Hi people!

Was spending a little time doing to extra audio research, and when checking out the madisound website I found this interesting contraption.

It's a Fostex driver which has a claimed frequency repsonse from 30hz - 20khz - I just had to check the response graph on this one and interestingly it looks like their claims aren't too absurd at all.

Looking at the graph it seems to realistically play up to 20khz without significantly dropping off, and looks to be down by only about 2dB at 60hz.

Even more interesting is that it actually seems to be ALMOST usable at 30hz, being 'only' about 6dB-7dB down. Defiantely a significant drop, but given the nature of the driver it's pretty dam impressive.

Has anyone actually heard one of these drivers at all?

My instinct is telling me this just can't be right, is there something I'm missing? Is this potentially the 'ultimate' 1-way front stage right here?

Here is a link to the driver page:
http://www.madisound.com/catalog/product_i...products_id=265

And a link to the driver specs:
http://www.madisound.com/catalog/PDF/fostexdrivers/f200a.pdf

At just under $800 a pair these drivers would actualy be pretty good value if they can come even close to achieving what they claim.

boyd(total recoil, melbourne) makes fullrange 8" , i have listened to his home audio 8" at my mates joint, i thought there was a tweeter but there wasnt, he also does a 8" car model that comes with a tweeter, the tweet has a passive crossover but the 8" runs fullrange.I could runa set in my van but havent got that far cause i like the complications associated with 3ways ....cors

Speakers are a compromise.
If you dont mind i driver with an underdamped cone playing through its breakup nodes, and dont mind fitting a rear horn loaded enclosure in your car to get lower end (as these sorts of full range drivers need large enclosures to help lower end) then sure, it can play full range.

That thing looks revolting at anything above 1.5k, and good luck trying to mount it on axis.

If you use -3dB as a reference point, like you should, its response isn't anything more then 100-2.5k. Basically a really good midwoofer, not much more. Also, with an Xmax of 2.0mm, Id be very surprised if you can even hear it at 30Hz without some serious waveguides.

The Legatia 4 IMO far surpasses that unit for full-range response.

i'm with matt, that response graph looks horrid. the driver may be able to play full-range, but would require extensive eq along with a large enclosure

Are you guys looking at the same graph?

From what I can see the response curve suggests the driver is down only by about 2dB at 60hz (3dB at the most) and on axis it seems to remain within 2dB up until about 3khz where the it begins to rise heavilly.

So from what I see that equates to a resposne of +/- 2dB from 60hz-3khz which would be far better then any other driver i've ever seen before.

Sure there is a nasty impedance peak at around 30hz, and distortion levels may be potentially horrid (although there is no way or knowing this based on the information provided)... but aside from those potential issues it seems to have low end performance of a 10", with an upper mid-range response to rival a 4" dedicated midrange.

The curve itself seems pretty flat, and within that 60-3k regioin id doesn't seem to ever exceed about 3dB in either direction.

I've been looking at the response curves of a lot of high end mids from some of the best manufactureres (scanspeak, seas, etc) and that response is flatter then most I've seen.

The excursion though as you say, would be a potiential issue.

What I'm interested in is how that could develop a speaker to be this linear? 8" drivers will typically do not a whole lot above 1khz, and many will still struggle to play flat below 100hz, so how could they (on paper) seem to overcome the laws of physics?

Normally I'd assume some type of inbuilt EQ, but is this even possible on a speaker?

Just for comparison, here is the spec sheet for some high end 8" audio drivers.

Scanspeak 8" Revelator:
http://www.madisound.com/catalog/PDF/scans...2w_8851tpdf.pdf

Seas 8" Excel:
http://www.madisound.com/catalog/PDF/e0045.pdf

Eton 8" Hexacone:
http://www.madisound.com/catalog/PDF/eton/8-472.pdf

Morel 8" MW267:
http://www.madisound.com/catalog/PDF/morel/mw267.pdf

Dynaudio MW172:
http://www.dynaudio.de/eng/auto/esotec/tech_mw172.htm

None of these seems to match the overall flatness or usable frequency range of the Foxtex driver.

i never look at graphs , what a waste of life.
just buy it and change the whole dynamics when u install it..........cors

this is why i love you corey,

your a doer, not a look at my grapher...

i do believe i am looking at the correct graph, and i stand by my statement
on paper, it does not resemble a great 8" full-range driver

Click to view attachment

The graph above has also been "smoothed" and would be even more raggedy IRL.

