explanation needed
10-12-2009, 09:22 PM
#1
0 Watt CAFz'r
Thread Starter
Join Date: Aug 2008
Posts: 15
explanation needed
Hi,
I'm not new to the car audio scene, but I'm not a genius at it either. I have read quite a few websites that try to explain all about car audio and speaker parameters, but I cannot grasp what they mean. I am looking to see if someone on here is willing to take a few minutes and try to explain to me what speaker parameters mean in layman's terms (simple English) things like: what does the sensitivity mean; fs, vas, qts, qes, qms, xmax. That sort of stuff.
Basically an explanation of the speakers and if a larger or smaller number in a certain parameter is better.
thanks
I'm not new to the car audio scene, but I'm not a genius at it either. I have read quite a few websites that try to explain all about car audio and speaker parameters, but I cannot grasp what they mean. I am looking to see if someone on here is willing to take a few minutes and try to explain to me what speaker parameters mean in layman's terms (simple English) things like: what does the sensitivity mean; fs, vas, qts, qes, qms, xmax. That sort of stuff.
Basically an explanation of the speakers and if a larger or smaller number in a certain parameter is better.
thanks
10-12-2009, 10:51 PM
#2
Here is the basics. Put the spec sheet up to your ear and listen to it, then tell me how it sounds to you. It is really that simple, a higher or a lower number does not necessarily mean it is a better or worse speaker.
10-12-2009, 11:05 PM
#4
These parameters are called Thiele Small parameters and here is a link for you to read up on them.
Car Audio: Thiele-Small Parameters
Car Audio: Thiele-Small Parameters
10-12-2009, 11:11 PM
#5
0 Watt CAFz'r
Thread Starter
Join Date: Aug 2008
Posts: 15
thanks... i think... still very confusing though. I do not know what they are talking about. They try to explain them, but there are terms in the explanations that I do not understand. Oh well, I guess I'll never really fully understand everything about car audio.
10-13-2009, 06:43 AM
#6
50 Watt CAFz'r
Join Date: Apr 2009
Posts: 132
If you're serious about this... start with http://www.mfr-eng.com/ldc.htm
If you still have questions about the terminology, find some college physics/electronics/acoustics text books and go from there. Or, if you have access to an electronics/electrical engineer ask them for their notes. I know it's not what you were looking for, but it's the only way you will truly understand and apply it. No easy ride here unfortunately.
Hope this helps!
10-13-2009, 08:53 PM
#7
Hi,
I'm not new to the car audio scene, but I'm not a genius at it either. I have read quite a few websites that try to explain all about car audio and speaker parameters, but I cannot grasp what they mean. I am looking to see if someone on here is willing to take a few minutes and try to explain to me what speaker parameters mean in layman's terms (simple English) things like: what does the sensitivity mean; fs, vas, qts, qes, qms, xmax. That sort of stuff.
Basically an explanation of the speakers and if a larger or smaller number in a certain parameter is better.
thanks
I'm not new to the car audio scene, but I'm not a genius at it either. I have read quite a few websites that try to explain all about car audio and speaker parameters, but I cannot grasp what they mean. I am looking to see if someone on here is willing to take a few minutes and try to explain to me what speaker parameters mean in layman's terms (simple English) things like: what does the sensitivity mean; fs, vas, qts, qes, qms, xmax. That sort of stuff.
Basically an explanation of the speakers and if a larger or smaller number in a certain parameter is better.
thanks
T/S parameters try to model the mechanical and electrical properties of loudspeakers so that we can design a speaker box to put it in as well as a cross over. You only need them if you are going to do this on your own and it is mainly for subwoofers. Most subwoofer manufacturers for car audio will also recommend a sealed and ported box so you dont have to design your own.
Think of a speaker something like a car and suspension.
The cone is the weight
the rubber surround and spider is the spring, but also acts like a shock absorber too. That thick rubber surround takes energy to deform! This is mechanical dampening.
the Voice coil moving in the magnet acts not only to drive the speaker but also damps its movement and thus is like the shock absorber too.. This is electrical dampening
If you now put the speaker in a box, the air in the box acts as an additional spring. It is like adding another set of springs or changing the springs on your car.
A subwoofer by itself will resonate at a particular frequency in free air, just as if you remove your car's shock absorbers it will bounce up and down at its own rate.
