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Old 01-12-2018, 02:19 AM   #16
basicxj

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Quote:
Originally Posted by SPL_Krayzie112 View Post
I had the idea that the damping factor of a driver dictates the fatness or leanness of the sound it creates. Where in the T/S Parameters would this measure be?

Pardon me for basically asking the question again, in verbatim, what is Damping Factor and what is Q Factor?
Drivers don't have damping factors- that is a function of the amplifier driving them. You are getting some terminologies mixed up that don't really have much to do with speakers or subwoofers.

Damping factor = ability of an amp to precisely control the speaker attached.

Q = the narrowness of the wideness of the band being equalized, with an equalizer (usually parametric)


Some examples for you-

1) a subwoofer in a large enclosure will play low, sound fatter down lower. Large enclosures reduce the amount of attack or impact on individual notes, but make up for it in low-end extension and flatness of frequency response. Large enclosures reduce power handling.

2) a subwoofer in a small enclosure will not play very low compared to a larger enclosure, will sound fatter in higher frequencies and exhibit more attack up high. You will lose some flatness in frequency response, and can run into peaks in frequency response towards the upper frequencies fed to the subwoofer. Smaller enclosures improve power handling.

3) every vehicle impacts what a given sub or enclosure does in a slightly different manner than the next vehicle. Closed vehicles exhibit a phenomenon called transfer function which naturally boosts certain ranges of frequencies, and you can compensate for this by choosing different approaches in enclosure design, aiming, crossover points (where the sub's frequencies transition to those of your mids).

You can tailor the response of a subwoofer by manipulating enclosure size, enclosure type, tuning of the port (in ported applications), where it is placed in the vehicle, and how it is aimed. Every manipulation will have pros and cons, so finding the right type and size of enclosure for any given subwoofer is about striking the right series of compromises based on the exact sub you are using. The T/S Parameters of the sub will help you do this, if you have encyclopaedic knowledge of what each number means, or (like I do) feed those numbers into enclosure design software and have the program do it for you. You can then model how that sub should respond in a variety of different enclosure types and sizes and see on a graph what output looks like.

Some more examples for you-

1) a typical 6.5" midrange/midbass type speaker dropped into a door panel will usually not play very low and will distort easily when fed lower frequencies towards the bottom of its suggested range of frequencies. A high pass filter on an amp or head unit will control this and roll those frequencies off to keep the sound you hear clean.

2) the same typical 6.5" midrange/midbass type speaker dropped into a door that has been sealed up, deadened to better approximate a proper cabinet will play lower and cleaner down low than a speaker that was simply dropped into factory locations, usually making the point the speaker will start to break up and distort happen at a lower frequency. This allows you to use a lower high pass filter point on your amp or head unit and give you better midbass response (where much of the "attack" part of the lower midbass/upper sub bass frequencies lie).

All the information you could ask for regarding T/S Parameters:

https://en.wikipedia.org/wiki/Thiele/Small_parameters

http://www.caraudioforum.com/showthread.php?t=249337

http://www.caraudioforum.com/showthread.php?t=249411

If you have problems you are trying to iron out in your system, a better approach might be to try to tell us what they are and where in the frequency response spectrum they lie rather than asking for detailed answers to questions that may or may not have anything to do with your system's problems. Downloading some test tones and sine sweeps, burning them to disk and playing them on your system (carefully) might narrow down what frequencies are problematic:

http://www.realmofexcursion.com/downloads.htm
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Old 01-12-2018, 11:27 AM   #17
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Quote:
Originally Posted by SPL_Krayzie112 View Post
So what's the meaningful difference between damping factor and Q factor since they can be used in the same sentence?

Damping factor is a parameter in home audio equipments. How come HUs cannot be measured relatively so?

I take it off the bat it's the Q Factor I'm looking for. What dictates the cushioness or flatness of a driver's response, am I right?

I'm looking for the term that suggests a driver's capability to create aural response in the low frequency area or imaging in the high frequency area. Basically smooth roll-off or fast attack.
I wouldn't use damping factor and q factor in the same sentence unless that sentence was to explain the differences in damping and q factor.

Damping factor isn't measured on HUs because HUs aren't used to drive big woofers/subwoofers. If you're really concerned about a HU's damping factor, you can contact the manufacture and see if they know the output impedance of the HU and then do the calculation for yourself.

I'm not sure what you mean by "aural response" since aural means "relating to the ear or the sense of hearing." Imaging in the high frequency area isn't determined by a driver or amplifier specs - imaging is determined by where you place the drivers and how you aim them and how the sound is reflected/affected on the way to your ears. Phase and time delay would also affect imaging. Imagining is a function of the install.