You would also be very surprised to see that most speakers in car will not perform "flat" (+/-3db) throughout their frequency range anyway naturally.

With all due respect, that's one the most flawed concepts I've ever heard. It's like buying a second hand car and saying "dont worry about inspecting it, if it looks good just buy it and then fix problems if / as they come up". Wouldn't it make more sense to get someone with an understanding of mechanics to tell you first whether it's a good car, or a explosion waiting to happen?

Graphs show you a close approximation of the natural frequency response of a driver.

The closest you can get to checking this in the real world (without buying the speaker) is to listen to the speaker in another person's car and measure it with an RTA - which 80%-90% of people don't have access to.

The other option of just buying the speaker that sounds ok to you and then trying to fix it with tuning is severely flawed... what's to say that the driver's installation in that car with have any likeliness to how it will perform in your car? There may be different variaitions in installation, driver location, tuning (they may have EQ'ed the crap out of it to get it to sound good).

The entire idea of buying any speaker just for the sake of it, hoping it's accurate, and then tuning the heck out of it if it isn't, is a highly flawed approach that will limit the potential of any system from the get go.

A good look at a frequency response graph of drivers before purchasing them will give you a good indication of the realistic lmitations of each driver, and give a better idea of what drivers will match well with what other driver.

For example, what's the point of running a two way setup if your mid-bass is only usable up to 1.5khz, and your tweeters are only realitically usable down to 3khz? You end up with the region of 1.5khz-3khz sounding like rubbish, with a significan't hole in between, and high levels of distortion because either your mid or tweeter is struggling to play a frequencies it simply can't handle.

Even in a three way setup, many 4" cone midranges will only play to about 2.5khz, and some will struggle to even reach that. Even many large format dome tweeters fail to play down to 2.5khz within 2dB and so again you have a potential gap.

In the real world any such gap (even a small one) will bring your down down significantly.

Also, Why buy a speaker that has a harsh frequency response curve (large peaks/troughs)? It will require all of the EQ you have available just to take out the large imperfections.

That's before you even get started on trying to deal with the extra peaks, boosts, cancellations and resonances that pop up in a car environment.

By going with drivers that have smooth, relatively linear, and well matching frequency responses from the get go you can achieve 80% of your linearity using your crossovers and level adjustment - leaving most of your EQ free to deal with any small (<3dB) imperfections, and in car accoustic effects.

I think that's one of the biggest problems with a lot of systems - they are limted by the frequency response of the drivers themselves, and the users are stuck with the endless cycle of trying to tune in / out natural flaws that simply can't be removed. Not enough people do the right amount of homework when chosing their drivers.

I wasn't wise enough to do this type of research when I chose my own speakers, because back then I was too young and inexperienced to think about it. I'm just very lucky that after putting my car on an RTA, I can confirm that my driver responses quite good, and match up very well.

At least, that's how I think about it - go by what you know rather then by what your ears lead you to guess.



So you think a dyno graph for a car is useless then?

Many performance car enthusiasts would disagree

I wouldn't. Ive seen the response of my Dyns in car....

Muzz, its not just the flatness of the curve you should be worried about, even though it does look quite nasty at anything above 2kHz. Its also the impedance curve, because that determines how difficult a driver will behave will coupled with an amplifier.

You shouldn't compare it to any of those other drivers, because its not comparing apples with apples. That 8" is supposedly a full range driver, and those other units are not. I wouldn't play a single one of those units above 1kHz, and I wouldnt run this 8" above around 1.5.

Also, take note that although it may look like a linear gradient, the response curves dependent variable is a log scale, and even though all the major gridlines look evenly spaced, the minors are not. In fact, I would doubt very heavily if you'd be able to tell the difference between 1 decibel and 3 on a graph of that resolution.

Im not saying that a Response curve doesnt tell the person a story. Im saying that one tells me that speaker isnt a full range driver.

