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07-06-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 21
Post ID: 16649
Reply to: 16648
What Rullit has to do with this thread?
fiogf49gjkf0d
Ok, let kill the subject of Oleg Rullit out of this thread. Rullit has very little to do with horn and consequentially with compression drivers. Sine this thread is about MF compression driver I think there is no reason to pay attention what Rullit does. Oleg does whatever is doible and sells whatever is saleable. He most likely has no interest or aptitude to evaluate compression drives.  If you look what playback he is involved then you will see only open baffles or very shallow horn that mostly work as open baffles. His drivers are basically full range drivers and it is very far from environment where compression drivers used.

BTW, I do not take audiofilofine unhappiness with Rullit too serious. Any critiques without providing specific reasons or justifications are just shaking of air.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-07-2011 Post does not mapped to Knowledge Tree
audiofilofine
Posts 29
Joined on 02-26-2010

Post #: 22
Post ID: 16650
Reply to: 16649
Donkey can not fly
fiogf49gjkf0d
 Romy the Cat wrote:
Ok, let kill the subject of Oleg Rullit out of this thread. Rullit has very little to do with horn and consequentially with compression drivers. Sine this thread is about MF compression driver I think there is no reason to pay attention what Rullit does. Oleg does whatever is doible and sells whatever is saleable. He most likely has no interest or aptitude to evaluate compression drives.  If you look what playback he is involved then you will see only open baffles or very shallow horn that mostly work as open baffles. His drivers are basically full range drivers and it is very far from environment where compression drivers used.

BTW, I do not take audiofilofine unhappiness with Rullit too serious. Any critiques without providing specific reasons or justifications are just shaking of air.

The Cat


donkeys can not fly,theese are specific reasons.
may be nice to assemble a sound box with strange objects,but with high fidelity has nothing to do.
07-07-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 23
Post ID: 16651
Reply to: 16650
…and some donkeys can’t even think.
fiogf49gjkf0d
Audiofilofine,
 
You do make some kind of drivers? Do they use any metal in them? Well, your drivers are craps because they use metals.  The reason is because pigs cannot climb atop of a peach tree. It is as simple as that. Audiofilofine, of you feel that this talk brings anything valuable to you then you are a very special person but I would like do not read the expression the celebration of your “specialty” at this thread.

Anyhow, the subject of somebody loves of hate Rulit drivers is over. The topic of this thread is a concept of Ultimate MF compression driver. If you have nothing to express on the subject then withhold yourself from posting anything. I will delete any other posted garbage in this thread if it will not be related to the subject of the thread.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-07-2011 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,571
Joined on 10-12-2006

Post #: 24
Post ID: 16652
Reply to: 16651
Idiosyncratic Sound
fiogf49gjkf0d
Of course I am not really talking about Rullit but only holding up his implimentations against his stated aims.  This is certainly no special case, since most smart people learn the talk and the "look" long before they learn practicum, if they ever do, and most people will finally settle into what pays the bills, in any case.

One thing that appears obvious in Rullit's designs is that the sound will be subordinate to the idiosyncratic materials and constructions of choice.  Of course (again) I have not listened to this stuff, but I have listened to a LOT of drivers over many years.  Anyway, my educated guess is that there are less spectacular ways to do what needs to be done with compression drivers by developing what is perhaps more readily available, "generic" material.

One thing that came out of my experience with "FR" drivers is appreciation for what a truly wide range driver can do.  Simply put, I believe the idea here is to get as much range out of this driver as possible without making it "idiosyncratic".  I am not sure, other than horn size, why the bottom would be cut at 500 Hz?  Not arguing (how would I know?), but genuinely curious.  Sure, the natural response will be humped, since that's how it goes (best case, one smooth hump); but that's what the other drivers are for, even "taking advantage of weakness" by contributing to lower output ends.  Looking back, I keep thinking one might critically tune a not-so-small diaphragm/throat to have quite a wide useful range.  Since tone always gets lost at LF, why not trail "MF" to 300 Hz?

Best regards,
Paul S
07-09-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 25
Post ID: 16658
Reply to: 16644
Ultimate driver and color control.
fiogf49gjkf0d

 Romy the Cat wrote:
I will slowly upload, as time permits to write them, different posts on the subject of Ultimate MF Compression Driver. 
This will be a bit controversial subject among the compression drivers users but it is only because the compression driver users are seldomly challenged in this subject, challenged in their accomplishment and challenged in their requirement. I am talking about color control in compression drivers loaded playbacks.

