Elemental Designs 13Av.2 Subwoofer ??

[bose301s 5,000+ posts]

You should head over to ecoustics where they can tell what grade of magnet you use based on videos to prove output. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

I love being into audio, it may be the only topic on earth more divisive than politics or religion, lol.

 

[Electrodynamic 10+ year member]

And has been pointed out, Klippel through testing has found that the single most important parameter to a driver is a low and linear Le curve.

Well, I don't think Klippel goes so far. A low and linear Le curve is good, but if you have a nonlinear BL or Cms curve, you're still going to have suckage. You want ALL your parameters that change with power, position, or both to be as linear as possible.

And the "low" part of inductance is that it should be as low as needed for the intended application - there is little point pushing a sub-300 Hz driver

(4 Ohm) to an inductance well below 0.4 mH. You won't gain anything in the bandwidth/application of the driver. Now, if that same driver needs output to 600-800 Hz or more (say, you're using a first order crossover), then a lower inductance would be fine. But getting below a certain point gets you into the "diminishing returns" area.

You need all three - BL, Cms, and Le - to be linear over stroke and power to make a low distortion/highly accurate speaker. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bose301s 5,000+ posts]

Well, I don't think Klippel goes so far. A low and linear Le curve is good, but if you have a nonlinear BL or Cms curve, you're still going to have suckage. You want ALL your parameters that change with power, position, or both to be as linear as possible.
And the "low" part of inductance is that it should be as low as needed for the intended application - there is little point pushing a sub-300 Hz driver

(4 Ohm) to an inductance well below 0.4 mH. You won't gain anything in the bandwidth/application of the driver. Now, if that same driver needs output to 600-800 Hz or more (say, you're using a first order crossover), then a lower inductance would be fine. But getting below a certain point gets you into the "diminishing returns" area.

You need all three - BL, Cms, and Le - to be linear over stroke and power to make a low distortion/highly accurate speaker. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Yes, true. It also helps to fix the flux in a permanent location to keep flux modulation at bay as well aka. keep the flux fixed in place in the gap.. They are all good things //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

This poster from Klippel is a good read for everyone.

http://www.klippel.de/download/Nonlin/Klippel_nonlinearity_poster.jpg

 

[ciaonzo 5,000+ posts]

I didn't have that one, thanks. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[NDMstang65 10+ year member]

It depends on a lot of things, not just the bandwidth, but the power and the amount of change in the system.

So if power is a consideration, shouldn’t things be overbuilt? Why rate a very short 4 layer coil at a point where it is about to fail, instead of including wiggle room for the end user to be foolish?

In terms of bandwidth, classical/traditional crossover filter theory suggests a self-inductance F3 at least one octave above your bandwidth of interest. For a 3.5 Ohm DCR at 100 Hz, that would be 2.75 mH. Ideally you should have an inductance lower than that, and many long voice coil drivers are considerably higher (see our old Mag’s, Q’s, etc).

4ohm coil, Inductance at 6, 4, and 2 millihenries respectively. Note the red arrow where your inductance is starting to become an issue and causing your impedance rise starting to cause your response roll off. According to your math that is not possible, but according to that plot you are still out of the frequency range that it matters in a subwoofer.

In terms of linearity versus stroke and power (both of which need to be considered, as inductance changes with both variables), Klippel suggests that inductance changes of more than 50% are audible issue, for any bandwidth system. Is it necessarily a bad sounding effect? Depends upon how accurate you like your audio reproduction. I used to think our v3 Mag’s sounded pretty darned good. But then I started using a Brahma instead of our Mag’s for HT duty and then I couldn’t get the v4 prototype out of my car for some odd reason.

