Who has overtaken lambdacoustics - some user tell: "The best bass I have ever heard"

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#61
Low Mms and High Bl

doug20 said:
Overkill, do you have any links or papers discussing the Mms/BL ratio?
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Hi Doug,

My attached article is more a general comment on what I see as the biggest " Elephant in the room " i.e. the true mass on a spring behaviour of all cone dome ribbons stats panels etc. The word pistonic as used to describe drivers is all wrong. Pistonic as used to describe cone rigidity is another issue altogether, and cone break up or the lack of it, is the single least important aspect of a drivers performance, IMO.

If you search my posts on this site I try to put forward why I believe low Mms and high Bl is so very important.
I do have great respect for John and his superb AE M series drivers but the old Adire white paper on Mms being irrelevant and or unimportant compared to a low Le is at best total rubbish and at worst pure and utter marketing **** designed to sell drivers by confusing the vast majority of the intended customers. Sorry to be blunt but that paper " just aint penguin...! "

All the best


Derek.
 

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#63
Overkill Audio said:
Hi Doug,

My attached article is more a general comment on what I see as the biggest " Elephant in the room " i.e. the true mass on a spring behaviour of all cone dome ribbons stats panels etc. The word pistonic as used to describe drivers is all wrong. Pistonic as used to describe cone rigidity is another issue altogether, and cone break up or the lack of it, is the single least important aspect of a drivers performance, IMO.

If you search my posts on this site I try to put forward why I believe low Mms and high Bl is so very important.
I do have great respect for John and his superb AE M series drivers but the old Adire white paper on Mms being irrelevant and or unimportant compared to a low Le is at best total rubbish and at worst pure and utter marketing **** designed to sell drivers by confusing the vast majority of the intended customers. Sorry to be blunt but that paper " just aint penguin...! "

All the best


Derek.
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how is this john's standpoint any different then what adire's paper states and their standpoint, both are documented states of opinion and applications?

I have heard and played with a few of Adire's creations and felt all were fat pigs.. so much that after reading so many peoples accolades that I was questioning my own hearing...lol..

guys we can all create moving targets and it shows no purpose and at best turns into a ******* match....
 
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#64
Overkill Audio said:
Hi Doug,

My attached article is more a general comment on what I see as the biggest " Elephant in the room " i.e. the true mass on a spring behaviour of all cone dome ribbons stats panels etc. The word pistonic as used to describe drivers is all wrong. Pistonic as used to describe cone rigidity is another issue altogether, and cone break up or the lack of it, is the single least important aspect of a drivers performance, IMO.

If you search my posts on this site I try to put forward why I believe low Mms and high Bl is so very important.
I do have great respect for John and his superb AE M series drivers but the old Adire white paper on Mms being irrelevant and or unimportant compared to a low Le is at best total rubbish and at worst pure and utter marketing **** designed to sell drivers by confusing the vast majority of the intended customers. Sorry to be blunt but that paper " just aint penguin...! "

All the best


Derek.
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But the paper showed that adding mass alone did nothing. This means that the ratio is not really a 100% meaningful since the value can be all over the map with different weights.

The reason I want a link to a proper research paper is because I have heard this sort of discussion many times and no one can ever produce any real evidence to back up their claim that the weight of the cone is absolutely meaningful on its own. I definitely see great discussion on what parameters dictate how fast a driver stops but to me weight alone isnt one of them, like in cars it has to be all about the 'Suspension" involved, no?

Im going with the guy that builds drivers on this one until the subjectivity about the ratio stops being subjective 😉
 
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#65
trusound said:
how is this john's standpoint any different then what adire's paper states and their standpoint, both are documented states of opinion and applications?

I have heard and played with a few of Adire's creations and felt all were fat pigs.. so much that after reading so many peoples accolades that I was questioning my own hearing...lol..

guys we can all create moving targets and it shows no purpose and at best turns into a ******* match....
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You obviously didnt care about really low bass.

btw, I agree about the pissng match stuff. Im definitely ineterested in expert opinion on how to determine which drivers stop the fastest.
 
#68
catapult said:
Hey, them's fightin' words, bub! Put 'em up! 😀

Any design, active or passive, is only as good as the designer. Either can be excellent and either can be crappy.
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lmao!

You know me...inferior really means that I can build an active design, I can not build a passive design 😀 Although, Im finally close. Anyways, Active vs passive isn't really important to a great design (like you posted).
 
#71
Mass and acceleration....

doug20 said:
But the paper showed that adding mass alone did nothing. This means that the ratio is not really a 100% meaningful since the value can be all over the map with different weights.

The reason I want a link to a proper research paper is because I have heard this sort of discussion many times and no one can ever produce any real evidence to back up their claim that the weight of the cone is absolutely meaningful on its own. I definitely see great discussion on what parameters dictate how fast a driver stops but to me weight alone isnt one of them, like in cars it has to be all about the 'Suspension" involved, no?

Im going with the guy that builds drivers on this one until the subjectivity about the ratio stops being subjective 😉
Click to expand...


Hi Doug,

My point exactly!

The whole paper is “ proved “ by the ridiculous conclusion that adding mass
( up to 100% extra...!) has no effect on acceleration... come on guys wake up and smell the coffee.
This is an insult to a 14 year school child’s basic physics.
The paper concludes that when you double the mass of the body at rest ( the cone ) and then apply the same force ( Bl ) to accelerate the mass there is no measurable ( or according to Adire’s golden ears audible....) difference.


Re car suspension... No. How a cars suspension affects its acceleration / deceleration is a very different set of parameters.
Re you wanting a proper research paper ( answer?)
It’s easy just ask any university physics professor to tell you what he thinks about mass not affecting acceleration....


