>>>
>>>>I accept your concession.
>>>>
>>>>Thank you for finally understanding.
>>>
>>>You must be insane! What concession? Talk about diversion.
>>
>>
>>I made the assumption that you had conceded based on your
>>comment that the argument was over. If you haven't
>>conceded, we have only begun trying to help you understand.
>
>Oh, I understand. And I don't need your help. I know not
>what reason you are here.

I am here because you made an attempt at discrediting me. You just didn't expect me to find out which is understandable. I showed up and you went on the defensive. Unfortunately, you didn't allow yourself to learn and instead just reacted in whatever way you could.

>I guess you have an inferiority
>complex or something.

I am inferior to some of those on this thread in regards to audio knowledge. I would never attempt to go toe to toe against the likes of Dan Wiggins, DN, RC, Tracy, Geo and others. I'm not afraid to challenge them to explain something they say, but I'm not afraid to learn from them.

> You must need the support of others
>you look up to.

It's not really a matter of needing their support. I was merely trying to help others understand and hoping we could sway you from your stance, for the sake of the people reading your posts.

> But fact is, they and you, do not have a
>single standard. You all contradict yourselves and cannot
>produce relevant analogies.
>

I believe that we have had a common front. Underpowering will not kill a subwoofer. All of the posts about DF, Mms, fast vs slow, etc were attempts at explaining that they were not relevant to the conversation.


>You are well versed in PR, but that don't matter to me, I am
>an island. I do not seek the approval of others. I could
>not care less.

I'm surprised that you have succeeded in your endeavors. Did you disagree with your professors in college and dismiss their teachings like you have here? Or was there a time during your maturation where you had an open mind and were willing to learn?

BTW, why haven't you changed that password on that email? Afraid to read irrefutable proof that you are wrong? Or is there just no way to retrieve email on the Island?

 

[updated:LAST EDITED ON 01-13-03 AT 03:15 PM (EST)]>>Can't we discredit any of your industry tech papers as
>>merely marketing jargon by saying they are just trying to
>>sell larger amps? I would never do it, but it seems like
>>the kind of response you would use.
>
>Sure, if you can first PROVE THAT THEIR ARGUMENT IS BUNK!!!


Can I do this by first claiming that Power is the greatest factor, then headroom, and then Damping Factor, and then cone weight? Or do I just have to pick one argument?

One thing to consider is that most of the links you posted regarding underpowering were making the assumption that the amp would be driven into clipping. I suppose I am going to have to agree with them and question the wording used in their titles as underpowering wouldn't be appropriate in the case of clipping. I know it is the easiest way to explain it, but obviously, not everyone understands the content fully and is confused by the wording.

 

>I am here because you made an attempt at discrediting me.
>You just didn't expect me to find out which is
>understandable. I showed up and you went on the defensive.
>Unfortunately, you didn't allow yourself to learn and
>instead just reacted in whatever way you could.

I prudent man will always pass on an argument when he knows he is right. He doesn't seek to change the minds of others but is comfortable of his own. You could have just let it go. You didn't have to come challenge me. I tried to shy from the challenge by stating I did not want to get into this pissing contest with you. I don't care to change your mind. However, this does seem to be important to you.

>>I guess you have an inferiority
>>complex or something.
>
>I am inferior to some of those on this thread in regards to
>audio knowledge. I would never attempt to go toe to toe
>against the likes of Dan Wiggins, DN, RC, Tracy, Geo and
>others. I'm not afraid to challenge them to explain
>something they say, but I'm not afraid to learn from them.

All men are create equal, none should feel inferior that they need a flashy system to be respected, or be the editor of a flashy magazine. Names mean nothing to me. I don't care about Wiggins, RC, DN, or who...just sound logic and experience.


>> You must need the support of others
>>you look up to.
>
>It's not really a matter of needing their support. I was
>merely trying to help others understand and hoping we could
>sway you from your stance, for the sake of the people
>reading your posts.

Why do you care so much about what they believe, can't you find peace in yourself? If they aren't smart enough to catch on now, they will eventually.

>
>> But fact is, they and you, do not have a
>>single standard. You all contradict yourselves and cannot
>>produce relevant analogies.
>>
>
>I believe that we have had a common front. Underpowering
>will not kill a subwoofer. All of the posts about DF, Mms,
>fast vs slow, etc were attempts at explaining that they were
>not relevant to the conversation.
>

Buying an underpowered amp will increase the likelihood of destroying subs. Therefore it should be RC's, DN's and your recommendation to always buy a larger amp, which it is not currently, because that would mean you had been previously wrong.