Right, but there is a huge following of people who do not like a woofer that is ‘flat’, for extenuating circumstances that are outside of what may or may not be ‘right’ according to laws of perceived ‘SQ’ and that quest for a ‘ruler flat response’. If you grew up learning that Oreo’s are good with mustard and ketchup on them, that is what you are going to accept as good. When somebody dips them in milk…you look at them like they are weird. Many people describe it as dead, and lifeless; as it lacks the dynamic and the attack…of a ‘conventional’ straight gap long coil and/or a split coil. Which has always made me wonder, Split coil is essentially a backwards form of XBL^2 (Take the wire away from the metal instead of the metal away from the wire). Why does it sound so different? (It isn’t the inductance). To me it does not sound lifeless and/or dry/sterile. I’ve messed with many xbl^2 equipped woofers over the years, including the very first Brahma and XXX, along with a series of Koda’s and what not. As far as a woofer, my personal tastes are not with xbl^2. I feel that it would be FANTASTIC for a mid/tweet combo or even a 3 way setup to save on mounting depth especially. Many people (on here as well as other places) agree as well, as it is like putting ketchup on an Oreo to them. We all grew up learning that Oreo’s and Milk are amazing…not Oreo’s with ketchup/mustard.

I see very few people advocating greater nonlinearity and higher levels of distortion as the best way to achieve sound quality. If you are only looking for maximum output or power handling, then I agree concerns of inductance are moot. But then again, my drivers aren't intended for maximum output or power handling, but rather sound quality.

Not talking about non-linearity’s, just inductance right now. That’s what the spectral vibrometry machine is for //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif. But what happens when you are so concerned about one specific thing that you overlook the forest for the trees? You can’t expect to attempt to tailor to a group of people (mainly the internet market) and pray to whatever god you pray to and hope that know what they are doing. Low inductance is great, I applaud for that. But what are the drawbacks for getting hung up on it? Less thermal mass, less room for wiggle, and FAR less room for ‘oops’ on a volume knob, gain, or subsonic filter.

That's actually wrong; a drop of an octave requires FOUR times the stroke to maintain the same output. *edit* I now see this has been addressed already on the previous page.

Yes, I was mistaken. Regardless, at 60Hz and 7mm of excursion you must be at 28mm of excursion at 30Hz to have the same level of output…which only makes the discussion stronger.

But to the larger concern of stroke... Is your hypothetical 14mm suitable? For the vast majority of people, it is. Think about just 12 years ago - the highest stroke subwoofers on the market were lucky to reach 10mm, and there was no shortage of great sounding vehicles back then. Some vehicles which are still considered high-water marks used drivers with less than 10mm of stroke, let alone 14mm.

7” mid-woofer sitting beside me that does 12mm linear…within 2.2dBa +/- from 70-2500Hz…the days of no excursion are far over. Doesn’t seem to have an inductance issue either…

But again, it depends upon what you want to accomplish; if you just want the loudest thump-bucket out there, then go ahead and buy the biggest magnet, the biggest diameter, longest wind length voice coil and hit it with 3 kW and enjoy your 145+ dB.
If you're looking for quality sound at a more realistic listening level, then 14-20mm is more than adequate for your situation.

Oh contraire ***** cat. What about Infinite Baffle? Is that not an “SQ” application? Where excursion reigns supreme? If I recall there are quite a few people running IB installs…”SQ” related installs. Both Mobile and HT combined…2 of the cars that I know of using an IB woofer uses a fair bit more then 14mm of their woofer…but whatever, that point is moot at best.

And realize that for many people, a 60 pound driver that is 10" deep is un-usable for their application. Smaller, shallower, lower weight drivers that sound very accurate and work great to generate 125-130 dB SPL (which is what you can get with a 12" woofer moving about 13-14mm one way). Albeit, this isn’t for everyone, but neither is a 27+mm monster that weighs 60+ lbs.

Who said it has to be 10” deep and weigh 60+ pounds? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I assume you mean
Cool. Plot the graphs of the true in-Car response from 15Hz-20kHz. Or should we just do an RTA? It will tell you everything that you need to know and see if/when you do run out of gas on the bottom end.

To generate an audible signal at 20 Hz, the Fletcher Munson curve and info tells us we need around 110 dB SPL to be perceived as "equally loud" as 85 dB at 1k Hz (which is quite loud – the 85 dB at 1k Hz, that is).

