LOUDEST subs on the market

[micb3rd]

Hi I am new to the forum but not new to Car Audio, it's been active hobby of mine since 1998.

I do occasional review of subwoofers online.

GSteg is quite incorrect in is post about FS/dropping ability and subwoofer sizes.

FS will determin where the driver goes from motor controlled (above FS) to situation to a suspention controlled situation (below FS).

Unfortunatly only one part of the pie as in the real word our woofers require an enclosure to make sound, as I'm sure you know a sealed acoustical system work like this:

In a sealed (acoustic suspention) system the size of the enclosure dictates the amount of air trapped inside the enclosure, this air acts as a resistance against the driver when excurting forward and backward, the smaller the enclosure the smaller the air space and the greater the resistance.

Lower bass requires more excursion, to hit 20hz you require far more excursion that at 60hz.

Thos does not mean how low the subwoofer will play at all, the enclosure is a massive factor.

In a undersized enclosure with a low amount of airspace this *reduces* cone excursion by restricting the driver (reducing lower bass output) and worsens transient response.

As an added effect the lower amount of airspace does not damp (i.e. *increases*) the resonant peak neer FS of the sealed system and colour the frequnecy response.

Neer the enclosures resonant frequency a peak appears in the frequnecy response.

High Q describes a tendency to ring and is easily excited, Low Q describes a damped condition which is more controlled.

This peak is underdamped by a low amount of air space.

This ring or upper frequnecy boom is redueced by larger amounts of airspace.

This is why larger enclosures decrease Qtc, small enclosures increase Qtc.

This is also why small enclosures sometimes get can get dubbed "one note sounding bass".

For example say the peak resonanse was at 48 hz and we played a 65 hz tone or a 35 hz tone, we could still hear a colouration ring @ 48hz.

This sounds boomy and can make a driver sound slow.

A common mistake in understanding a sealed acoustical system is that less air space controls cone excursion BUT does *not* dampen this peak at just above resonance.

The larger amount of air in a larger sealed enclosure or in extreme cases IB installs allows the driver to excurt further to play lower bass, it also dampens (i.e. reduces) the resonant peak neer FS, smooths the response and gives better transient response.

So finally.....

If take a 15 inch woofer say a JBL GT4 15 and put it in a tremendiously undersized sealed enclosure for it say 0.5 cubic foot, this will be very high Qtc, so resonant boomy (sounding longer) upper region and as the airspace is so restictive for the cone area it would have a massive reduction in low bass, it would most likey not play well at all below 35hz.

Then I could take the 10 inch version JBL GT4 10 put it in a slightly over sized 1.0 cubic foot enclosure, this would be low Qtc, would have a verysmooth frequnecy respose, little boom and exclent entended low end powerfull down to 20hz.

Ported systems also alow you drop down if you tune them correctly, tuning 33hz and below will give good dropping ability, tune them too high and you get the system rolling off quickly, (24db per octave on vented systems) so if you try to play low bass the driver unloads mechanically as it is effectively playing free air, half a octable below port tuning point is usually where problems start.

Personally I like to tune around 25-26hz this gives driver protection on all bass frequnecys, a very flat in car response and still increased output over sealed.

[micb3rd]

RE Audio XXX/SX, Digitial Designs 95 series, PBX Extreme, MMATS Juggernaughts, JL Audio W7 all with decent enclosures and plenty of power can get loud while still sounding fine.

[GSteg]

micb3rd, no doubt that enclosure has an affect on low end response, but my comparison is between drivers of different size with the same motor. This way, the only variable would be the cone size.


Keeping everything else the same, adding mass to the cone will decrease the Fs. You can add as much mass as you want, just as long as the suspension can handle it. Thereafter, the suspension will sag and will be useless.

Adding mass will also decrease sensitivity, requiring more excursion to produce those low notes.

We are comparing raw drivers. Adding an enclosure to the mix would be adding a second variable. A 10" subwoofer and a 15" in their own optimal box would not have the same frequency response. This comparison is solely for driver design, not actual applications


A few years back, I gathered these information from Dan Wiggins of Adire Audio and had talks with Steven Ponte of DLC Designs (where DUMAX machine lives). They both told me the same thing, of course, from a driver design standpoint

[sr20de4evr]

micb3rd - most of what you said is indeed true, but you didn't really refute GSteg's argument at all. Yes the enclosure size will affect the frequency response of the speaker, but it's not the ONLY thing that affects the frequency response of the speaker, the speaker affects it too.

For a speaker in a given alignment, say .707, the -3dB point will occur at 1*Fs*.707/Qts. If you then go in and add mass to the cone, you lower Fs which lowers the -3dB point for the same .707 alignment. This is what GSteg was saying, and it is true. Sure if you change the alignment you will change the -3dB point and the overall frequency response of the system, but that's a given. If you take a driver, increase the cone size (increase Mms, lowering Fs), keep the motor the same (roughly the same Qes, and since Qes is the dominant term for Qts, you have roughly the same Qts), for a given alignment you'll lower the -3dB point, extending the low end response of the sub. It's all math and physics, there's no arguing that.

About the rest of your post, for the most part it's true, there are just a few quirks. First you seem to be confusing the resonant frequency of the sub and the resonant frequency of the system. The sub is a simple 2nd order mass-spring-damper system. The mass is the Mms, the spring is the suspension and surround, and the damper is the voice coil/motor assembly. Any 2nd order mass-spring-damper system will have its own resonant frequency, and that's the Fs of the sub. When you put the sub in an enclosure you're keeping the damping the same and increasing the spring, which will push the system towards underdamping and raise the resonant frequency, this is the resonant frequency of the system. In comments like this:
"The larger amount of air in a larger sealed enclosure or in extreme cases IB installs allows the driver to excurt further to play lower bass, it also dampens (i.e. reduces) the resonant peak neer FS, smooths the response and gives better transient response."