>>You are well versed in PR, but that don't matter to me, I am
>>an island. I do not seek the approval of others. I could
>>not care less.
>
>I'm surprised that you have succeeded in your endeavors.
>Did you disagree with your professors in college and dismiss
>their teachings like you have here? Or was there a time
>during your maturation where you had an open mind and were
>willing to learn?

If it did not make sense, I would challenge them, yes. That was very rare, however, I did take a course in logic and one in philosophy, were it was the point of the class to challenge concepts.

>
>BTW, why haven't you changed that password on that email?

No one said to. No one said anything was there, I thought you gave up.

>Afraid to read irrefutable proof that you are wrong?

Why would I be? Of course, if I came back and said I didn't agree, then what would you say? I bet I know already. So, why does it even matter now.

>there just no way to retrieve email on the Island?

Don't read much do you?

 

Hi Randawg,

My name is Dan Wiggins. I'm the CEO and partner of Adire Audio. We're a high-end audio company located in Seattle, WA and have been in the audio business for 7 years. We started in advanced acoustics research and consulting, and over the last 4 years we've branched out into retail products as well. One of our many technologies that we've developed and license is in our Brahma woofers, the XBL2 motor, which set a world record in terms of linear excursion at 27.32mm one way.

My design partner is Dr. David Hyre. He earned his undergrad degree in physics, and his PhD in nuclear magnetoresonance spectroscopy, and has spent several years in advanced biochemistry where he worked on isolating and reversing the spin on individual electrons. This required use of extremely strong and precise magnetic fields, with gradients measured in the range of a few Teslas per millimeter.

Anyway, I see you have a few questions about our paper. Perhaps I can explain. I don't know what your background is (my is a BSEE, and 13 years of advanced SONAR system design prior to the last 7 in the audio acoustic range), so I'll try to keep things fairly simple. But if you need more thorough explanations, please let me know and we can flesh things out further.

- Underpowering destroys drivers. I believe Tracy (hi Tracy! Missed you at CES; I'm still here in LV, enjoying a bit of sun...) summed it up correctly: underpowering isn't a problem. Overpowering or overexcursion are.

A driver's excursion is a function of the current flowing in the motor AND the stiffness of the box behind it. A larger box means less current flow required (less power, since power is current squared times impedance) to reach a given excursion level. In fact, you can push just about any driver to full linear excursion with a couple hundred watts, depending upon the box and signal used.

Overexcursion is bad for a sub in two ways. The first is physical damage. You can snap tinsel leads, bottom the voice coil, wedge the voice coil on the top plate (if you walk it out the front of the gap; a common occurance with flux modulation effects), tear spiders, etc.

The second problem with overexcursion is reduced cooling. Over 90% of the heat dissipation in a driver comes from air movement in the motor, not conduction through the pole, top plate, etc. When you linearly scale air motion with power - like when a driver is still within it's linear range of motion - you're generally OK. But when you reach the suspension limits and keep increasing power, you get into trouble. It's like restricting the cooling air to the motor; akin to placing a restrictor plate in front of the radiator in your car. As you run with more and more motor output, heat builds up. And if you restrict the cooling - or hold it's level constant - you can't remove the heat as effectively, meaning a meltdown in imminent.

As far as damaging from underpowering, it really can't happen. It can happen if you CLIP the amp, but that's not from the amp being underpowered; it's from the amp generating even more power. Please see the eatel.net site for a VERY good description of the way the power envelope increases from a clipped signal. It's not the fact the amp is underpowered; it's the fact that you are increasing the power to the speakers, usually beyond it's rating.

- Mass affects transient response. Please investigate the works of Tom Danley, Dr. Floyd Toole, Dr. Wolfgang Klippel, Thiele, Small, Benson, Bullock, Geddes, and several others. They all make the complete conclusion that inductance is the primary limiter of frequency response, NOT mass. Mass can have a very small second-order effect (due to the way mass shows up as an inductive reactance in the electromechanical model), but it is often two orders of magnitude below that of the voice coil. Voice coil inductance is the limiter.

As far as the ability to infinitely slew current, you are of course correct about the speed of light. However, I guess I was not clear enough about the whole statement: IF you could slew the current at an infinite rate, then you would have infinite transient response. obviously you can't do that (I assume a certain level of education in the reader), but the point is still valid; what limits transient response is how fast you can change the current.

