Axiom Home Page Forums General Discussion Technical Questions Impedence curve and frequency response

Pardon another newbee question. Since speakers apparently have different impedences at different frequencies and various amplifiers' power outputs respond differently to different impedences, doesn't that mean that the actual frequency response of a speaker is very dependent on the amplifier?

Could this be an uncontrolled variable that accounts for the appearent variation in sound and reviews of different amplifiers; could the apparent sound variation of amplifiers be really depended on based on the speakers used in reviewing them? Is the output of tube amps any more or less impedence-dependent than IC amps?

Hi bobcox,

In what is a very complex technical matter (too long for discussion here), think of solid-state amplifiers has having essentially 0 ohms output impedance--the speaker "sees" an impedance of about 0 ohms at the other end of the cables. So the amp's output does not interact in way that changes frequency response of the system, as long as the measured frequency response of the amplifier is ruler-flat, and virtually all are, unless they were designed by a bonehead.

However, this is NOT the case with tube gear. Tube amps have output transformers with fixed impedance taps at 8, 16 and 4 ohms. This may interact with the speakers impedance curve and introduce response anomalies. The latter often account for some of the mystique surrounding tube amps-- subjective descriptions of traits (depth) attributed to tube gear. Accuracy is not a virtue of tube amplification.

Regards,