Re "Im going with the guy that builds drivers on this one until the subjectivity about the ratio stops being subjective" ... It never was subjective....

Hi Trusound,

I aggree about the "******* contest" and many years have passed and so has the infamous paper, and now AE make some great low Mms high Bl Mseries drivers...! Plus they make some great home cinema drivers which have a different set of performance targets. Plus John can customise, do OEM drivers and generously gives advice to the DIY community for free.
So please dont get me wrong, I admire John, respect his vast knowledge and would love to try his drivers, but on this particular point I believe he is wrong. Sorry!

All the best
Derek.
 
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#74
Again for clarification BLi is the force factor equation in a driver. BLi=ma. B being flux density. L being length of windings and i being current applied. The physical mass does not change. The change in acceleration of the driver is directly proportional to the current applied. As current is decreased the driver will "slow".

How is current decreased? As the resistance goes up. This happens as inductance goes up. On the outward stroke inductance is decreasing. Inward stroke it is increasing.

Again, another explanation.
Woofer Speed - SSA Car Audio Forum

Also, keep in mind that another HUGE issue in terms of the time domain is flux modulation. The permanent magnetic field of the driver is moved around. If i can dissect a power point file i'll post some images of how inductance variation/flux modulation affects position of the coil with respect to time.

John
 
#76
tinitus said:
Yes, they found this issue when going from alnico magnets to ceramics

Its many years ago
They invented the copper shortrings to deal with this issue

Why was it forgotten
Well, I think it was patented, and thus kept from being widely used, for many years
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Yes, alnico is much less prone to flux modulation as the density is much higher in the magnet itself. However the geometry has a lot to do with it too. The flux modulates more in the steel than in the magnet itself. You have to use more steel with a larger diameter ceramic magnet than you do with smaller alnico. Flux modulates the most in air though. The larger the VC, the larger the gap, the easier the flux modulates. Again a reason that smaller coils often sound better, simply less air gap.

John
 
#77
John_E_Janowitz said:
Again a reason that smaller coils often sound better, simply less air gap.

John
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Ahh, yes some enthusiasts do claim that
Its an interesting subject
I guess very low bass maybe would be an exception, or maybe not ?

Any chance we will see paper voice coil formers too 😀

Nah, just joking
But leads me to a different question

I have found that copper in the gap weakens the field
Then I thought hell, the whole voice coil assembly is like solid copper

All that moving copper, might that be another issue ?
Some claim that silver wired paper voice coil sounds much better
Same people who prefer small voice coils (very small)🙄

Maybe not so realistic, but maybe there are other ways around it ?
I suppose we are talking compromises now
 
#78
John_E_Janowitz said:
Y

Flux modulates the most in air though. The larger the VC, the larger the gap, the easier the flux modulates. Again a reason that smaller coils often sound better, simply less air gap.

John
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Hey, wait a minute
Are you suggesting that thinner poleplates are better than thicker poleplates, in terms of flux modulation
It sounds like thats what you say

Doesnt look good on underhung designs 😕
 
#80
Light at the end of the tunnel

John_E_Janowitz said:
Again for clarification BLi is the force factor equation in a driver. BLi=ma. B being flux density. L being length of windings and i being current applied. The physical mass does not change. The change in acceleration of the driver is directly proportional to the current applied. As current is decreased the driver will "slow".

Hi John,

I think we might have some common ground where can agree!
From the above you are saying that the physical mass of the voice coil / magnet does not vary, well of course I 100% agree! Changes in the magnetic force exerted on the voice coil as it moves back and forward in the magnetic gap won’t affect the mass.
But, ( here we go...) the whole point of the old Aidire paper was something very different i.e. it claimed adding mass to the cone did not affect the acceleration / deceleration. Now that is 100% wrong.

Can you give a once and for all clear cut yes or no to the basic question:
Does adding / subtracting mass from the cone affect acceleration / deceleration? Yes or no I promise to drop the subject....!


Now moving on your next point is interesting...

Johns quote :
" How is current decreased? As the resistance goes up. This happens as inductance goes up. On the outward stroke inductance is decreasing. Inward stroke it is increasing. "
Another elephant in the room :THERMAL COMPRESSION due to voice coil heating. This has a far greater effect on resistance than the variations in the magnetic force exerted on the coil. Please read Michael Gerstgrasser brilliant paper attached on the subject.
In addition I would point out that most of the dramatic graphs and figures used to illustrate the variable Bl force refer to extreme cone movements i.e. close to or exceeding Xmax. This is (a) misleading as 90% of the time drivers are not bouncing off their end stops and ( b) is totally avoidable by simply choosing the appropriate drivers i.e. use large fast drivers with low Mms, high Bl and high power handling and run them well within their limits so you never use more than 30% to 40% of their Xmax. This cures the variable BL problem in the vast majority of quality pro drivers, also it ensures the more serious problem of thermal compression is reduced to very low level i.e. less than 0.4 dB in the PD 158 case when I am running it a full power ( 300 watts between140Hz and 600Hz ).

Johns quote:
" Also, keep in mind that another HUGE issue in terms of the time domain is flux modulation. The permanent magnetic field of the driver is moved around. If i can dissect a power point file i'll post some images of how inductance variation/flux modulation affects position of the coil with respect to time. "

Again not as important as thermal compression, IMO!

Last suggestion, how about using Carbon Fibre ( similar to Van Den Hul cables ) for voice coils? This will 100% totally eliminate thermal compression.
You could even use a one piece voice coil / former... incredible strength, non resonant, never oxidises or corrodes, basically indestructible with MASSIVE power handling....
I think some bright spark ( excuse the pun ) could really make the concept work.

All the best

Derek.
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