Romy the Cat wrote:

"...Let pretend that some kind of company take the Jessie’s idea under the wing and begin to commercialize it..." "...I really think that someone who is willing to be in the business should look at the Jessie’s idea of frame-motherboard and take it further..."

Paul S wrote :

"...Jessie, you know I am not a horn guy. I played with horns for 5 years, and I have heard plenty of them, and so far none have worked for me, musically.  But I have remained mindful of horns' potential, and I keep coming back to that, for various reasons..." 

Paul, first thanks again for the input, and second, watch out...One of my objectives in pursuing this project is to get you back into horns!

"...Perhaps you could figure the circumference of your big horn at given lengths and thereby turn the form(s)/mold(s) in sections..."

Ok I lied when I said "no the large horns will not be turned"... I am able to turn big chunks, and at one point was thinking (once again) exactly as you suggest (are you a Taurus or what?)... The original construction process I had in mind was in fact to turn one 1/8th segment of the large end (see CAD images in previous posts)... Regardless of the final material used for the actual horn, I still may end up "turning" the mold from plaster.

See below a large chunk of the tool I turned/molded (keep wanting to spell it like in French "mou...") for the Upper-Bass horn :

Above : The clients visiting my workshop checking on progress... On
the table is part of the tool I use to make the Upper-Bass horns... It is
turned and molded... From here I make a 2-piece "female" copy, into
which I load the plaster and hemp for the actual horn.



Above : Same but end view (the photo is sort of pixelated, making the horn
look rough... In reality it is not... I however really do look this rough)


Above : Same but showing interior (on the right is the internal forming
tool, which serves only once, so its constructino is rather thin by comparison;
just enough to do the job one time.)

BTW, these are my disposable "horn-making-clothes"... In all future photos
you are likely to see me wearing these same clothes, until I throw them out...
The plaster does not come out in the wash.

"...Of the large horns I have heard, tossing out the plywood ones, only two were concrete (one poured in place, one gunnite), both "exponential", neither worth the effort, IMO, and I'm sure you would agree if you heard them. One was round, one was rectangular (no parallel walls, however).  I do not suppose for even one second that the "exponential" profile was "the cause" of the problems..."

There are many reasons why they may not have been effective, however, I would suspect throat diameter as the most often over-looked criterion.

jd*

be wrote:

Regarding the shape of dazzies horn: I can only see a decorative reson to make it round, I dont believe that round is better than rectangular in this range, in fact a rectangular shape will make a much better coupling to the room boundaries possible and extend the useful range 1-2 octaves lower, depending if dazzie can place it against a floor (or ceiling) and a wall.

Well, I do not think that it would be as much as 2 octaves but rather a .5-.7 octaves at it’s max but still the point is extremely valid. Unfortunately I do not think that there is a final judgment on it. I would also intellectually agree that round might not be better than rectangular in this range but what for our intellectual analyses would be the definition of “better”?

If a round bass horn is crossed at 240Hz with a second order then I would question that rectangular horn is the ultimate shape. The problem is that the differences might (or might not) be only in the very fine details of imaging, that it VERY difficult to judge or to compare. Even if someone would make, let say 100Hz, round and rectangular horns then it would be also very difficult to observe the imaging differences as this range the relationship between the horn and room would be too influential.

So, if I were doing that project I would not care about “decorative reasons” or “imaging rational” it will be no conclusion in there anyhow. I would rather ask myself: how many times in life a person has guts, stupidity, conditions and courage, not to mention the wife’s blessing, to build a round 45Hz horn? I never seen anyone who did it twice but I have seen very many people who did it zero times…

Still, being adult and pragmatic, and taking under consideration that you “be” is very correct - with boundary loading I might consider the following: if I go for segments (let say 5-7-9-11 segments) and then if I decided to ceiling-load my horn then I would NOT need to remake the horn but only to change the bottom profile of one or two segments. I think it would preserve the “decorative objectives” of the roundness but at the same time it would be utilitarian enough to serve the might-be-changing RTA’s objectives.

Jessie, I’m very ignorant in materialology but I have a “common sense” concern. I do not see that you imbedded into your plaster construction any tightening points from a stronger material. I mean: the holes in plaster – how strong you will be able to tight the bolts before the plaster will give up? Did you think what you will be using for the bolts or studs bases?

Rgs, Romy the cat

Erik,

The high pressure zone near the throat does not create distortions; the distortions (the turbulence of the wave’s front) are created right after that zone (according to William Hall, MIT, 1932, though no one said hat he is right). Also, it is very much frequency-related and at relatively low frequencies the waves propagate very linear across the horn. Do not forget that we do not have linear dependences between the horn size and the wave length…

Moreover, Erik, the AES experiment that you described unquestionably was very interesting but let look critically (my favorite mode :-) to what went on there.

