hz tone or something, right? Hmm, seems like some simple logic solves this one. Or you can do the experiment chad listed