Technical Questions

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

dragonfyr — Tue, 06 Sep 2005 23:09:35 GMT

Bottom line:

So, after all of your objections, the bottom line is that the cardioid sub is not only a real item, it also works remarkably well in the real world!

And whether someone can make a horn subwoofer, or any of the myriad variations on a theme - sure, I suspect anyone can do just about anything! Go do it! And go find and talk to someone actually proposing such a scheme!

Unfortunately all of these scenarios exist only in your vivid imagination and not in the article! You can postulate all the 'what if' combinations and permutations you like. I really have no intrerest in pursuing them! I was interested in discussing the finer aspects of the underlying concepts of the cardioid sub as presented.

The bottom line is that the cardioid subwoofer is real and it performs remarkably as described and measured!

And as far as the patent for a low frequency horn, I find it ludicrous that I am supposed to go back and read it when I started the thread with the intent to discuss the, and I will go very slowly here, C A R D I O I D S U B W O O F E R, as described in the article posted.

I can only imagine the ramifications that might be imagined!? And what if these were used for underwater applications!? Oh, oh! I shouldn't have mentioned that even in jest, as I suspect we may get reactions to their imagined use in outer space and on Uranus!

Sounds to me like Don Quixote is wandering about lost while out looking for windmills.

Not surprisingly, this thread is trashed and I no longer have any interest in it. Have fun!

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

D-MAN — Tue, 06 Sep 2005 22:53:31 GMT

Here it is! look it up yourself, cause it's a long one!

DM

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

D-MAN — Tue, 06 Sep 2005 22:40:47 GMT

Patents are NOT required to PROVE anything; they are NOT scientific publications. They are a legal protection for "manufacturing purposes". That is ALL. If someone wants to make something for sale, the patent is the means by which the particulars of the invention, being unique or an improvement to some other invention, may be legally protected and restricted from being manufactured for sale by others.

Patent inventions are NOT required to actually work - they must only provide a reasonable EXPECTATION to those familiar with the particular art that they would work in the manner OR for the purpose claimed in the patent, but the DEGREE to which that particular work is achieved remains a matter of opinion and is regarded as unsubstantial and is not patentable in itself.

For example, one of my favorite patents of all time is the removable charcoal filter for underwear. Does it actually work?! Who in their right mind wants to find out? Not me. But it's conceivable that it MIGHT actually do some gaseous "filtering" due to its constituent construction and placement (ahem). Scientific proof, however, is not required in order to obtain a patent.

DM

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

Arkytype — Tue, 06 Sep 2005 22:34:07 GMT

First, we are concerned with shaping an omnidirectional LF polar response to conform with a cardioid polar response without changing its frequency response. With a cardioid subwoofer we are essentially taking a 'ultra low', essentially non-Q device and modifying it into a higher Q device without modifying its frequency response.

You also mention shaping the units "frequency response" into a "cardioid frequency response" pattern, a goal that is as spurious as it is non-sensical. We have no interest in affecting a "cardioid EQ", whatever that is!

Of course, I should have written "cardioid polar response".

Czerwinski's horn has little to do with a cardioid subwoofer. Despite its attempt to reconfigure the Q of the unit, it has little or no application within the niche we are talking about!

Who says that the horn he proposes can't be designed for a low frequency cut-off of (say) 20 Hz? Would that meet your definition of a subwoofer?

And a low frequency horn is not an omnidirectional device.

Says who?

If a subwoofer or low frequency horn (fc=20 Hz) is positioned near a planar surface with dimensions approaching the wavelengths of interest, then, by definition, neither will exhibit an omnidirectional polar response pattern.

However, if we fly them with rigging above the center of a large hall, then they would exhibit true "omni" directional polar response pattern.

We are specifically dealing with mocifying the polar pattern of an omni-directional source to increase it's (sic) Q and to provide a larger measure of well-behaved control over its radiated acoustical energy.

I stand by my original response to your statement: Perhaps if you read Mr. Czerwinski's patent more closely you would see that he is proposing exactly the same end result as the DIY Cardioid Sub article: directional control of a loudspeaker's polar response.

To quote Czerwinski's patent application, "The output of the (horn) loudspeaker is a monopole and therefore is omnidirectional." "...When the first and second (dipole) transducers are added...their radiation output in front of the loudspeaker is a dipole.....The combined monopole and dipole produces a cardioid-shaped wave."

How does the end result Czerwinski proposes differs from that in the Do-It-Yourself Cardioid Sub article?

