Home » Sponsored » Pi Speakers » Why do horns handlice twice the power?
Why do horns handlice twice the power? [message #42836] Thu, 30 October 2003 03:06 Go to next message
Adrian Mack is currently offline  Adrian Mack
Messages: 568
Registered: May 2009
Illuminati (1st Degree)

Why do people say basshorns handle twice the electrical power of, for example, a vented box subwoofer?
They don't [message #42841 is a reply to message #42836] Thu, 30 October 2003 11:19 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
Illuminati (33rd Degree)

This refers to the acoustic loading and how it is reflected back as electrical impedance. Both horn and vented systems unload at a specific low frequency, and this is where they are most vulnerable. Above this frequency, both are limited by the dissipation ability of the motor. If it's the same motor in each cabinet, then the power limit is the same. The impedance may be different though, which then means that the voltage limit is also different.

Some make the case that horn loading increases efficiency, so more power is converted to acoustic energy leaving less to be wasted as heat. I don't agree with this because while it is true in theory, in practice even the most efficient horns dissipate a great deal of heat, usually more than 50%. And since most speakers remove heat via venting, the reduced excursion from horn loading limits their ability to cool the voice coil. Where power handling is concerned, the reduced excursion is a two-edged sword. Mechanical limits are increased but thermal limits aren't; In fact, the reduced excursion may reduce thermal limits in some cases.

Re: They don't [message #42846 is a reply to message #42841] Thu, 30 October 2003 14:55 Go to previous messageGo to next message
Adam is currently offline  Adam
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Registered: May 2009
Illuminati (1st Degree)
Yup. Thermal power handling may even be decreased slightly by horn loading. Particularly in the case of low frequency motors, cone motion is critical to the ventilation and cooling of the motor. Since horn loading dampens cone motion, this effect is somewhat retarded and can result in lower thermal power handling. Mechanical is a different story ;)

Adam

hmmm but [message #42848 is a reply to message #42841] Thu, 30 October 2003 16:21 Go to previous messageGo to next message
toxicport.e is currently offline  toxicport.e
Messages: 48
Registered: May 2009
Baron
quoting some one

"
A cool thing about horns is that they can increase the effective power capacity of a driver (remember a 300 Watt driver can handle 500-600 Watts on a 50% efficient horn).
This output corresponds to about 400 acoustic Watts per box which is a very significant energy.
The stack of 6 should produce about 3.2 acoustic horsepower without exceeding Xmax.

"

;-)

it makes sense if the energy is being transferred into sound not heat..light a more efficient light bulb-more light less heat but same power in and out in total..

/end simplistic post

:-)

Voltage and Power [message #42849 is a reply to message #42848] Thu, 30 October 2003 22:17 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

A horn increases electrical impedance of the driver through the horn's passband, which increases the voltage limit but not the power limit. Unless you're doing something to dissipate the heat from the voice coil windings, you still have the same power limits there. Nothing changed the structure of the motor; You may get more output per watt and you may increase impedance, but you won't increase the motor's ability to dissipate power.

To use your light bulb analogy, it's like having a reflector or lense that focuses the light and makes it brighter in one spot. You may not need as much power to get the same amount of light in a concentrated area. And you may even be able to reduce the voltage input to the light bulb and get the same candle-power at a specific pinpoint location. But if you increase current through the filament past the limit of the bulb, you'll burn it out whether you have the reflector installed or not. Same thing with the speaker motor, whether installed in a horn or not.

Again, even with increased efficiency, we're still talking about a large amount of heat in the motors of a high-power horn. With excursion reduced because of horn loading, it is questionable whether the woofer's venting is as effective.

Re: Voltage and Power [message #42850 is a reply to message #42849] Fri, 31 October 2003 00:48 Go to previous messageGo to next message
toxicport.e is currently offline  toxicport.e
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Registered: May 2009
Baron
well how can a well respected (by some people) person post what i quoted, and treat it as fact?

people run 2kw per labhorn cabinet, no problems. and the woofers are 450watt rms or so.

Cheers wayne!


Re: Voltage and Power [message #42851 is a reply to message #42850] Fri, 31 October 2003 01:24 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

Just because someone connects LABhorns to amplifiers rated 2000 watts doesn't mean they're actually dissipating 2000 watts. Eminence makes good speakers but I'd be willing to bet any amount of money that a pair of LAB12 woofers cannot handle 2000 WRMS for more than a few minutes, more likely seconds, in any style cabinet.

Re: Why do horns handlice twice the power? [message #42852 is a reply to message #42836] Fri, 31 October 2003 03:06 Go to previous messageGo to next message
Walt is currently offline  Walt
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Registered: May 2009
Chancellor
If we put 2000W electrical power in, that power should also come out as sound and heat. Since a good horn can have a 30-50% efficiency this would mean that up to half of the input power is converted into sound. The other half will be lost as heat. A direct radiating system usually has only 1-10% efficiency so the coil has do dissipiate a lot more power. Therefore the horn will handle more power!

Best regards,

Walt

physics-no cheating allowed [message #42853 is a reply to message #42851] Fri, 31 October 2003 03:17 Go to previous messageGo to next message
Mike.e is currently offline  Mike.e
Messages: 471
Registered: May 2009
Illuminati (1st Degree)
''I'd start saving for a second 3402 - in theory that should give you 12-1400w per cab

''Even with 2500 watts a box I haven't really discovered what seems to be a clear power limitation.''

''I run my 3002's bridge-mono giving 3000 watts @ 4 ohms per cabinet. The first green (labeled "signal") LED on the amp just tickle's on and stays on for the majority of the signal input. I hit LED's 2 & 3 (-20 and -10) for the transient bursts''

Regardless of what people say they use, and what music with bass content they may use-
the issue remains that certain people beleive that u can input more power into efficient horns, and i beleived them, it made sense.

i see both sides of the issue, only 1 can be correct
;-)

should i try it-make a labhorn and input 2kw sine for a week?
perhaps its a simple matter of some one saying RMS instead of Music power in a post i saw, setting me off on a tangent.


Cheers
Mike.e

Transformation [message #42854 is a reply to message #42852] Fri, 31 October 2003 03:33 Go to previous messageGo to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

Yes, there is more power transformed from electrical energy to acoustic energy in a 30-50% horn than in a 1-10% direct radiator. But then again, there is also a reduction of excursion, making the thermal management system - the cooling vents - less effective. So I'm not sure it is reasonable to expect a doubling of power handling from horn loading. I think it will definitely increase the mechanical limits, but am not sure the thermal limits are improved. In fact, I think in some cases, thermal limits may be reduced.

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