主题：基本问题2--功率放大器和扬声器在功率上的搭配

Properly matching loudspeakers
and power amplifiers
By Keith Clark
PSW Editorial Director
 

1 2

 

One of the questions most commonly asked of loudspeaker manufacturers

concerns the matching of power amplifiers to loudspeakers.

Manufacturers will tell you that the majority of loudspeaker failures

encountered by their service department are the result of improper

power matching. It might seem logical to use a smaller amplifier as a

safety measure; after all, it stands to reason that there won't be

enough power to damage the loudspeaker.

Yet they see many more loudspeaker failures due to under powering than

any other cause. When the amplifier exceeds its maximum voltage

capability, it can "clip" the peaks off the electrical signal it is

supplying.

Once the amplifier starts clipping, the average (or RMS) level rises,

which can be extremely damaging to the loudspeaker. In layman's terms,

for example, your 200-watt amplifier can approach delivery of 800 watts

of power, but it will be volatile and heavily distorted, and thus

potentially quite harmful to the loudspeaker.

However, using an amplifier that is much more powerful than the

loudspeaker's rating can do just as much damage. Supplying the speaker

with more power than it can handle will often result in thermal (heat)

and/or mechanical damage.

Basically, any amplifier with a 20Hz - 20kHz power rating that matches

other specifications of a given loudspeaker will safely drive that

speaker at full output under most conditions. Therefore it's vital to

understand the meaning and impact of the most important loudspeaker

specifications as they relate to amplifiers.

First, there's power handling capacity, usually defined by terms such

as "Continuous," "Program" and "Peak". Continuous is the level of long

-term average power accepted by the loudspeaker; Program is based upon

a test signal that simulates a "real-world" program signal; and Peak

refers to the maximum amount of short-term power the loudspeaker will

handle.

Based on these terms, then, what is the proper amplifier choice to

capably and safely drive a loudspeaker rated at 100 watts continuous,

220 watts program, and 400 watts peak? The best choice would be an

amplifier delivering about 200 (continuous) watts per channel. Plenty

of power for normal full-range operation while also capable of meeting

short-term peak demands without going into clip.

 
 
 
 

 
  It should be noted that although an amplifier delivering 200 watts

per channel is appropriate for use with a full-range loudspeaker rated

at 220 watts program, subwoofer enclosures tend to require a bit more

power to generate their lower frequencies. In other words, a single

mono subwoofer rated at 200 watts should be paired with an amp offering

absolutely no less than 200 watts.

In fact, a good rule of thumb when dealing with subwoofers is to employ

an amp rated somewhere in the vicinity of 20 percent higher than the

subwoofer. With that in mind, a 250-watt amplifier would be ideal in

this application.

Another factor to be aware of is the impedance load that the amplifier

is being required to drive. Impedance is the resistance to the flow of

the audio signal by the loudspeaker. Measured in ohms, it is usually

called "nominal impedance" by most loudspeaker manufacturers.

A mismatch in impedance between an amplifier and loudspeaker can result

in poor performance, in the form of improper frequency response and

excessive distortion. Serious damage to one or both components is also

a very real possibility.

Most professional loudspeakers are rated at either 8 ohms or 4 ohms,

although a number of power amplifiers are specified to drive loads

ranging from 16 ohms to 2 ohms. You'll notice that the lower the

impedance, the greater the amplifier power rating. More power is

required to overcome the increased resistance.

For example, a loudspeaker delivering 110 watts at 8 ohms will also

likely be specified to deliver about 150 watts at 4 ohms. Consider our

prior discussion of power handling, and you quickly see why its

important to note a loudspeaker's impedance specification in the

matching process.

It's usually best to avoid 2-ohm operation, which can unnecessarily

stress an amplifier, and also can require much larger (heavier gauge)

cable to effectively and safely transport the load.

And speaking of cable, why go to all of the trouble of properly

matching loudspeakers and amplifiers if the link between them is

subpar? Most manufacturers recommend using heavy gauge (#14-#10),

professionally manufactured cable in all applications. A good rule of

thumb is the heavier the cable, the more efficient it will be as a

conduit between the devices.

(Thanks to the gang at EAW for their input on this topic.)

