what makes one sub louder than another

[nissanrider06 10+ year member]

Ok so I know the subs cone creates sound waves... now what makes one sub with the same box and same power louder than another, is it the excursion? is it the speed the cone moves? what is it? What makes a 400 sub louder than a 40 dollar sub i know they have bigger motors and take more power but what is it science wise?

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[ahole-ic]

you're going to get into a convoluted mess here because the RATING called efficiency throws you off.... but the answer to your question is efficiency. How effectively does one woofer translate power applied into acoustic energy? The rating "efficiency" is for a frequency much higher than what we use and therefore is not relevant to the discussion (1000hz), BUT the answer to your question is certainly efficiency. It's just that we don't actually have an efficiency rating for sub-bass frequencies.

 

[modskwod 10+ year member]

Like eCrack said, if you have two drivers with equivalent power handling, it's mainly a matter of efficiency. Motor force and displacement can come into play as well.

 

[nissanrider06 10+ year member]

Ok say they have the same efficiency what makes the sounds wave louder? is it the speed of the woofer or the xmax? all the ppl on this forum that are gurus someone has to have an answer...

 

[nissanrider06 10+ year member]

and mod hopefully when i get my new system ill be a on the MN loudest team, i've been talking to anton and hopefully will be meeting him soon he seems like a cool dude!

 

[Hydrastas 10+ year member]

To narrow down your question im pretty sure the speed of the woofer determines what sound wave is created so both subs would have to be at the same speed to make the same wave right? like 30 hz for instance both would be moving at 30 cycles a second. For the loudness isn't it excursion? If one sub has more then it would tech be louder cause it's pulling in and moving more air per cycle? i remember asking this is the past a long time ago but never really figured it out lol. And the bigger motors/amperage come into play with the xmax cause it takes more energy to move more air at the same speed it all trickles down to producing the energy needed to make the sound wave which determines how long/"hard" it will travel through the air. Which makes me wonder what the formula is for sound waves and the energy needed to determine how far it will go lol i've never come across that one. And when a sound wave fades out what happens to it, does it have to do with it's energy fading through heat from friction? And when sound waves pass through a person does the energy they trail off have any effects on our molecules? Has there been any studies done on mice or some **** to see if one that lives in a sound proof box lives longer or the like? It'd still have it's heartbeat and feet etc but i mean outside sounds lol.

 

[Hydrastas 10+ year member]

**** maybe one day everyone will walk around with sound deadening suits on to add 20 yrs to their lifespan lol, i don't even smoke weed and im thinking up weird ****. We all know free radicals are bad for our bodies and antioxidants help keep them at bay but could soundwaves be similar to them? then we got radio waves and all that **** too, seems like way too many variables to test out to bother with imo.

 

[snoopdan 5,000+ posts]

put down the crack pipe.

 

[audioholic 5,000+ posts]

Cone speed is dictated by two things, frequency being played, and excursion. The higher the freq, the more cycles per second. The more cycles per second, for a given excursion, the faster the cone must move to accommodate. Excursion also factors in. For a given freq, the higher cone excursion is, the faster the cone must move in order to sustain that excursion at the proper cycles per second. This is called cone velocity.

What makes one sub louder than another is way too general a question to answer. Vented setups have different speaker requirements for performance than do sealed systems. So, at the very least, you need to decide if you are asking about vented or sealed systems.

You are trying to get more specific by saying same enclosure, same excursion, same freq, same efficiency... at some point you'll simply be describing two identical subs.

I'll give you guys a hint -> cone acceleration has a lot to do with potential output, given a specific enclosure, amplifier, etc. Lets see who can tell us how cone velocity contributes. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[nissanrider06 10+ year member]

Cone speed is dictated by two things, frequency being played, and excursion. The higher the freq, the more cycles per second. The more cycles per second, for a given excursion, the faster the cone must move to accommodate. Excursion also factors in. For a given freq, the higher cone excursion is, the faster the cone must move in order to sustain that excursion at the proper cycles per second. This is called cone velocity.
What makes one sub louder than another is way too general a question to answer. Vented setups have different speaker requirements for performance than do sealed systems. So, at the very least, you need to decide if you are asking about vented or sealed systems.

