Romy wrote :

"...do not forget also while you do your alignment experiments to listen the system from different distance. Get a reference whatever it is and then make a step back and a step forward... You might eventually found a distance from where the "angled sound" will suddenly "click"..."

To help establish the best listening point in the new place, I decided to use an office type chair with wheels (its also nice to slide up to the equipment rack without having to get up!). When doing the tilted horn experiment I did try moving toward and away from the horns.

"...Try to discard the upperbass changes and pay attention only to the frequencies that you are trying to align..."

Yes, I started off listening to music with a lot of violin and cello for exactly that reason, but then realized that because my fundamentals channel goes quite low (700 Hz 1st order), is not attenuated, and was the most steeply tilted, I was curious to know what was going on around the crossover point between this horn and the upper bass... So I started paying attention to that crossover point as well; though I realize that it is less critical.

"...With the parallel horn’s axises the "click zone" will be way larger. I personally tend to recognize that with parallel horns the imaging still better then with the tilted horns and a listener located in the "click zone"..."

Loss of imaging was by far the most noticeable effect with horns tilted. This loss may be more pronounced in my case because I started off with such strong imaging. This capacity for imaging (with horns parallel) may be due to the fact that the top of the upper horn is positioned about 2 ft below the ceiling, which is higher than normal and opens toward the listener (not parallel to the floor). So the stack of horns, with the upper bass horn on the floor and MF + HF in between, is sort of like a line array.

be wrote :

"...I think that Romys preference for non tilting lies in, that by not tilting the horns, the directivity, beaming or on axsis frequency iregularities are avoided, simply by pointing them where they dont do so much harm, below or above the ears..."

A lot of horn users seem to have these issues. I have not heard any other systems using Vitavox S2 drivers, but I know it is possible to get the S2 to generate on-axis unpleasentries. In the case of the system I am building, one can happily sit straight in the firing axis of any of the horns without experiencing the above-mentioned unpleasantries... No cringing. The reason for this I believe is directly related to the fact that I'm not asking each horn to cover such a wide frequency range. In other words, there is a lot of "horn margin" on either side of the frequency range being produced... Which probably looks like a high percentage of wasted horn to some.

jd*

jessie.dazzle wrote:

I have not heard any other systems using Vitavox S2 drivers, but I know it is possible to get the S2 to generate on-axis unpleasentries. In the case of the system I am building, one can happily sit straight in the firing axis of any of the horns without experiencing the above-mentioned unpleasantries... No cringing. The reason for this I believe is directly related to the fact that I'm not asking each horn to cover such a wide frequency range. In other words, there is a lot of "horn margin" on either side of the frequency range being produced... Which probably looks like a high percentage of wasted horn to some.

Hm… it is would be debatable.  S2 on-axis might be brutal, particularly with originals metal cones and one of the ways to deal with the brutal is using various low-pass filters or transient filters. Turning the horn slightly off-axis, using deeper horns and some other methods are low-pass filters. Loading the out tube harder probably is the most effective transient filter. The S2 is very much sensitive to quality of electricity. Since you are at 12 feet, sine you use the 16R tap on ML2.0 I think you might go away with on-axis shooting. I personally prefer to load the ML2’s output tube slightly idler (8R top) and to turn point the horns to my shoulders instead of my ears.

Be,

I do not think that effect you describe has anything to do with demand of horns have strictly parallel axis. I also came across to some situations where the extremely indirect sound was superbly interesting but it is I feel is very different subject and has very different underlying reasons.

My presumption is that with non-parallel case the different frequencies get time-aligned at different distances, something to what we in photography (my first trade) was called chromatic aberration. If you look at the nature of chromatic aberration in optical system then you will see a perfect model why the unparallel horns do not sound right. If you have a lens and hold it’s axis on the line of infinitely located light source then you have one level of chromatic aberrations. If you then angle the lend 5 degree  for instance  then you will have the very same focusing but the amount of chromatic aberrations will avalanche.

I do not insist that it is right explanation but it does it to me. After all - they are my Axioms… :-)

be wrote:

There is no analogy to chromatic aberration in acoustics of air.