You said: “two round and straight  horns where made with the same theoretical cut off frequency, something like 100Hz, they had the same mouth and throat diameter, hence the exponential horn was somewhat longer.”

There is something in this experiments that make it methodologically not kosher for me as they did not equalize the conditions. The exponential horn is longer then conical or Tractrix and if all those horns have the same mouth’s and throat’s diameters then the exponential will have larger volume of the horn bell and consequentially the larger amount of air inside of the horn. The larger amount of air produces more air mass and consequentially creates higher throat reactance. From now, it will only depend from what kind of driver the horn uses. With a driver that has a relatively low diaphragms mass (any compression driver for instance) then the minuscule change in the throat reactance will be sufficient to change the cone’s damping and certainly the sound of the entire horn. So, if we have different horns, with different air volume, use the same drivers and they are wiling to compare them, then the drivers’ resonances shell be also equalized. Here is where another problem hits – as soon you begin to EQ the driver’s resonances then the drivers begin to change sound; to change sound depends what other methods of resonance EQ you have chosen. Therefore you do not observe anymore the sound of identical horns of the different profile but rather you hear two fundamentally different sound producing sources.

I personally, dealing with horns do not use theoretical bases to observe what happen with them and I tend to use purely empirical ways. It is my believe that NO one TRULY knows what the hell it going on with horns and no one has any idea how a driver will sound when it will be horn loaded. Just listening the thing, developing better listening understanding and compiling it into more and more accurate listening evaluation techniques I think is more beneficial then knowing the theory about the horn operation.

Romy the Cat wrote:

I personally, dealing with horns do not use theoretical bases to observe what happen with them and I tend to use purely empirical ways. It is my believe that NO one TRULY knows what the hell it going on with horns and no one has any idea how a driver will sound when it will be horn loaded. Just listening the thing, developing better listening understanding and compiling it into more and more accurate listening evaluation techniques I think is more beneficial then knowing the theory about the horn operation. Rgs, Romy the Cat

Marcus, my opinion about it does not change.

Any systematic methods of simulation of horn driver/horn systems are true only within a scope of very specific coordinate systems that was chosen for predictions or simulations. It is wonderful for patent applications, for writing PhD theses or for participating in intellectual discussion about horns operation, or perhaps for better understanding roles of drivers but unfortunately no one of those people who do it ever was able to associate their research with actual Sound. Sure, the systematic and conceptual methods might prevent some rudimental mistakes but those people never (at least I did not see) were able to make Sound better in term of it human/musical nature.

I am sure it would be a lot of people who disagree with me but what important to understand is that I do not built in my mind an abstract knowledge base about horns. My interest about entire horn subjects is as deep as it has relation to the very practical Sound that I am able to experience and as long it serve my auditable interests. All the rest conversations about horns, although I perfectly acknowledge their rights to exists, are just do not attract my interest.

By distortion in the throat I mean distortion caused by the nonlinearitiy of air that manifest itself by high pressures.
I dont think this was known in those days.
If this makes any significant audible difference in this particullar case I dont know, but I wanted to compare a somehow comparable Tractrix with an Exponential, since there was some concern on  Jessies behalf regarding this.
Turbulence does not cause distortion as amplitude nonlinearities does, maybe it should be termed noise? Is this really a problem?

You are absolutely right that the conditions of the experiment can be questioned, and maybe comparing two horns of same volume or maybe same length would be more significant to our practices.
You can make the tractix to go as low as an Exponential, but then it would have a larger mouth diameter.
On the other hand in many cases the maximum allowable horn diameter can be the limiting factor and then the little AES paper is very helpful.

I agree  again, one cant predict how the result is really going to be unless you make the horn and listen to it in the intended set up etc. etc. but lets hope we are not completely blind and can make some reasonable predictions with our minds and whatever other means we have.

be wrote:

By distortion in the throat I mean distortion caused by the nonlinearitiy of air that manifest itself by high pressures.

Erik, I do not see why higher pressure atomically implies nonlinearity. Gas pushers its walls very linear in all directions and, as I remember from my high school, the nonlinearity of pressure come only from the nonlinearity of temperature and volumes. Mostly likely you refer NOT to “nonlinearity of air that manifest itself by high pressures” but to the nonlinearity of jointing the profiles of horn and internal waveguide of a compression driver. This does take place but I never seen anyone bitch or even care about it beside me…. (Read my Vitavox  S2 with electromagnet thread)

be wrote:

I dont think this was known in those days.