A smooth roll-off is also a function of your install. If you have a peaky ported enclosure, then you won't have smooth roll off on the low end. Some drivers will have better/faster attack than others. Usually it's the drivers with lighter cones than give you that faster attack, low Le also helps. Dan Wiggins of Adire Audio fame wrote a good white paper on Le and woofer speed. IMHO, Dan is only half right. In the subwoofer realm smaller lighter drivers DO tend to sound faster. Dan points out the ability of the driver to change directions is a function of Le and BL, not the size or weight of the cone, so I believe it's just the lack of low end that makes the smaller drivers sound faster. IOW, a 10" driver would have a higher F3 than a 15" driver. If we were to equalize the 10" driver so that it had a similar f3 to the 15" driver, then I suspect a lot of that "faster" sound would disappear.

http://web.archive.org/web/200404032...ofer_speed.htm

Last edited by Jimi77; 01-12-2018 at 03:12 PM.
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Old 01-12-2018, 03:03 PM   #18
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Also a lot of times "attack" can be related to cone material. Stiffer materials tend to provide better attack than well damped materials (paper and poly). You can see this in a CSD/waterfall plot, but that's not something that the manufactures make available to the public. Zaph Audio has CSD plots for a lot of midbass, midrange and tweeters, but you have to be able to read 3 dimensional graphs and know what you're looking for and what you're willing to sacrifice to achieve "attack." Some of that "attacking" sound be achieved thru effective equalization.

For example, in my quest to find a midbass driver that had really good attack with the snare drums, I ended up with Focal Utopia midbass drivers and it did have great attack and fast decay; the snare drums never sounded snappier. However, after extended listening, I noticed the Focals lacked "fatness" with the bass guitar - I suspect the decay was too fast. So when it came to reproducing snares, the Focal Utopia with it's stiff W cone material was the clear winner, but when it came to bass guitar I had several paper and poly cones that sounded better (to my ear). In theory, a perfect driver would have 0 decay and therefore there should be no such thing as decaying too fast, however in practice a speaker can decay too fast in some instances. And then there is the matter of the subjective nature of listening, while I thought the Focals lacked "fatness" or presence with bass guitars, others might say that Focals brought a higher level of clarity and detail to the bass guitars than other drivers.
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Old 01-13-2018, 04:08 AM   #19
SPL_Krayzie112

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So if I want to listen to an accurate reproduction of speech (not "a speech"), the damping factor should be a high or a low number?
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Old 01-13-2018, 04:30 AM   #20
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Quote:
Originally Posted by SPL_Krayzie112 View Post
So if I want to listen to an accurate reproduction of speech (not "a speech"), the damping factor should be a high or a low number?
An AM radio powering a paper coned speaker will do a reasonable job of that...no extreme damping factor required.
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Old 01-13-2018, 04:52 AM   #21
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Like I said, I'm not planning to listen to a speech. If I were to subjectively calibrate my audio setup's sound using speech, will I want a high damping factor number or low damping factor number?
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Old 01-13-2018, 05:13 AM   #22
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Quote:
Originally Posted by SPL_Krayzie112 View Post
Like I said, I'm not planning to listen to a speech. If I were to subjectively calibrate my audio setup's sound using speech, will I want a high damping factor number or low damping factor number?
Damping factor doesn't really apply to the midrange, it's really a spec we look at with low frequency drivers. The only time I use speech to calibrate an audio system is the "in-phase, out-of-phase" track on tuning CD. Generally, I'm not concerned about what the sub is doing when I do that part of the calibration - as a matter of fact I usually turn the sub off for that portion of the tuning process.

I guess (hypothetically) lower damping factor would give you more "arual presence" around the driver's FS. OTOH, usually people want a higher damping factor or lower amplifier output impedance because that means greater cone control around the driver's FS. So I guess if I wanted a lot of presence on the low end, I'd probably go for a lower damping factor and if I wanted the low end to be as tight as possible, I'd opt for higher damping factor. In the end, I think the subwoofer, enclosure and other install factors will have a much bigger impact on how your low end sounds than the amplifier's damping factor, which is an inherently inaccurate spec anyways.
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Old 01-13-2018, 05:20 AM   #23
basicxj

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Quote:
Originally Posted by SPL_Krayzie112 View Post
Like I said, I'm not planning to listen to a speech. If I were to subjectively calibrate my audio setup's sound using speech, will I want a high damping factor number or low damping factor number?
About the only time you'd shoot for an amplifier with low damping factor would be incidentally, when you are limited by extreme budget constraints and buying rock bottom gear in terms of price and quality.

