Current vs. Watts??? Need clarification.

W = E X I X P.F.

P.F. (Power Factor in %) refers to the phase shift between current and voltage at various frequencies. Some speakers are more prone than others.

So, the more phase shift you have the more current required to achieve the rated watts.

A sufficient power supply will help sustain the voltage during larger phase shifts, and some amps are able to deliver more current.

I guess there are a lot of ways to skin a cat and some amps do it better than others. :-)....?

In theory, an amp rated at 128 wpc, will deliver a sound level of 110 dB at 1 meter when paired with 89 dB speakers. However, it will only deliver about 104 dB at 3 meters...which is where most of us listen to our music.

Also, at about 60% of the amps rated power, distortion will start to creep in. Consequently, we must reduce the theoretical output of the amp by another 3 dB if we want clean , undistorted sound.

Conclusion = Not accounting for the many other factors which may further reduce the sound level (listening room acoustics, age/condition of components, headroom to cover peak dynamics, etc., etc.), we will be lucky if our 128 watt amp delivers 101 dB of "clean" power at 3 meters.

HG

I always heard that a 50 watt tube amp puts out the same current as a 100 watt solid state amp because of the higher voltage. Is there any truth to that?

Tube amps do not deliver a higher voltage to the speakers. The higher voltage from the tubes is run through an output transformer to send the correct (lower) voltage to the speakers.

Many people ascribe the tendency of tube amps to sound louder than solid state amps of the same wattage to a difference in clipping properties when a tube amp is overdriven. Tubes tend to have a softer clipping characteristic so don't sound near as harsh and distorted as when a transistor amp clips.