You would be very surpassed what know in those days… :-)

be wrote:

I know they knew a lot in those days and could have dealt with the nonlinearity of air if they wished to or if there attention was drawn to it.

Actually, you are right. The problem during those days was not with shortage of knowledge but with absent of needs to do better then they did.

be wrote:

Actually air is nonlinear with a uneven order nonlinear connection between pressure and volumen by audio frequencies at least. An uneven order nonlinearity produces even order distortions, this might explain our preference for single ended devices, that predominantly produces distortion of the same nature as air. Our brain have due to natural selection been optimised, with ease, to filter out excactly the kind of distortions that dominates the medium that we are in: Air. It would be to our disadvantage if we just by being, would get a headache due to the overload of our signal processing device between our ears.

I understand it very well, but you also have to take under consideration that no one even approach to construct of driver-horn as Sound source but they rather treat it as a pressure transducing system.

be wrote:

More down to normal engineering: Manufacturers of compression drivers have in the "recent" years introduced drivers with short throats and larger flare rates to measurebly minimize the amount of produced distortion that stems from airs pressure nonlinearity.

Yes, I know about it, but at the same they a lot of other “inventions” that do not work out… Anyhow, Erick, let keep this thread dedicated to Jessie’s project.

While not qualified to comment on the subject at this depth, I am very much following the discussion, and though it may seem slightly "off-thread", it does not go unappreciated. A technical understanding is necessary and I am always trying to learn more...

That said, I tend to agree with Romy’s statement:

"...It is my believe that NO one TRULY knows what the hell it going on with horns and no one has any idea how a driver will sound when it will be horn loaded..."

While I am wary of those who speak with absolute certainty on subjects like the genesis of man, life after death, and to some extent, horns, horns are something we might one day understand. Just how much of this might be helpful is another question.

The grace with which one descends a flight of stairs does not depend on his ability to consciously solve in real-time the pages of logarithmic (?) equations describing his movements.


jd*

jessie.dazzle wrote:

A technical understanding is necessary and I am always trying to learn more...

Romy,

Thanks for the thoughtful writing... Sorry my response is not exactly "time-aligned"... I've been meaning to reply for the past few days, but my other life has been in the way...

Romy's quotes in blue :

In  a few month, after you installed your 6-chenals, power it -  is the most interesting, the most complex and the most thrilling things will take place – you would need from an array of “frequencies pushing channels” to teach your acoustic system to play sound PROPERLY.

This is a moment I have been anticipating for a long time, and will address it as sincerely as possible; taking no shortcuts... It is the reason I designed so much versatility into the horn locating frame and into the horn making process.

Unfortunately this step, the most important step among all, is not just undermined by the Morons out there but even the discussing the methods that might be used to do so is a semi-banned subject among the most audio people.

Yes... Things might be different if there were a manufacturer that squarely addressed these issues while at the same time educating his elected communicators (his distributors and the press), and then built a comprehensive data base (a web address) that skillfully educated potentially interested customers in terms they could easily grasp. This may in fact already exist, but if so, it is the super-rare exception.

That all might eventually bring you to a very complex question: how you would like Sound to be…. and ultimately it might lead you to the biggest subject of the entire audio: who we are. It might take a year or two to learn experiencing and reacting to the needs and capacity of your “6-chennals”. During that time the evolution of your “6-chennals” will follow the substance of your personality and depth of your musical/sonic interests.

I believe that any serious audio installation will absolutely reflect the character of the user.

What would be the most interesting is that you might discover that you do not need to know a lot of technical things in order to “know” them. Some purely technical aspects will become an organic extension of your sonic interests.

Instinct and intuition are my main tools. Developing them (and my confidence in them) is the result of their continued use. Both are in fact based on technical experience and the ability to project and extrapolate from it and from that of other domains.

Do not be surprised if at that time you might loose any interest to a cookie-cutter audio industry’s offering.

Well this weekend a buyer came for the speakers of my previous life. I had kept them until now as a reference. I have owned them for eight years in 4 locations; I know their performance very well... They have been one of few audio devices that I would consider educational in a long-term sense. I would not have sold them so early if they had not been so clearly dwarfed by the indicated potential of this project.