Once you connect the speaker to an amp, the resistance in the voice coil dampends the cone vibrations just like a shock absorber does.
now for some of the T/S terms:
Fs is the free air resonant frequency of the sub. Normally the lower the better.
Vas is the built in spring of the speaker (surround and spider) it is expressed as an equivalent volume of air (like air springs!)
a low Vas means a stiff spring while a high Vas means a soft spring.
Fs will increase when you put the speaker in a sealed box because of the added spring of the air in the box. Just like stiffer springs in a car will make it bounce faster. The lower the Vas, the less the Fs will increase. Manufacturers make different tradeoffs of Vas, Fs, mass of the speaker, magnet weight etc.
Now for Qms Qes and Qts. Q (also called quality factor) is a number that combines the spring and the dampening into one value. A high Q means that the dampening is low while a low Q means the dampening is high.
In other words, a High Q speaker means that there is very little dampening to prevent it from vibrating by itself.. just like a car with weak shocks. A low Q speaker means that there is alot of dampening in it to prevent it from vibrating once it started. Qms is the mechanical Q. Qes is the electrical Q and Qts is total Q or combined Qms and Qts.
A speaker is a bunch of tradeoffs.
In order to have a low Fs, you want either a week spring or heavy mass.. weak springs make for low Q and *muddy sound* So to lower Fs, you need a heavyer cone. A heavy cone takes more power to move, thus is less efficient. That is the dB/watt value called efficiency.
You can make the magnet stronger but then you play with the Q again... etc...
Xmax is the maximum one way linear allowable motion of the cone without damage.
A manufacturer will juggle all these factors to make different subs with different characteristics. The rest you can read about on the web.
Now dont ask how to chose a speaker based on T/S parameters... Go and listen!
Oh I forgot about ported cabinets. A speaker in a sealed box has only one resonant frequency. A speaker in a vented box has 2 reasonant frequencies. One based on the resonant frequency of the speaker and box. and another, lower one, based on the resonant frequency of the box and air in the port. They work together to make the sub louder at lower frequencies but with some drawbacks. Usually a sealed box has better sound quality.
All these T/S parameters are used by speaker design software.
hope this helps.
Last edited by zoomer; 10-13-2009 at 08:58 PM.
10-13-2009, 09:10 PM
#8
let me help you in simpler terms.
T/S parameters try to model the mechanical and electrical properties of loudspeakers so that we can design a speaker box to put it in as well as a cross over. You only need them if you are going to do this on your own and it is mainly for subwoofers. Most subwoofer manufacturers for car audio will also recommend a sealed and ported box so you dont have to design your own.
Think of a speaker something like a car and suspension.
The cone is the weight
the rubber surround and spider is the spring, but also acts like a shock absorber too. That thick rubber surround takes energy to deform! This is mechanical dampening.
the Voice coil moving in the magnet acts not only to drive the speaker but also damps its movement and thus is like the shock absorber too.. This is electrical dampening
If you now put the speaker in a box, the air in the box acts as an additional spring. It is like adding another set of springs or changing the springs on your car.
A subwoofer by itself will resonate at a particular frequency in free air, just as if you remove your car's shock absorbers it will bounce up and down at its own rate.
Once you connect the speaker to an amp, the resistance in the voice coil dampends the cone vibrations just like a shock absorber does.
now for some of the T/S terms:
Fs is the free air resonant frequency of the sub. Normally the lower the better.
Vas is the built in spring of the speaker (surround and spider) it is expressed as an equivalent volume of air (like air springs!)
a low Vas means a stiff spring while a high Vas means a soft spring.
Fs will increase when you put the speaker in a sealed box because of the added spring of the air in the box. Just like stiffer springs in a car will make it bounce faster. The lower the Vas, the less the Fs will increase. Manufacturers make different tradeoffs of Vas, Fs, mass of the speaker, magnet weight etc.
Now for Qms Qes and Qts. Q (also called quality factor) is a number that combines the spring and the dampening into one value. A high Q means that the dampening is low while a low Q means the dampening is high.
In other words, a High Q speaker means that there is very little dampening to prevent it from vibrating by itself.. just like a car with weak shocks. A low Q speaker means that there is alot of dampening in it to prevent it from vibrating once it started. Qms is the mechanical Q. Qes is the electrical Q and Qts is total Q or combined Qms and Qts.