I wrote a lot about colors at my site and people know that color discrimination of channels is very high in the list of my proprieties .  The color discrimination is a complex subject itself that encompasses the Absolute Tone and, color sensitively, continuing color, stability of colors and many other subjects. It is not my intention to elaborate on color topics in this thread. However, thinking about Ultimate MF compression driver I can’t avoid to think about colors and what is the most important – the color control.

First think first – I do not know where color comes from in compression drivers. Many  people make many claims that they do know but I did not see yet single compression driver that has deliberately proper amount of colors.  Many people think that more colors the  better, they are wrong as usually. Colors in compression driver is like salt on your steak. Without salt the meat might not feel cultivated, with too much salt the meat is destroyed. It has to be very right amount and it has to be very right amount of colors. With excessive amount of colors playback or a channel begin to demonstrate colorations of the satiation when specific colors become overwhelming force. Many audio Morons do not understand different between color power and colorations, I do.  I not only understand it but have ways in my own playback to enforce it.

Still, my way to enforce the deliberateness of colors (with use of Injection Channel) is superbly powerful and I do not even think to use have Macondo without Injection but it is not Ultimate way to have color control. In Macondo I use Vitavox S2 driver that is the most powerful color discriminator I have heard among compression drivers. Furtherer I drive it with very unique output tube that has a lot of own color attitude. Still it is not near enough to serve the colors in the way how I feel they have to be and the additional Injection is employed. The Ultimate way would be to have drivers, and the most prominent MF driver, with color control built in. I mean whatever in a driver is responsible for color need to be adjustable. I do not know what it would be but this is my requirement for Ultimate MF compression driver.

A reasonable question would be: if a manufacturer (if the manufacturer “get” the subject as most of them do not) could not make a compression driver with right amount of color force, then the color strength would not be need adjustment? It is good question. The color strength is dissipate-able force. The precise force of color setting would wary with listening distance, room acoustic, type of loading, amplification, the use of a given channel, the way how the neighboring channels interact with the given MF channel. The Ultimate MF compression driver is like puberty: the driver shall ability to be pregnant but to consummate the pregnancy is the business of the driver end user.

There is no know to me drivers with the adjustable color strength, no one even look in the direction. Still, if I am thinking about Ultimate MF compression driver then it must have control over own color output.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-10-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 26
Post ID: 16659
Reply to: 16658
Ultimate driver and texture control.
fiogf49gjkf0d

Here is another subject that many people would not understand, however some of the advanced Vitavox S2 user will be able to follow me.

The MF compression drivers hat go all the way to 12K-13K region all have own idiosyncratic way to present own upper region. In this article I would like to touch one subject – the texture. I am not taking about musical texture but the texture of sound presentation. This texture is very fine balance between consistency, coarseness and granularity of upper MF range. In upper MF the diaphragms of compression driver begin to break up. The small 1” metal cones that used in direct radiators tweeters break up at 30K-35K but the large 3”-4” cones that are used in typical compression drivers with 1.5”-2” exit break up at much lower frequency  (break up mans to have non-linear resonances). There are many different ways to prevent or to moderate the breakup of cones and here is where the main question arises: how a driver sounds in near to the break up state?

Before I was introduced to Vitavox S2 I was under impression that break up in compression drivers is something that I need to run away and the best drivers are “clean drivers” where all metallic nastiness is well damped or taken care by many other  than damping means. However, living with S2 and with injection later on I come to realization that not the breakup of diaphragms is a problem but the HOW the diaphragms breakup and the precision of the ration between the “clean” sound of driver and the driver resonances in breakup mode.

I know that some Morons who read this site will scream “Ok, now Romy advocates the sound of distorted drivers and sound of compression driver diaphragms with auditable breakup!” Well, I am glad that Morons have their typical idiotic feelings; the fear of what they cannot understand is their main guiding principle. The reality is that a properly implemented MF with properly tuned deliberate metal diaphragms breakup does sound as clean than any other driver topology but it has something else that not many other topologies offer: it has an ability to present very fine texture of compression driver in breaks up mode as the part of organic sound that driver produces. The key in it is right amount and right quality of that none-existing artificial texture.

