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In Reply to: RE: Can It Be a Horn If It Doesn't Look Like One? posted by Larry I on November 06, 2024 at 06:29:09
Larry, very helpful explanation, thanks!
On the Aristocrat/12TRXB combo,I assume the LF's would be routed out the back, and the HF's have their own little coaxial horn...but what about the vocal range? Out the rear, or Direct Radiator?
Follow Ups:
I am not that familiar with this particular system, but, I believe it is a triaxial speaker meaning it has a midrange cone and a horn tweeter all centered in the middle of the woofer cone. It is only a "horn" system in that the tweeter has a horn type wave guide. The woofer part of the cone will deliver bass and midrange frequencies firing forward. The rear wave is loaded in a conventional bass reflex cabinet so that the output of the port is primarily very low frequencies.
But, these types of systems which are meant to be put into the corner of the room are also sometimes referred to as corner horns because the walls at the corner act as wave guides directing the sound toward the listener. This is another example of how the term "horn" is used in different ways. The Klipschorn is also described as a corner horn because of similar placement, but, it is also a horn system because it employs compression drivers and horn wave guides while the E-V triaxial driver is not a compression driver.
A room corner isn't a wave guide. When a corner horn like the Aristocrat or Klipschorn is in a corner the room walls act as an extension of the horn. Combined with the 1/8 Pi space loading of a corner the lows are significantly boosted, although any speaker placed in a corner will get 1/8 Pi space loading at low frequencies.As to the term wave guide it's vastly overused. Technically speaking a wave guide is a horn with a throat that's at least one wavelength in dimension. That being the case it doesn't have the gain that a horn with a throat less than a wavelength in dimension has. We never saw the term 'wave guide' used until roughly 20 years ago. Someone started using it interchangeably with and in favor of 'horn', not for technical reasons but for marketing reasons, to overcome consumer resistance of the unwarranted poor reputation of high frequency horns. IME at least 90% of what are called wave guides are actually horns. If it's got a one inch throat it's a horn below 13.5 kHz.
Edits: 11/06/24
enn tee
all the best,
mrh
Yes wave guide is probably the wrong term. The walls limit the area that the speaker radiates into and thereby boosts efficiency and bass response (because bass otherwise goes in every direction).
Yours is a much more precise description.
The term "waveguide" was borrowed from the microwave area and came in to use when the constant directivity horns were first developed. These were needed for use when there is an audience listening vs a listener.
Horns can increase the efficiency by coupling more of the radiation impedance to the cone.
Horns can also appear to increase the efficiency by confining the radiation to a smaller angle so what one measures is normally the product of both things.
These two points both have a rule of thumb; for the impedance transformation, this stops at a frequency related to the horn passages circumference. This is why in the old days, people would say a 30Hz horn has to be 10 feet in diameter which is the point where the transformation stops BUT it doesn't mean the horn won't work if smaller.
On the other hand the expansion rate has a "high pass" corner in this transformation, for example a 30Hz exponential horn can't expand any faster than doubling it's area every 2 feet or so.
On the other other hand, the point that the horn stops controlling the radiation angle is approximately 10^6 / horn angle / / horn mouth dimension (inches) as cited by don Keele.
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