 

Speaker / Amplifier matching
by: good-hifi( 3742Feedback score is 1000 to 4,999) Top 25 Reviewer
203 out of 219 people found this guide helpful.
Guide viewed: 4568 times Tags: amplifier power | rms pmpo | loudspeaker | speaker volume | watts loudness

A common misconception is that the rated power of loudspeakers is a measurement of how loud they are and an amplifier has to have the same power output as the rated power of the loudspeakers it is used with. This is a very brief summary which dispels this misconception
 
To put this into some kind of useful information. I have driven loudspeakers rated at 300 watts with valve amplifiers that have an output of 20 watts per channel. The amplifiers drove the loudspeakers with consummate ease. The loudspeakers were what is called 'efficient' and the amplifier did not struggle. Similarly I have driven loudspeakers of which the rated power closely matched that of the amplifiers input and the amplifier struggled, these loudspeakers were what is classed as inefficient.
 
'Efficiency' is determined by sound output for a given input and is usually measured in decibels at one metre for an input of one watt. A good efficiency is usually about 90 dB, highly efficient loudspeakers may go as high as 102 dB and the lower scale efficiency might be 82 dB.
So, the lower the efficiency of the speaker the higher the power of the amplifier would need to be to drive it well.
 
One very important point to note is that a low power amplifier driving low efficiency speakers is not a good idea. It is often distortion caused by having the amplifier turned up too high which damages loudspeakers and this happens far more often than damage cause by too powerful an amplifier. If you find you are using the amplifier in excess of two thirds volume, or you often hear distortion, then the amplifier is probably not powerful enough for your speakers. (or you are deaf!)
 
The best thing to do is to try to match the amplifier with the speakers such that most of your listening is carried out with the amplifier at half volume. This ensures it is delivering enough power to hear the full frequency range clearly with a bit of power left for transient or fast notes and enough oomph left for good bass response.
 
This is all a bit of a science on it's own and my best advice is, if you really need to know more, to search Google for websites dedicated to loudspeakers, loudspeaker design and loudspeaker efficiency.
 
If the seller of the loudspeakers, or amplifier, appears to be a regular HiFi seller you should be able to get some useful information from them but don't except them to know all about your amplifier or speakers so if you want some good information you will have to give the specifications of the items you intend to partner.
 
If you have found this guide useful please help others to see it by clicking the YES button below. Your vote is for this guide alone and not for all of the guides I have written

Guide ID: 10000000000957267Guide created: 18/05/06 (updated 27/03/08)

Acoustics / Audio
July 2000
Basics of Loudspeaker Design & Technology (Part II)
By Jon Sager

One of the questions most commonly asked of loudspeaker manufacturers concerns matching power amplifiers to loudspeakers. We've found that the majority of loudspeaker failures encountered by our service department are the result of improper power matching.

It might seem logical to use a smaller amplifier as a safety measure; after all, it stands to reason that there won't be enough power to damage the loudspeaker. Yet we see many more loudspeaker failures due to under powering than any other cause. When the amplifier exceeds its maximum voltage capability, it can "clip" the peaks off the electrical signal it is supplying.

Once the amplifier starts clipping, the average (or RMS) level rises, which can be extremely damaging to the loudspeaker. In layman's terms, for example, your 200-watt amplifier can approach delivery of 800 watts of power, but it will be volatile and heavily distorted, and thus potentially quite harmful to the loudspeaker.
However, using an amplifier that is much more powerful than the loudspeaker's rating can do just as much damage. Supplying the speaker with more power than it can handle will often result in thermal (heat) and/or mechanical damage.

Basically, any amplifier with a 20Hz - 20kHz power rating that matches other specifications of a given loudspeaker will safely drive that speaker at full output under most conditions. Therefore it's vital to understand the meaning and impact of the most important loudspeaker specifications as they relate to amplifiers.

First, there's power handling capacity, usually defined by terms such as "Continuous," "Program" and "Peak". Continuous is the level of long-term average power accepted by the loudspeaker; Program is based upon a test signal that simulates a "real-world" program signal; and Peak refers to the maximum amount of short-term power the loudspeaker will handle.

Based on these terms, then, what is the proper amplifier choice to capably and safely drive a loudspeaker rated at 100 watts continuous, 220 watts program, and 400 watts peak? The best choice would be an amplifier delivering about 200 (continuous) watts per channel. Plenty of power for normal full-range operation while also capable of meeting short-term peak demands without going into clip.