Also, that 'nasty' impedance bump is meant to be there. Thats its resonant frequency. All drivers have it.

were talking freq responce graphs champ, not dyno graphs,

didnt bother reading the rest as im already reading one novel and dont need another... ;D


talking about reality, reality is sound in car, reality is not sitting on the computer for hours inspecting graphs...


if the graphs are so accurate, then how can an 8 play down to 30 with 2mm of xmax??

graphs neve lie ey??

muz , i cant read your posts im sorry.
Of course its not flawed, hehe . You just use someones oppinion who has wasted their life looking at graphs.
Theoretically i have the knowledge and i didnt waste my life.
I could show u 100,000 example where u steal the knowledge from the grapher person...........cors

Its because its playing free air, and the response is around, 76-77db (20Hz). This is around 'chatting' level, or standard earplug level for an Ipod. You dont need heaps of xmax to do that sort of response. The speaker is not maxing out when performing those tests

If I was running that driver full range, it would have to be on axis. Which also means the speaker becomes VERY directional. Good luck trying to mount it for a good image

Oh, the Legatia 4 does around 8 octaves (100kHz-17kHz) too, if you're looking for a practical full range.

By all means, I know it won't play an entire frequency response accurately by any means.

All I'm trying to say is that it is an 8" driver, and priced similarly to other high quality 8" drivers. Compared to those other 8" drivers (claimed full range or not) they don't either:
1) Play as low as this driver
2) Play as high as this driver
3) Play as overall flat as this driver

In otherwords, based purely apon the graphs displayed, all I'm trying to say here is that this 'full range' driver does display a far superior frequency response to any 'normal' 8" driver.

Impedance control is definately an issue, and as is probably distortion (the likely result of a speaker playing frequencies outside of it's comfort zone).

As you guys are saying the response is far from perfect, but it's at least as good as i've seen on any other 4"-8" driver I've seen.

Looking at your notes on the graph:

1) You have listed a peak of 6db at ~3.5khz, drop of 3dB @ 12-14khz and general unevenness in between. If you take a look and the response curves for a lot of tweeters you'll find they won't be any better. In fact very, very few tweeters will perform within +/-2dB from 2khz - 20khz.

2) You listed a 10dB droppoff from 150hz to 30hz. Such a drop-off will be common (and usually far worse) in almost every driver up to 8" in size, and even in many 9" and 10" drivers.

3) Nice regoin between noted from 150hz - 2khz is extremely well controlled, and at least comparable to many of the very best drivers between 4" - 8".

So at the end of the day, what does this all mean?

The driver has a bottom end response comparable to a very good 8" mid-bass driver, a midrange response comparable to a very good 4" cone midrange, and a top end response comparable to a fairly typical 1" tweeter - and does so with a single driver.

In that regard, it really does achieve the claim of a 'full range driver' in my opinion... I'm more concerned with other potential issues, nor related to frequency response (phase, distortion, resonances, etc).

Go and ask any high end loudspeaker manufacturer how much time they spend during the R&D process measuring speakers (for more then just frequency response) as well as undergoing many mathematical computations regarding the speakers/boxes/environment they're to be placed in.

Trial and error is not a cheap way to learn. In car audio however, it is regarded as the easiest (maybe because people dont know how to measure/interperet the data?).

http://hybrid-audio.com/Legatia%20L4.pdf

http://hybrid-audio.com/Legatia%20L6.pdf

http://hybrid-audio.com/Legatia%20L8.pdf

Personally, the L8 doesnt look too good above 500Hz, buts its not designed to play up that high.

Have a look at the L4. Its quite a unique and very nice looking Frequency Response curve, and the impedance is good too. Plus, you can get the waterfall plots, impulse response and phase curves on request.

Actually no, a dyno isn't that much different to a frequency response graph at all. One measures power at different engine speeds, the other measures sound pressure at different frequencies. There's nothing stopping people from just getting into a car, pressing the accelerator, and using their 'senses' to guess-timate how much power a car has - yet the serious people still make use of dyno graphs and readouts.

Our senses can generally pick when there is a flaw in something, but our mind rarely has the ability to identify where it is, and the magnitude of it. Yet when we use electronic measurments to identify and fix problems, our senses immediately pick up that they are no longer there.

Electronics are there to measure, identify and fix flaws - our ears are just there to enjoy the result.


Correct, graphs don't lie - but they don't always tell the full story either. The rest of the story (as well as the answer to that question) is what I'm trying to figure out.

P.s.
Your 'real world, in car' ears claim that your 6.5" Polk drivers can play down to 50hz no problems - so why is it so hard for you to belive a graph that says an 8" can play down to 30hz?

