Glossary-ice-terminology

[jkdas]

great, thanks guys; seems I need to activate it too.

[navin]

JK if your speakers are not complainin dont activate it. Most sealed box speakers do not need help from a subsonic filter.

[kb100]

What is 'Qts', 'Qes' and 'Qms' of speakers??.. what does it do to sound??

[low_bass_makker]

let the experts handle it first then i will dive in to stir it up.......

[navin]

Qms is the Q of a driver at fs in free air considering only its mechanical resistance and Qes is the Q of a driver at fs in free air considering only its electrical resistance. Qts is Qes and Qms in parallel.see the links below for more.
http://sound.westhost.com/tsp.htm
http://www.winebase.com.au/audio/avsbdm.htm

The Qes adn Qms of the speaker determine the type of box the speaker is more sutiable for. THere is no "right Q" but in general most woofers have a Qts somewhere between 0.2 and 0.7. In one wants to generailise one can say that Low Qts woofers are more suitable for sealed boxes and High Qts speakers should work better in bass reflex boxes.

I hope this was simple enough.

[low_bass_makker]

Originally Posted by navin

In one wants to generailise one can say that Low Qts woofers are more suitable for sealed boxes and High Qts speakers should work better in bass reflex boxes.

Navin ji sorry for pointing out and going in such detail I have read on the following site it is the reverse what you are talking about and it has add a bit to my confusion.....

Drivers with Qts between 0.3 to 0.4 are usually best used in vented systems, and drivers with higher Qts are usually best suited for sealed systems.

http://www.diysubwoofers.org/sbc/sbc5.htm

[navin]

Originally Posted by low_bass_makker

.....

Drivers with Qts between 0.3 to 0.4 are usually best used in vented systems, and drivers with higher Qts are usually best suited for sealed systems.

You are right. I was doing too many things at the same time. It is backwards. woofers with low Qts (under 0.4) prefer vented (bass reflex) boxes and woofers with higher Qts prefer sealed boxes. In fact woofers with very high Qts (above 0.7) tend to prefer aperiodic (lossy-sealed) boxes.

[morten]

hi gurus,how is everybody .what is signal to noise s/n ratio in car audio.what does it mean and is higher s/n ratio better than a lower one and how much difference does it make.in alpine hu's s/n is 110-115 and in some pioneers s/n is 95-100 in a eclipse it was 100 .please tell me what does it signify.

[jkdas]

A higher SNR is better. When a signal passes through a medium, noise to may addon to it. So, its always better when we have more signal at the receiving when compared to the noise ( undwanted signals).

"Ratio of the magnitude of the signal to the magnitude of noise usually expressed in decibels."

http://searchnetworking.techtarget.c...213018,00.html
http://en.wikipedia.org/wiki/Signal-to-noise_ratio

mods could you pls lock this thread or merge with this thread http://www.team-bhp.com/forum/car-en...rminology.html

[low_bass_makker]

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://66.49.188.60/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)

[navin]

LBM you forgot Mms and Mmd which is the mass of cone with and without air mass. and BL is the product of B and L. The ONLY reason I say this becuase the BL/Mms ratio can give a designer a very good idea as to how efficient the speaker is.

[Bass&Trouble]

This may have been discussed earlier, but I'm looking to explore this with renewed depth, so please don't ignore this as a repost, or a previously debated subject.

Whenever some newbie pops onto the forum and asks for reccomendations on a car audio setup, the first question generally asekd ranges from "What kind of music do you listen to?" to "What is your preference, SQ, SPL or SQL?". What do these terms very precisely mean? What sort of music is each one supposed to be ideal for? Are these the only 3 kinds of classifiable setups possible for a car, and between any one of these 3 choices, a user would be able to achieve whatever is desired?

And based on what they exactly mean, what brands are best recommended to comprise in a configuration catering to the three requirements?

I am looking for inputs from the kind gentlemen (it's a pity we don't have ladies on here) who have been repeatedly asking these questions to help configure any kind of setups.

[low_bass_makker]

B&T this is gonna be a nice topic here is something to kick start it. Here only sub is discussed will be talking about other things later.....

SPL
If your goal is sheer output, and you don’t mind sacrificing decent sound to accomplish that goal, then you’re going to want to look for subs that are SPL optimized. What you want to look for is a sub that has high excursion, large cone area, and high power handling. Don’t assume that just because a sub has a massive stack of magnets and a big fat surround that it can get loud. There are many subs out there that look the part, that don’t act the part. If you intend to build a massive SPL rig, then you’ll want to use a large quantity of smaller subs, say 8 10” subs instead of 2 18” subs. This lets you maximize your cone area for the space that you have to work with. 8 10” subs and 2 18” subs will both take up a mounting area of roughly 20x40”. The 2 18” subs will have approximately 500 in^2 of moving cone area, where 8 10” subs will have approximately 600 in^2. Likewise, since ported enclosures are much larger than sealed enclosures for a given sub, your big SPL vehicles that are full of subs usually use sealed enclosures so that they can fit more subs into a given area. If you’re only going to use a limited number of subs, you can get more maximum output out of that given quantity by using a ported enclosure, but that will be explained later on. Quite often a sub designed for SPL will have a fairly high Qts and/or Vas, and the suggested enclosure will be smaller than what an “optimum” enclosure would be. This results in a very high Q alignment that increases output over a narrow frequency range, at the expense of a smooth frequency response that you’d want from an SQ subwoofer. There are a lot more variables involved with an SPL setup than a few sub parameters, so it’s a good idea to spend some time talking to various people (who know what they’re talking about) about their SPL experiences, as well as taking in a soundoff or two in your local area. Watch the DB drags and see how people are scoring, but pay particular attention to their whole setup, not just the brand of sub. What box are they using, what size is the box, what is the port tuned to if it’s ported, what amp, what kind of car, etc. All of that will effect the sub’s output abilities.