Transient response is a 3rd order function. It is the rate of change of acceleration; it is NOT acceleration itself. With the equation of BLi=ma, BL and m are both constants (when doing the time-based derivative). They will scale your results, but are not changing things in a time-dependent manner. That leaves i ~= (proportional) to a, so that to change a one must change i. That is, changes in acceleration - transient response - are proportional to changes in current.

What limits current flow in a time-dependent manner? Inductance. This is where the limit comes from. You can only slew the current through the inductance of the voice coil so fast; the lower the inductance, the faster you can change, and vice versa. In fact, if the current never changed, the acceleration would never change, and you would have zero transient response!

Mass and BL are scalars in the response system of the driver; they will change how much current is required to change the transient response of the driver. increasing mass will definitely mean you need more current to reach a given acceleration; however, it will not place an upper limit on how fast you can accelerate.

Likewise, BL is a scalar of transient response. The higher the BL, the faster you can accelerate for a given current. If you increase BL, you need less current to reach a given acceleration. But BL does not limit transient response itself.

For those who stop by our shop, I often do a demo to disabuse them of the notion that moving mass means slow response. I start with a Brahma 10, and run it through some healthy, 2" peak to peak excursion down around 15 Hz. Then I turn the power down, and start increasing the frequency. 50 Hz, 100 Hz, 200 Hz, 500 Hz, etc. until we reach 10 kHz, 11 kHz, and finally 13 kHz where it starts rolling off strongly. And this is for a driver with a moving mass of 160 grams.

As far as "audiophiles" using light cones, it's more a belief in the audio myth than for real reasons. I do work in the high-end market, and having just spent 4 days at the high end section of CES, I can assure you that voodoo and snake oil and lack of understanding about the fundamentals of physics are quite prevalent. Simply because of driver sounds a certain way does not mean that any theory applied to it is correct; often the description of the sound is correct but the wrong reasoning is applied, and thus the fundamental understanding of the technology is flawed. That is one reason why the audio field advances at a much slower rate than other high technology fields - many working in audio simply lack the training and knowledge to make correct correlations.

Thanks,

Dan Wiggins
Adire Audio

 

>Can I do this by first claiming that Power is the greatest
>factor, then headroom, and then Damping Factor, and then
>cone weight? Or do I just have to pick one argument?
>

Therefore, you have made my point. You guys have said clipping will produce considerable power indeed, even from a small amp. If you instead buy a larger amp and turn down the gain a bit, you effectively safeguard against clipping. Thus, the larger amp is safer to run the the smaller. Don't go down the path of changing your mind again, like geolemon and David Navone.

>One thing to consider is that most of the links you posted
>regarding underpowering were making the assumption that the
>amp would be driven into clipping.

Probably so, as a large driver needs more current, as the Admire guy said with that mass argument of his. BTW, I haven't heard a challenge to that yet. Is Einstein correct or is that name not big enough for you.

>I suppose I am going to
>have to agree with them

Good choice

>and question the wording used in
>their titles as underpowering wouldn't be appropriate in the
>case of clipping.

Well, you get the point though, just remember to buy as large of an amp as you can and set the gains right. Then no worries about damage and enjoy good sound.

>I know it is the easiest way to explain
>it, but obviously, not everyone understands the content
>fully and is confused by the wording.

Maybe so, would you like to spend your time telling me this or sending emails to them so they may correct this situation? It is your interest to serve the public, right?

 

Hey Dan!

Sorry I missed the show, and you as well. I have already heard reports back from the show, that it was a better turnout than last year.
I see there are new and exciting things to come once again from Adire...good job!
We appreciate you stopping in here, and showing your vast knowledge as well.

Hope to see you this summer at a show...have any plans so far to attend any?

If you can, when you get out of that vegas sun (:-) ) shoot me an email!

Good to hear from you, have a safe trip home.

Tracy Focht
Kicker Car Audio
www.kicker.com

 

>>I am here because you made an attempt at discrediting me.
>>You just didn't expect me to find out which is
>>understandable. I showed up and you went on the defensive.
>>Unfortunately, you didn't allow yourself to learn and
>>instead just reacted in whatever way you could.
>
>I prudent man will always pass on an argument when he knows
>he is right. He doesn't seek to change the minds of others
>but is comfortable of his own. You could have just let it
>go. You didn't have to come challenge me. I tried to shy
>from the challenge by stating I did not want to get into
>this pissing contest with you. I don't care to change your
>mind. However, this does seem to be important to you.

You are in a position of power because of your past experiences. I thought we went through this? If we were able to show you the light, the results would compound exponentially.


