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In the Forum: Horn-Loaded Speakers
In the Thread: The 5-ways from Germany.
Post Subject: One note devise.Posted by Romy the Cat on: 7/13/2012
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 rowuk wrote:
Brass instruments function much differently than audio horns. First of all they are built extremely resonant by mismatching length and horn taper. The taper of the bell is there not for horn type efficiency, rather to change the acoustical length of the instrument depending on the played frequency. In addition, we get different notes out of the trumpet by "overblowing" the fundemental resonance. Our Pedal note is the fundemental - one wavelength in the instrument, let's call this note C, the next "natural note" is 2 wavelengths or one octave higher also a C. The next is 3 wave lengths (G), 4 wavelengths is a C again, 5=E, 6=G(octave higher than the 3 wavelength g), 7 is discordant but close to a Bb, 8 wavelengths are the octave again. This continues until the 17th overblown partial where the resonance of the instrument no longer is sufficient for control, the entire work is now performed by the lips.

It is interesting that the sound of the trumpet comes from acoustic mismatch. What we hear is what leaks out from the standing wave - NOT an amplified buzz of the lips! Throat and reactance matching on musical instruments is done with the construction of the mouthpiece


How does this apply to loudspeaker horns? Well, Romy has posted that we should NOT use the horns at the bottom of their calculated possible range. The reason is that they become resonant there like a musical horn. Overblowing is very much like harmonic distortion. The voice becomes that of the standing wave, not the driver. We need to use the horn in the range where we have pattern control, not resonant support.
The "feedback" that Klaus and Reinhard use actually could correspond to the braces used on brass instruments. They must be critically placed or the response and articulation is destroyed. Some of the braces on musical instruments are used for feedback, others short circuit resonance by damping it.

Rowuk, the subject you touched is incredibly interesting. Yes, acoustic horns are resonant devises but audio horns are not resonant devises, or better not to be. Still, I do not think that there are last fat dot in that statement.  I was thinking a lot about it in past. In my view the main difference between music horn and audio horn in not in compliance with resonant principle but in the fact that audio horn has no lips, or no controlling mechanism to express intend. If we has some kind of super adaptable driver in audio horn then we would be able to USE resonances in audio horns. Unfortunately we do not have active driver and the compression drivers that we use are all passive. We for sure might change in real time the way how our compression drivers operate but the degree we can change it not near where it might be used effectively. So, we basically in audio horn have one single set of lips that blow one single note all time. Our audio horn is effectively one note devise. If you look all theory of audio horn building then you will see that horns are not only narrow band devises but they have ultimate consideration ONLY for one single pitch and any deviation from it is deviation from “ultimate”. I am sure the Morons who propose a single horn from 20Hz to 20kHz will enjoy to read it.

Rgs, The Cat

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