In a way it works very much like a Photoshop. An image that was shot always has some room for applying a very deliberate amount of Unsharpened Mask. So it too much and you kill the image but if the amount is very deliberate, sensible and very well measured then it works very fine. After all the beef ageing is just a control deliberate spoiling of meat…

So, from all said above I envision that an Ultimate MF compression driver shall have some kind of mechanical HF texture control. Vitavox S2 has fine result in term of texture control but it has no internal way to do it and to set S2 in right controlled break up mode it requires a LOT of ballet with this driver and lot of experience, not to mention that at time some of the ways to control S2’s texture might be worsening for other aspects of this driver sound. So, what I would like to see is the Ultimate MF compression to have an independent from anything else texture control that would allow very accurately to see the bandwidth, depth and damping of the driver HF break up. I think it might be possible by modifying the acoustic impedance of the throat’s screen and creating a front contra-pressure.  It might be also possible to do by having the geometry of phase p-lay to be very slightly modifiable in order to rearrange how pressure is reflected back to the diaphragms. Think about the jet fighter with adjustable configuration of wings… There are a few other ways that I might think of but this is not an attempt to design the Ultimate MF compression driver but rather to build requirements for it.

In conclusion, the most important message is that Ultimate MF compression driver shall have upper knew break up control INDEPENDENT from the way how the driver loaded of low-passed. To my knowledge there are no such drivers in existence.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-10-2011 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,571
Joined on 10-12-2006

Post #: 27
Post ID: 16660
Reply to: 16659
The Part of the Pieces and Parts
fiogf49gjkf0d
I like those ideas for tuning texture, and would add the way the surround is done and how it is clamped/bedded, which might be relatively easy to control, maybe even on the fly (with some sort of cam, for example).  So far, it seems to work best to "distribute" resonance.  So far, attempts to "eliminate" resonance result in "signature" ups and downs and/or kill the sound; garishness, and/or no color and no life.  So far, the "perfect piston" has not proven itself in terms of results.

Another thing I wonder about is the different diaphragms, their composition and construction, with respect to sound(s).  It seems like much could be done with this, just as much remains to be done with the cones of direct radiators.  But what can we expect from an "industry" that is dominated by "PA/sound reinforcement" and "engineers" in the case of compression drivers, and electric guitar players (and "engineers") in the case of "cone development"?.  In developing "modern" drivers and speakers, texture and tone are usually reviled or worshipped in and of themselves; they are seldom given due consideration in terms of the expression of serious Music.

Basically, the parts of a driver add up and interact in a complex electro-mechanical matrix to make the whole.  Still, it appears to be a straight forward (albeit daunting...) matter of going through the parts and the interactions to arrive at the desired sound.   Too bad no one else who actually does this has MY references...  How sad is it that my best hopes now hinge on adapting +/- random DIY efforts?

Yes, it is madness to try to re-make "perfectly good" drivers to meet new requirements.  The only thing more nuts would be to start from scratch...

Best regards,
Paul S
07-10-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 28
Post ID: 16661
Reply to: 16660
Beryliam and cohearent design
fiogf49gjkf0d
THE ONLY COMPANY THAT HAS ADVANCED THE DESIGN OF A MODERN DRIVER IS JBL,,, GOING FROM THE WESTERN ELECTRIC DESIGN TO THE 375,,376...PRO VERSION 2440,,2441...  TO the 2450 types..USEING COHERIENT PHASE PLUG DESIGN TOPOLIGY that unit was adapted to the new 475..476 ultimate PHASE COHERIENT PLUG DESIGN AND USEING BERYLLIAM DIAPHRAMS...    TAD HAD TO REDESIGN THE 4001 driver to the new 4003 driver,,REDESIGNING there PHASE PLUG (5 slit configuration) TAD BERYLIAM MANUFACTURE IS DONE DIFFERENTLY THAN LANSING,, TO KEEP UP WITH JBL,,,JBL HAS ALSO DONE A SMALLER VERSION,,WITH TAD FOLLOWING,,     BRUSH WELMAN,,TRUEXTANT is now making BERYLIAM diaphrams to be used in earlier older JBL UNITS,,,($700 each)  JBL IS NOW MAKING A MAGNESIUM DIAPHRAM for the 476, YOU CAN ORDER either type of diaphrame,,BUT driver are costly..  I FEEL THE NEW VITAVOX S2 is a none starter in design,,  BUT MAYBE BRUSH WELLMAN WILL MANUFACTURE A Be diaphran to fit...
07-11-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 29
Post ID: 16663
Reply to: 16661
About the diaphragms cult.
fiogf49gjkf0d
 zako wrote:
THE ONLY COMPANY THAT HAS ADVANCED THE DESIGN OF A MODERN DRIVER IS JBL,,, GOING FROM THE WESTERN ELECTRIC DESIGN TO THE 375,,376...PRO VERSION 2440,,2441...  TO the 2450 types..USEING COHERIENT PHASE PLUG DESIGN TOPOLIGY that unit was adapted to the new 475..476 ultimate PHASE COHERIENT PLUG DESIGN AND USEING BERYLLIAM DIAPHRAMS...    TAD HAD TO REDESIGN THE 4001 driver to the new 4003 driver,,REDESIGNING there PHASE PLUG (5 slit configuration) TAD BERYLIAM MANUFACTURE IS DONE DIFFERENTLY THAN LANSING,, TO KEEP UP WITH JBL,,,JBL HAS ALSO DONE A SMALLER VERSION,,WITH TAD FOLLOWING,,     BRUSH WELMAN,,TRUEXTANT is now making BERYLIAM diaphrams to be used in earlier older JBL UNITS,,,($700 each)  JBL IS NOW MAKING A MAGNESIUM DIAPHRAM for the 476, YOU CAN ORDER either type of diaphrame,,BUT driver are costly..  I FEEL THE NEW VITAVOX S2 is a none starter in design,,  BUT MAYBE BRUSH WELLMAN WILL MANUFACTURE A Be diaphran to fit...