Disagree. Regardless the reason for Chromatic Aberration in context of the given illustration we care ONLY about the arrival time. In case of lens we have the discrepancy of arrival time as a deviation of focusing distance. In case of speakers we pay the penalties of misalignment. Do not forget that when we are talking about crossover aliment we are talking about the arrival of a single wave at the middle of the cut off. Let say that we have 10K cut off and use 10K sinus.  What would happen what we use 7K signal or 13K signal? In case of parallel horns we have no discrepancies and 7K, 10K and 13K will require the same alignment. However, with none- parallel horns you can get a perfect alignment only for a single frequency. In the case of Chromatic Aberration it will be the alignment for a single distance. The speed, distance and time are the very same subjects and in that I see a lot of similarities between optics and sound. With all that said I would like to remind that the “Chromatic Aberration Syndrome” as an explanation for sonic problem of non-parallel horns is juts my working hypnosis. I do not insist that it is so. As I said before I have no definitive enlightenment about the true reasons. The subjective evaluations that I did 7 year ago did indicate that the non-parallel horns are a big taboo. I never care seriously look deeper into the reasons. I feel that Chromatic Aberration is adequate enough explanation to satisfy my interest on the subject.

be wrote:

I suspect that your negative views about on axis listening due to sensitivity to listening position must be to some narrow angle on axis frequency anomaly of the driver/horns you tried.

I do not think so. Pay attention I did not bring any subjective arguments to defend my pro-parallel axis portion. If you experiment with aliment yourself and play with horn tilting during aliment then you might discover some aliment inconsistencies. To keep the horns parallel is about do not have those inconsistencies. How it affects sound? I could propose any theories or to refer to my listening experience but in order you and others agree or acknowledge it we need to sit in the same room and listening the same playback. Since it does not happen I did proposed the easy way to objectively confirm the problems with horn tilting. The only contra-argument that I would consider if somebody would align the channels and then by tilting one of the channels will NOT observe the introduction of mis-alignment.

be wrote:

If you insist to use chromatic aberration as a working hypnosis!!

Oh, no, I do not INSIST to use chromatic aberration as a working hypnosis. It is the explanation to myelsef with which has settled. If you of anybody else would offer something more lucid then I would be glad to contemplate it.

be wrote:

I sugest that those inconsistencies ar due to on axis frequency anomalities of the used horns. Elimminate these, and the inconsistecies will vannish, and the concerned axiom wil be void.

be wrote:

"Since most horns have frequency response problems, at and nearby their axsis, it is advisable

be wrote:

I have a two horns covering from around 150Hz and up, with a crossover frequency around 700Hz, So my system is probably less sensitive than yours with the many chanels and higher crossover frequencies. But I have changed my mind and will try anyway.

OK, let keep the “frequency response problems nearby horns axis” aside as I do not think I will hear any further explanation about it (they just do not exists :-). You should be able to observe the effect at 700Hz, to keep it more demonstrable you might contra-phase the driver and look for redaction of sum signal instead of increase the signal.

In another note: this conversation kind of “got me” and I consulted with people, who know theory well, asking them to provide their explanation of the angling phenomena. They explained the phenomena by the smearing the arrival time due to introduction of distance difference (when we angle the driver) between one side of the diaphragm and another side (let call it Distance Smearing). So, with angled driver the waves from one side of cone have different distance to travel then the waves from other side of cone.  I admit that it might be more elegant explanation then my Chomical Aberration but even the Distance Smearing explanation does not explain everything to me. For instance accruing to the Distance Smearing the best positioning shell be when multiple drives are located on curve and point directly to the listening spot, or all channels are angled. In practice is it never works - as I said above - it very severely shorts the acceptable listening distance.

Romy the Cat wrote:

… this conversation kind of “got me” and I consulted with people, who know theory well, asking them to provide their explanation of the angling phenomena. They explained the phenomena by the smearing the arrival time due to introduction of distance difference (when we angle the driver) between one side of the diaphragm and another side So, with angled driver the waves from one side of cone have different distance to travel then the waves from other side of cone…

Two other speakers theorists with who I consulted today confirmed what other proposed about.  It looks like the negative effect of non-parallel axis is due to the dimension of diaphragm introduce “distance smear” when tilted. The same reason explains directivity and sharpening impulse response of axis. They might be right (and it fact they are right) but it does not work out for my own understanding. If the diaphragm distance smears the ONLY factor then the position multiple driver on curve point directly to the listening point should be the best solution of all – it is not the case practically. The second thing that controversial to me in this explanation – the geometry of the traducing surface should matter. Let take for instance my “Water Drop” driver. The ribbon is 21cm by 0.6 cm. In this case the tilting of the driver up and down should kill aliment VERY aggressively, and it does. However, considering a very small dimension in horizontal plane and considering its 120 degree horizontal radiation the tilting of the driver right-left should cause no time miss-aliment effect. Nevertheless it does.