Unless the Polk mids have significantly more then 10mm of xmax, that seems like a wee bit of a contradiction there...

Oh but wait a second... the fact that you own the Polks gives them a right to defy the laws of physics, doesn't it?

Oh, and please don't try to argue that your ears are more accurate then a graph. Lets take a 1dB peak at 400hz (around our ears most sensitive point) and see what is more likely to pick up that peak - an RTA or a person's ears. Remember, to oversimply it these graphs are essentially just printouts from an RTA.

I don't mean to sound like I'm having a go at your or anything, just realise there is more to car audio then just listening. Regardless of whether you are into SQ or SPL, thought and theoretical knowledge are also required for building a great audio system.

dont get off topic or ill close this one down .......cors

nice work zion, that was a fantastic call

Yeah, definately. I've actually found on-axis works the best for me. It's more sensitive to precision, but once you get it right it has far more potential to blow you away.

I've heard some nice sounding 'off axis' installations, but they have always sounded like they have always sounded dull and soulless. It seems that you just lose so much detail once you go off axis (if greater then 30 deg). and then most people try to EQ that that drop off back up - but it never brings back the detail. Adding EQ to the lowered regions just increased distortion and stress on the components and the result never seems to really sound natural.

I think a lot of on axis installations turn people off because they aren't tuned and installed with linearity in mind. An on-axis installation can really be stunningly ambient, detailed and well imaged yet beautifully refined if tuned correctly.


Back to the drivers, that legatia sounds interesting, I'll take a look at that


This whole thing actually came about when I was looking around to try to come up with a means to design the theoretically 'optimal' two way in car system.

A lot of people don't have the money, time or space to go with a fully active (or custom passive) three way setup and so 90% of people in the past have settled for the compromises of a two way system.

I've been working on trying to come up with a way in which people can get away with the convienience of a two way system, without the high degree of compromise in audio performance.

Have even been playing with the idea of building a two way setup using these concepts just to show people that in the real world, it is possible to have a great performing and relatively inexpensive two way system if you put thought into it.

My initial idea was to use a nice flat 5" driver (Scanspeaker 5" Revelator is the current pick) to play from 150hz to 1.5khz, then blend that in with a nice tweeter that can legitimately play flat down to 1.5khz (Seas Millenium is it at the moment). Next option would be a decent pair of 8" subs that can work well in small enclosures (Image Dynamics ID8, good down to 9L) to be mounted in the floor of the car, and play from 150hz down.

When I stumbled across this 'full range driver' it got me a little curious

Looking at (and understanding) graphs and specifications is knowledge. Listening to something in the real world is experience. Building a great system requires the use of both.

When a company designs a driver, do you think they just take a thousand different components and put them together in various different combinations until they get a sound they like?
- No, because it would cost them too much and take them too long.. and in the end they still may never get the combination they are looking for.

When someone outfits the audio in a movie cinema, do you think they just put any speakers in there, and then just keep changing the speakers and locations until it's right?
- No, because they can't afford mistakes - their audio engineers are being paid for their knowledge, not their ears.

When you ask a proper prefessional installer to build you a sub encosure, do they just take some MDF, and built the box to any dimensions as long as your sub fits into it?
- No, because it's more likely to be wrong then right.

Like it or not. in all of these situations, professionals make use of precise measurements and calculations to ensure things come out pretty much right from the start.. then after these measurements if things are still a little off, they made necessary adjustments.

A car audio system will generall come out the best if taken with the same approach. You need to know what you are aiming for from the start, and build a solid foundation by choose the right component for the job to begin with. If you start with products that are significantly flawed or don't match up well, then you are potentially creating yourself more problems then you can fix.

As for accuracy and reliablity of frequence response graphs, try this excercise.

Think about all of the speakers you can come up with (most notably, tweeters) that are known for being harsh (such as a lower range Focal tweeter) and then check out the frequency resposne graph - any money says the graph shows considerable peaks or drops in the frequency response.

Now think of a tweeter that is know for being very smooth and accurate...say a Dynaudio Esotar. Look at the graph for that, and you'll like find that the graph probably won't have many peaks or drops greater then about 2dB.

Believe it or not, a resposne graph does give a pretty good reflextion of how a speaker will sound, and if you think about it and plan thigns out well, can often design yourself a system that sounds great from the start with very little tuning.

