By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.
View post (ENGL powerball or Peavy 5150 II)
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the price doesnt reflect it.. well it does to an extent. I think. Mesa amps are far more expensive compared to the powerball and 5150 and yet are no better from what i've heard !