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11-23-2012 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007

Post #: 21
Post ID: 18760
Reply to: 18759
More causes for prejudise against horn sound.
fiogf49gjkf0d

"Then there are flutter echo like bathroom sounds that horns also sometime produce, especially if they have a glossy surface."

What I meant was that the glossy surface causes a effect that is like or resembles the hard fluttery sound in a bathroom,  maybe it is due to the higher order modes being facilitated, anyway elliminating the hard glossy sufaces inside the horn can make a big difference in the level of unpleasentness of the horns sound as described long time ago by Romy at this site.

11-23-2012 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 229
Joined on 07-05-2012

Post #: 22
Post ID: 18762
Reply to: 18760
It ain't the surface
fiogf49gjkf0d
I have read Romys post about the fine hairs and such but do not necessarily agree with the interpretation here. Romy always has a specific UseCase and makes very clear what he is after. He has often mentioned his search for interesting sound and even why his preference for big horns is black. There are too many great sounding shiny horns for this to be "generally" true. Earl Geddes adds foam to his speakers to solve a problem (HOMs) that should not even exist if the horn is designed and used properly.
My point with the musical instrument reference is that we have several tools at our disposal: Mass, Resonance, Feedback and Earthing. We can make very heavy horns to limit their ability to resonate, we can design horns in a way that the horn itself "leaks" energy to the outside surface, we can attach a frame, cable or other mechanical device to transfer vibration from one part of the horn to another, or to conduct the vibration to a much greater mass (like a floor through spikes) and we can design the horn with parallel walls, too short or too long and have resonance actually build up in the device itself. Any of those parameters can be good or bad depending on how they are implemented (except maybe horns that are too long or short). My main point is that our expectations about horns should be guided with a knowledge about what they do instead of an experience of how they should not have been used. Every comment about the sound of any device has a deeper reason and it can be great fun to try some of this stuff out instead of just believing it.
I personally believe if a absorptive surface is on the inside of the horn, the pressures in the device will cause them to deform and change the sound. How much of this is audible depends on so many other things that is probably a moot point for all but the very few with the time, ears and analytical attitude. Most of the best ears that I know are not capable of describing what they hear to someone that does not have a common musical/technical base. That makes Romys work here amazing to me. His descriptions are very vivid - often enough to make the casual reader/listener jump to some pretty stupid conclusions.


Whenever I feel blue, I start breathing again.
11-23-2012 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,157
Joined on 10-12-2006

Post #: 23
Post ID: 18763
Reply to: 18760
Trying to Learn Through "Criticism"
fiogf49gjkf0d
"If the horn contour is used in a way not complementary to its contour/length, reflections can cause phase/amplitude artifacts."  -  Rowuk

Robin, as a horn player, you obviously understand the differences between the horn as an instrument and the horn as a hi-fi LF gain device.  Again, the question for me has always been how - exactly, in the most practical terms -  to wind up without "characteristic" "phase/amplitude artifacts" that swamp "pure" LF gains.  I am sure you are also quite sensitive to tone, which has been another problem for me with the hi-fi horns I have used or heard, with respect to certain stubborn "characteristics".  Perhaps you simply dismiss either or both of these "concerns" outright, or perhaps you have reognized and "dealt" with them successfully.  If the latter, will you please discuss it in rote terms, specifically as it may apply to hi-fi horns?

By the way, for whatever reason or reasons, I have also found horn material and finish to be a factor contributing to a horn's "characteristic sound", so please let this inform any response, as well.  FYI, I mean "the same" horn where the only difference is the material and/or finish.

Best regards,
Paul S
11-23-2012 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007

Post #: 24
Post ID: 18764
Reply to: 18762
Trust is good but control is better
fiogf49gjkf0d
" Every comment about the sound of any device has a deeper reason and it can be great fun to try some of this stuff out instead of just believing it.
I personally believe if a absorptive surface is on the inside of the horn, the pressures in the device will cause them to deform and change the sound. "

Don belive it rowuk, try it.

I would like to mention that the non glossy suface I use is non deformable, very thin and has the roughness of very fine sanding paper.

11-23-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,544
Joined on 05-28-2004

Post #: 25
Post ID: 18765
Reply to: 18762
About non-shiny horns and different animals.
fiogf49gjkf0d

 rowuk wrote:
There are too many great sounding shiny horns for this to be "generally" true.