In my own car, I only have a 5 band parametric EQ, and out of those 5 bands I'm only using three of them... that's because the response of the drivers is relatively smooth, so I can get most of my ballance right with just crossovers and gains. Then I can use the EQ and an RTA to take out any small (<2dB) variations and overall linearity is tuned by ear. In all honestly I didn't do enough reasearch before getting the speakers and so it's out of pure luck that they are as well ballanced as they are.

Driver response is even more critical in more typical factory passive setups, where EQ is the only tuning feature you have available and so you need to use it efficiently.

no, i dont want to read the graph.

seriously though , as ive explained in other threads , the amount of time i spend looking into a speaker i may aswell work at work and buy it . Dont think i buy speakers people put up links too either , i have my sources and im not telling which members you should trust for the free graph/spec info, but be sure that there are people that know about these things and in greater detail than me spending 5 years doing a degree.

Ill give u one real world example that denotes my theory>
Pro curciut racing header and muffler for pro championship racing (world championship).
I get the pipe from the pro curciut dude and he says yeah give ita go,then i install it and brrrrrp brrrrrp around the joint, then a pro comes allong and says yeah use that muffler size baffle cause our team spent 100 of hours testing it, u just need to lower the main jet needle to lean it out a little bit.
All done and i didnt even read the installation manual.This approach is used everywhere.
If u like reading graphs then its not a waste of your life...........cors

Completely understandable if you prefer to do things that way, some people prefer to take a hands on approach rather then thinking and planning things out - if it works for you then that's fine

I tend to read up a lot, and think alot. From combining technical knowlege and rational understanding, I build up my own theories and ides - then I jump into the car and test them.

80% of the time they work, and my car improves dramatically because of it. 20% of the time it has a negative effect or no effect and so I scratch it off the list.

Information defiantely doesn't replace real world experience and listening - it just compliments it.

I'd say probably about 75% of the improvements I've made to my car have come from some 'theoretical' idea I thought up and then decided to try.

The other 25% came from me just sitting there and going "hmm wonder what will happen if I change this setting to this..."

I do like to study too and i think alot.
Right now im planning on a idea to run plasma tweeters in the dash, the cancer causing radiation will be offset by a DD 15".
peace............cors

The response isn't bad on the Legatia 4" - it's not the flattest frequency response i've seen for a 4", but it's one of the broadest. Looks very much usable from 150hz-5khz, so using crossover points at 200hz and 4khz it should love it.

The 6 looks usable from about 80hz to about 1.5khz which is a bit above average for a 6"/7" driver. I've seen flatter responses, but it's still pretty good and seems to be mostly within +/-2dB from 100hz - 1.5khz. Defiantely better then most.

The 8 is only really usable from 40hz - 200hz which as you said, doesn't make it that useful as a mid-range but does make it quite good as a dedicated mid-bass in a three way front stage. Impedance peaks a little high, but nothing dramatic given it's intended use.

One those 4's combined with the 8's could prove to be a very impressive combination

Any idea of roughly the price point?

I love the Rainbow's, but one day I'll probably want to try something new just for the sake of experimentation.

I'm weird

I think a fair question is what is it that those graphs DON"T tell you?



Off axis response? This is reasonably important, as your unlikely to able to get on axis response from both drivers.

Power compression. Sure at one watt this just "peachy" , but at 20 watts, which is far more likely RMS, how does it look?

XMAX, as pointed out this is at one watt, how does it preform at the required volume.

Now this one is the "biggy". The vast majority of a drivers distortion is at the range of the BL curve, unlikely this plot is going to show you that.

Surround breakup, hardly show up at this level, show me 20 watts and we will see how well they have got this aspect right.

Cone modal distortion. This again is hard to read at one watt, however at 20 watts such events become painfully obvious. This is cone rigidity versus internal dampening.

Cone mass. Yes I can get my sub woofer up to 5 kHz no problem at all. Do I want to hear it? This is very important as it determines how well it follows the input, transient response.(There is a reason for tweeters)



Put it in a baffle at 20 watts RMS, then show me the RTA response (Preferably MLS).

Then we will discuss its usefulness.