A speaker is a bunch of tradeoffs.
In order to have a low Fs, you want either a week spring or heavy mass.. weak springs make for low Q and *muddy sound* So to lower Fs, you need a heavyer cone. A heavy cone takes more power to move, thus is less efficient. That is the dB/watt value called efficiency.
You can make the magnet stronger but then you play with the Q again... etc...
Xmax is the maximum one way linear allowable motion of the cone without damage.
A manufacturer will juggle all these factors to make different subs with different characteristics. The rest you can read about on the web.
Now dont ask how to chose a speaker based on T/S parameters... Go and listen!
Oh I forgot about ported cabinets. A speaker in a sealed box has only one resonant frequency. A speaker in a vented box has 2 reasonant frequencies. One based on the resonant frequency of the speaker and box. and another, lower one, based on the resonant frequency of the box and air in the port. They work together to make the sub louder at lower frequencies but with some drawbacks. Usually a sealed box has better sound quality.
All these T/S parameters are used by speaker design software.
hope this helps.
T/S parameters try to model the mechanical and electrical properties of loudspeakers so that we can design a speaker box to put it in as well as a cross over. You only need them if you are going to do this on your own and it is mainly for subwoofers. Most subwoofer manufacturers for car audio will also recommend a sealed and ported box so you dont have to design your own.
Think of a speaker something like a car and suspension.
The cone is the weight
the rubber surround and spider is the spring, but also acts like a shock absorber too. That thick rubber surround takes energy to deform! This is mechanical dampening.
the Voice coil moving in the magnet acts not only to drive the speaker but also damps its movement and thus is like the shock absorber too.. This is electrical dampening
If you now put the speaker in a box, the air in the box acts as an additional spring. It is like adding another set of springs or changing the springs on your car.
A subwoofer by itself will resonate at a particular frequency in free air, just as if you remove your car's shock absorbers it will bounce up and down at its own rate.
Once you connect the speaker to an amp, the resistance in the voice coil dampends the cone vibrations just like a shock absorber does.
now for some of the T/S terms:
Fs is the free air resonant frequency of the sub. Normally the lower the better.
Vas is the built in spring of the speaker (surround and spider) it is expressed as an equivalent volume of air (like air springs!)
a low Vas means a stiff spring while a high Vas means a soft spring.
Fs will increase when you put the speaker in a sealed box because of the added spring of the air in the box. Just like stiffer springs in a car will make it bounce faster. The lower the Vas, the less the Fs will increase. Manufacturers make different tradeoffs of Vas, Fs, mass of the speaker, magnet weight etc.
Now for Qms Qes and Qts. Q (also called quality factor) is a number that combines the spring and the dampening into one value. A high Q means that the dampening is low while a low Q means the dampening is high.
In other words, a High Q speaker means that there is very little dampening to prevent it from vibrating by itself.. just like a car with weak shocks. A low Q speaker means that there is alot of dampening in it to prevent it from vibrating once it started. Qms is the mechanical Q. Qes is the electrical Q and Qts is total Q or combined Qms and Qts.
A speaker is a bunch of tradeoffs.
In order to have a low Fs, you want either a week spring or heavy mass.. weak springs make for low Q and *muddy sound* So to lower Fs, you need a heavyer cone. A heavy cone takes more power to move, thus is less efficient. That is the dB/watt value called efficiency.
You can make the magnet stronger but then you play with the Q again... etc...
Xmax is the maximum one way linear allowable motion of the cone without damage.
A manufacturer will juggle all these factors to make different subs with different characteristics. The rest you can read about on the web.
Now dont ask how to chose a speaker based on T/S parameters... Go and listen!
Oh I forgot about ported cabinets. A speaker in a sealed box has only one resonant frequency. A speaker in a vented box has 2 reasonant frequencies. One based on the resonant frequency of the speaker and box. and another, lower one, based on the resonant frequency of the box and air in the port. They work together to make the sub louder at lower frequencies but with some drawbacks. Usually a sealed box has better sound quality.
All these T/S parameters are used by speaker design software.
hope this helps.
I may have to copy and save that....I'll stash it with the "setting gains" novelette I wrote a while ago......
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