To quote Shirk, "Herein lies the trade-off. The amplifier power required will increase as frequency decreases..... Two octaves below the design frequency, the output capability of the array will be 6 dB lower...."

Congratulations, you read well! Unfortunately your understanding and conclusion that this approach requires "10 times" the power is completely absurd!

Let's take a typical horn-loaded woofer with a sensitivity of 100 dB SPL/watt . Is it absurd to think that the same woofer mounted in an open-back baffle would have a sensitivity of 90 dB SPL?

I was not referring to the example in the DIY article when I wrote the 10X power factor.

Wonderful math, except you demonstrate your complete ignorance of what constitutes an octave considering a sub-woofer is not being used to reproduce mid-bass frequencies!! For a sub-woofer, the most common lower two octaves would be 20Hz-80Hz!

The example given in the DIY article is a subwoofer with a high frequency cut-off of 140 Hz. Guess the author is demonstrating his complete ignorance of what constitutes subwoofer frequencies.

And as anyone would realize if they read for meaning, as the frequency bandwidth increases, the increasing effects of comb filtering renders this technique problematic, both from a frequency prespective and from a polar pattern perspective!

Are you stating the obvious for a reason or did you think I might not have grasp that concept by reading it in the article?

Providing a 6dB increase in amplification is not prohibitive!

So let's carry this through to the logical conclusion! We are dealing with a subwoofer! A subwoofer whose response will be crossed over on a high end at ~100Hz( 2 octaves ranging from 25-100Hz), or more appropriately at ~80Hz. "Two octaves below the design frequency" of say 80Hz is 20 Hz. 6dB gain is not 10x the power required!

Once again, I never stated that 10x power would be required for the DIY article example. Keep re-reading my explanation above--maybe it'll sink in.

And to say that more power is required for equivalent gain at low frequencies is a given! Unless you know of commonly used woofers that are more efficient then MF or HF drivers!

I was only repeating the trade-off of the proposed design in the article--I mentioned no other type of loudspeaker.

And since you yourself make referance to a KHorn, one wonders to what mystical LF transducer exhibiting an efficiency greater then a MF or HF driver you are referring!?!?!?n The K-33 woofer???? Right!!!

My reference to modifying my Klipschorns was, like the valve stem remark, written tongue-in-cheek. Wonder if the above statement (as well as your petty personal attacks) was written head-up-a...?

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

dragonfyr — Tue, 06 Sep 2005 21:41:42 GMT

If and when you wish to accurately add to the understanding of the technologies instead of your confused 'mix and match' treatment of two different technologies arbitrarily addressing two different issues as if they are the same, please feel free to do so!

It is humorous that you evidently have issues with the concept and application of cardioid subwoofers, a demonstrably real and proven technique. This is not a concept paper except that it attempts to explain and bring the concept within the practical realm of others who might not be familiar with its implementation.

So your fascinating hangup with this thread is rather entertaining in a pathological sort of way!

And it is amusing as you seem to treat LF horns in the same breath that you treat subwoofers. An interesting concept, but not one that neither paper attempts to bridge. And to think that someone would use 1000 watts for a subwoofer! Oh my! Is that ALL?!?

...So now what am I going to do with the Macro-techs sitting at home! And even if I employ them, they are going to sit on a maximum setting of "2"! And did I say "they"? What a waste of resources! I should have said "it" will sit on a setting of "2"!

...And to think that my PC has 2GB of RAM! Let me sit down before I succumb to the vapors! Oh the world of rampant excess!

May I suggest a better evaluation of the application and your appropriate available resources!

You remind me of Lipshitz and Vanderkoy when waxing so eloquently over how the PZM microphone will never function properly! ...Not to mention how they felt that Heyser's research was nonsense as well!

So, after all of your objections, the bottom line is that the cardioid sub is not only a real item, it also works remarkably well in the real world!

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

Arkytype — Tue, 06 Sep 2005 20:27:06 GMT

"This would be accomplished by filling the enclosure with a gas whose density is less than that of air. Gene, would this speaker come with a valve stem for periodic replenishment? "

Since you didn't bother to read it, I'll help you out here. The gas should be heavier than air, so it won't leak out. Dayton Wright used SF6 in some of their speakers, although for a different reason.

djk---Don't presume to know what I have or have not read.

I did read Czerwinski's patent several times. Since I didn't have access to gas density info and the formulas involved at the time, I relied on Czerwinski's patent wording and erroneously concluded the gas density needed would be less than that of air.

