Why does qts matter

[loudenuff]

Why is it that high qts subs are meant for IB/Sealed and low qts works well for ported. Sparked my interest when I noticed the SSA evil 18, which is not a sub I think anyone would run sealed, comes out with a .6 qts? Does it matter that much? Because ive been cutting certain subs out of my next build based on that.

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[Papermaker85 5,000+ posts]

Yes it matters somewhat. Looking at one spec will never tell you the whole story. Its is even less accurate than qes because its more of a raw dampening. Where qes is your dampening after electrical/mechanical losses/resistance and QMS is your mechanical dampening.

 

[loudenuff]

Yes it matters somewhat. Looking at one spec will never tell you the whole story. Its is even less accurate than qes because its more of a raw dampening. Where qes is your dampening after electrical/mechanical losses/resistance and QMS is your mechanical dampening.

So what does this all mean? Which specs determine this and how would I figure it out myself

 

[hispls 5,000+ posts]

Source: Audiopulse » Myths About Subwoofers

# 3 Subwoofers are fast / slow

More appropriately labeled Damping or Ringing, these concepts are really reciprocals of one another have nothing to do with speed, tightness, “boomieness” or any other misused and inappropriate term for subwoofers. Subwoofers, or rather bass drivers, all move at the same frequency when instructed to via an input single. The difference is really about the Q alignment of the system. There are many famous Q alignments which produce various frequency responses, but beyond the complex mathematics is a fundamental principal of force and acceleration and the driver will respond to a sinusoidal wave at various accelerations depending on the moving mass and force that the voice coil and motor generate on the cone. Therefore any driver can be faster or slower depending simply on the voltage! It makes little sense to call any driver faster or slower.

Damping or Ringing is really what we’re after and the amount of either is really a function of system volume along with the electro-mechanical damping factor of the driver. For example, in a sealed box system, as the volume of the cabinet becomes small, the internal pressures increase when the driver pushes in and out. This pressure is a force which, not nearly as strong as the electromotive damping force, works in the opposite direction. Contrary to intuition, higher internal pressure (which we tend to associate with tightness or stiffness) decreases damping and promotes ringing at one particular frequency (Fc in the case of a sealed box). The pressure from the air inside the box works against the driver’s natural damping factor of 1/(Qts). When the pressure becomes large relative to the motor’s damping factor, the driver will ring more and cause a peak in SPL at the given resonate frequency (Fc). This tends to be somewhere around 40-60Hz in a given sealed box, but could be outside that range under abnormal circumstances. This peak is ill desired and is accountable to the proclaimed “boomy” sounding subwoofers which tend to lack clarity, good transit response and dynamics. However some people prefer some ringing because it provides a natural boost in a very audible frequency band. Likewise, in a larger box, the Q will decrease and the ringing and SPL around that frequency will too, but the low end will open up and you’ll have more deep bass. This tends to sound better and more controlled.

On the flip side, over dampened drivers tend to have poor low frequency response and require equalization to boost the low frequencies. They tend to work better in vented boxes where their larger motor force factor (BL^2/Re) is put to good use with a resonator which then makes the low end much more efficient with its increased displacement. Likewise, drivers with high Qts will work better in sealed boxes and should be exempt from being used in a ported system without careful consideration. When high Q drivers are used in a vented system they will ring at the tuning frequency of the box (Fb in this case) and the “boomy” problem is considerably worse.

 

[trumpet 5,000+ posts]

Qts can only go up, it can never go down, so when you put a subwoofer in an enclosure that must change the response. Generally speaking, Qts above .707 is over-damped, and for bass that means it gets more boomy sounding with less low end(the fun deep bass).

 

[hispls 5,000+ posts]

So what does this all mean? Which specs determine this and how would I figure it out myself

That guy is a buffoon and just throws things around that he doesn't understand to try to impress people. Read the link I posted from the old TC website, that clears up a lot.

The cliff notes version is a .6 Qts sub might well sound fine but you'll want to model it out in box design software and see. Actually a lot of Fi built subs model terribly on that software but I've heard a few in person that were pretty decent. Depending on your goals it won't really matter anyway. If you're just going to dump a ton of power at them for the sake of getting loud don't even worry about TSPs, build a big box, big port, add power and it'll be loud.