The point was, speech is not challenging to reproduce, so damping factor of an amplifier will not be playing into it.
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Old 01-13-2018, 05:33 AM   #24
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So I guess to make the long story, damping is the cone control factor. If I want the diaphragm to move faster, I'll want a high damping factor number?

I'm not quite sure why damping factor would only be limited to within subwoofer topics, quite frankly I'd opt for an relative/equal measurement of higher frequency drivers' damping factor.
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Old 01-13-2018, 08:04 AM   #25
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Quote:
Originally Posted by basicxj View Post
About the only time you'd shoot for an amplifier with low damping factor would be incidentally, when you are limited by extreme budget constraints and buying rock bottom gear in terms of price and quality.

The point was, speech is not challenging to reproduce, so damping factor of an amplifier will not be playing into it.
Basicxj thank you and Jimi77 for the CEA info. And the headroom you talked about is it necessary or can I evenly match my amp with my speakers(EXAM. NVX JAD1200.1 and four 2ohm subs at 300rms each)?
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Old 01-13-2018, 09:04 AM   #26
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Quote:
Originally Posted by Tony Reed View Post
Basicxj thank you and Jimi77 for the CEA info. And the headroom you talked about is it necessary or can I evenly match my amp with my speakers(EXAM. NVX JAD1200.1 and four 2ohm subs at 300rms each)?
IMHO headroom is nice but not necessary.
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Old 01-13-2018, 09:44 AM   #27
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Quote:
Originally Posted by SPL_Krayzie112 View Post
So I guess to make the long story, damping is the cone control factor. If I want the diaphragm to move faster, I'll want a high damping factor number?

I'm not quite sure why damping factor would only be limited to within subwoofer topics, quite frankly I'd opt for an relative/equal measurement of higher frequency drivers' damping factor.
There are two ways to make the cone move faster. First would be to increase power. If you increase output by 3db, the cone moves twice as far and therefore twice as fast at any given frequency. The other method would be increase the frequency being played, double the frequency and the driver would have to move twice as fast at any given input power. An amp with a high damping factor does not move the cone any faster or slower.

The reason damping factor is only considered for low frequency drivers is because it's easy for the amp to control cone movement in mid/high frequency drivers because there is less back EMF because of the smaller motor, the lighter cones and drivers aren't required to move as far. Manufactures don't even do damping factor calculations for high frequencies; usually if/when they list the frequency they calculated at you'll see it's in the subbass realm.

Why the sudden interest in damping factor? There is no magic spec that's going to make one amp sound better than another. On top of that (as I said before), at FS the any amp is going have a damping factor that goes thru roof. It isn't uncommon for a sub's load to increase 5-10 fold at FS, which means the amplifier's damping factor at that frequency also increases 5-10 fold. People who are into exotic amp designs will tell you a damping factor of ~10 is plenty. Some people say >50 is fine and others go with >100. In car audio we use solid state designs that have high damping factor (usually 100+) and in real world use, you can expect the damping factor at FS to at least twice the rated number if not 10x. One thing most people agree on when it comes to damping factor is that it isn't a very important spec and that as DF increases, it's impact becomes less an less.

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Old 01-13-2018, 09:50 AM   #28
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If you just have to have the highest damping factor possible, then run 8 ohm midbass and tweeters and run your subwoofer system at 4 ohms instead of 1 ohm. This will double your damping factor for mid & tweet and quadruple your damping factor for the sub. With the right amp and sub combo you might be able to get your damping factor into the 10k range at FS.

In the real world, the Alpine PDX-V9 is pretty comparable to the JL HD 900/5 (similar power output, similar designs). The Alpine's damping factor is >1000 vs >400 for the JL - I think you'd be highly challenged to tell the difference.

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Old 01-13-2018, 10:20 AM   #29
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Quote:
Originally Posted by Jimi77 View Post
If you just have to have the highest damping factor possible, then run 8 ohm midbass and tweeters and run your subwoofer system at 4 ohms instead of 1 ohm. This will double your damping factor for mid & tweet and quadruple your damping factor for the sub. With the right amp and sub combo you might be able to get your damping factor into the 10k range at FS.

In the real world, the Alpine PDX-V9 is pretty comparable to the JL HD 900/5 (similar power output, similar designs). The Alpine's damping factor is >1000 vs >400 for the JL - I think you'd be highly challenged to tell the difference.
thanks Jimi77
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Old 01-13-2018, 03:29 PM   #30
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Quote:
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thanks Jimi77
Keep in mind headroom can be a dangerous thing. While ample headroom guarantees you'll avoid clipping, it also means it's that much easier to over power your drivers and smoke them.
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