Power vs. Current: Which is more important?

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!

9 thoughts on “Power vs. Current: Which is more important?

  1. Josueminerva says:

    As I understand the question should be watts vs current designated as Amps or Amperes . Watts is only a term used in order to determine power measuring heat output of a particular device . That being as it is it is a rather vague unit to determine the capability of an ampifier to drive a speaker . Why then is it used ? Because the ” HiFi asociation ” determined to use this unit of power measurement in all hifi equipment specifications . Why is it a vague spec to determine output ? Because a particular speakers power requirements change constantly depending on its impedance which changes as frequency changes , so a speaker might need 2 watts to develope 90 decibels at 1000 Hz at 8 ohms the same speakers impedance takes a dip at 100 Hz which could be at 4 ohms doubling the power requirements to 4 watts in order to replicate the same 90 decibel output . And to further complicate matters for every 3db increments , which is the sensitivity to hear volume differences , you need to double the power .

  2. Josueminerva says:

    That being as it is current is a more confident manner in real world use to determine the capabilitiy of a particular amp to drive a speaker which is specified as amperes . You can have one amplifier which is spec as 100 watts at 8 ohms at 1000 hz with current capability of a continous nature of 10 amperes and another one with 75 watts at 8 ohms , 1000hz capable of 35 amperes of continous current . As you might suspect , the amp with the 35 amp specification , even with 25 watts lesser then the other amp , will better drive a speaker to a particular volume level . So as you can guess by now , current is better able to tell you what a particular amp will do with a speaker then the watts specification or as you say ” power “

  3. Wharf_Creek says:

    A ‘high current’ amp is really just another description of how the amp is designed in order to reach it’s final output stage numbers.   Likewise, one could say the same thing about a ‘high voltage’ amp if referring to the plate voltage on some Tube Amps out there.   As I see it, when you connect your speakers to the amp, you’ve got several things to be thinking about, but ‘current’ vs ‘voltage’ isn’t one of them    ‘Power’ IS one of them.   But, ‘power’ alone is not the only issue.   In theory, if an amp is rated at 50 watts, it should be able to produce an undistorted sine wave across the entire musical spectrum of frequencies right up to the 50 watt power level.   However, this is where ALL those ‘other’ considerations come in.   The concept of ‘continuous’ power vs ‘peak’ power is a HUGE factor in this area as some manufacturers will call their amps a 50, 100, or 200 watt unit, when in reality that figure is only being based on the sine wave hitting the peak level for a split-second of time…..or ‘peak’ power level.  So….’continuous’ power, low distortion, and ‘quick recovery’ within the power supply…..to me…those are the important factors.   That…..and of course, the speaker efficiency. There is a HUGE difference between speakers at 89 db efficiency vs those at 100+.   I’m a ‘tube’ guy….and use speakers of 104 db efficiency….and run amps as little as 5 or 6 watts.   But, from a ‘volume’ standpoint, I can drive most people out of the room…..and do so with good clean undistorted sound!

  4. Nakdoc says:

    Since music is an AC signal, and almost all speakers are complex impedances (with inductive and capacitive phase shfts that alter the amplifier’s ability to keep voltage and current drive in-phase), the best amplifier is one that handles the specific speaker best. In other words, there is no answer!  Does this explain why high end audio has been matching speakers and amps since 1960?  A fine example is the Quad Electrostat speaker and the Quad 303 amp. Read up on this combination and apply the same principles to your system.

    • Thomas_w_bowman says:

      Also why bi-amping can deliver better performance than using one amp for all drivers.
      The only meaningful answer is to listen yourself and evaluate.

  5. Ed VE says:

    Neither.     voltage is more important.     Remember, power is equal to E squared divided by the speaker resistance.   Power will be limited by the power supply voltage to the out putamps  —  not enough voltage and you will get clipping.   

  6. Nsenape says:

    It is all about the current in the end to get clean watts. Think in terms of a fire hose, high presure will bore through burning wood and make 2 fires, distortion, a 4 inch pipe will dump a lot of water and snuff the fire out, real work gettimng done quick by volume. Valves turn the water down, ha ha!! Better detail usually. A real problem is industry has no incentive to produce high quality solid state devices for the high end guys. Try to find great power devices, Bi-Polar, Mos, and J-FET, they are almost as old as NOS tubes and nobody ever made stockpiles like tubes. They made complimentary P and N channel unlike tubes! I hope like Record stampers, someone buys up smome old equipment and copies the unutilized potential, unlike tubes no toxic substances or dangerous working conditions to produce the best ever.

  7. Thomas_w_bowman says:

    Along with Power supply, capacitors can help drive short-term peak power above and beyond the limits of the Power supply. Capacitors basically generate something like a ‘static’ (not ‘moving’) charge, which can be added to power supply output – but is quickly drained (and then must accumulate the ‘reserve’ charge befre delivering max added power again.  In general, the more substantial (powerful) the capacitor, the more momentary boost it can add to a power peak. Computers use capacitors smaller than a pinky-nail, ut I’ve seen capacitors that could be potentially quite dangerous that are larger than beer cans. Remember that when the power is shut off, it may take a while for the capacitor to discharge – so it could remain ‘hot’ for a while, even unplugged. The ultimate authority on what’s best for your configuraiton is simply to test – using your components. Some ‘less efficient’ speakers have much better ‘Damping Factor’ (cessation of movement when power stops), which lends a crispness to sound. Higher efficiency speakers may continue vibrating for a few cycles after the power stops. Again, no substitute for listening yourself (to varied sources, some ‘electronic’ music may sound better with low damping factor – but other sounds may be best with the speaker closely following the power waves due to better damping.

  8. Thomas_w_bowman says:

    Also, remember that the components tend to deliver their bet performance at 40-70% of maximum potential – although I tend to look for speakers that can handle a max RMS power matched to the Peak rating of the Amp (this makes it considerably less likely to ‘blow’ the speakers while it will minimize clipping by the speaker). Digital sources are especially noxious when they clip because they tend to make a ‘square’ wave, which sounds muddy without getting louder – because the speaker is actually getting a signal ‘telling’ it to “Not Move” when amp clips it can actually be quieter when the souce should be louder.

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