That's more like what I wanted to hear

I have sifted through this thread, and there is some good ones, and some really stupid ones too.
In terms of a 8" playing full range, in a home audio application this is very possible,
the box can be tuned right quickly and easily, the speaker can always be easily on axis.

in the real world, it's niether practical or likely in a car,
the fact is cars don't allow speakers to just automatically play flat, just because they play flat in the test lab.
doesn't under any circumstances means they will play like that in a car.
I will agree a smoother freq response to start with, means less messing with in the long run however.

Almost every car I ever sat down to tune peaked between 300 and 1khz, then repeaked again at 2.5khz
no matter what speakers it had, $500 or $5000 speakers.

Running On Axis often increases this, but I would rather run on axis and Remove the peak by EQ, than run off axis and have to add EQ where there is a dip!

Some speaker systems produce massive peaks when installed, so those speakers we often prefer to install
off axis to try to soften the blow of the peaks, where other speakers that are smooth, tend to sound dull and muffled when mounted off axis.

I'm not really a big believer in the one speaker does all, idealistically it would be perfect.
but in the real world, Big Speakers playing low freqs can't play high freqs properly at the same time.
This is why we have different sized dedicated speakers,

Big Speakers can produce lower freqs easily, because they only have to make slow movements, and in doing so can shift alot of air to produce those low frequencys at a reasonable volume.

However to expect a big floppy heavy speaker cone to turn around and make 15 000 micro movements every second, while at the same time making 40 huge wavy floppy movements and not to distort the sound that those movements create when a reasonable volume load is placed is basically a stupid expectation.

YES it is possible for it to do it, can it do it cleanly with no distortion or colouration.. theoretically yes.. technically and physically.. err no.

This is why the larger speakers (8" or bigger) have better capability to play sub frequencys, but then often suffer when coming to the midrange type frequencys.
once you hit about 300-500hz the 8" speakers and bigger struggle to shift there heavy floppy cones quick enough.

This is why 3-4" speakers perform so well in that 300-3000hz range, because there lightweight stiff cones
can easily make those hundreds and thousands of micro movements every second without difficulty.

when it comes to higher freqencys like 3000hz or above, smaller drivers like 1"-2" tweeters and dome mids really can produce these freqs without distortion or colour, because they are so small making 10 000 micro movements each second isn't really such a big issue for a tiny 1" super stiff cone or dome.

it's a obvious conclusion for anyone to make that low freqs need a bigger movement from a speaker cone than do a higher freq.

my point is simply that, in theory any large speaker can attempt to play both low and high freqs at the same time, however when the volume goes up, the cone starts to get some pressure on it, it starts to flex and wobble and at that point in execution any type of sound quality in the mid to upper freqs goes straight out the window.
But the low frequencys tend to remain somewhat uneffected by this.

small speakers play high nice, big speakers play low nice.. at this point in time, thats the rule of thumb.
and no company has successfully proven otherwise for car use.

What a speaker can do at 1W and what it can do at 100W is always going to be 2 very different things.

Juls

How many times have I stressed this notion??????

Phil

Some well made points, and defiantely true that not many (if any) speakers will play close in a car.

I was lucky with my car to avoid the peaks you mention - my only natural issues are peaks at 800hz and 1.2khz, and a drop off above 15khz (all on axis). The tweeter's are essentialy flat from 2.5k - 14k which is pretty impressive - after 14k they begin to roll off, but this may well be due to the fact that about half of each tweeter is blocked by my dash.

Expected more issues with the mids, being metal cones - surprised to see that they don't seem to suffer any major cone breakup problems.

Cone breakup is a serious issue, while there are some gains to be made with cone material and composition, the main determiner is producing concentric modal lines radiating from the apex to the surround. It is the surround which decouples this to reduce termination (closed or open) to reflect the wave back again. Cone rigidity, internal dampening must be balanced against mass, as this is the main constituent for the transient response (Q aside), efficiency and of cause, the FS of the driver.



It is important to know the TS specification of a driver to analyse the usefulness in a given application. The SD and the xmax should give indications of the expected sound pressure level, the Fs and the impedance curve, the maximum possible bandwidth. The diameter of the cone should indicate the frequency of the off axis response considerations.



Like most "agreed specifications" they are designed to allow the "lowest common denominator" to compete on equal footing with the best. Possibly a salient example is the agreed testing frequency of 1000 Hz, even on rating a sub woofers efficiency.