Well, I agree to perceive that subject in the same way how I perceive allergy. I for years did not believe in allergies, considering allergies as a BS invention of US pharmaceutical industry. Then a few years ago I suddenly developed all kind of allergies. Now I do have allergies but I still refuse to believe in them. Ask me about allergies and I will tell you that is a stupid American invention… Go figure. I think I am a walking proof that Perception is Reality.  But let it be our big secret...  :-)

Hi!

I just thought of something that could have some relation to this topic:

Take a horn with a driver, the driver produces a signal, the pressure wave will travel outwards more or less like a spherical wave front along the axis of the horn, think of the 2D waves in the surface of water when you throw a stone.

Eventually the wave will reach the mouth of the horn and leave it, when the wave hits the edge of the horn mouth, it will experience a discontinuity, this will produce a disturbance due to diffraction.

This disturbance will contain not only the frequencies of the original wave but also distortion; it will say higher harmonics of the signal. (This is a fact according to acoustics)

The edge of the horn mouth, will in case of a circular horn, function as a parasitic sound source shaped like a ring with the same diameter as the horn mouth and emitting a time delayed and distorted version of the original signal.

The time delay will depend on the path length from the driver to the horn mouth.

The large diameter of the parasitic sound source, as determined by the diameter of the horn mouth, will mean that the distorted and delayed emission will be extremely directive and concentrated in a narrow angle around the horn axis.

The directivity will depend on the frequency of the signal, interestingly the distortion due to its inherently higher frequency content will be more directive.

In case of traxtrix horns and like, with their large opening angels, this effect will be less pronounced than in something like conical horns, since the wave front in the horn will have detached itself more from the horn wall at the horn mouth, and will not see the discontinuity of the horn mouth as much.

Never the less, some effect will remain.

How can this be avoided?

1. Direct the horns away from listening position.

2. Cut the rim of the horn into a star shaped pattern.

    This will smear out the diffraction of the wave front in the horn, in time and space, and maybe render it harmless.

3. Place triangular pads of felt of suitable size and thikness, at the horn wall at the perimeter but still inside the horn.

4. Use non circular horns so the wave front will not reach the horn mouth at the same time every where, same effect as 2.

The Macondo's Axioms are the concepts that I employed to make Macondo but it does not mean that Macondo takes care about all things that are I feel are important.  Some important this were intentionally left out the Macondo’s and mine attention. One of the problem is what Be describe – the mouth’s edge distortions due to the discontinuity of horn. It is important subject but Macondo's deals with it in a way ignorably.  One of the best ways to deal within horn’s edge problems is to use LeCleach profile. It should be better solution for HF. The Macondo's tweeter went to a full length to deal with the horn’s edge problems having the Water Drop shape or the whale body shape. The Macondo's MF horn just ignores the problem completely…. and it doe it absolutely deliberately.

The consideration I took do not deal with MF horn’s edge problem is because the LeCleach profile with its negative opening takes more vertical real-estate to implement. To run LeCleach profile at my MF 400Hz horn I would loose approximately 3” to implement the negative opening. What you go for implementation of 5-way multi-wave horns and you objective is to be able to INTEGRATE THEM IN EXTREME NEARFIELD then each inch in vertical plane became very countable. If I use my horns from 15-20 feet then I would go for LeCleach-like solution and hive to horn more space to birth. However, since I am at 9 feet I am at very different restriction to vertical integration and 3” are too important for me. So, I feel that benefits for narrowing the vertical window are more important than the hassles I might pick from horn’s edge. So, as the result the edge of the Macondo’s MF horn is made for vertical compression.

