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Old 5th August 2010, 07:25 PM   #11
GM is offline GM  United States
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Because the weaker the driver, the weaker the cab's air mass 'spring' must be for a given Fb.

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Old 5th August 2010, 07:46 PM   #12
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so what constitutes a "weak driver" loose/stiff suspension? heavy motor? power rating?

i am working with square kicker L7s and they need to be in a huge box and i am trying to unsderstand why
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Old 5th August 2010, 08:22 PM   #13
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A motor that is not very powerful is probably the simplest description.
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Old 5th August 2010, 09:42 PM   #14
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Yeah, if Trevor's and Cal's answers didn't make it plain enough I can't think of a simpler, yet educational, way to explain it ATM.

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Old 5th August 2010, 10:00 PM   #15
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Quote:
Originally Posted by Cal Weldon View Post
Qts: the higher the number = the drivers inability to come to rest after the electrical signal has ceased. a rating of 0.707 is just right for a lot of folks. If you like drier bass, around 0.5 - 0.6 is better. if you like speakers from the 70's, a little higher 0.8 - 1.0 will make your ears happy.
Do you mean a QTC of .707 or QTS...

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Old 6th August 2010, 01:24 AM   #16
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I guess I mean Qtc of 0.707
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Old 27th March 2013, 12:04 AM   #17
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Quote:
Originally Posted by scampo77 View Post
so what constitutes a "weak driver" loose/stiff suspension? heavy motor? power rating?

i am working with square kicker L7s and they need to be in a huge box and i am trying to unsderstand why
Thanks to all for their input on this. I am in Mexico and it's hard to find books a) in English b) about these things. Plus ordinary folk on forums sometimes explain things in a way that easier to understand than books...

Scampo77, have you come across any great links/books about all this?
I am especially interested in having an idea of :

- what is a better? Higher or lower ?
- what is a good figure ?
(for basically all the Thiele Small parameters, such as for example here :
Celestion TF0510 5" Professional Speaker 30W 294-2050)

Many thanks guys!
Rick
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Old 27th March 2013, 03:10 AM   #18
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actually you have the right idea with regards with electrical damping analogy of under/critically/over damped; they purposely describe the "ringing" in this physical system. Since an electrodynamic loudspeaker is simply a force driven, damped spring-mass harmonic oscillator, the electrical analogue is very well known and can be found in any college level Physics 101, Electromagnetics, Differential Equations, etc college/university level textbooks.

The same terminology describes the Frequency Response magnitude vs Frequency of a speaker. Lower Qts= more overall damping (not necessarily over-damped because it is all relative), higher Qts= less overall damping. Too high Qts (not enough damping) can result in a peak in the magnitude response within the pass band; too low Qts can result in a very high F(-3) high-pass roll-off, which can hinder bass response. Again, this is all relative as there are an infinite number of loudspeaker alignments to consider.

Qms and Qes are simply the two constituents of the total Quality Factor (Qts). They [Qms and Qes] work together in the "product over sum" rule to establish the total Q(ts).

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Old 8th November 2013, 12:16 PM   #19
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Quote:
Originally Posted by Trevor White View Post
The Qms is a measure of the damping caused by the mechanical damping of the diaphragm suspension. A higher Qms means less mechanical damping.

The Qes is a measure of the electromechanical damping caused by voice coil resistance and the interaction of the voice coil in the magnetic gap. A higher Qes means less electromechanical damping or a smaller magnet.

The Qts is the total damping which is the combination of mechanical and electromechanical damping.

Qms is always much larger than Qes because the electromechanical damping always dominates.
I've been on a steep learning curve and am trying to get a better grasp on these and other notions. I think I have a reasonable enough understanding of Qms and Qes (at least for my lay purposes), but I'm still puzzled about something.

If Qts is the sum of Qms and Qes, then why is it that when I look at speaker stats, the Qts is a lower number than both Qms and Qes? There must be something simple that I'm missing here.
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Old 8th November 2013, 12:25 PM   #20
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It's not the sum. It's product over sum.
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