Rowuk,

To talk about shine vs. harry horns surface is very difficult as, in my view, people who talk about it do not have data that was methodologically properly collected and intelligently interpreted.  Even if people did make own experiments (and very few out there who actually did it) and did hear the sonic differences than it is very difficult to interpreter the difference in proper format.

Let pretend you build a let say 300Hz MF horn and drive some kind of good 600Hz driver through it. The horn is raw polish wood and you get some kind of sound. Let pretend that you went over it before and truly know what to listen while you are listening… than you read at let say Romy’s site that the horns have to be harry  and have not gloss but some kind of texture and you want to confirm it. Here is where fan begun.

First you want your horn to be shiny. You made it shiny…but you suddenly realized that within the 2-4 days as your shine is hardening the sound of the horn is changing. You conclude that the sound in this case affected not by the surface granularity but by the density of the horn’s top layer that contact with air. You will not be wrong. You will take polyurethane for instance and seal the horn. The sound will be changed again. Then you get textured pain and mad your horn. Sound will be change again. Then a layer of mat poly. The sound will be changed again. Pay attention – it will be change and in context of the current listening you might or not might find it beneficial. Can you I bring to the game the sonic changed from electricity fluctuation? Did you equate those changes? How about the mitigation of the sonic differences from horn surface by changes in amplification, cabling, filtration etc… Who has intelligence, time and zeal to understand all dependencies/connection and to give some more or less definitive answer?

Well, the right answers will be manufacturers, right.  Well, it is not so simple. I did spoke with a few very serious horn makers who in my view do have brain and eras. They told me that cosmetics of the horns, the high sine and expensive/exotic wood is the way for them to make money. I advocated to them the notion that best sounding horn is an ugly looking horn but as you understand it will not serve their interests. I perfectly understand and respect where they stand.

I personally chose the textured finish as I feel it is a good balanced between benefits that we get from rough surface and more of less attractive look. The textured finish is pain in ass to clean. I use a compressor to blow dust from horns… The main sonic reason why I stay with textured finish is that I feel that textured finish hold slightly higher dynamic and expressive range at very low volumes. As music play very soft then textured horn (in my view) has wider ability to express emotional and dynamic nuances of original music. Do I insist that it an authoritative statement? Not at all.  I had interest in the subject; I went and spend my time to look into this. I found a conclusion that looks like satisfying my curiosity and objectives and I have settled on it. BTW, I did not invent this method. It was advised to me by John Hasqun, I just spent some efforts to test his findings and I found that he was very correct.

One more thing. I think you are committing a mistake by comparing audio horns with musical instruments. Musical instruments are resonances producing crap, literally crap from audio perspective. The whole beauty of the Musical instruments/horns is that the resonating crap is managed by human awareness. It is up to a human consciousness to structure that “resonating crap” in order to convey via expressed sound some kind of performing intentions. In case of audio horns human awareness is NOT involved in real time and the resonances and colorations that audio horns produced are fixed once and for good. This advises that ANY resonances and colorations are not good unless they highlight something that you want to be highlighted  - that has to do with your objectives as system designer… whole another subject. Anyhow, I juts would like to stress that audio horn and musical bass are very different animals, even if they have the same shape.

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
11-23-2012 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 229
Joined on 07-05-2012

Post #: 26
Post ID: 18766
Reply to: 18763
Explaining is not meant to be criticism
fiogf49gjkf0d
Paul,
I have been working with trumpets since 1966 and horn speakers since 1975. I have built both and am pretty familiar with what they are, the similarities and the differences.

If I had to pick THE major sin when thinking about all of the horns that I have ever heard, I think disregard for the lower cut off would be in first place. This also applies for most of the PA devices too. Most designers try and use the horn as low as it can go without regard for what happens to the sound when the horn no longer loads the driver in a reasonable way. If I think about the Klipsch LaScala, they pushed the midrange horn down to 400 Hz, that was an octave lower than it should have been, but the woofer sounded ratty up higher so it was less of a comprimise. I ended up with a much larger 200 Hz wooden radial horn that actually smoothed things out quite nicely. There was no real bass, but the rest was capable of very realistic reproduction of what I listened too back then, large orchestra and chamber music. The interesting thing was that big music sounded big and chamber music was intimate. Piano was phenomenally real, I was using a Quad II pre and poweramp and had a bunch of years of being able to come home after playing a symphony concert and not be disappointed. I built that radial horn several times, out of paper, pine, oak, cement, MDF, industrial ceramics and alternating layers of materials. At intimate room levels, there was no appreciable difference, but when cranking it up, the hardest materials had the least "artifacts" and seemed to keep the orchestral texture intact. A highly polished surface always presented the greatest amount of detail. In the following years I had exposure to quite a few metal horns but never was able to get the rest to work as I thought it should. I always imagined that there was some coloration although many of my musician friends thought they were fine.

