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High Efficiency Speaker Asylum: Re: What makes "horn" speakers different , ? I mean sound quality ,,, ! by tomservo

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Re: What makes "horn" speakers different , ? I mean sound quality ,,, !

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Hi

There are probably pages of possible answers, here are a few thoughts in no particular order.
Horns were the begging of reproduced sound, horns were necessary because amplifiers of the day were of limited power / costly per Watt so the high efficiency of a horn was “the” way to go. Early hifi’s were usually horn systems for the same reason, these were often commercial speakers moved into the living room.
With the development and then popularity of push pull tube amplifiers (and then adjustable damping) bass reflex boxes became popular.
These were large (by today’s standards) vented boxes, in the days before Thiel Small parameters that were lower in efficiency than a full horn but made bass.
Then, Acoustic research came out with the acoustic suspension enclosure, these were
Tiny boxes for the low cutoff they had, these were even less efficient but by then SS amplifiers that were even more powerful were popular.
Somewhere along in here, it became the norm to design amplifiers to have a low output impedance to make them a Voltage source, which then allowed Thiel Small parameters based designs to be derived and used.

The down side of horns is that they are much more involved to deal with and are bigger and more complicated to build than a simple direct radiator.
For example, while a text book filter will work fine using a resistor as the load, a high frequency horn is VERY different than a resistor so crossover design is much more difficult.
For example, since horns cannot normally be made to cover the full frequency range, more than one must be used per channel. At crossover, these horns are physically large and acoustically too far apart to add coherently so one must align the system based on "on axis" response (same for most all direct radiators except the distances are smaller).
The last down side, maybe the real show stopper is the physical size, some fools in marketing have somehow convinced the opposite sex that one does not need large speakers to get the best sound. “Honey, just hide those cute tiny little cubes behind the couch and see, they even have a baby subwoofer.”

The up sides of horns.
Most horn drivers on suitable horns are able to produce 10 to 100 times more output than a direct radiator. This means that in the home, one is usually just tickling the driver so it will usually have low distortion and very low power compression.
In general, all the problems loudspeaker have increase at some “power” of the change in input level. In other words, doubling the power will often result in a more than doubling of one issue or another.
Discussing dynamic compression does not help sell speakers so mfr’s don’t but the “dynamics” horn fans speaker of is partly (the lack of) this effect.
In real life, power compression begins on modern drivers, somewhere between 1 / 8 and 1 /10 rated power. Older drivers handled less power because the voice coil glue would melt easier, on the other hand, at there rated power, they had less power compression than a modern driver because of the VC temp was lower.
Bottom line, headroom is your friend.
Horns have more directivity than a direct radiator, this is very important if your in a room as this confines the sound to a narrower angle, not reflecting as much off the walls and floor etc (bad). While reflected sound can sound “realistic” is always interferes with the recorded signal reaching your ears.
Better than “some” directivity is constant directivity. This means the sound is confined to some essentially constant H and V angle, down to some frequency (where pattern control goes away) set by the mouth size and horn wall angle.
This has the advantage that the reverberant sound has roughly the same spectrum as the sound in front of the speaker and anywhere within the horn pattern sounds the same.
In an acoustically bad room like a typical Church, gymnasium or cave, directivity is essentially the only way to get intelligibility.

Anyway this is a rough overview, hope it helps.

Tom


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Topic - What makes "horn" speakers different , ? I mean sound quality ,,, ! - D.D.C 08:09:28 07/29/06 ( 27)