GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Battling stupid Horn Criticism as a concept

Post Subject: Simple is often the hardest thing to understandPosted by rowuk on: 11/21/2012

I am really enjoying myself here at Romys site. I like the idea of someone documenting their efforts in a very (self) critical way.

I think that anyone solving issues in a methodical way uses similar techniques. They all involve stripping the problem of its symptoms to find out what the root cause for the phenomenon is and then creating a plan based on the root instead of the symptoms.

In the case of horns, I think that most fail to see that it is a simple band pass device. I am a trumpet player and my instrument demonstrates very clearly that there is a lowest and highest note with an acceptable trumpet sound and that at the top end, the response rolls off requiring extra "effort" if we want to use that range. The same applies to audio horns. The criticism of something having a horn sound is like accusing blueberries of being blue (limited color frequency bandwidth) or women of having a period once a month. It has been often written that horns are "decade" devices (500-5kHz/1000-10Khz/100-1KHz). This very adequately explains what we can expect. Applying a high and low pass filter to a standard speaker driver creates a similar "honk", albeit with much higher distortion for a given loudness.

If we measure driver frequency response and then measure again attached to various sized horns, we see the "simple" band pass effect change based on the horn size and geometry. We also see the directivity change outside of the pass band. So, simple logic says that if we can leverage the band pass capabilities in a predictable and repeatable way, we may be able to reduce the complexity of the audio chain elsewhere.

I read the comment about honky PA speakers. Well, I have fixed the honk on many just by leveraging the band pass effects. That involved changing the crossover to match the characteristics of the horn. It is clear to most people that a 2" woofer will have limited bass and predictable distortion based on acustic output. With a bit of reading and listening , it can become equally clear that a 12" mouth horn regardless of driver will be challenged to create sounds under 1000Hz (or above 10KHz) without comprimise.

So, the next time honk becomes apparent, don't blame the horn - it is not "flawed", it simply what it is.

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