>
>>>I guess you have an inferiority
>>>complex or something.
>>
>>I am inferior to some of those on this thread in regards to
>>audio knowledge. I would never attempt to go toe to toe
>>against the likes of Dan Wiggins, DN, RC, Tracy, Geo and
>>others. I'm not afraid to challenge them to explain
>>something they say, but I'm not afraid to learn from them.
>
>All men are create equal, none should feel inferior that
>they need a flashy system to be respected, or be the editor
>of a flashy magazine. Names mean nothing to me. I don't
>care about Wiggins, RC, DN, or who...just sound logic and
>experience.

I am inferior only in terms of the level of knowledge in audio and I hope that through the years, I will increasingly come closer to their level. I feel no inferiority complex in any other respect.



>
>
>>> You must need the support of others
>>>you look up to.
>>
>>It's not really a matter of needing their support. I was
>>merely trying to help others understand and hoping we could
>>sway you from your stance, for the sake of the people
>>reading your posts.
>
>Why do you care so much about what they believe, can't you
>find peace in yourself? If they aren't smart enough to
>catch on now, they will eventually.

Are you referring to others spreading misinformation? If so, I feel that I have to at least make an attempt to educate those who are lacking in knowledge.


>
>>
>>> But fact is, they and you, do not have a
>>>single standard. You all contradict yourselves and cannot
>>>produce relevant analogies.
>>>
>>
>>I believe that we have had a common front. Underpowering
>>will not kill a subwoofer. All of the posts about DF, Mms,
>>fast vs slow, etc were attempts at explaining that they were
>>not relevant to the conversation.
>>
>
>Buying an underpowered amp will increase the likelihood of
>destroying subs. Therefore it should be RC's, DN's and your
>recommendation to always buy a larger amp, which it is not
>currently, because that would mean you had been previously
>wrong.

This is the core of the problem. Clipping is an issue of user error which we can never count on eliminating. What makes you think that a user who doesn't know how to set the gain on a small amp will know how to do it on larger amp? You can't which makes the larger amp more dangerous. Providing they understand all the aspects of power handling, both thermally and mechanically, I could safely recommend a larger amp, but on the same token I can just as easily recommend the smaller amp without increasing the risk of blowing a sub.

>
>
>>>You are well versed in PR, but that don't matter to me, I am
>>>an island. I do not seek the approval of others. I could
>>>not care less.
>>
>>I'm surprised that you have succeeded in your endeavors.
>>Did you disagree with your professors in college and dismiss
>>their teachings like you have here? Or was there a time
>>during your maturation where you had an open mind and were
>>willing to learn?
>
>If it did not make sense, I would challenge them, yes. That
>was very rare, however, I did take a course in logic and one
>in philosophy, were it was the point of the class to
>challenge concepts.
>

Logic and Philosophy were my favorite subjects. I am glad that you have also taken them.

>>
>>BTW, why haven't you changed that password on that email?
>
>No one said to. No one said anything was there, I thought
>you gave up.

In my response right after you questioned me posting the password, I stated that you could change the password if you felt more comfortable and left that decision up to you.
>
>>Afraid to read irrefutable proof that you are wrong?
>
>Why would I be? Of course, if I came back and said I didn't
>agree, then what would you say? I bet I know already. So,
>why does it even matter now.
>

I have no idea, I don't know how others think. If you still didn't agree, I would have to assume you are a lost cause and move on with my life at least knowing that I made an attempt to help.

>>there just no way to retrieve email on the Island?
>
>Don't read much do you?

I read quite often. You made the comment that you were an island, I was attempting to add a little humor.

 

[updated:LAST EDITED ON 01-13-03 AT 04:05 PM (EST)]>
>The best I can explain the difference between strong and weak watts
>is like this. Connect a 3w clock radio to a speaker, it sounds like
>crap. Connect a 3w zen triod tube amp to a speaker, it sound great.
>That is the difference. How ever you want to quantify that, be my
>guest, because I can't. Neither can the maker of the Zen amp, but
>its commonly called 'strong' watts.

I can poke about a hundred holes in this, but ill just start with two for now. 1.) Hook a clock radio speaker to a Zen amp, and i bet it sounds like *****. Hook a high fidelity speaker to a clock radio, and I bet it sounds FAR better. 2.) most clock radio's are made to be as cheap as possible, and are not nearly flat in output. They are there to wake you up with obnoxious noises, not lull you to sleep with beautiful music.