That should be the resonant frequency of the system, not the Fs (which, by definition, is the free-air resonant frequency of the sub)


And for this:
"For example say the peak resonanse was at 48 hz and we played a 65 hz tone or a 35 hz tone, we could still hear a colouration ring @ 48hz."

I'm sorry but that's just not true, if you're playing a 65hz tone you're getting a 65hz tone, it's impossible to get any other frequency out of it unless you have some non-linearity in the system (such as BL distortion, cone breakup, etc), and the resonant peak from a high Q system is not a non-linearity. I can only suppose what you meant to say is that if you play music, the 48hz region will seem to overpower everything else because its amplitude is being increased by a larger amount, and if one frequency is being played more than ~10dB louder than another, we can't hear the quieter frequency because of the way our ears work.

[micb3rd]

Originally Posted by GSteg

micb3rd, no doubt that enclosure has an affect on low end response, but my comparison is between drivers of different size with the same motor. This way, the only variable would be the cone size.


Keeping everything else the same, adding mass to the cone will decrease the Fs. You can add as much mass as you want, just as long as the suspension can handle it. Thereafter, the suspension will sag and will be useless.

Adding mass will also decrease sensitivity, requiring more excursion to produce those low notes.

We are comparing raw drivers. Adding an enclosure to the mix would be adding a second variable. A 10" subwoofer and a 15" in their own optimal box would not have the same frequency response. This comparison is solely for driver design, not actual applications


A few years back, I gathered these information from Dan Wiggins of Adire Audio and had talks with Steven Ponte of DLC Designs (where DUMAX machine lives). They both told me the same thing, of course, from a driver design standpoint

People on this thread were asking about actual applications though, you did not make it clear to them that you were talking from a driver design point.

[micb3rd]

Originally Posted by sr20de4evr

When you put the sub in an enclosure you're keeping the damping the same and increasing the spring, which will push the system towards underdamping and raise the resonant frequency, this is the resonant frequency of the system. In comments like this:
"The larger amount of air in a larger sealed enclosure or in extreme cases IB installs allows the driver to excurt further to play lower bass, it also dampens (i.e. reduces) the resonant peak neer FS, smooths the response and gives better transient response."

That should be the resonant frequency of the system, not the Fs (which, by definition, is the free-air resonant frequency of the sub)


And for this:
"For example say the peak resonanse was at 48 hz and we played a 65 hz tone or a 35 hz tone, we could still hear a colouration ring @ 48hz."

I'm sorry but that's just not true, if you're playing a 65hz tone you're getting a 65hz tone, it's impossible to get any other frequency out of it unless you have some non-linearity in the system (such as BL distortion, cone breakup, etc), and the resonant peak from a high Q system is not a non-linearity. I can only suppose what you meant to say is that if you play music, the 48hz region will seem to overpower everything else because its amplitude is being increased by a larger amount, and if one frequency is being played more than ~10dB louder than another, we can't hear the quieter frequency because of the way our ears work.

Top part you are right, I meant system resonance not speaker fs.

My good old speaker enclosure book was stolen a few months back (need to source another copy).

I'm pretty sure if you have a high Q system you also get the resonant peak of the system produced as well, I would bet it is measurable on a RTA or spectrum analsys.

Also don;t forget about harmonics!

When you play a 65hz tone you don't just get 65hz, you get upper harmonics played also.

For example bear in mind this is picture one of the better low distortion home subwoofers.



Look at 40hz and 60hz and 80hz. Noticable extra notes played even though the single frequnecy is played.



Drop than tone to infrasonic level level like 15hz and look at the peaks deadon 30hz, 45 hz, 60hz and 75hz.

That 30hz, 45hz, 60hz and 75hz will be right there in the response!

Thats 4 - 12 inch drivers in large low tuned vented system, drivers just think what happens on single driver on a small closed box system!

[GSteg]

Originally Posted by micb3rd

People on this thread were asking about actual applications though, you did not make it clear to them that you were talking from a driver design point.

That's because it's up to the installer to make use of the potential

Just like debates of xmax versus real world SPL. It's how the user utilize the potential of the driver. The potential information is just something to realize when implementing into an application much like T/S parameters

[sr20de4evr]

Originally Posted by micb3rd

....too long to quote....

Sure you'll get harmonics, you'll always get harmonics when you're at high output. That's due to the non-linearities in the speaker though (and for the most part, BL non-linearities), it has nothing to do with the enclosure. I guess you could say that if you played a sub beyond its Xmax (to really bring those harmonics out, and I'm betting that 2nd plot is way beyond the Xmax), in a severely underdamped application, at a frequency exactly half of the system's resonant frequency, that 1st harmonic just might be more powerful than the fundamental frequency because of the resonance of the system at that frequency. If you played any other frequency though, the harmonics wouldn't occur at that resonance peak and it will sound just like any other harmonic-laden low frequency tone played through a sub in a box. And if you played at a lower output where the fewer non-linearities introduce fewer harmonics (or if you use a BL-optimized sub), then you wouldn't get that effect.

[Jet-Lee]

Cerwin Vega Strokers > All

[Mannyb18b]

RE XXX & MT.......destroy the cerwin vega stroker. dont make a stupid post like that again.