Actually, horns behave reasonably predictably. Many of the awful PA combinations can be made reasonable by changing the crossover to one better suited to the horn. That also means that often a midrange driver has to be added as the woofers don't always go high enough. For little money though, acceptable results can be achieved.

For serious listening, the horn also is not that tough to manage because of its predictability. Currently I have a very small listening room and horn LF simply does not fit. I am experimenting with various 12" woofers and cabinets for everything under 800Hz. It is work in progress, but the horns are causing me no grief.


Whenever I feel blue, I start breathing again.
11-24-2012 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 229
Joined on 07-05-2012

Post #: 27
Post ID: 18767
Reply to: 18765
Audio Crap from acoustic instruments
fiogf49gjkf0d
Romy,
I could not agree more! The only reason that I mention it is because we do see enough speakers with exactly these acoustic instrument problems: energy that leaks through the horn material, ringing from undamped material, wrong cutoffs (a trumpet uses the "wrong" cut off to make it resonate).  I have found that the words to explain how musical instruments work are valuable to explain design mistakes for audio. I have experimented with glass, steel, wood, carbon fiber, lead and ceramic trumpet bells too.

One of the most important musical instrument discoveries for me was bracing. Here we solder or screw connectors from one part to another. The results are so profound and few artisans understand this. The bracing can transmit or damp vibration. String instruments also implement bracing in the form of a sound post ( http://www.violins.on.ca/luthier/soundpost.html ). I think that there could be some advantages to looking over the edge of the audio plate to find techniques perhaps useful for audio.

Thank you for the explanation on "Hairs and Hardening". It is very interesting to get the original context.


Whenever I feel blue, I start breathing again.
11-24-2012 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 229
Joined on 07-05-2012

Post #: 28
Post ID: 18768
Reply to: 18764
Absorption is not diffusion/diffraction
fiogf49gjkf0d
Hi BE,
we may not be in disagreement at all. Sandpaper finish is not necessarily absorptive. I was more referring to popular HOM-treating methods like foam or using softer materials to build or coat the horn.

I still have my doubts about how a rough surface can work as the grain is so much smaller than even a quarter wavelength of any frequency that would be reproduced and the "speed" of sound when it runs into a wall is ZERO unless the wall is conductive (absorptive/resonant) at that frequency. If this "grain" is a factor, then micro millimeter changes in the horn SHAPE (like with a coat of anything) will change things even more. Maybe the effect you notice is due to the horn being "slightly" smaller than before the coating? Granted, improvements in sound cannot always be explained as we do not have infinite knowledge of all of the parameters at work.

My doubts are based on my "primitive" understanding of how sound waves move. the acoustic generator "vibrates" and the air molecules next to it vibrate and bump into the next molecules that vibrate, and so forth. The air molecules in front of the driver do not travel to our ears. Also the acoustic "pressure" in a horn is different than physical pressure like filling up a balloon with air. So, what are the air molecules next to the rougher surface doing differently? The distribution of the density of the sound wave? I do not know. In any case, as Romy notices his effect at lower volumes, is this causing a non-linearity in the playback based on amplitude?


Whenever I feel blue, I start breathing again.
11-24-2012 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007

Post #: 29
Post ID: 18769
Reply to: 18768
I dont know how, but it works
fiogf49gjkf0d
Hi rowuk.

Shark skin decreases the formation of vortexes in fluid flows over surfaces and thereby reduces drag.
Shark skin resembles fine sand paper and has actually been used as such.
Of cource there is a difference between a stady flow around a shark and the forth and back movement of the air in a horn, but it could still make a difference, but how?
I certainly can hear a difference in the sound comming from the (well designed) horns where I tried it. It is noticeable in the high mids and up, where the sound seems to be cleaned up for a some noise and dirt.
At one stage I tried to cover the conical inner surface of the compression driver throat with sand paper on a very thin base, but with different grain sizes to find what worked best. The result was that corn size 200-400 was the best, using finer ones like corn size 1000 had less effect, the thickness of these papers where quite similar, but I did not check out the possible influence of this parameter. 
11-24-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,544
Joined on 05-28-2004

Post #: 30
Post ID: 18770
Reply to: 18769
Wow!
fiogf49gjkf0d
 be wrote:
Shark skin decreases the formation of vortexes in fluid flows over surfaces and thereby reduces drag.Shark skin resembles fine sand paper and has actually been used as such.
A phenomenal association!