>
>No, if it is a perfect signal with no kind of distortion of any
>kind, and has sufficient headroom for transients and such so that no
>distortion can enter, and is at the max capacity of the amp, then I
>have just described something that is impossible

You still don't get it. You CAN clip an amp and not damage your sub. The only time clipping will damage a sub is if the power of the clipped signal exceeds the rated RMS power of the sub. If the max capabilities of your amp arent higher than your sub, you will not damage the sub. You can blast 300W RMS square waves all day long into a 500W rms speaker and it will do nothing but play the square wave. This is what we want you to understand. Hell, We can blast 300W RMS of white noise(100% distortion) into a 500w RMS sub all day long and not damage it.


>>
>>Its this simple. A distortion free signal (read: unclipped,
>>no outside distortion making its way in) will not blow a
>>speaker rated above this power. Installation error or driver
>>error may cause an undesireable sound. In a perfect setup,
>>with gains set correctly and all outside interference set to
>>a minimum, an underpowered amp can not physically blow the
>>sub. If you believe so, explain once again under the
>>conditions i listed above.
>
>I don't know, too tired. What did I say before? You sound like a
>cop. All I need is the bright light in my eyes and a room filled
>with smoke

You never did explain. You posted a bunch of links about clipping and declared victory, even though none of the links supported your conclusion.


>
>According to the theory from you guys, you would need more than ten
>times the power due to clipping from the 150w amp. Since clipping
>increases the power output exponentially, right?

Wrong. Clipping merely raises the RMS output of an amp to it peak output. In an absolute worst case scenerio (pure square wave), an amp can only put out double it's rated RMS power.


>**He is correct here given power is unlimited.
>However, ask any serious SQ audiophile and you find they own
>extremely light cones.

Yeah, because they have all blindly bought into the markineering like you have. Ever hear of psychoacoustics? It sounds better because YOU THINK it sounds better. Why do you think no one has ever passed a blind or double blind ABX test? Not for RCA's, not for speaker cables, not for amplifiers. Anyone who "claims" to have passed one is wrong, the test was not properly set up. Hell, I'm a victim of this myself. I was tuning my car one day, and was tweaking with the phase on my subwoofers. I would make an adjustment, and listen, change it back, listen again. After about 10 mins of tinkering i decided on a setting I liked most and kept it. As i was putting the cover back on my amp rack, i realized the night before I had hit the bypass switch accidently. I NEVER MADE A SINGLE CHANGE BUT THOUGHT IT SOUNDED BETTER. Boy did i feel stupid, I was SURE i heard a difference The mind is easily fooled.


>
>This guy is just trying to sell subs by taking advantage of gullible >people.

You know you can be sued for slander for comments like that right? Anyway, I digress. I suppose you tink W7's sound terrible and have poor transients too right? I mean after all, it is a high mass, large long coil sub.

>
>>We find no evidence that underpowering speakers is a
>>cause for a premature driver loss. Like i stated in my
>>earlier post, it is usually from
>>a) overpowering
>>b) pushing past mechanical limits
>
>Well, hate to break this to you, but Richard Clark and geolemon said
>clipping an underpowered amp causes the output power to increase
>exponentially. Therefore, it is possible to overdrive a speaker with
>an underpowered amp. There is some evidence for you. You can no
>longer legally make those claims, since you went public.

Not exponentially, a 50 watt amp is not going to put out a 2500watt (50^2) clipped signal.

>
>Whatever you call it, you cannot recommend customers buy a small amp
>for your drivers. period.

Why not? I can think of 100s of times I have done it. I have set up MANY a sound system off a 50x4 amp by bridging the rear channels to get 100w and running an infinity perfect sub off it, and putting a nice comp set on the front channels. Never seen one come back yet, In fact infinity kappa 6.5" comp set, us acoustics USX-4065, and infinity perfect 10 is my best selling set. Cheap, loud, and sounds GOOD.


>
>>So if I give a Ford Lighning 1/2 throttle, should I expect
>>the engine to blow? If the engine is built right, I surely
>>hope not...but I run it without oil (read: clipping) I can
>>expect it to blow....
>
>This has nothing to do with anything. You cannot make a speaker
>analogy with a car. Why do you guys keep trying this one. It makes
>you look silly, if anyone would step back and truely take a look.
>Just like that voluime **** argument, silly. And the toaster?

It's a perfectly valid analogy. Just like my strong/weak watts and long/short inches analogy.