I have to admit that when I ordered the Macondo’s MF horn in 2001 from John Hasqiun and requested the profile as is then it all was not in my head. I was much-much less experienced with horns then and drown that profile just because I looked sexy to me. Accidentally that “sexy” profile is allowing having the best vertical space compression. So, I did not change it for years. Would I change it? Yes I would. A year or so ago, what I was thinking about my Water Drop tweeter I came up with a new edge  profile for MF horn that deals with the horn’s edge problems but do not consume space as LeCleach does. Below is the depicting of the idea. I did not try it but it should work. Sometime in future when I have a good horn maker whom I would be able to torture I am planning to convert my current MF horn into this profile. Since it a first time I make it public I would like to grand a name to this way of horn termination. I would like it to be called the “Water Drop Edge“

Now, about your idea of doing that:

“ Place triangular pads of felt of suitable size and thikness, at the horn wall at the perimeter but still inside the horn.”

This is VERY good idea and I have a lot of talk about it during the last years. In facts some of the versions of your idea I intend to try sometimes. The idea was introduced to me by Bud Purvine and his EnABL Patterns

http://www.romythecat.com/Search.aspx?UserID=155&Phrase=

This is very interesting subject, thoght Bud attacks the boundary problems, wich is looks like a diferent thing (they migh not me).  Talking with Bud I figure: why do not use the very same random patterns at the edge of the horn to (I quote you) “to smear out the diffraction of the wave [at the edge] in time and space, and maybe render it harmless. “

Bud, uses paint of different heaviness to deal with the drivers’ cones. In our case it might be any material randomly extending over the profile of the horns edge. Manipulating by profile, height and material of the “edge pimples” I think it might be possible to very interning result. I DI NOT trey it myself but I keep my mind very open toward the Budanization of the horn’s edge

jessie.dazzle wrote:

I now feel a sort of responsibility toward other S2 …  and still no cringing.

Well, I lost that responsibility long time ago. There are 6 external factors that besides everything affect the “cringing” of S2:

1)    Electricity
2)    Electricity
3)    Electricity
4)    Amplification
5)    Dirt that the driver suck from air
6)    Type of low pass filter used

I can report that when everything is good then the driver is cleared from any accusations…

Romy the Cat wrote:

1) Horn loaded drivers are narrow-bandwidth transducing system. The wider range a horn channel covers the more it conflicts with restrictions of own topology. 2) All channels shell have strictly parallel axis 3) All channels shell be time-aligned, preferably naturally. 4) Horns shell have a minimum trout size, assuring proper LF equalization; still the length of the horns shell assure proper excursion of LF mouths over HF mouths. 5) Horns shell have a sufficient mass properly projected to a given channel’s LF boundary and the horn’s mass should be properly distributed within a horn. 6) The drivers within the channels should be selected not by own sonic merits but also by their ability to demonstrate similar sonic characteristics with the neighboring channels. The Absolute Tone of the drivers should be as close as possible to be transparent across all channels. 7) The acoustic system shell follows the principles of Imbedded Macro-Positioning  and shell peruses to hit the DPoLS – the ultimate setting for any acoustic system. 8) No dipole radiation or back-phase ingestion allowed. 9) Bass below the horn’s rate shell be unloaded from all horns 10) Horns channel shell be high-passed with min minimums crossover gap assuring no effect of the Horn Choking present 11) All channels shell use no crossovers higher then first order, no equalization of any kind, no Zobel or impedance compensation, no notching. Any higher orders crossovers, if ought to be used, shell use Bessel curve. 12) If a filter requires a phase inversion then it is preferable to flood crossover point with amplitude and do not invert phase. 13) Horns channel should use spherical horns, otherwise the only on-axis use of that acoustic system allowed. 14) No axis offset in horizontal dimension shell be used. To be continue. To be continue? The Cat

Here and there people talk about the bass time delay is not auditable. Well, it all depends if you know what to listen. Yesterday I took my MiniMe with it’s new very little bass modules crossed around 100Hz and move them closer and further. Yes, I was not able to hear any problems with 1/32” precision but I was able very clearly to hear the problems when bass modules were more then let say 5” away from MF monitor. All you need is to learn HOW and WHAT to pay attention  at while you are listening. The time delay enforcement at LF is as efective axioms and any other of Macondo Axioms.  I wonder how many midbass horn have their sound evaluated with inclusive bass time -misalignment? Interesting (and this is VERY important observation!)  that the effect of time misalignment in bass DOES sound like something what some Morons considers as “horn bass”. This is a VERYvloaded comment....