# What Should Manufacturers Specify: Peak Power or Average Power in Audio Systems?

• Physicslearner500039
In summary: DcRvOmxRc&ab_channel=AllAboutCircuits In summary, the conversation discusses an example problem involving an audio system's power output. The user has a misconception that the power output is a sine wave and fluctuates from minimum to maximum values. However, this is not correct as the power varies many times per second and the listener hears a smooth, steady note. The user also asks if they can clamp the output power to always generate the peak value and if the manufacturer should specify the average or peak power. The expert responds that clamping the power is not possible and the manufacturer should provide information on whether the power is input or output, and if it
Physicslearner500039
Homework Statement
An electric hair dryer is rated at 1500 W (the average power) at 120 V (the rms voltage). Calculate (a) the resistance, (b) the rms current, and (c) the maximum instantaneous power. Assume that
the dryer is a pure resistor. (The heating element acts as a resistor.)
Relevant Equations
P = ##V_{rms}*I_{rms} ##
It is an example problem and i could understand the solution and the answers are
## R = \frac {V_{rms}^2} {P_{av} } = 9.6 \Omega##
##I_{rms} = \frac {P_{av}} {V_{rms}} = 12.5 A##
##p_{max} = VI = 2P_{av} = 3000 W##
But main problem is the statement given by the author below the solution which says "Some unscrupulous manufacturers of stereo amplifiers advertise the peak power output rather than the lower average value". My understanding is something like the output power is a sine wave, since it is a pure resistance circuit the power keeps fluctuating from min value to max value and the user should actually feel the sound decreasing from min to max sine wave value. Is it correct? Can i clamp the output power coming from the speaker that is the audio to always generate Peak value (3000 W)? The manufacturer should specify the average power or the peak power? Please advise.

Hi. I notice you haven’t any replies yet. That’s unusual and I think I know why. What you have written contains major mistakes/misconceptions and it is hard to explain them. But let me have a go.

My understanding is something like the output power is a sine wave, since it is a pure resistance circuit the power keeps fluctuating from min value to max value and the user should actually feel the sound decreasing from min to max sine wave value. Is it correct?
No. Let's take a simple example of an audio system playing a single pure musical note (say an 'A' which has frequency of 440Hz). The voltage applied to the loudspeaker oscillates 440 times (cycles) each second. A single cycle take $\frac{1}{440}$s, which is 0.0023s approximately (this is the 'period').

Suppose the peak voltage is 5V. Each cycle, the voltage goes from 0V to 5V, then to zero, then to -5V and than back to 0V. The power depends on voltage squared so hits a maximum twice each cycle (for 5V and for -5V). Most of the time the power is less than the peak power. The power is oscillating between zero and Pmax 880 times each second.

The listener can't tell this is happening as these oscillations are far too fast to hear; the listener hears a smooth, steady note of power Prms (which Pmax/2)

Can i clamp the output power coming from the speaker that is the audio to always generate Peak value (3000 W)? The manufacturer should specify the average power or the peak power?
No. The power varies (many time per second) as explained above. To 'clamp' the output power you would have to apply a steady voltage (DC) which would produce no sound (and damage the speaker due to overheating).

3000W for an audio system is huge (rock-band level).

A manufacturer should include the following sort of information for a stated power:
- if the power is input (electrical) power or output (audio) power, as these are very different, as audio system efficiencies can be very small;
- if the power is peak power or rms power;
- to what frequency the power level figures apply.

This video should help understand rms and peak values better:

Physicslearner500039

## 1. What is the difference between peak power and average power?

Peak power refers to the maximum amount of power that can be produced or consumed in a given time period, while average power is the average amount of power produced or consumed over a longer period of time.

## 2. How are peak power and average power measured?

Peak power is typically measured in watts (W) or kilowatts (kW), while average power is measured in watt-hours (Wh) or kilowatt-hours (kWh).

## 3. Which is more important, peak power or average power?

The importance of peak power or average power depends on the specific application. For short-term, high-intensity activities, peak power may be more important, while for longer-term, sustained activities, average power may be a better indicator of performance.

## 4. How do peak power and average power relate to each other?

Peak power is typically higher than average power, as it represents the maximum amount of power that can be produced or consumed. However, the relationship between peak power and average power can vary depending on the specific activity or system being measured.

## 5. How can peak power and average power be used in practical applications?

Peak power and average power can be used to evaluate the performance of different systems or to compare the effectiveness of different training methods. They can also be used to determine the power requirements for various devices or equipment.

• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
4
Views
1K
• Electrical Engineering
Replies
10
Views
2K
• Electrical Engineering
Replies
28
Views
12K
• Engineering and Comp Sci Homework Help
Replies
3
Views
3K
• Electrical Engineering
Replies
7
Views
1K
• Electrical Engineering
Replies
1
Views
3K
• Atomic and Condensed Matter
Replies
11
Views
6K
• Calculus and Beyond Homework Help
Replies
2
Views
7K