I’m not talking about something as being “apparently as loud” or something that is “perceived as loud” I’m talking about something that is as loud, better known as a “Flat” response that you keep speaking of. 110dBa is..110dBa regardless of frequency. That is flat. Not 85dBa @ 1kHz and 110dBa at 15Hz. That comment right there just shot holes in your entire ground that you are standing on. You just said according to Mr. Munson in order to perceive something as loud that it can not be flat. Perception, if I recall correctly, is the basis of all reality? Right? How you see, feel, and hear things? So it must be at 110dBa at 15Hz to be as "apparently as loud" as 85dBa at 1kHz? But isn't that not flat??

Given the 25-28 dB boost a typical car has at 20 Hz, we need a transducer that can generate 85 dB SPL at 20 Hz. A 12" piston only needs to move less than 10mm one way to do so. So how would a 14-16mm driver result in "inaudible" bass at 20 Hz? How would it not be capable of reproducing less than 35 Hz?

Isn’t something inaudible if you can’t hear it? Sub-20Hz frequencies…the human ear can not ‘hear’. We may be able to detect them by other means (or think we are hearing it from mechanical noise of other things flexing such as the cone or the spiders locking up) but we can’t hear it. I never said it would not be capable of reproducing less than 35Hz. I said it will roll off very quickly on the south end if you do not have enough coil there to make the thing move. Which is why I referred to 100dBa at 60Hz, and 100dBa at 30Hz. Whether you are at 7mm of xmax at 60Hz you must now be at 28mm of xmax at 30Hz to be at the same 100dBa level. (Change the level of output to whatever you want, the law of science still stays the same and still applies, if you run out of coil, you run out of excursion, and you run out of your “flat” response that you are aiming for)

It doesn't. It may not win you SPL competitions, but for a wide section of the market, it's more than useful. Be careful to not project your own desires upon the entire car audio crowd; it may not work for your situation, but I bet that there is little that Scott Buwalda and Alan Dante would agree on in what a subwoofer needs, but both would be 100% correct for their own applications.

As a matter of fact ask Mr. Budwala what woofer he is running…I bet it is quite the contrary as to what you perceive as being a “SQ” based woofer. (Pssst. It has HORRIBLE inductance..and it rolls off TERRIBLY…and ya know what? It has a straight gap, and a very long coil…and seems to won him a sound quality title, or two if I remember correctly)

[/QUOTE][/QUOTE]

 

[NDMstang65 10+ year member]

As is stroke, which you are hitting. Here's the deal, though - if you're going after sound quality, then inductance is ALL the pepperoni. Stroke is just one piece of onion, and power handling is a small piece of sausage.

Note the graph at the very beginning…your pepperoni is spoiled by 2 cars and a few world titles where it seemed to sound pretty dang good to those fine gentleman that judged them and that own them as well. Maybe one day the world will be changed…a very low inductance subwoofer will be in everybody’s hearts and desires. But, for the vast majority, they do not know what it is, nor do they care. They just listen and live for music…as they always have. Regardless if something is ‘right’ or not by your definition.

Thank you, and good night.

 

[bose301s 5,000+ posts]

So if power is a consideration, shouldn’t things be overbuilt? Why rate a very short 4 layer coil at a point where it is about to fail, instead of including wiggle room for the end user to be foolish?

4ohm coil, Inductance at 6, 4, and 2 millihenries respectively. Note the red arrow where your inductance is starting to become an issue and causing your impedance rise starting to cause your response roll off. According to your math that is not possible, but according to that plot you are still out of the frequency range that it matters in a subwoofer.

