Rumors on Sub size/ end them here

[audioholic 5,000+ posts]

Ha ha...I was right AND posted a link. Thanks for validating my post.
I understand the premise, but not all the jargon and formulas.

Yep, you were right. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
And... I guess I didn't notice you'd already linked to the adire paper...

 

[PendulousThread 10+ year member]

thank you so much!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Prowler573 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/hilarious.gif.02a037aad04aa96f19982b298a3d70a8.gif

Probably the most appropriate response to yet another thread of this ilk //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[audioholic 5,000+ posts]

Gotcha'.
So, a subwoofer can indeed be "faster" at the same cycle/sec because we're talking the amount of time it takes to reach excursion...not the actual cycles.

Speaker A is playing 50hz (moving back and forth 50 times in one second) while maintaining 10mm of excursion. Subwoofer B is playing 50hz while maintaining 30mm xmax. Speaker B's cone is moving 'faster'.

As I said before, BOTH excursion and cycles per second will affect actual cone velocity. Why? Because both affect the actual 'distance' the cone must travel in one second. The excursion affects how far it moves in each cycle, frequency (cycles per second) affects how many times it must do this in one second.

Frequency will depend on the signal material being played, excursion will depend on input power to the coil(s) and enclosure effects.

 

[Flipx99 5,000+ posts]

Speaker A is playing 50hz (moving back and forth 50 times in one second) while maintaining 10mm of excursion. Subwoofer B is playing 50hz while maintaining 30mm xmax. Speaker B's cone is moving 'faster'.
As I said before, BOTH excursion and cycles per second will affect actual cone velocity. Why? Because both affect the actual 'distance' the cone must travel in one second. The excursion affects how far it moves in each cycle, frequency (cycles per second) affects how many times it must do this in one second.

Frequency will depend on the signal material being played, excursion will depend on input power to the coil(s) and enclosure effects.

So woofer speed is more of a function of excursion than of diameter.

The two speakers travel different distances, and do it at different speeds. I would assume the speed would be negligble as they have to both cycle the same amount of times per second. It is just the cycle of sub 1 occurs faster than the cycle on sub 2?

Is this close?

 

[bikinpunk 10+ year member]

So woofer speed is more of a function of excursion than of diameter.

I would almost say the same, but with "frequency" being in place of "diameter".

 

[Flipx99 5,000+ posts]

I would almost say the same, but with "frequency" being in place of "diameter".

I was assuming at a given frequency.

 

[bikinpunk 10+ year member]

I was assuming at a given frequency.

Gotcha.

 

[newusername 10+ year member]

Well, I hate to disagree, but Dan's paper is a tad misleading. Perhaps a more detailed article on the concept is appropriate and I will work on that tonight.

Let's make an analogy for a moment, shall we?

I put a baseball on a tee, like I'm 4 years old again. I take a bat and swing at a 5lb ball with a given amount of force. The ball travels a distance relative to the weight of the ball and the amount of force I applied with the bat (just trying to keep things simple here). What if we use a 50lb ball and all other factors remain constant? Do we really think the ball is going to travel at the same velocity at any point in it's flight?

Again, that's a very loose analogy, but there are certainly more factors to be considered in the transient response equation than inductance. Dan's paper assumes that rise time is equivalent to transient response, when in fact, step response (the rise time and any ringing associated) is more appropriate.

 

[audioholic 5,000+ posts]

Well, I hate to disagree, but Dan's paper is a tad misleading. Perhaps a more detailed article on the concept is appropriate and I will work on that tonight.
Let's make an analogy for a moment, shall we?

I put a baseball on a tee, like I'm 4 years old again. I take a bat and swing at a 5lb ball with a given amount of force. The ball travels a distance relative to the weight of the ball and the amount of force I applied with the bat (just trying to keep things simple here). What if we use a 50lb ball and all other factors remain constant? Do we really think the ball is going to travel at the same velocity at any point in it's flight?

Again, that's a very loose analogy, but there are certainly more factors to be considered in the transient response equation than inductance. Dan's paper assumes that rise time is equivalent to transient response, when in fact, step response (the rise time and any ringing associated) is more appropriate.

I dont think Dan was concluding the laws of physics do not apply (mass/inertia) but that inductance is the dominate factor.
Also remember we are talking about 20-120hz frequencies here. If we were talking midrange or tweeters then yes, certainly mass will play a bigger role.

