Treble and bass audio controls w/o phase shift?

[Bob S]

Simple treble and bass controls in audio equipment use RC networks that have a phase shift equal to a radian per neper, or about 6.6 degrees per dB of boost or attenuation. Are there analog treble or bass control circuits that have no phase shift?

 

[dlgoff]

Could you use active filters to pass the frequencies you want? Maybe use a high pass filter to attenuate the low frequencies and a low pass to attenuate the high frequencies.

 

[bipolar]

Active crossovers still give some phase shift. The only "phaseless" boost at certain frequencies would have to be done digitally, but there are phase shifts involved there if not designed properly. Unless applying a DSP from a digital source to the next component, a DAC/DSP/ADC seems to be overkill for bass and treble only.

Still, some audiophiles might buy it, in spite of the fact that "all digital is bad", selling something that can dynamically cancel out the natural phase shift caused by woofer woofer movement ("Doppler effect") could be a big hit.

Just a matter of adding in your bass and treble controls while you are at it. :P