Right, but there is a huge following of people who do not like a woofer that is ‘flat’, for extenuating circumstances that are outside of what may or may not be ‘right’ according to laws of perceived ‘SQ’ and that quest for a ‘ruler flat response’. If you grew up learning that Oreo’s are good with mustard and ketchup on them, that is what you are going to accept as good. When somebody dips them in milk…you look at them like they are weird. Many people describe it as dead, and lifeless; as it lacks the dynamic and the attack…of a ‘conventional’ straight gap long coil and/or a split coil. Which has always made me wonder, Split coil is essentially a backwards form of XBL^2 (Take the wire away from the metal instead of the metal away from the wire). Why does it sound so different? (It isn’t the inductance). To me it does not sound lifeless and/or dry/sterile. I’ve messed with many xbl^2 equipped woofers over the years, including the very first Brahma and XXX, along with a series of Koda’s and what not. As far as a woofer, my personal tastes are not with xbl^2. I feel that it would be FANTASTIC for a mid/tweet combo or even a 3 way setup to save on mounting depth especially. Many people (on here as well as other places) agree as well, as it is like putting ketchup on an Oreo to them. We all grew up learning that Oreo’s and Milk are amazing…not Oreo’s with ketchup/mustard.

Not talking about non-linearity’s, just inductance right now. That’s what the spectral vibrometry machine is for //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif. But what happens when you are so concerned about one specific thing that you overlook the forest for the trees? You can’t expect to attempt to tailor to a group of people (mainly the internet market) and pray to whatever god you pray to and hope that know what they are doing. Low inductance is great, I applaud for that. But what are the drawbacks for getting hung up on it? Less thermal mass, less room for wiggle, and FAR less room for ‘oops’ on a volume knob, gain, or subsonic filter.

Yes, I was mistaken. Regardless, at 60Hz and 7mm of excursion you must be at 28mm of excursion at 30Hz to have the same level of output…which only makes the discussion stronger.

7” mid-woofer sitting beside me that does 12mm linear…within 2.2dBa +/- from 70-2500Hz…the days of no excursion are far over. Doesn’t seem to have an inductance issue either…

Oh contraire ***** cat. What about Infinite Baffle? Is that not an “SQ” application? Where excursion reigns supreme? If I recall there are quite a few people running IB installs…”SQ” related installs. Both Mobile and HT combined…2 of the cars that I know of using an IB woofer uses a fair bit more then 14mm of their woofer…but whatever, that point is moot at best.

Who said it has to be 10” deep and weigh 60+ pounds? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Cool. Plot the graphs of the true in-Car response from 15Hz-20kHz. Or should we just do an RTA? It will tell you everything that you need to know and see if/when you do run out of gas on the bottom end.

I’m not talking about something as being “apparently as loud” or something that is “perceived as loud” I’m talking about something that is as loud, better known as a “Flat” response that you keep speaking of. 110dBa is..110dBa regardless of frequency. That is flat. Not 85dBa @ 1kHz and 110dBa at 15Hz.

Isn’t something inaudible if you can’t hear it? Sub-20Hz frequencies…the human ear can not ‘hear’. We may be able to detect them by other means (or think we are hearing it from mechanical noise of other things flexing such as the cone or the spiders locking up) but we can’t hear it. I never said it would not be capable of reproducing less than 35Hz. I said it will roll off very quickly on the south end if you do not have enough coil there to make the thing move. Which is why I referred to 100dBa at 60Hz, and 100dBa at 30Hz. Whether you are at 7mm of xmax at 60Hz you must now be at 28mm of xmax at 30Hz to be at the same 100dBa level. (Change the level of output to whatever you want, the law of science still stays the same and still applies, if you run out of coil, you run out of excursion, and you run out of your “flat” response that you are aiming for)

As a matter of fact ask Mr. Budwala what woofer he is running…I bet it is quite the contrary as to what you perceive as being a “SQ” based woofer. (Pssst. It has HORRIBLE inductance..and it rolls off TERRIBLY…and ya know what? It has a straight gap, and a very long coil…and seems to won him a sound quality title, or two if I remember correctly)

There are woofers out there that destroy your argument fully. Look at AE Speakers line of TD and AV woofers. They have 23 mm of Xmax one direction, 46 mm total obviously, and have inductance that is extremely low. They have enough stroke to keep up with your scenarios you keep bringing up as well as inductance much lower than most mid range drivers. Even without that much excursion I am perfectly happy with the level of output from my Mag from 20Hz to 100Hz and it sounds better than any driver I have heard before. Seriously, I would love for you 2 to just admit that there is more than 1 way to skin a cat, but I think you like arguing too much to do that, lol.