Yes, the diaphragms are tremendously important in compression drivers and since ordinary people in their basements would hardly be able to make diaphragms many audio people attribute to diaphragms some kind of intrinsic quality.  They feel that “special” quality of diaphragms defines Sound. Unfortunately it is only partially true. The truth is that in the park of existing drivers and the existing diaphragms the selection of diaphragms does defines now the driver will sound. However, the characteristics of diaphragms are very much related to the entire driver design and if the driver is designed from scratch then in the first place come not the selection of exotic material for diaphragms or exotic material for suspension but rather a correspondence of diaphragm design to the driver design. Very few, if any, have luxury to be flexible and creative in those experiments and practice.  


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-12-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 30
Post ID: 16665
Reply to: 16663
Guts and fortitude
fiogf49gjkf0d
IN THE NEW DIAPHRAMS,,,LOW MASS HIGH STRENGTH AND HOW THE PHASE PLUG IS DESIGNED HAS A CORRILATION OF WIDER BANDWIDTH AND LOWER DISTORTION...BUT JBL ADDED ONE MORE DESIGN TO THE EQUASION,,,THAT WAS TO REDESIGN THE DIAMOND PATTERN OUTER SURROUND FOR SMOOTHER HIGH FREQUENCY EXTENSION,,,  THIS IS ONE ITEM BRUSH WELLMAN WAS NOT ALLOWED TO DO BECAUSE OF DESIGN PATENT..BY JBL RESTRICTION..GREAG TIMBERS , CHIEF DESIGN ENGINER OF JBL,STATED,,THE ONLY THING LEFT TO DO IS GO TO THE 5 SLIT PHASE PLUG DESIGN PLUS COHERIENT PHASE APPROACH,,  THIS WILL NOT EXCEED TADs DESIGN OF THE TAD 4003 BUT WILL KEEP JBL IN A PERFORMANCE AREA EQUAL TO TADs ACHIEVEMENTS,,,   I HAVE BEEN WATCHING THIS SMALL BUT FORWARD ADVANCEMENT OF DRIVER DESIGN BY BOTH COMPANYS,, THE SOUND IMPROVEMENT IS SEGNIFICANT BUT COSTLY,,   I BRING THIS ALL UP BECAUSE I THOUGHT VITAVOX WOULD INTER INTO THIS FREY WITH ADVANCEMENTS IN A BETTER DRIVER AND WAS DISAPOINTED,,,HELL EVEN ALTEC CAN DO BETTER THAN THAT IF THEY HAD THE BACKBONE AND GUTS..
07-12-2011 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-11-2007

Post #: 31
Post ID: 16666
Reply to: 16665
Phaseplugs etc.
fiogf49gjkf0d
Zako, TAD's newer drivers came about 10 years before the newer JBL's and the 4003 has 6 slits, not 5 as the sales material say.

Rgds.

e
07-12-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 32
Post ID: 16668
Reply to: 16666
Cutaway diagram..
fiogf49gjkf0d
THE CATALOG I HAVE FROM TAD STATES AND SHOWS A SIDE CUTAWAY WITH 5 SLITS... CAN YOU SHOW A NEWER CUTAWAY DIAGREAM ???ITS PRETTY COSTLY TO REDESIGN AND PRODUCE..BUT PIONEER HAS THE MONEY,
07-12-2011 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-11-2007

Post #: 33
Post ID: 16669
Reply to: 16668
6 slits
fiogf49gjkf0d
Hi Zako

There is a slit that is not vissible on cut away drawing, it is located right next to the junction of the speech coil former and the diaphragm.