>Sorry to say, but it is true, if you are Distribution Director, I am
>qualified to be your boss. I am trained in manufacturing processes
>and logistics, as well as plant layout, time study and so on. This
>is what and Industrial Engineer does. Again, no offense

And I am qualified to be YOUR boss. I have 5 years in management, 1 year away from my masters in EE, and own and run a rather successful audio shop. What's your point?


>And I quote directly from one of your previous posts
>
>>"**Same for cars. Light weight + powerful motor = fast
>>acceleration.
>>Ask any drag racer."
>
>Interesting....

Ohh Ohh wait a minute! what happened to we cant make a speaker analogy with a car?


>
>I am agreeing with Einstein, who said mass increases with velocity.
>Therefore, if your acceleration approaches infinity, your mass will
>be very heavy indeed.
>
>consider this equation M = Mrest/(1-(v/c)^2)^.5

That formula is used to calculate mass as you approach the speed of light. Subwoofers do not move NEARLY fast enough for this formula to be valid.


>I don't care to change your mind.

Then stop posting You know we are right, and your not going to prove otherwise, so just admit it and stop posting.


>All men are create equal, none should feel inferior that they need a
>flashy system to be respected, or be the editor of a flashy
>magazine. Names mean nothing to me. I don't care about Wiggins, RC,
>DN, or who...just sound logic and experience.

Dejavu! Oh the Irony!

>Buying an underpowered amp will increase the likelihood of
>destroying subs.

You can add just a few words to make this correct you know. All you had to say was, "Buying an underpowered amp and setting the gains incorrectly will increase the likelihood of destroying subs."

EDIT:
*grumble* stupid typos

 

>Therefore, you have made my point. You guys have said
>clipping will produce considerable power indeed, even from a
>small amp. If you instead buy a larger amp and turn down
>the gain a bit, you effectively safeguard against clipping.
>Thus, the larger amp is safer to run the the smaller. Don't
>go down the path of changing your mind again, like geolemon
>and David Navone.

And this power added from clipping... Would that underpowered amp now be considered overpowered or not?

You have yet to prove that if you send an actual 200w to a 300w sub it will blow. (If you are clipping, then you aren't actually sending 200w to the sub)

 

>Hi Randawg,
>
>My name is Dan Wiggins. I'm the CEO and partner of Adire
>Audio.

I am very glad to meet you.

>We're a high-end audio company located in Seattle,
>WA and have been in the audio business for 7 years. We
>started in advanced acoustics research and consulting, and
>over the last 4 years we've branched out into retail
>products as well. One of our many technologies that we've
>developed and license is in our Brahma woofers, the XBL2
>motor, which set a world record in terms of linear excursion
>at 27.32mm one way.

Wow, I think that is amazing! You must be very proud indeed. Did you do all the engineering?

>
>My design partner is Dr. David Hyre. He earned his
>undergrad degree in physics, and his PhD in nuclear
>magnetoresonance spectroscopy, and has spent several years
>in advanced biochemistry where he worked on isolating and
>reversing the spin on individual electrons. This required
>use of extremely strong and precise magnetic fields, with
>gradients measured in the range of a few Teslas per
>millimeter.

This is outstanding! Very interesting work.

>
>Anyway, I see you have a few questions about our paper.
>Perhaps I can explain. I don't know what your background is
>(my is a BSEE, and 13 years of advanced SONAR system design
>prior to the last 7 in the audio acoustic range), so I'll
>try to keep things fairly simple. But if you need more
>thorough explanations, please let me know and we can flesh
>things out further.

Very respectable background. Agreed.

>
>- Underpowering destroys drivers. I believe Tracy (hi
>Tracy! Missed you at CES; I'm still here in LV, enjoying a
>bit of sun...) summed it up correctly: underpowering isn't
>a problem. Overpowering or overexcursion are.

I thought we covered this infintite times before

>
>A driver's excursion is a function of the current flowing in
>the motor AND the stiffness of the box behind it. A larger
>box means less current flow required (less power, since
>power is current squared times impedance) to reach a given
>excursion level. In fact, you can push just about any
>driver to full linear excursion with a couple hundred watts,
>depending upon the box and signal used.

Even if the driver's cone mass is VERY large??? I think not.

>
>Overexcursion is bad for a sub in two ways. The first is
>physical damage. You can snap tinsel leads, bottom the
>voice coil, wedge the voice coil on the top plate (if you
>walk it out the front of the gap; a common occurance with
>flux modulation effects), tear spiders, etc.
>
>The second problem with overexcursion is reduced cooling.
>Over 90% of the heat dissipation in a driver comes from air
>movement in the motor, not conduction through the pole, top
>plate, etc. When you linearly scale air motion with power -
>like when a driver is still within it's linear range of
>motion - you're generally OK. But when you reach the
>suspension limits and keep increasing power, you get into
>trouble. It's like restricting the cooling air to the
>motor; akin to placing a restrictor plate in front of the
>radiator in your car. As you run with more and more motor
>output, heat builds up. And if you restrict the cooling -
>or hold it's level constant - you can't remove the heat as
>effectively, meaning a meltdown in imminent.

