Originally Posted by kb100
What is 'Qts', 'Qes' and 'Qms' of speakers??.. what does it do to sound??
FS- is the free air resonance of the driver. this in its simplest form means the driver moves easiest and impedance is at its highest. so you get the most output with the least work.
VAS- its the volume of air that has the same compliance as the suspension. compliance is the measure of the elasticity of the air equal to the suspension. so a VAS of 3.5 cubes means that the suspension has the same stiffness as 3.5 cubic feet of air.
CMS- is how "stiff" the suspension is. this is the measure of the elasticity of the suspension in n/m usually, where the VAS is the measure of the elasticity of the suspension in cubic feet related to the air that is equal to its CMS. think about this in a tire. you have the same amount of space to fill, but you put 25PSI in the left tire and 40 PSI in the right tire(off the car) the left tire has about the same air space but the amount of air inside is lower so CMS is lower. while the 40 PSI tire very similar amount of space but the amount of compressed air inside is greater, so CMS is higher the result is the tire with the lower CMS and same VAS(amount of space) is a stiffer tire!. QES
- is the electrical dampening. so in other words you pass a signal through the voice coil, and the QES is how well the energy in converted to usable electromotive force on the magnetic field. QMS
- is the damping of the mechanical aspects of the driver. so the QMS is how it controls the cone movement when the woofer resonates. the higher the QMS the more it opposes resonation. the lower the QMS the more it resonates. QTS
- is the total Q before you has electrical and mechanical dampening losses so to say. its the raw driver dampening.
RMS- is the losses of the suspension meaning that the stiffer the suspension with the same vas the higher the "losses".
KMS- is the measure of how linear the suspensions stiffness remains through its excursion. the result of the suspension stiffness exceed 4X its CMS is defined as Xsus.
Xmax- this spec is often over looked and very hyped. It is the measure of excursion of the motor in linear terms similar to KMS but for the electrical side of the driver. its defined as when the B/L drops to 71% of total B/L you have a QES that has doubled and its consider non linear.
Xmag- is the measure of how far the motor can move the coil. this is limited to coil height and the gap's fringe field also power handling. some woofers may have a Xmag well beyond its coil height because of the flux fields outside the gap and extreme power handling(DD9515 for example) this is a good indicator of how strong the motors actual strength is beyond linear excursion. both the magnetic field and electromagnetic field from the coil.
B- is the measure of the flux density in the gap. the less space between the gaps the more density you have. this is often complemented with a lower QTS.
L- is equal to the length of the voice coil in the gap. so the longer the voice
the higher your L. so if you use a smaller gauge wire you can get more L, but you add more MMS. some you have to have some kind of standards when designing the motor/woofer.
B/L is both the B and the L combined.
RE- is the at rest DC resistance. so when no voltage is applied and when the amp first turns on this the resistance the amp sees.
Impedance- is the measure of the resistance of the voice coil when a AC signal is passed through. this varies as frequency varies and it also varies in ported boxes because you can "tune" them and there for @ tuning you have the highest impedance and most "movement" except its done by the port instead of the woofer.
Pe- is the power handling of the woofer. its not thermal or mechanical but both. i think there should be both a thermal and mechanical spec but oh well.
FB- is the tuning frequency of the alignment in a box.
F3- is the -3 DB down point of the woofer, meaning that you are no relying on the mechanical dampening of the woofer instead of the dampening of the box and the woofer. in ported alignments you can hear anything under about -3 DB point, while the sealed boxes compliance stays much more linear so below this you can often hear it when you have the cabin gain.
SD- is the measure of the woofers cone area. alot of people use 1/3 of the surround but i don't like to use this for a few reasons. as it doesn't relate to the actual cones displacement as its not constant.
MMd -Diaphram mass, in grams
Mms-The driver's effective mechanical mass (including air load), in kg. "This parameter is the combination of the weight of the cone assembly plus the ‘driver radiation mass load’. The weight of the cone assembly is easy: it’s just the sum of the weight of the cone assembly components. The driver radiation mass load is the confusing part. In simple terminology, it is the weight of the air (the amount calculated in Vd) that the cone will have to push."
taken from http://www.the12volt.com/caraudio/thiele.asp
other sites -> http://en.wikipedia.org/wiki/Thiele/Small http://sound.westhost.com/tsp.htm http://yu-ra.tripod.com/ts_parameter.htm http://www.silcom.com/~aludwig/Sysd..._parameters.htm http://www.speakerfactoryusa.com/glossary/index.html http://www.diysubwoofers.org/definitions.htm http://www.mmxpress.com/technical/terms.htm http://www.faqs.org/faqs/car-audio/part3/ http://www.mhsoft.nl/TSP_ex.html http://188.8.131.52/tsp_calc.html
(will try to use it) http://hometheaterhifi.com/forum/showthread.php?p=10678
Page edited (thanks navin ji for pointing out the left out part)