"Watts" Versus "Current"

Depends on the speakers.

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.

In my case, with large Ohm Walsh 5 speakers, I swapped a 360 w/ch but low current Carver amp for a 120w/ch Musical Fidelity that delivers a lot more current/watt for this reason with very positive results.

The switch also produced similar positive results with my Dynaudio Contours.

Both Dyns and OHMs like lots of power AND current.

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 SS 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.

Forgive the intrusion, but I've got a pratical question about the use of the two different amps, i.e. low power high current and high power low current.

When driving a speaker at say 10 watts max (including peaks) and your two amps are, say 200wt, one which has 'high current' and doubles down to 2 ohms, and the other which can only produces say a 50% watt increas at 4 ohms, will you hear a difference because of the difference when you play speakers with a mean impedence curve, or does that only happen when you start to approach the power limits available at any particular frequency/impedence demand?

Just curious.

Current is a component of watts (power) as Dan just indicated. Therefore, all watts are not created equal.

1 amp (of current) X 10 volts = 10 watts of power. But 10 amps X 1 volt also = 10 watts. Further, the basic W =A x V really works for direct current (DC) only. The formula is a bit more complicated for AC (as in: music signal). But leaving that aside for now, how the power is created will either be better or less good for certain kinds of speakers.

Why? Because every kind of driver generates a reactive signal BACK TO THE AMP. When the signal from the amp moves a cone back and forth, for example, the action of the cone's voicecoil in the magnetic field actually GENERATES a reverse electric current BACK to the amp! This reverse current adds to the impedance (load) the amp "sees".

What's CRITICAL (in amp selection) IMO, is HOW how that (let's call it 'phantom') impedance is created. If the amp sees a capacitive type of load (an electrostatic speaker) it needs for its available watts to consist of lots of amps (current). If it sees a resistive type load (like cones, domes, ribbons and planar magnetics) it needs for its available watts to consist of lots of volts (to overcome the reverse voltage created by those kinds of drivers.)

I'm going to generalize here, but 1 tube amplifier watt (a typical push-pull circuit with an output transformer, nothing exotic!) will be rich in the current it can make available (for that 1 watt of output.) 1 solid state amplifier watt (a typical push-pull circuit with the output transistors directly coupled to the speaker) will be rich in the voltage it can make available (for that 1 watt of output.)

You can guess where this is headed ;-) Tubes are better than silicon for capacitive loads, and silicon is beter than tubes for resistive loads. All right -- this is a sweeping generalization! HOWEVER, because the impedance of all speakers varies widely depending on frequency (the rated impedance of speakers is only a nominal figure) there could be times when you'd need a HUGE tube amp to drive those dynamic drivers (God forbid acoustic suspension woofers!) properly. Or if you are driving electrostatics (panels only, we're talking about) you might need a HUGE solid state amp to give those stats the current they need when a tube amp of far less output would sound as good (and likely better IMO ;-)

People into fine audio are generally at the 3-digit Stanford-Binet level. But many (probably most) have had little occaision to become familiar with the nature of (yikes!) circuit design. But if you will take a little time (good bathroom reading for instance as it takes several passes to sink in ;-) and go through this excellent and (reasonably) clear, easy to understand online tutorial, you will find yourself more informed than many of the self-appointed/annointed 'know-it-alls'/'experts' that haunt the halls of audio-underworld ;-)
http://www.allaboutcircuits.com/vol_1/index.html
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