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-25-2012 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 229
Joined on 07-05-2012

Post #: 31
Post ID: 18772
Reply to: 18769
The vortexes are additional out of band noise................
fiogf49gjkf0d
Hi Be,
the thread is about the "bad" reputation horns have with "audio" people. Applying liquid dynamics gives them more fuel for the fire, that is why I avoid using stuff that really doesn't apply. We have no real flow of air or "turbulence" in a horn (it is not a bass relex port.....). We have diffraction - especially when the contour has edges like with early CD designs or when the horn is of improper design or used in the wrong band. Earl Geddes also has written about the horn throat-compression driver transition and he uses clay to make it perfectly smooth. Without the clay, he claims to have measured additional audible HOM artifacts. In fact, he uses foam in the "waveguide" to correct for these HOM. This to me means that the horn in his case is not properly designed and that the sound "wants" to do something else much different than the horn thus creating artifacts. I think that there are horn shapes that have more "problems" than others. Clay is probably a great idea though to make sure that the horn/driver transition is free of a stepped contour. http://www.diyaudio.com/forums/gedlee/122318-diy-waveguide-loudspeaker-kit-112.html   post 1112

If foam or sandpaper help with a particular design, then I guess all that counts is what comes out of the front. I just have no explanation that fits with the physics that I have learned. That should never slow someone else down though. Again, if something the size of sandpaper grains makes such a big difference, then so does a coat of paint thick enough to hold the grains. Sandpaper regardless of how thin changes the dimensions of the mouth of a compression driver in a very big way - at one of the most sensitive parts of the whole system. That will change response strictly based on decreased size/volume. The binder for the grains (paint/glue) also "damps" the surface of the horn. This also could make a big difference - with or without sand.

I do not doubt that there is a "difference" in sound with any treatment that we apply to anything audio. Trumpets sound different when they are lacquered too (When they are gold or silver plated however, I have never noticed a difference). I have never added sand to the lacquer however. I will try this sometime.


Whenever I feel blue, I start breathing again.
11-25-2012 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007

Post #: 32
Post ID: 18773
Reply to: 18772
Out of textbook noise.
fiogf49gjkf0d

I have actually tried to roughen the surface of a glossy horn, witch did increase the horn size, and the effect was similar to painting it with a grainy paint, therefore I am sceptical your proposal that the heard effect was due to the dimmensional alteration.
If the dimmensional change where the cause, it is very unlikely that an increase and a decrease has the same effect.

It is true that that there can not be turbulence in a horn as seen by steady flows, yet the formation of turbulence is affected by surface roughness, hence surface roughness does affect the motion of fluids over the surface, therefore it can not be dissmissed that surface roughness can have an effect also in horns.


11-13-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,544
Joined on 05-28-2004

Post #: 33
Post ID: 20262
Reply to: 11270
Some Brit’s take on the Horn sound....
fiogf49gjkf0d
http://www.hifiwigwam.com/showthread.php?95128-Horn-sound


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 2 of 2 (33 items) Select Pages:  « 1 2
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  An Interview With Dr. Bruce Edgar..  An Interview With Dr. Bruce Edgar...  Horn-Loaded Speakers Forum     0  55241  07-10-2007
  »  New  Horn high-sensitively around Boston..  Horn high-sensitively around Boston...  Horn-Loaded Speakers Forum     0  10541  10-29-2008
  »  New  The most interesting horn ideas to me so far..  Looking for best horn values...  Horn-Loaded Speakers Forum     4  36748  04-30-2007
  »  New  The state of High-Efficiency Loudspeakers...  Tom Danley’s brilliant law...  Horn-Loaded Speakers Forum     6  64564  02-25-2009
  »  New  Some Horns propaganda..  Old paper direct-radiation tweeters...  Horn-Loaded Speakers Forum     4  64914  07-04-2004
  »  New  Some horn writing by Thomas Dunker. ..  Some horn writing by Thomas Dunker. ...  Horn-Loaded Speakers Forum     0  42186  01-14-2006
  »  New  Macondo's Axioms: Horn-loaded acoustic systems..  No wonder...  Horn-Loaded Speakers Forum     72  407127  07-29-2007
  »  New  “Why horns”, years later...  Power-to-weight...  Horn-Loaded Speakers Forum     4  29356  09-26-2010
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