I agree with this totally! Furthermore, I love the way you put it, very concise.

>
>As far as damaging from underpowering, it really can't
>happen. It can happen if you CLIP the amp,

David Navone took issue with this earlier saying, "Clipping doesn't damage speakers"

Richard Clark had said, "clipping is not the key to anything"

>but that's not
>from the amp being underpowered; it's from the amp
>generating even more power.

Yes, I have heard this, it is in agreement here.

>Please see the eatel.net site
>for a VERY good description of the way the power envelope
>increases from a clipped signal. It's not the fact the amp
>is underpowered; it's the fact that you are increasing the
>power to the speakers, usually beyond it's rating.

Rather, your lack of buying a stronger amp and setting the gains down a bit. Call it insurance if you want, or just appreciate good sound.

>
>- Mass affects transient response. Please investigate the
>works of Tom Danley, Dr. Floyd Toole, Dr. Wolfgang Klippel,
>Thiele, Small, Benson, Bullock, Geddes, and several others.
>They all make the complete conclusion that inductance is the
>primary limiter of frequency response, NOT mass. Mass can
>have a very small second-order effect (due to the way mass
>shows up as an inductive reactance in the electromechanical
>model), but it is often two orders of magnitude below that
>of the voice coil. Voice coil inductance is the limiter.

You could be correct, it does not matter. Does a drag racer seek only to gain engine power and not seek to lighten the car? I think not. Therefore, it is wise to consider both parameters. In terms of acceleration I use this analogy only, not to imply some how the operation of a speaker is similar to that of a car.

>
>As far as the ability to infinitely slew current, you are of
>course correct about the speed of light. However, I guess I
>was not clear enough about the whole statement:

Didn't think I would be reading it did you? Sorry.

>IF you could
>slew the current at an infinite rate, then you would have
>infinite transient response. obviously you can't do that (I
>assume a certain level of education in the reader), but the
>point is still valid; what limits transient response is how
>fast you can change the current.

Let me add to that mass and inductance.

>
>Transient response is a 3rd order function. It is the rate
>of change of acceleration; it is NOT acceleration itself.

OK, meters/sec/sec/sec. IS that not more sensitive to mass than just acceleration?

>With the equation of BLi=ma, BL and m are both constants
>(when doing the time-based derivative).

We have shown that m is not always constant, even though the change is small. Just to point that out.

>They will scale
>your results, but are not changing things in a
>time-dependent manner. That leaves i ~= (proportional) to
>a, so that to change a one must change i. That is, changes
>in acceleration - transient response - are proportional to
>changes in current.

So where does that leave mass??? Can you then conceive of a 10 ton cone and coil and send googles of current thru it and expect it to perform like any other driver? (of similar proportionality of course)

>
>What limits current flow in a time-dependent manner?
>Inductance. This is where the limit comes from. You can
>only slew the current through the inductance of the voice
>coil so fast; the lower the inductance, the faster you can
>change, and vice versa. In fact, if the current never
>changed, the acceleration would never change, and you would
>have zero transient response!
>
>Mass and BL are scalars in the response system of the
>driver; they will change how much current is required to
>change the transient response of the driver.

I LIKE THIS NEXT ONE
>increasing
>mass will definitely mean you need more current to reach a
>given acceleration;
THAT'S WHAT I'M SAYING

>however, it will not place an upper
>limit on how fast you can accelerate.

No one is saying this, at least not me.

>
>Likewise, BL is a scalar of transient response. The higher
>the BL, the faster you can accelerate for a given current.
>If you increase BL, you need less current to reach a given
>acceleration. But BL does not limit transient response
>itself.
>
>For those who stop by our shop, I often do a demo to
>disabuse them of the notion that moving mass means slow
>response. I start with a Brahma 10, and run it through some
>healthy, 2" peak to peak excursion down around 15 Hz. Then
>I turn the power down, and start increasing the frequency.
>50 Hz, 100 Hz, 200 Hz, 500 Hz, etc. until we reach 10 kHz,
>11 kHz, and finally 13 kHz where it starts rolling off
>strongly. And this is for a driver with a moving mass of
>160 grams.

