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RE: Can It Be a Horn If It Doesn't Look Like One?

73.69.21.1

Bill Fitzmaurice

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 11:10:46

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

Follow Ups:

I like Bill Fitzmaurice's assessment of the 'waveguide', FWIW ;) (nt) - mhardy6647 05:51:55 11/07/24 (0)
enn tee

all the best,
mrh
RE: Can It Be a Horn If It Doesn't Look Like One? - Larry I 12:07:05 11/06/24 (1)
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.
- RE: Can It Be a Horn If It Doesn't Look Like One? - tomservo 05:54:34 11/09/24 (0)
  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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