Looking forward to your article Neil. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[newusername 10+ year member]

I dont think Dan was concluding the laws of physics do not apply (mass/inertia) but that inductance is the dominate factor.
Also remember we are talking about 20-120hz frequencies here. If we were talking midrange or tweeters then yes, certainly mass will play a bigger role.

Looking forward to your article Neil. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

And he makes a good argument, but I'm not sure why we consider Fs and Qms to be important if mass does not relate at all. For low frequency response, inductance actually plays a very small role (in my opinion) relating to transient response, unless we are utilizing an abnormally large voice coil. Again, it is worth noting that our friend Richard Small equated driver mass to an inductor in a series RLC equivalent circuit.

I think Dan once mentioned since you cannot achieve ringing until you have experienced the "rise time" portion of transient response, that inductance was more important as it is the gateway to transient response. However, what if our intended bandwidth is narrow enough that the drivers upper frequency bandwidth is irrelevant? Why, that sounds like a subwoofer!

Gotta get fo of dem 13dub7s ya herd? Put them *****es in a box wit a 10dub7 so you got dem punchy and low bass fo realz

Thank you for a totally useless post in the middle of a decent thread. May I ask, which is worse: the noobs who don't know well enough not to ask that question, or the experienced poster who perpetuates it?

 

[mrogowski 5,000+ posts]

And he makes a good argument, but I'm not sure why we consider Fs and Qms to be important if mass does not relate at all. For low frequency response, inductance actually plays a very small role (in my opinion) relating to transient response, unless we are utilizing an abnormally large voice coil. Again, it is worth noting that our friend Richard Small equated driver mass to an inductor in a series RLC equivalent circuit.
I think Dan once mentioned since you cannot achieve ringing until you have experienced the "rise time" portion of transient response, that inductance was more important as it is the gateway to transient response. However, what if our intended bandwidth is narrow enough that the drivers upper frequency bandwidth is irrelevant? Why, that sounds like a subwoofer!

Call it more of a shared opinion. I plan to do some measurements of my own if I can get ahold of the right equipment..

 

[PendulousThread 10+ year member]

the experienced poster who perpetuates it for sure, I may be biased however hahaha.

 

[TeoTorriatte 10+ year member]

And he makes a good argument, but I'm not sure why we consider Fs and Qms to be important if mass does not relate at all. For low frequency response, inductance actually plays a very small role (in my opinion) relating to transient response, unless we are utilizing an abnormally large voice coil. Again, it is worth noting that our friend Richard Small equated driver mass to an inductor in a series RLC equivalent circuit.
I think Dan once mentioned since you cannot achieve ringing until you have experienced the "rise time" portion of transient response, that inductance was more important as it is the gateway to transient response. However, what if our intended bandwidth is narrow enough that the drivers upper frequency bandwidth is irrelevant? Why, that sounds like a subwoofer!

I agree that the natural lpf effects created by high inductance can be minimized by intentionally limiting bandwidth (via an external lpf).
But what are your thoughts on the other side effects of high inductance -- namely the fact that a VC is an inductor (which stores energy in the magnetic field). Is Dan accurate in stating that the higher the inductance, the longer the VC will hold the current before it starts to change?

I have also seen some reference to using the ratio of Re/Le to determine a more accurate representation of effects caused by inductance (the higher the ratio, the better). Any thoughts on that?

A few of the subs I've used most recently would agree with that last theory:

Dayton 12HF: 3.3/.95 = 3.47

Dayton DVC12: 2.69/1.85 = 1.45

eD 12O.14: 5.8/5.5 = 1.05

Could be coincidence though, too. //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[newusername 10+ year member]

I agree that the natural lpf effects created by high inductance can be minimized by intentionally limiting bandwidth (via an external lpf).
But what are your thoughts on the other side effects of high inductance -- namely the fact that a VC is an inductor (which stores energy in the magnetic field). Is Dan accurate in stating that the higher the inductance, the longer the VC will hold the current before it starts to change?

I have also seen some reference to using the ratio of Re/Le to determine a more accurate representation of effects caused by inductance (the higher the ratio, the better). Any thoughts on that?

A few of the subs I've used most recently would agree with that last theory:

Dayton 12HF: 3.3/.95 = 3.47

Dayton DVC12: 2.69/1.85 = 1.45

eD 12O.14: 5.8/5.5 = 1.05

Could be coincidence though, too. //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

I'm going to touch on some of that tonight. Dan is 100% correct beginning at a given corner frequency, which is determined by the ratio of Re:Le (there are other equations applicable as well).