You are trying to get more specific by saying same enclosure, same excursion, same freq, same efficiency... at some point you'll simply be describing two identical subs.

I'll give you guys a hint -> cone acceleration has a lot to do with potential output, given a specific enclosure, amplifier, etc. Lets see who can tell us how cone velocity contributes. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

So it doesn't have to do with like motor size creates more speed and..... I dont know what im trying to say, nump for someone to help me, ill come back when Im not :stuck: lol

 

[T3mpest 10+ year member]

SPL is always about total displacement. SPl at any frequency is given by the forula Pa = p/(2 pi c) (Sd w^2 x)^2 where

p - nominal density of air = 1.18 kg/m^3

c - nominal speed of sound = 345 m/s

Sd - emissive area of piston in m^2

w - radian frequency = 2 pi f

x - excursion in m

Basically as frequeny goes up you need less excursion to maintain equal pressure, since you getting more cycles/second. That's why tweeters don't need to be very large to produce high SPL's, moving 20,000 times/ second helps alot vs only moving 50. A sub in a sealed enclosure, we can simply look at SPL vs frequency as a pure function of overall displacement. If you know how far a speaker can move at a given frequency you can calculate it's SPL potential at that frequency. Power matters because it takes power to a make a speaker move that far in the first place. If the design is too low in effeciency, or the frequency is so high that it'll never reach that mechancial limit, then you have to look at the thermal limitations. Generally this is why IB setups are so well regarded at low end bass. Ultimately the SPL in a sealed box is all about how far the cone can move since power limits generally aren't hit at 30hz unless you design is very ineffecient (think small box). Using no box keeps the woofer from having to counteract back pressure from the box, this loss of compliance leads to increased effeciency down low and more SPL for watt.

In a ported scenario you have the port doing most of the work near tuning. This keeps cone excurison low overall, so BL becomes important. BL is motor force, this is what allows the motor to overcome the intertial forces damping the cone at tuning. More BL means more excurison near tuning, hence the cone will be able to excite the port more. That why alot of SPL setups that are very loud, especially teh ones using smalelr subs, use HUGE ports and high power handling with woofers that have high BL. The big port is what moves the air near tuning and it gets excited quite a bit since the small subs are moving quite a bit since they have high BL that allows it to actually move. 2 18's with low BL and low power handing with a small port will often lose to a single 12 if the design has a large port and enough BL ot allow for more overall displacement at that frequency.

Outside of subs, like high freqency drivers like regular speakers 1 watt effeciency is king. The speaker wont' run into mechanical limitations above 100hz if it has even a few MM of xmax in most cases. How loud you can get is determined by how far you can move the cone at high frequencies where the cone simply does not want to move 3mm each way 5000 times/second. You also have small coils that can't take power very well without getting hot (high impedence as heat increases). A single set of high effeciency midranges/tweets can easily be louder than several sets of lower effeciency speakers. A good example is a HLCD (horn loaded compression driver). A horn increases the acoutic coupling with the air (area of high pressure near the cone is slowly brought to a more regular pressure that matches the room). A horn can be as high as 112db/1w/1m. A standard tweeter is about 90db/1m/wm. Doubling the number of speakers and adding equal power to all sets is good for 6db's. A single set of horns at that SPL would be equal to about 10 pairs of tweeters.

edit: To go back to what proof was saying Acceleration of the cone is what term actually links directly to SPL. This is why the velocity doubles as you drop an octave, and the displacement quadruples as you drop an octave (assuming the SPL level stays the same). The relationship beteen velocity and acceleration (acceleration is the rate of change of velocity, hence first derivative)