You might feel then that if a person does not practice his own “tailored sound” (and it has NOTHING to do with DIY movement) then the person does not deserve your audio interest

The typically-primitive audio people conduct random events and then talk about consequences

By comparison to the rest of society, I have observed that people who "do audio", are in general quite intelligent, articulate, and literate... Those who spend big money continually swapping components do what they do, knowing deep down that they are playing a game of chance, but they do have the cash and they do get some satisfaction (sometimes even sonically speaking) from this game. They frequently cannot defend their actions on logical grounds, but can easily afford to go on this way. Because they are otherwise intelligent, it is normal that they become emotional when asked to defend their illogic... Though it is kind of moronic, I find it human. They may even believe they have found absolute truth in audio... There are worse things to do with one's cash and time. I am however convinced that if given the chance to have their ears pointed in a more right direction, these people would take the event very seriously... It is a question of exposure. For now, they are trying to make sense of a lack of information. The sort of exposure that might help is not easily organized. I believe that in sound reproduction, any person can naturally recognize large-scale right from wrong, if presented with something that is more or less right...

My opinion is that there is simply a lack of "right" out there. This leaves those who "do audio" to extract "audio truth" from what is a pre-polluted base... Basically, subtly varying levels of what is in any case fundamentally wrong... Imagine the objective in Audio were to produce pure yellow (a primary color)... Its like we have been presented with a short cut to simulate pure yellow, which involves starting with brown and adding copious amounts of "negative violet" (violet being the compliment or opposite of yellow). And so rather than being subjected to varying levels of rightness, we get varying levels in the quality of the disguise which masks a nevertheless perverted origin.

Interestingly that at this point you might discover a completely new definition of the very common audio words: resolution, soundstage, imaging and the similar, however, then those words will have absolutely DIFFERENT meaning then for other people and you will push completely different buttons to get your new understanding of “resolution” or “imaging”.

You might discover a new ways to think and to talk about acoustic systems, or about audio generally

I have always been very uncomfortable using (or processing) "the accepted" audio vocabulary and perceptions... I think it has to do with a general dislike for code-heavy communication (all codes, including visual)... When forced to adopt too much code that is foreign to my own constitution my body starts leaking acid. This has been a source of unimaginable problems since birth! On the other hand, I admit that I can't resist employing these codes in a humorous context!

jd*

Romy quotes in blue (pulled from the "Adding one more channel to the Macondos" thread)

"1) Make sure that your cone is properly center in a gap. It is very important as misaligned cone will do compression at bottom end"

I feel confident that I am able to get the diaphragm centered... I don't fight it. It is also important to apply the same torque to all screws securing the diaphragm calmping plate. Those having experience with mechanical assembly will have developed a good feel for this sort of work.

"2) Make sure that the driver’s center are absolutely in the center of the horn and absolutely parallel to the horn’s axis. That is also very important with MF driver. If the driver does not sit in a perfect optical center of the horn then it will have very sever anomalies, particularly when the horn is towed in or out. With the spherical, low throat horns, as we have, it is very simple to misalign the center of the driver for a few fractions of mm"

To locate the S2s I use a plate made from 10mm thick aluminum, which is cut and trued on a lathe... the large central hole for the S2 is bored and threaded while still on the lathe. Six mounting holes are then drilled in the plate using a mill. This plate is then paired with a concentric spacer which allows establishing the axis of the horn as it is "turned". Once done, the S2 has no choice but to be centered.

Here are some images of the mounting plate and the process :


S2 with mounting plate (rear view)


S2 with mounting plate with spacer (front view)...
This spacer is of a thickness that corresponds to the
non-threaded tip of the nose of the S2.


Mounting plate with anchor (plates cost a fortune to
have machined, but the result is worth the cost)


Critical step part I : Verifying that the plate is centered
before locking it in place with hemp and plaster...
To do this the entire assembly is rotated on its axis while 
measuring and adjusting the clearance between the plate
and the stationary template (at right)


Critical step part II : Locking the plate
anchor in place with hemp and plaster


Plate and upper stabilizer amr (horn is done in this
image)


Done and waiting for the core to drop out

This horn required that I do a special little dance involving candles, insence, and a big rubber mallet before it would release the core... Next time I will film the ritual and post it on YouTube.

jd*

Ah, your horn this way does not have own axis and the axis of the back plate become actually the axis of the horn? This way you get rid the ugliest element of co-axising – the integration of the axis of horn and the back plate. Very-very cool indeed! I wish I was able to do it. My MF driver has two metal plates that have a few mm freedom between each other allowing them to be re-centered.

It looks like a very elegant solution of the centering problem but in practice it is not so elegant and more pain in ass. 

BTW, in your scenario the center pipe that is sitting in the throat looks like smaller then 1.5”. Does it mean that you will eventually open up the horn intake diameter with sand paper until the throat hit the S2’s output diameter?

Do not tell me that in order to do so you will be using the methods that Zeiss used in 30s when they polish their Leica!  Well, it will be one way to assure your new horns’ Wife Acceptance  :-)