T/S Parameters Simplified

[Mi10]

Speakers and Subs are important components in any ICE setup. Because as output devices, they have a larger role in play when it comes to determining how effective a speaker or a Sub is. Most people have trouble understanding the Power ratings mentioned behind speakers. They still think a 330W Pioneer Coaxials will sound better than a 240W Kenwood Coaxials when driven from a 5K HU!! What they fail to understand is Speakers are not Power generating Devices, but power using Devices. and that 330 or 240 doesnt even matter when all your giving is paltry 18 rms from Head Unit!!

One more Common misconception is a High Power Rated Speaker is always a better. And Most of them dont even care to see beyond Rated Power and Rated Impedance. Yes, they may be enough for a layman, But when it comes to ICE brotherhood in GH, we love to dig it into details. Simply becasue its more of an obession to us. This T/S Paramters will help you understand a lot more things on speakers than mere Power values. This is Applicable to all Cone Based Drivers (Component speakers, Midbass drivers, Coaxials, Sub Woofers and Mid Range Drivers). I ve put things in a simple way, so that all of us can understand. However, pls feel free to add / question anything in this regard.

The Thiele/Small parameters, shortly called T/S parameters, were brought about in a bid to standardize and bring meaning to the behavior of a cone loudspeaker. They were first published as research papers by A.N. Thiele and R. Small (and hence T/S). I am not going to cover the entire T/S params' but only the few which are of greater significance.


fs/fo - Free air resonance of the Driver / SpeakerThe point at which all the moving parts of the driver achieve a Balance or in another words resonate. Generally a Drivers Resonance freq is one below which the driver will not be too comfortable playing.
So a driver with an fs of 50 Hz will not produce say, 35 Hz very well. However a driver with an fs of 30 Hz will produce 35 Hz, very comfortably.

Example:
Morel Hybrid Ovation Midbass fs: 56 Hz
DynAudio MW 162 Midbass fs: 55 Hz
HAT L6SE Midbass fs: 50 Hz

Morel Ultimo Subwoofer fs: 18 Hz
JL Audio 12W6 Subwoofer fs: 25 Hz
DD 1012b Subwoofer fs: 42 Hz


Qms - Mechanical Q of a Driver
Qms is the mechanical Q of the speaker and only takes the speaker's mechanical properties into consideration. It is a measurement of the control coming from the speaker's mechanical suspension, which is made up of the surround and spider. Hence the Nautre and type of Surround, Number of Spiders all make up for the overal Qms value
Drivers with a very high mechanical Q can sound more open and have better dynamic freq range. The surround is also more flexible, the spider is better constructed, and hence they have also better air flow, making them Cool drivers.

Example:
Morel Hybrid Ovation Midbass Qms: 2.4
DynAudio MW 162 Midbass Qms: 2.2
HAT L6SE Midbass Qms: 1.94

Morel Ultimo Subwoofer Qms: 1.72
JL Audio 12W6 Subwoofer Qms: 7.1
DD 1012b Subwoofer Qms: 6.9


Qes - Electrical Q of the driver
Qes is a measurement of the control coming from the speaker's electrical suspension system - which is the Voice coil and Magnet. The Significance of Surround and Spider in Qmes is comparale to that of VC and Magnet in Qes.
The higher value of Electical Q of a driver denotes a much larger Voice Coil capable of handling lot more Power as well as Heat. They also result in higher value of Magnetic Flux density as well as the Magnetic Motor Structure also indicates the authority or control they have over thier mechanical counterparts.
Hence Drivers with higher Q can handle lot more power and thermal absue for extended periods. They also exhibit much better control thereby earning adjectives like precise and accurate apart from exhibiting better sensitivity figures.

Example:
Morel Hybrid Ovation Midbass Qes: 0.55
DynAudio MW 162 Midbass Qes: 0.57
HAT L6SE Midbass Qes: 0.62

Morel Ultimo Subwoofer Qms: 0.46
JL Audio 12W6 Subwoofer Qms: 0.48
DD 1012b Subwoofer Qms: 0.92


Qts - Total Q of the Driver
Q is basically a used to describe a quality or characteristic about the electrical or mechanical part of the driver. Qts is the overall Q of the driver, both electrical(Qes) and mechanical(Qms) put together.
Qts is defined as 1/Qts = 1/Qes + 1/Qms
Qts reflects how strong the motor and magnet system of a driver are.
A driver with a low Qts of around 0.20 would have a large magnet and be able to move the cone with a lot of force. This makes for a very tight driver which plays low Bass very powerfully. A driver with a Qts of 0.45 would have a smaller magnet and less control over its cone making it more tight and Punchy. So low values of Qts give a tight and punchy sound but with little weight or low bass and high Qts values give a slow and heavy sound that will give you lots of low frequency output.
Higher Q values suggest the need for large volume of enclosures for them to sound accurate. Few have Q values more than 0.7 indicating the need for very large enclosures, or even to be mounted on the rear parcel shelf, so that they can take the entire Boot volume as enclosure.
Qts provides an understanding of influence of a Drivers Mechanical and Electrical Components. Qts, Qms and Qes form integragal part of Speaker designing itself. They are quite important values to be considerd when designing Enclosures or using them in infinite baffle applications