It should be noted that although an amplifier delivering 200 watts per channel is appropriate for use with a full-range loudspeaker rated at 220 watts program, subwoofer enclosures tend to require a bit more power to generate their lower frequencies. In other words, a single mono subwoofer rated at 200 watts should be paired with an amp offering absolutely no less than 200 watts. In fact, a good rule of thumb when dealing with subwoofers is to employ an amp rated somewhere in the vicinity of 20 percent higher than the subwoofer. With that in mind, a 250-watt amplifier would be ideal in this application.

Another factor to be aware of is the impedance load that the amplifier is being required to drive. Impedance is the resistance to the flow of the audio signal by the loudspeaker. Measured in ohms, it is usually called "nominal impedance" by most loudspeaker manufacturers.

A mismatch in impedance between an amplifier and loudspeaker can result in poor performance, in the form of improper frequency response and excessive distortion. Serious damage to one or both components is also a very real possibility.

Most professional loudspeakers are rated at either 8 ohms or 4 ohms, although a number of power amplifiers are specified to drive loads ranging from 16 ohms to 2 ohms.

You'll notice that the lower the impedance, the greater the amplifier power rating. More power is required to overcome the increased resistance. For example, a loudspeaker delivering 110 watts at 8 ohms will also likely be specified to deliver about 150 watts at 4 ohms. Consider our prior discussion of power handling, and you quickly see why its important to note a loudspeaker's impedance specification in the matching process.
It's usually best to avoid 2-ohm operation, which can unnecessarily stress an amplifier, and also can require much larger (heavier gauge) cable to effectively and safely transport the load.

And speaking of cable, why go to all of the trouble of properly matching loudspeakers and amplifiers if the link between them is subpar? We recommend using heavy gauge (#14-#10), professionally manufactured cable in all applications. A good rule of thumb is the heavier the cable, the more efficient it will be as a conduit between the devices.

To learn more about the issue of power handling, EAW offers an application note entitled "Understanding Loudspeaker Power Handling and Selecting the Proper Power Amplifier." To obtain a free copy, contact us at 800/992-5013. ·

Matching Amps to Speakers

Tapco's J-1400 offers 1400W @ 4 ohms (bridged)

When you're matching a Power Amp to a PA Speaker, a good rule of thumb is to pick an amplifier that can deliver power equal to twice the speaker's continuous IEC power rating. This means that a speaker with a "nominal impedance" of 8 Ohms and a continuous IEC power rating of 350 watts will require an amplifier that can produce 700 watts into an 8 Ohm load. For a stereo pair of speakers, the amplifier should be rated at 700 watts per channel into 8 Ohms. A quality professional loudspeaker can handle transient peaks in excess of its rated power if the amplifier can deliver those peaks without distortion.

Using an amp with some extra "headroom" will help assure that only clean, undistorted power gets to your speakers. Some professional amplifiers are designed so they have additional headroom. These amps can cleanly reproduce transient peaks that exceed their rated power. In this case select a model with an output power rating equal to the continuous IEC power rating of the speaker. Consult the amplifier manufacturer or owner's manual to learn more.

In some applications, such as critical listening in a studio environment, it is important to maintain peak transient capability. For these applications, use an amplifier that can deliver 6db (or four times as much) more power than the continuous IEC power rating.

If budget restraints or legacy equipment force you to use an amplifier with less power, extreme care should be taken to see that the amplifier is not driven into clipping. It may surprise you to learn that low power can result in damage to your speaker or system.

上面引用的文章只是给大家一个参考.

我的两个想法:

1.各有各的市场和需求,俗话说,各有各的高招.
2.支配正确搭配的原理应该是一致的,
目前有没有标准呢?
我记得IEC是有过草稿的.

一些企业也是有内部标准的.

看来关心的人不多啊.

说一个我所认同的例子.

消费性产品,平板电视,基本级.
功放IC块的功率(小于10%THD)是1的话,扬声器的正弦功率可选为1,扬声器的噪声功率则为2.

这样的选择是有实验为证的.

好多E文啊，留名，待看

一般的失真都是在1W下测得的吧

 好文要顶啊