Rgds.
07-12-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 34
Post ID: 16670
Reply to: 16669
Coil corner
fiogf49gjkf0d
I SEE IT NOW,,,I DONT UNDER STAND HOW MUCH AUDIO ENERGY COMES FROM THAT COIL CORNER (Thats what I call it) BUT I GUESS EVERY BIT HELPS...
07-13-2011 Post does not mapped to Knowledge Tree
tuga


Posts 174
Joined on 12-26-2007

Post #: 35
Post ID: 16673
Reply to: 16670
All-CAPS
fiogf49gjkf0d
 zako wrote:
I SEE IT NOW,,,I DONT UNDER STAND HOW MUCH AUDIO ENERGY COMES FROM THAT COIL CORNER (Thats what I call it) BUT I GUESS EVERY BIT HELPS...


Hi Zako,

I'm sure you are not doing this intentionally but your all-CAPS writing style makes your messages hard to read.
Besides, writing in CAPS is considered offensive as you can read here.

Cheers,
Ricardo


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
07-13-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 36
Post ID: 16675
Reply to: 16673
Cursive Drivers
fiogf49gjkf0d
RECARDO,,,,ITS OBVIOUS YOU DONT KNOW HOW TO READ...SOON ALL SCHOOLS WILL ALSO DROP CURSIVE WRITEING,,,HOW WILL THE KIDS PLACE THE SIGNATURE ON A DOCUMENT,,,PRINT IT?  YOUR LUCKEY A DIDNT WRITE  IN RUSSION,,,OFFENSIVE WOULD BE IF I TOLD YOU TO FECK OFF,,AUDIO SPEAKER DESIGN HAS TAKIN A SLOW BUT POSITIVE ADVANCEMENT IN QUALITY DESIGN.. A GOOD EXAMPLE IS THE JBL 1501 WOOFER A ENGINEERING MARVEL..THE NEW VITAVOX COMPANY IS GOING OVER OLD GROUND HOPEING TO CASH IN ON OLD NOSTALGA..I HOPE IN THE FUTURE THEY WILL INTRODUCE SOME THING BETTER..
07-14-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 37
Post ID: 16677
Reply to: 16675
Come on, zako!
fiogf49gjkf0d
 zako wrote:
Recardo,,,,its obvious you dont know how to read...soon all schools will also drop cursive writeing,,,how will the kids place the signature on a document,,,print it?  Your luckey a didnt write  in russion,,,offensive would be if i told you to feck off,,audio speaker design has takin a slow but positive advancement in quality design.. A good example is the jbl 1501 woofer a engineering marvel..the new vitavox company is going over old ground hopeing to cash in on old nostalga..i hope in the future they will introduce some thing better..
Zako, I truly surprised with your reaction.  I have sent you emails asking do not use caps at least for titles. In the past I did edit your posts converting your titles caps to a sane lower case.  The titles of posts make the site front page and beside that it looks absurd it also breaks up my algorithm that circulates the title width and abridges the title in order to fit in the front page columns. Whatever drives you to use all caps I do ask you do not use all caps for titles/subjects of your posts. Regarding the use all caps in the body of the posts – I is all yours but be advised many people, sometimes including me who do read all caps posts, at my site, or anywhere else. It is a labor to read them, regarding what you think.

I will not talk about it again and will not reply to further talk about all caps. The subject of this thread is compression drivers not to discipline others writing style, witch would look ridicules coming from me. Still, your all caps insisting does appear irrational.

hAvE A gOoD DaY,
Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-04-2012 Post does not mapped to Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 38
Post ID: 17903
Reply to: 16644
Larger diaphragm area vs. inductance increase
fiogf49gjkf0d
 Romy the Cat wrote:
So, if the Ultimate MF Compression Driver is used from 1000-1500Hz then why shall it be able to play 500Hz? The answer is: he harmonic reserve – the driver that will be suited for 500Hz will have larger cone and softer sustention and consequentially it will play 3khz with more harmonic richness.