Example:
Morel Hybrid Ovation Midbass Q: 0.46
DynAudio MW 162 Midbass Q: 0.45
HAT L6SE Midbass Q: 0.46

Morel Ultimo Subwoofer Q: 0.34
JL Audio 12W6 Subwoofer Q: 0.45
DD 1012b Subwoofer Q: 0.8


Vas - Volume of air equal to the driver compliance
This can be thought of as how stiff the movement of the cone is. The value is given in litres or cu inches. There are a lot of variables that determine the Vas, so you can’t really say that high values of Vas mean a certain thing or are better. A single or double suspension spider will affect Vas, so does the size of the cone. The temperature of the air and also the humidity will affect Vas and so it is one of the hardest parameters to evaluate. However Vas, along with Qts and Fs is quite important when designing perfect enclsoures for Subwoofers


Xmax - The amount of voice coil overhang
This is usually in mm and it represents the distance over which the coil can travel in one direction and maintain a constant number of turns in the gap. So a driver with an xmax of 10 mm can move is cone twice as far as one with an xmax of only 5 mm.
Do note that, Xmax is not maximum excursion. Maximum excursion is how far the cone will travel before the coil hits the back plate or the cone moves so far that it is restricted by its suspension.
Xmax is how far the cone can travel with the coil still in the magnetic gap. More xmax means the cone can move in and out further while still being under control.
Note that the xmax figure is for one direction only, so an xmax figure of 5 mm means the cone can travel 5 mm outwards and 5 mm inwards past it’s resting place whilst still being under the control of the motor system.

Example:
Morel Hybrid Ovation Midbass X, one way: 7 mm
DynAudio MW 162 Midbass X, one way: 6 mm
HAT L6SE Midbass X, one way: 9 mm

Morel Ultimo Subwoofer X, one way: 12.5 mm
JL Audio 12W6 Subwoofer X, one way: 17 mm
DD 1012b Subwoofer X, one way: 19 mm

---

Apart from this there are few other Non T/S paramters one should look before deciding on a Speaker or a Subwoofer

Sensitivity: Sensitivty is simply how loud will a speaker go. It is denoted in db and is mostly measured at 1watt / 1metre length. Higher the better.

Example:
Morel Hybrid Ovation Midbass: 90 db
DynAudio MW 162 Midbass: 91 db
HAT L6SE Midbass: 92.5 db

Morel Ultimo Subwoofer: 85 db
JL Audio 12W6 Subwoofer: 86 db
DD 1012b Subwoofer: 85 db


Frequency range: Frequency Range which the driver can play without losing out on more than -3db loudness. Higher the Better

Peak Power: Peak power values determine the max power before which the Voice Coil gives up. Higher the better


Hope you enjoyed reading this.

Cheers Mi10


PS:

• Please note that all paramters given above only indicate characteristics of different drivers, the ultimate sound is determined by many parameters including the Source, amplifications enclosure etc..
  
• Comparison of Drivers are made for better understanding. Choice purely based ease of info availability
  
• If you need more understanding on technical front, suggest you to read this -> http://www.the12volt.com/caraudio/thiele.asp i found it very nice.
  

[piyush7243]

Its wonderful knowledge shared here and kudos to Mi10 for it.

[sumeetonweb]

Excellent write up.

Aren't these ratings and tests conducted in ideal scenarios in labs? If yes, wouldn't the performance differ from car to car, and considering very few among us really install the drivers way they are supposed to be? I don't doubt T/S parameters and their relevance - but is there a rule of thumb to look for certain parameters before shortlisting high end speakers?

[Mi10]

Aren't these ratings and tests conducted in ideal scenarios in labs? If yes, wouldn't the performance differ from car to car, and considering very few among us really install the drivers way they are supposed to be?

Hmm, in a way yeah - they are measured in lab conditions, however they dont change based on usage. Rather T/S Parameters give you an indication for ideal usage. Like you know, few brands recommend Sealed enclosure, few Ported and few even free air - The basis for recommendation is your T/S Parameters.

I don't doubt T/S parameters and their relevance - but is there a rule of thumb to look for certain parameters before shortlisting high end speakers?

There are lot of T/S Paramters like BL, Cms, Mms etc.. I have shortlisted the ones that are quite effective for Indian scenario. Like most common of them, where any one can understand and put to use

[sumeetonweb]

Like most common of them, where any one can understand and put to use

Pardon my being a n00b but is there a relation we can draw between resonance of a driver and the xo point? In other words, should xo be set for the woofer to play above the reso freq to get better results? And similar thing for tweeter?