"This patent (like a couple of his other ones) is an apparent cure for no known disease. "

Lack of low frequency directivity is a real problem in PA, as dragonfyr mentioned.

I'll concede that lack of low-frequency directivity can be an issue for venues larger than a home listening environment.

Actually, the C-V patent is more of a dipole than a cardioid. Dipoles can exhibit 6dB of gain compared with a simple sealed box. Too bad you didn't understand this either.

Apparently, it is you who have not read or understood Czerwinski's patent.

In it, he states (no less than six times) that, "The combined monopole and dipole produces a cardioid-shaped wave.".

Now, I may be an Arkansas Hillbilly educated beyond his intelligence, but Czerwinski's patent description doesn't sound like the resultant polar pattern is a dipole to me.

The dipole driver also fires into the horn, the parameters of the driver determine the load match for the distance down from the throat. See the Unity patent from Tom Danley if you don't understand how this works.

The Danley patent you cite (U. S. Patent 6,411,718) has nothing to do with dipole drivers or modifying the the polar response of a loudspeaker. The rear radiation from each driver is sealed.

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

djk — Fri, 02 Sep 2005 06:00:55 GMT

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

Arkytype — Thu, 01 Sep 2005 21:54:30 GMT

dragonfyr wrote:
Arkytype wrote:
Eugene Czerwinski is better known as the founder of the loudspeaker company Cerwin Vega.

This patent (like a couple of his other ones) is an apparent cure for no known disease. Perhaps his most noteable patent is # 4,101,736 which offers a " ...Device to effectively enlarge the volume of the speaker enclosure...". This would be accomplished by filling the enclosure with a gas whose density is less than that of air. Gene, would this speaker come with a valve stem for periodic replenishment?

It would seem it is easier to get a patent for an "improvement" of an existing invention than for the invention itself. In the patent dragonfyr refers to, Czerwinski cites several well-known existing patents and then offers (without proof) that adding woofers to the outside of a bass horn will create a "cardioid-shaped wave."

Hmmm. Did he account for the fact that the external woofer would probably require ten times more power than the horn-loaded driver to have the desired effect of acoustically combining to form this long-sought-after Holy Grail of directionality?

Can't wait to cut holes in the rear of my Klipschorns to try this.

Huh? What in hell does this have to do with a cardioid sub? This has quickly become very confused! Or, more correctly, the replies are rather confused!

I think djk was simply responding to your post with info on another approach to achieving a cardioid frequency response.

Your insights, I mean observations, or, well, simply assertions, have NOTHING whatsoever to do with what I posted nor the topic of this thread!!

And that would be in violation of Forum rule number.......?

"Hmmm. Did (YOU) account for the fact that" Czerwinski's horn has NOTHING to do with a cardioid subwoofer.

Perhaps if you read Mr. Czerwinski's patent more closely you would see that he is proposing exactly the same end result as the DIY Cardioid Sub article: directional control of a loudspeaker's frequency response.

And "In the patent dragonfyr refers to", Dragonfyr NEVER referred to any such patent! In fact, I have never even heard of the $*#&% thing!

My mistake, I should have written, "In the patent djk refers to..."

May I suggest that you go back and try reading the original post!

And with the wealth of well behaved constant directivity and other associated horn formats offering various well-controlled and behaved Q's, I am not sure where it even fits.

Nor do I have any idea what the cardioid horn has to do with the cardioid sub that uses the principle of superposition to achieve its resultant polar pattern.

And superposition has little to do with excessive amplifier power! In fact is is almost independent of it, provided that the various sources are closely matched.

To quote Shirk, "Herein lies the trade-off. The amplifier power required will increase as frequency decreases..... Two octaves below the design frequency, the output capability of the array will be 6 dB lower...."

That means (using his example) at 35 Hz you'd need four times the amplifier power than at 140 Hz for the same acoustic output. If you are averaging 250 watts at 140 Hz, you'd need 1,000 watts at 35 Hz.

Cardioid subs are rather common and are a proven commodity. This was not a proposed concept paper!

And where does this "10X" power requirement come from????

It's probably a fair assumption that (in Czerwinski's patent) a horn-loaded woofer would require a tenth of the power of the non-horn loaded woofers shown in the drawings.

And cut holes in the back of your KHorns? My first reaction would be to fill in some of the holes located elsewhere!