 

[loudenuff]

That guy is a buffoon and just throws things around that he doesn't understand to try to impress people. Read the link I posted from the old TC website, that clears up a lot.
The cliff notes version is a .6 Qts sub might well sound fine but you'll want to model it out in box design software and see. Actually a lot of Fi built subs model terribly on that software but I've heard a few in person that were pretty decent. Depending on your goals it won't really matter anyway. If you're just going to dump a ton of power at them for the sake of getting loud don't even worry about TSPs, build a big box, big port, add power and it'll be loud.

Well that's not necessarily what my goals are, I do want them to be loud but I want them to sound as clean on the low end as I can. Was thinking about getting another ZCON 15, or a custom sub from some guy who owns PAP who is local to me. But his subs don't come with specs because they're built with off shelf parts

 

[Papermaker85 5,000+ posts]

That guy is a buffoon and just throws things around that he doesn't understand to try to impress people. Read the link I posted from the old TC website, that clears up a lot.
The cliff notes version is a .6 Qts sub might well sound fine but you'll want to model it out in box design software and see. Actually a lot of Fi built subs model terribly on that software but I've heard a few in person that were pretty decent. Depending on your goals it won't really matter anyway. If you're just going to dump a ton of power at them for the sake of getting loud don't even worry about TSPs, build a big box, big port, add power and it'll be loud.

Are you serious? Thats the best joke of all time. I waa defining parameters before you knew what they where

 

[Papermaker85 5,000+ posts]

Can anyone even define qts and what they mean by damning? I sure in the hell dont define it as ringing.

Fyi. Qts/qes/and qms are measurements that are taken at resonance.

It describes how the transducer responds to the signal.

A lower qes means the signal is more damped or the signal stops earlier than it would when critically damped.

Critically damped means the signal is played perfectly with no impedance or delay in the signal from a mechanical/electrical standpoint.. The lower the qts/qes the faster the driver tries to stop the signal being played. While .707 is said to be near perfect in signal response and above. 9 is said to be under-damped. In other words the signal plays and after the signal has passed through but the divers diaphragm hasn't stopped. It is still resonating. .

also a LOWER QES means that the driver is more efficient at resonance and resonates more aggressively and controlled but only very close to resonance meaning its more efficient at resonance but its also peaky and more limited in bandwidth..

 

[The_Quiet_One 10+ year member]

Are you serious? Thats the best joke of all time. I waa defining parameters before you knew what they where

Do you know the definition of defining?

 

[hispls 5,000+ posts]

Can anyone even define qts and what they mean by damning? I sure in the hell dont define it as ringing.

Because calling China and asking them to send you a woofer makes you far more of an authority than Thilo Stompler who has a string of patents to his credit and OEM'd woofers 10 years ago that are still highly sought after.

You're joining Spider Monkey on my ignore list you cretin. And FFS have the decency to write coherent English, proofread and use your spell check. It really is just a sign that you have no respect for yourself or anybody else to take such little care in what you post.

 

[Papermaker85 5,000+ posts]

Because calling China and asking them to send you a woofer makes you far more of an authority than Thilo Stompler who has a string of patents to his credit and OEM'd woofers 10 years ago that are still highly sought after.
You're joining Spider Monkey on my ignore list you cretin. And FFS have the decency to write coherent English, proofread and use your spell check. It really is just a sign that you have no respect for yourself or anybody else to take such little care in what you post.

You dont have a clue. Lamba came up with the shorting rings and how to implement them. I've yet to see a useful patent from theo..or who ever.. I learned much more from dan wiggins and a few others than anyone..

I use my own theories.. I was around when wiggins was shaking things up. I also had theories and tested several drives.. The lms is the least useful tech for flattening a bl curve. Terrible mass issues. Motors had to be overdamped to makeup for it and the suspensions while linear wheren't nearly controled enough for ported/ car audio apps.. From tge eclipse to to the xxx ive tested them.

If you want to talk about drivers we can.. That copy and paste was not close to how i can describe in in a few sentences

 

[Papermaker85 5,000+ posts]

Do you know the definition of defining?

Misspelled it. Forgive me god..

 

[Papermaker85 5,000+ posts]

Thats the problem. There are no more good discussions anymore. Op i can draw it out for you with a sinewave showing the difference..

But typicall for sealed boxes a qe from .45 to .75 with a softer suspension ( higher cms numbers) do much better sealed..

 

[garychurch84 10+ year member]

Loudspeaker design cookbook

 

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