I am unashamedly biased towards dedicated drivers for the best results, there may have been some reasonable postulation for conceiving "two way" networks because of the limited bandwidth and expense. Today there is no real reason to limit yourself with substandard inception.

LONG thread and lots to read. I got 1/2 before I decided to hit reply.

When did Xmax start having an effect on response?

IMO the graph provided is not real world testing. I does represent the best the driver can do. Sadly the best it can do is in an environment in which it would never be used.

Loudness versus frequency

BL curve versus frequency. (IE the major source of distortion if your operating close to, or over the limits)
At 2mm xmax on a 8" driver I believe your going to be there in a car.

didnt mean to upset you muzz, ill leave you to your graphs champ

Hey Juls, its not the speaker mass that corresponds to response times (quick or slow movements). Its the inductance of the coils. The lower the inductance, the faster the driver can respond to a change in direction. Also why low inductance style speakers can play quite high.

Moving mass plays a big part also!

If not why use Kevlar, aluminum and other light weight materials? You could make the coil, cone and former out of cheaper, heavier materials if low moving mass wasn't advantageous.

Phil

Here's a little quote I found about inductance,


"The importance of low inductance continues to impress upon me. I've written lots about transient response of subs, hopefully shedding some light on some bad info that floats around the web. But low inductance really is a very desirable parameter ... think of higher inductance (in concert with coil resistance) as a built-in low-pass filter ... with attendant magnitude and phase shifts ... which will limit the high-frequency extension of the sub, and can make for difficult times integrating with midbass drivers."

Low inductance, is one of the reasons why the JBL's WGti series subs sound so good (well to me and lots of others) is because, due to there unique motor design they have the inductance of the average 6"- 7" driver or in other words extremely low for a sub which allows for excellant transient response.

Luke

Very interesting and informative read.

http://www.adireaudio.com/Files/WooferSpeed.pdf

Moving Mass plays almost no part at all on woofer speed. Inductance vs Motor Strength plays almost all the 'parts'. Moving mass being responsible for the speed of a woofer is the one of the biggest audio myths of all time. This is of course, excluding damping characteristics of the system (inclusive of the box).

Material selections has more to do with stiffness, and the ability of the cone to resist surface flexing (forgot the technical term). With SQ, it prevents cone distortion. With SPL, it prevents the speaker from tearing itself apart.

Cone mass can affect the performance of a speaker at higher frequencies, where the difference in inductance is 3/5ths of f**k all, but with midbasses/subwoofers, unless you strap on a kilogram of lead (and even then its only affected if the BL is low) you wont have a problem. Certainly not between 50 grams and 65 grams.

So when you have an inch of throw and the cone is oscillating 80 times a second, the mass has no effect?

Low moving mass is advantageous!

Phil

The mass of the cone is the prime determiner of efficiency (This is the impedance mismatch, the cone mass versus the mass of air) it is also the “main” effect of FS.

The advantage of a larger cone is you gain SD (area), however mass is increased, with the “gain” of a lower FS. (More useable bandwidth). Using a larger motor increases inductance and therefore decreases bandwidth. While I agree at sub woofer frequencies a cone’s amass is less relevant to transient response, it still is important.

(Momentum = mass times velocity squared, and therefore velocity is the primary initiator)

Generally speaking,

Lighter cone = greater efficiency and therefore less energy (power amplifier), however it requires a larger volume enclosure and has a higher FS. (less useable bandwidth) This can be combated with a larger cone diameter, alas with the loss in and even larger enclosure.

Higher mass cone: smaller enclosure, less efficient, higher energy use (More power) and greater temperatures. Has a lower FS and therefore will play lower, but the higher the inductance, reduces the higher frequency roll off point.

My advice is to use the largest cone diameter that will allow you suitable off axis and frequency bandwidth that you can allow. The enclosure volume has to be considered, the larger the volume the more efficient the driver you can choose.

The idea that “sloppy” bass comes from larger cones may not be true, however the enclosure is the main contributor. ( The Q)

I hate full-range speakers.

They have nasty phase aberrations, and don't do highs or lows very well.

They are a good compromise, in that they have no crossover to be poorly designed, and some of the better ones are not complete poo. But again, I don't like them.

Don't worry, I have no problems with ya.

Just being a biatch

really, didnt notice!

sooooooo


ummm how does it sound?