What does any of this nonsense have to do with a cardioid sub!?!?

I am very confused regarding the additional non sequitur posts!!!

But it appears that I am NEITHER the only,nor the most confused person here !

It appears I'm in a battle of wits with a half-armed opponent.

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

dragonfyr — Thu, 01 Sep 2005 13:31:24 GMT

Arkytype wrote:
Eugene Czerwinski is better known as the founder of the loudspeaker company Cerwin Vega.

This patent (like a couple of his other ones) is an apparent cure for no known disease. Perhaps his most noteable patent is # 4,101,736 which offers a " ...Device to effectively enlarge the volume of the speaker enclosure...". This would be accomplished by filling the enclosure with a gas whose density is less than that of air. Gene, would this speaker come with a valve stem for periodic replenishment?

It would seem it is easier to get a patent for an "improvement" of an existing invention than for the invention itself. In the patent dragonfyr refers to, Czerwinski cites several well-known existing patents and then offers (without proof) that adding woofers to the outside of a bass horn will create a "cardioid-shaped wave."

Hmmm. Did he account for the fact that the external woofer would probably require ten times more power than the horn-loaded driver to have the desired effect of acoustically combining to form this long-sought-after Holy Grail of directionality?

Can't wait to cut holes in the rear of my Klipschorns to try this.

Huh? What in hell does this have to do with a cardioid sub? This has quickly become very confused! Or, more correctly, the replies are rather confused!

Your insights, I mean observations, or, well, simply assertions, have NOTHING whatsoever to do with what I posted nor the topic of this thread!!

And your response bears allot incommon with the "patent (that) is an apparent cure for no known disease." Only in this case I certainly wish we could find the cure for dementia!

Perhaps you have some equally valuable addition insight into, say, variables contributing to the instability of the market relationship between Thai umbrellas and Emperor penguins!

"Hmmm. Did (YOU) account for the fact that" Czerwinski's horn has NOTHING to do with a cardioid subwoofer.

And "In the patent dragonfyr refers to", Dragonfyr NEVER referred to any such patent! In fact, I have never even heard of the $*#&% thing!

May I suggest that you go back and try reading the original post!

And with the wealth of well behaved constant directivity and other associated horn formats offering various well-controlled and behaved Q's, I am not sure where it even fits.

Nor do I have any idea what the cardioid horn has to do with the cardioid sub that uses the principle of superposition to achieve its resultant polar pattern.

And superposition has little to do with excessive amplifier power!
In fact is is almost independent of it, provided that the various sources are closely matched.

Cardioid subs are rather common and are a proven commodity. This was not a proposed concept paper!

And where does this "10X" power requirement come from????

And cut holes in the back of your KHorns? My first reaction would be to fill in some of the holes located elsewhere!

What does any of this nonsense have to do with a cardioid sub!?!?

I am very confused regarding the additional non sequitur posts!!!

But it appears that I am NEITHER the only,nor the most confused person here !
-----------------------------------------------------

First, we are concerned with shaping an omnidirectional LF polar response to conform with a cardioid polar response without changing its frequency response. With a cardioid subwoofer we are essentially taking a 'ultra low', essentially non-Q device and modifying it into a higher Q device without modifying its frequency response.

You also mention shaping the units "frequency response" into a "cardioid frequency response" pattern, a goal that is as spurious as it is non-sensical. We have no interest in affecting a "cardioid EQ", whatever that is!

And that would be in violation of Forum rule number.......?

It's referred to as 'common sense', or within the communication realm, as 'parallel structure'! And yes, it's significance is wasted.

Czerwinski's horn has little to do with a cardioid subwoofer. Despite its attempt to reconfigure the Q of the unit, it has little or no application within the niche we are talking about ! And a low frequency horn is not an omnidirectional device. We are specifically dealing with mocifying the polar pattern of an omni-directional source to increase it's Q and to provide a larger measure of well-behaved control over its radiated acoustical energy.

Perhaps if you read Mr. Czerwinski's patent more closely you would see that he is proposing exactly the same end result as the DIY Cardioid Sub article: directional control of a loudspeaker's frequency response.

So do line arrays and Bessels and techniques such as comb filtering, and any number of other intentional acoustical designs and anomalies! The fact that they have nothing to do with modifying the omnidirectional nature of direct radiating subwoofers into a higher Q cardioid subwoofer has obviously been missed!