In which case, to cover the entire spectrum from may be 50Hz to 5 KHz, one should plan out the various drivers (sub, woofer, tweeter and/or midbass) accordingly and then set the xo points accurately? At times, I have seen the Qms and Qes paramtrs of woofer and subwoofer are almost similar - is this why these components give a good kick bass even if there is no subwoofer running? I know subwoofer would have a lower Fs - but should other parameters not differ as well since power handling of both are totally different?

[Mi10]

sumeetonweb
Yes, a lot depends on the Fs of a Midbass or Tweeter. Not only the XO point, but the slope also is decided on fs of a driver. Generally, its safe for choosing an XO point one octave above the Fs of a driver (for Dome based Midranges and tweeters) and about half Octave above the Fs of the driver (applicable for Cone based Midranges and Midbasses) and 2-5Hz about the Fs in case of Sub Woofers.
This is why in an Active setup, you get to choose the right XO and slope so that it covers the entire spectrum.

Eg: I was running this setup in my Fiesta

Sub: Ultimo
Fs: 20 hz
XO: LPF 50 Hz @ 6 db (Subsonic filter at 20Hz)

Midbass: Hybrid Ovation
Fs: 55 Hz
XO: BP 63 Hz @ 24db to 500 Hz @ 12 db

Mid Range: CDM 88
Fs: 280 Hz
XO: BP 500 Hz @ 18 db to 3800 Hz @ 6 db (LPF Via passive XO)

Tweeter: MT 22
Fs: 950 Hz
XO: HPF 3800 Hz @ 6 db (Via Passive XO)

Reg: Qts, the value will directly impact the performance based on the volume of the cabinet (or doors, in case of Midbass). This is why few Midbasses which sound great in few cars, sound not so great in other cars.

[karanbhatia]

Posts regarding Summet's setup plans moved to his Build Log

Doing it Third Time Right! - Page 3

[Gilead]

Eventually, it was a toss the HAT Legatia V2/Rainbow Profi Kickbass/Dynaudio 242GT.

Rahul, you seem to have made a typical error that a lot of us made when we didn't know much about HAT. You have compared their products with other products in the same price range. But HAT products typically punch well above their price bracket. You should have compared T/S parameters instead. Take a look at the specs below and you'll know for yourself. How much does the Esotar cost globally and in India?

Fs

Legatia L6v2 49 Hz
Esotar 650: 49 Hz
Esotec MW 162GT: 60 Hz


Qts

Legatia L6v2" 0.433
Esotar 650: 0.44
Esotec MW 162GT: 0.48 Hz

[mclaren1885]

Rahul, you seem to have made a typical error that a lot of us made when we didn't know much about HAT.

Error? I've looked around the net for every conceivable mention of Legatia & HAT. There were "mixed" reviews. I also looked around for Dynaudio & weirdly just 1 bad review which was later rectified due to a faulty install. From what I read, almost everyone seem to rave about them. So let's see how they sound after they break-in.

You have compared their products with other products in the same price range. But HAT products typically punch well above their price bracket.

Heard great stuff about the Clarus on Car Audio & Electronics Mag, but again very little on Legatia. Will wait for you Chennai guys to run a few pairs & maybe for my next car.

Oh here is what Casey Thorson had to say about the Dyns

Conclusion: Detailed, dynamic and accurate, these Dyanaudios are surely one of the finest performing 2-way systems I've evaluated. That, in a nutshell, is how I'd describe the Dynaudio Esotec System 242's. It's a shame, but with a formidable retail price of $990, they're certainly not going to fit into everyone's budget. But, considering the sound reproduction capabilities and the overall level of performance they achieve, I still deem the System 242 an absolute bargain, especially since they better most components costing two or three times their price. If you have pockets deep enough to afford them, I'd encourage you to take a listen. They're certainly lustworthy.

So guess with Dyns too I'm getting the same deal. Paying for speakers that could outperform stuff twice or thrice the price

Dynaudio Esotec System 242 Review - Speaker Reviews - Car Audio and Electronics

You should have compared T/S parameters instead

If there is one thing I've learnt in ICE, never go by the "specs". If that were the case Tru Tech, Genesis, Celestra amps would have never had the fan following. Sony's PMPO would rule the roost

How much does the Esotar cost globally and in India?

Will let you know when I get around to upgrading to the Esotar 1200 in 2yrs from now & trust me that's one upgrade I've decided on once I go to Delhi & check out these subs playing in a few installs done at Patel Auto

There are some awesome reviews on the Esotars as well.

[Gilead]

T/S parameters are published for a reason. Looking at them, Esotar's parameters are much more closer to the Legatia v2's than the Esotec's. And there's also the Legatia SE and Legatia Carbon on top of the Legatia v2. I think I may be the only one on GH who has heard the Legatia SE in the IASCA Reference setup so I may be a bit biased. But nothing like hearing them. Let's have your review and that of others' after installation. And we'll run an SQ test when we all meet. I have the CDs ready.