SQ
When trying to decide on a subwoofer for use as part of a system with sound quality as the main focus, you’re going to have to put more faith into your listening and less into published specs. The big problem with this approach is being able to do an apples to apples comparison. If you hear 2 different subs, to have any honest insight into what one sounds best, they both have to be in the same type of box, but one that’s optimized for that sub. Subs will also sound different based on the car (or showroom) they’re in, so that complicates things even more. However, if the manufacturer provides in-box response plots, or if you can simulate the plots yourself, you can at least get a decent idea of what your final frequency response may look like, keeping in mind that cabin gain (explained later) will play a significant role in your in-car frequency response.

SQL
Like I mentioned above, SQL basically describes a setup that attempts to strike a suitable compromise between SQ and SPL. An SQL setup is one that will provide good sound quality and good SPL, though perhaps not the best of either. Since most high quality subs will provide both good sound quality and good output capabilities, the line between SQ and SQL really blurs once you get into the better quality stuff, but that’s not necessarily a bad thing. There are a LOT of very good sounding subs on the market that can sound very good, and still get quite loud. One thing that you’ll want to remember too, is that thanks to the cabin gain of our cars, even subs that aren’t geared for SPL or even SQL can still get painfully loud. My own car uses a pair of Oz 300L subwoofers, which are an SQ sub by almost every account. They are not at all designed for SPL, yet in my old Firebird, I was measured at 141.1dB with my SQ tune and a sealed enclosure. That’s not really as remarkable of a number these days as it was 8 years ago when I was measured, but it is still uncomfortably loud, and more than you’ll really ever be able to use day to day. Those subs had an x-max of 10mm and were rated to handle 250 watts RMS. Compared to the average sub today, those numbers are pretty modest. The point is, in thirdgens, you can get great SPL numbers with almost anything, so even if you want a combination of SQ and SPL, in our cars, you’ll be able to get that with almost any good sub as long as you give it enough power.

[jkdas]

cant we merge this thread to
http://www.team-bhp.com/forum/car-en...rminology.html

[Bass&Trouble]

So LBM, from your account, an SQL system is one that does moderate SQ and SPL, without being very good at either. So what does that make a system which can hit 140 dB, for instance, and still maintain the same SQ that it was producing when playing at 95dB? Is that not SQL then? Why? Isn't it doing exactly the same thing that it was at a lower output level, but with higher magnitude? Why would it be termed as a compromise between SQ and SPL?

Isn't most SQ equipment designed to handle a decent amount of power? And hence, when fed with the optimum power, those guys are going to get loud, and athough the line between them is blurred, would it imply that the definition of an SQ system is either one with very little power, or one that has loads of reserve power, but never intended to be listened to at loud volumes?

If you relate to the sound that you hear in discotheques, you would have to probably agree (although some may not) that club music of all sorts is best enjoyed with a setup of the sort found in nightclubs. So what kind of sound is that? SQ/ SPL/ SQL? It couldnt be SQ cos it's loud. I wouldnt call it spl, the idea of spl is to drag, with no concern whatsoever for tonal balance etc. It couldnt be SQL, cos it isn't exactly a SQ setup that's capable of being turned up loud. No?

Wouldn't nearly 90% of all car owners listen to club music like Chill-out, Hip-hop, RnB, House, Trance etc? What sort of setup would best suit a listener of this sort? SQ/ SPL/ SQL? What brands? Is there one or a few brands that can take care of all of these?

If it's SQL, does this mean that the ideal set of speakers to listen to this music at home would be a Nautilus 801, or some other giant loudspeaker capable of huge SPL numbers while retaining sound quality?

Fact is that most DJs at nightclubs use poor/ average quality downloaded mp3 music. I know this for sure. All the top guys do this. Only a fraction of their repertoire is original CDs, or well pressed LPs. Some genres of music, especially like house which heavily relies on cover versions, mostly bootlegged have inherently poor original masters. Don't they still sound fairly decent in nightclubs? I think they do. The system is very forgiving of such shortcomings. And a system which does that cannot be called a SQ setup. And you don't want to try and listen to Rebecca Pidgeon on a setup like that, no way. But don't people (does not include Navin, does NOT!! ) desire sound like that too? So what kind of sound is this then? A Nautilus on the other hand with comparable electronics would just massacre such stuff. It would be unbearable to listen to. There are of course, some really good professional equipment manufacturers, but none would compare to the sound quality of a great high-end home setup, or a super SQ car setup.