One additional main difference is that well behaved designs DO NOT try to change the polar pattern of a 'loudspeaker's frequency response', but rather they attempt to control the radiated acoustical energy over the full frequency range. Words mean things.

A "cardioid frequency response" is non-sensical.

May I suggest that you go back and try reading the original post!

To quote Shirk, "Herein lies the trade-off. The amplifier power required will increase as frequency decreases..... Two octaves below the design frequency, the output capability of the array will be 6 dB lower...."

Congratulations, you read well! Unfortunately your understanding and conclusion that this approach requires "10 times" the power is completely absurd! Wonderful math, except you demonstrate your complete ignorance of what constitutes an octave considering a sub-woofer is not being used to reproduce mid-bass frequencies!! For a sub-woofer, the most common lower two octaves would be 20Hz-80Hz!

And as anyone would realize if they read for meaning, as the frequency bandwidth increases, the increasing effects of comb filtering renders this technique problematic, both from a frequency prespective and from a polar pattern perspective!

Providing a 6dB increase in amplification is not prohibitive!

So let's carry this through to the logical conclusion! We are dealing with a subwoofer! A subwoofer whose response will be crossed over on a high end at ~100Hz( 2 octaves ranging from 25-100Hz), or more appropriately at ~80Hz. "Two octaves below the design frequency" of say 80Hz is 20 Hz. 6dB gain is not 10x the power required! Especially as you have not even factored in the potential effects of acoustical boundary and room gain or a proximity effect depending upon the specificc application and or sitaution being addressed.

And to say that more power is required for equivalent gain at low frequencies is a given! Unless you know of commonly used woofers that are more efficient then MF or HF drivers!

And since you yourself make referance to a KHorn, one wonders to what mystical LF transducer exhibiting an efficiency greater then a MF or HF driver you are referring!?!?!?n The K-33 woofer???? Right!!!

Fortunately the cardioid subwoofer is not only both practical and achievable, it is also very effective in that it provides a real solution to a real problem! This is not some theoretical concept paper! It is an application note, if you will! A significant distinction which has utterly escaped your astounding insight!

It appears I'm in a battle of wits with a half-armed opponent.

For someone who is unable to understand the original restrictions upon the design and the intended application, I guess anything can be seen to relate! Unfortunately such a simple demonstration of pattern recognition demonstrates neither insight nor understanding. But congratulations on recognizing the word "cardioid" in both articles! Now maybe you you can discover what it means and how it is apropos to the situation! And while you are at it, spend a bit of time to figure out just what a "cardioid frequency response" is!

And unlike your response, the cardioid subwoofer provides a very practical solution to a very real problem.

It's a shame when a 'half-wit' understands this, while such a capable individual does not!

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

Arkytype — Thu, 01 Sep 2005 11:11:09 GMT

Eugene Czerwinski is better known as the founder of the loudspeaker company Cerwin Vega.

This patent (like a couple of his other ones) is an apparent cure for no known disease. Perhaps his most noteable patent is # 4,101,736 which offers a " ...Device to effectively enlarge the volume of the speaker enclosure...". This would be accomplished by filling the enclosure with a gas whose density is less than that of air. Gene, would this speaker come with a valve stem for periodic replenishment?

It would seem it is easier to get a patent for an "improvement" of an existing invention than for the invention itself. In the patent dragonfyr refers to, Czerwinski cites several well-known existing patents and then offers (without proof) that adding woofers to the outside of a bass horn will create a "cardioid-shaped wave."

Hmmm. Did he account for the fact that the external woofer would probably require ten times more power than the horn-loaded driver to have the desired effect of acoustically combining to form this long-sought-after Holy Grail of directionality?

Can't wait to cut holes in the rear of my Klipschorns to try this.

Re: Cardioid Subwoofers - Modification of LF Polar Directivity

djk — Thu, 01 Sep 2005 05:37:21 GMT

Gene Czerwinski has an interesting patent on a cardioid horn.

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=3&f=G&l=50&co1=AND&d=ptxt&s1=Czerwinski.INZZ.&s2=Eugene.INZZ.&OS=IN/Czerwinski+AND+IN/Eugene&RS=IN/Czerwinski+AND+IN/Eugene

Cardioid Subwoofers - Modification of LF Polar Directivity

dragonfyr — Wed, 31 Aug 2005 18:34:35 GMT

As there seems to be allot of talk about LF omnidirectivity (there is no 'lack' of directivity!), I thought I would post this article that I think you will find is both educational and pretty darn complete in its treatment of the subject.