I definitely know where both of you are coming from and both approaches obviously work, just you two definitely believe your approach is the correct approach.

I do want to address the claims that the Mag coil can't handle what it is rated for. BS, I ran a test on a B stock Mag that Nick sent me using my Sundown 1000D which will do ~1200 watts. I ran the things full bore into a Mag on tones and bass music for 10 minutes and nothing, didn't cause any problems at all, no smoke, no burnt coil, no failure. The Mag coil is rated fine if you aren't running a 1500 watt amp to it.

 

[Michael Savage 10+ year member]

Where does the Funky Pup sit on the inductance spectrum? Wherever it lies should dictate the winner of this debate.

 

[bose301s 5,000+ posts]

Where does the Funky Pup sit on the inductance spectrum? Wherever it lies should dictate the winner of this debate.

I agree with this.

 

[NDMstang65 10+ year member]

There are woofers out there that destroy your argument fully. Look at AE Speakers line of TD and AV woofers. They have 23 mm of Xmax one direction, 46 mm total obviously, and have inductance that is extremely low. They have enough stroke to keep up with your scenarios you keep bringing up as well as inductance much lower than most mid range drivers. Even without that much excursion I am perfectly happy with the level of output from my Mag from 20Hz to 100Hz and it sounds better than any driver I have heard before. Seriously, I would love for you 2 to just admit that there is more than 1 way to skin a cat, but I think you like arguing too much to do that, lol.

I definitely know where both of you are coming from and both approaches obviously work, just you two definitely believe your approach is the correct approach.

I do want to address the claims that the Mag coil can't handle what it is rated for. BS, I ran a test on a B stock Mag that Nick sent me using my Sundown 1000D which will do ~1200 watts. I ran the things full bore into a Mag on tones and bass music for 10 minutes and nothing, didn't cause any problems at all, no smoke, no burnt coil, no failure. The Mag coil is rated fine if you aren't running a 1500 watt amp to it.

Can do a 2 layer split coil that has virtually no inductance and tons of excursion...23mm is weak for a split coil design..why not talk in terms of..2..3..4 inches..linear? With

There are 9 ways to skin a cat, as it has 9 lives.

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[bose301s 5,000+ posts]

Can do a 2 layer split coil that has virtually no inductance and tons of excursion...23mm is weak for a split coil design..why not talk in terms of..2..3..4 inches..linear? With
There are 9 ways to skin a cat, as it has 9 lives.

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Haha, I know. But from looking and hearing people who have tested them take, even the new XXX, which can have huge amounts of excursion, is severely limited by its suspension design, also get that split coil to less than .3 mH and we will talk though. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[NDMstang65 10+ year member]

I do want to address the claims that the Mag coil can't handle what it is rated for. BS, I ran a test on a B stock Mag that Nick sent me using my Sundown 1000D which will do ~1200 watts. I ran the things full bore into a Mag on tones and bass music for 10 minutes and nothing, didn't cause any problems at all, no smoke, no burnt coil, no failure. The Mag coil is rated fine if you aren't running a 1500 watt amp to it.

Never once made a comment about that.

I said, a short, 4 layer coil. Will not take as much power as a long, 4 layer coil.

Therefore it will burn, before the longer one will.

 

[NDMstang65 10+ year member]

Haha, I know. Now get that split coil to less than .3 mH and we will talk though. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

No problem chief. Daddy can do that all day, every day.

 

[bose301s 5,000+ posts]

Never once made a comment about that.
I said, a short, 4 layer coil. Will not take as much power as a long, 4 layer coil.

Therefore it will burn, before the longer one will.

Obviously, but if it can take rated power and more why build it to handle 3kw when you don't need or want it to?

 

[bose301s 5,000+ posts]

No problem chief. Daddy can do that all day, every day.

Ok, good, but I have yet to see an actual design do so.