User, Dodgealum, asked, between power and current, which is more important? He said, “Can someone discuss, in layman’s terms, the differences here? I’ve seen some high wattage amps that do not produce much peak current and some low wattage amps that produce a lot of current. Which stat is more important–watts or current–in terms of deciding on a match with speakers? If current is more significant why do we (and manufacturers) talk mostly in watts?”
Here’s a bit of a breakdown on what these mean. Power (watts) = Voltage (volts) x Current (amperes). Power is the rate at which energy is transferred, used, or transformed. An electric current is a flow of electric charge through an electrical conductor. But what does this really mean for the sound produced? It can be rather confusing. No wonder there are lots of opinions on this subject!
We found this article helpful on what other factors you need to look for in combination with the wattage produced.
As it explains, in order for one amplifier to reproduce sound twice as loud as another in decibels you need 10 times more wattage output. So you do need more watts/power if you are looking for more volume. However, more wattage output and volume can also lead to greater distortion, which can make things unlistenable. You will need to be careful of this, and you may be better off with a lower wattage amplifier if you are also trying to eliminate any distortion.
Another factor in amplifier quality is Signal-To-Noise Ratio (S/N), which is the ratio of sound to background noise. The larger the ratio, the more the desirable sounds (music, voice, effects) are separated from acoustical effects and background noise.
An additional factor in this equation is the ability of a receiver or amplifier to output its full power continuously. In other words, just because your receiver/amplifier may be listed as being able to output 100WPC, doesn’t mean it can do so for any significant length of time.
Here’s what some of our users had to say about the power vs. current debate.
Mapman: Both are important depending on the speaker. Watts will determine how loud the speakers will go cleanly. Current will determine how balanced top to bottom the sound is on speakers whose impedance loads vary greatly at different frequencies, particularly at lower to moderate listening volumes.
Danmyers: Watts = Current * Voltage, Watts = Power = W, Current = Amps = A (current is similar to water flow), Voltage = Volts = V (voltage is similar to water pressure)
So you can see that both current and voltage are important in making up a power/watts rating. A good example you may be familiar with is tube vs solid state amps. Tubes are voltage driven devices. They operate at low current but high voltage and control/amplify it easily. Transistors operate at low voltages but control/amplify current easily. So you can see that to get 1W you can have 1000V * .001A or .1A * 10V
As Mapman says, which is better depends on your speakers. Everything above is in general, and in general, woofers sound better with lots of current. So solid state is generally considered a better choice over a tube amp with a similar rating. Tweeters don’t use much current so they tend to sound better with tube amps. And yes, midranges are in the middle so it’s your choice. Now marketers say just about anything and everything so you just have to take all that with a grain of salt. It’s really not which is better (wattage based on high voltage or high current), it’s which sounds better in your system to you.
Gs5556: Basically, the power supply determines the current available and the speaker load at a frequency determines the power. A high current amp is an over sized beast that has a bigger transformer wound down to a lower secondary voltage to get the extra current.
Nsgarch: You’re quite right, nothing really happens until those watts are called for, but when they are, the device appears to the amp as a certain kind of load. And it’s the nature of the speaker load (or more accurately, the nature of the speaker’s reactance) that will determine mix of amps x volts the amp must supply.
So it’s not just that speakers present different impedences at different frequencies, but that those impedances can be resistive or capacitive. Remember that current flows easily through a voice coil (so volts are called for), but almost not at all across the [air-space + step-up-transformer] assembly of an electrostat (so current is called for).
Swampwalker: Amp choice is highly dependent on whether your speakers are current optimized or voltage optimized. Which strongly suggests that at least a part of “system synergy” can be predicted.
What have you found to be the best advice in this conundrum? Have something to add to this discussion? Have a different opinion? Comment below to get involved!