Sure, I’m also supporter of the big diaphragms in general, and they really provide more harmonic richness in the midrange, just as you said, but I also see one very big disadvantage with them in context of compression drivers. The problem is that the larger the diaphragm becomes, the larger its driving voice coil has to be. For the same length of wire in the gap, the inductance raises proportionally with raising the VC diameter. So 4” VC will have twice more inductance compared to 2” VC. And since the VC inductance acts as electrical low-pass filter for the input signal, the more the inductance, the lower the frequency it will start to rotate the electrical phase of the incoming signal within the usable bandwidth of the driver. Everybody knows what happens when the phase shift enters the game – it starts to kill the time (phase) relation between the higher and lower overtones of a given instrument and this instrument starts to lose its tone identity and sense of realism…
It is practically very difficult for a big diaphragm compression driver to have low inductance and to be efficient at the same time. One could perform the following experiment. He has to disassemble a given CD, and then to remove the second layer of wire out of the VC. He will loose 3dB of efficiency, but when he hear the effect of the more than halved inductance (it is not mistake – inductance is lowered more than 2 times, because with just one layer there is no additional mutual inductance between the layers) and the effect of the extended with a whole octave phase linear response, he will quickly understand the amount of inductance is essential for the harmonic relation and expression of the upper midrange and the lower HFs in context of the midrange. So as we see, the "ultimate" compression driver should have big cone (in order to reproduce the fullness of the midrange correctly) but at the same time it should have very low inductance to avoid the huge phase rotations within its working range. So the only solution remains to sacrifice some efficiency by lowering the amount of voice coil turns...
 
Best regards,
P. Haralanov



"If you can't explain it simply, you don't understand it well enough." -A.E.
03-04-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-27-2004

Post #: 39
Post ID: 17904
Reply to: 17903
Not unequivocal evil.
fiogf49gjkf0d
Hm,… yes and no. Inductance is not necessary an evil. Well, it is an evil for open-top-end drivers but you need to look at the life of compression driver all around and then you understand that inductance is not limiting evil. Sure with grow of diameter inductance grows but so what? With grow of diameter the larger surface of diaphragm become more hanging in free air. You can’ make the diaphragm stiffer as you would like to keep mass as low as possible. As the result the driver pick up some break-up at higher frequency if the diaphragm is too large for given suspension. While it happens the low-pass filtration base upon the inductance of VC become quite a blessing as it slightly subdues the resonances that takes place over 25kHz. Do not forget that in case of compression driver no one wants it to go too high anyhow. A compression driver is load into horn and horn has own optimum bandwidth of 2-3 octave. No one need a compression driver that make 300Hz and 15kH. Well, idiots need it as they have no idea what they are doing but then have shitty 300Hz and shitty 15kH, thankfully for them idiotism in technical aspect comes alone  with idiotism in sound perception and they luckily do not understand that they are get garbage.

The point is not in larger or smaller diaphragm but in a very delicate balance of diaphragm size, mass, suspension, mechanical and electrical dumping alone with dozens of other parameter, I do not see anybody make any claims that they know how to do it. There are success in one or another direction but no one owns the Unified theory of compression driver design. I think that inductance is not too much in the picture in compression driver. I am not the best example but take a look what I do. I have no obstacles to get any driver I want and to use it in any way I want and what I do with Macondo MF channels? I use relatively resonating driver with VERY resonating output tube and I deliberately introduce after my MF amp my own manageable inductance to hold the driver resonances in the format I want. So, I am not the best person to confirm that inductance is evil in unequivocal compression drivers.

The Cat
 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-05-2012 Post does not mapped to Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 40
Post ID: 17905
Reply to: 17904
You must hear the actual sound result
fiogf49gjkf0d
Romy, if you have some spare diaphragm/VC assemblies for your S2 drivers, do the experiment I mentioned above (remove the outer layer of the VC) and we will talk about the inductance in terms of sound after you hear the results with your own ears...  You can use 3-4” paper cone in front of the horn to block the HF content above 11-12-13kHz – this acoustic filter does not rotate electrical phase of the signal. At the same time you can use very small series coil as a lowpass filter at 16-17kHz in order to lower the density of the frequency spectrum which makes the diaphragm to resonate. Of course this coil will also rotate the electrical phase, but it will do it at much higher frequency compared to the high self inductance of the VC.

In my previous posting I haven’t said that the compression driver must be used in 300-15000Hz range – it is more than obvious the horn itself will be the limiting factor and I don’t know why mentioned it. The low inductance is needed not to use a given driver up to 15kHz, but to avoid phase fluctuations in the upper midrange.

Best regards,
Petar



"If you can't explain it simply, you don't understand it well enough." -A.E.
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