That is amazing indeed, my congratulations are in order for your accomplished product. However, it's transients will not compete with a lowther, of course, the lowther is not exactly a subwoofer either. In any case, very nice driver you have for its purpose. Oh, how much power did you feed it for that flat response? You said you turned the power down?

>
>As far as "audiophiles" using light cones, it's more a
>belief in the audio myth than for real reasons.

I disagree.

>I do work
>in the high-end market, and having just spent 4 days at the
>high end section of CES, I can assure you that voodoo and
>snake oil and lack of understanding about the fundamentals
>of physics are quite prevalent.

I can agree with that, but I don't seek to change it. I'd sooner put a bullet in my head.

>Simply because of driver
>sounds a certain way does not mean that any theory applied
>to it is correct;

In terms of a large sample size, yes it does! Statistically speaking, yes it does!

>often the description of the sound is
>correct but the wrong reasoning is applied,

I agree completely.

>and thus the
>fundamental understanding of the technology is flawed. That
>is one reason why the audio field advances at a much slower
>rate than other high technology fields - many working in
>audio simply lack the training and knowledge to make correct
>correlations.

Another fine point.

>
>Thanks,

My pleasure in fact.
>
>Dan Wiggins
>Adire Audio

This has to be the best piece of work I have seen here in more than 300 posts. I truly enjoyed the reading.

 

>>- Underpowering destroys drivers. I believe Tracy (hi
>>Tracy! Missed you at CES; I'm still here in LV, enjoying a
>>bit of sun...) summed it up correctly: underpowering isn't
>>a problem. Overpowering or overexcursion are.
>
>I thought we covered this infintite times before

"- Underpowering destroys drivers." is a topic you dolt. notice the hyphen? you know the little - thingy? If you had a college education you would know that though. its bascilly like saying "Our next topic will be how underpowering destroys drivers." For some one who's supposed to be an IE you sure dont know very much.

 

[updated:LAST EDITED ON 01-13-03 AT 04:33 PM (EST)]>>
>>A driver's excursion is a function of the current flowing in
>>the motor AND the stiffness of the box behind it. A larger
>>box means less current flow required (less power, since
>>power is current squared times impedance) to reach a given
>>excursion level. In fact, you can push just about any
>>driver to full linear excursion with a couple hundred watts,
>>depending upon the box and signal used.
>
>Even if the driver's cone mass is VERY large??? I think not.

Yes, even if the mass is very large. More mass just needs more current to move, high mass does not effect transient response NEARLY as much as inductance. A 10g moving mass will have the same transient response as a 5000g moving mass given equal inductance, but the 5000g cone will require FAR more current to reach the same SPL.

 

>>>As far as damaging from underpowering, it really can't
>>>happen. It can happen if you CLIP the amp,
>>>
>>>David Navone took issue with this earlier saying, "Clipping
>>>doesn't damage speakers"
>>>
>>>Richard Clark had said, "clipping is not the key to anything"
>>>
>>but that's not
>>from the amp being underpowered; it's from the amp
>>generating even more power.

>Yes, I have heard this, it is in agreement here.

Clipping alone does nothing. It's when the extra power from the clipped signal exceeds the RMS power of the subwoofer, that clipping is dangerous. You still havent tried my experiment have you? Make a 100watt RMS amp, and play a square wave through it, into a 500W rms speaker, and see how long it takes to blow.

 

>>Please see the eatel.net site
>>for a VERY good description of the way the power envelope
>>increases from a clipped signal. It's not the fact the amp
>>is underpowered; it's the fact that you are increasing the
>>power to the speakers, usually beyond it's rating.
>
>Rather, your lack of buying a stronger amp and setting the gains
>down a bit. Call it insurance if you want, or just appreciate good
>sound.

Again, you dont understand. You dont have to clip an amp to blow a speaker. You can blow a 300watt speaker with 600 clean watts easily.

 

>>Therefore, you have made my point. You guys have said
>>clipping will produce considerable power indeed, even from a
>>small amp. If you instead buy a larger amp and turn down
>>the gain a bit, you effectively safeguard against clipping.
>>Thus, the larger amp is safer to run the the smaller. Don't
>>go down the path of changing your mind again, like geolemon
>>and David Navone.
>
And this power added from clipping... Would that
underpowered amp now be considered overpowered or not?

You have yet to prove that if you send an actual 200w to a
300w sub it will blow. (If you are clipping, then you
aren't actually sending 200w to the sub)