How Do Tone Controls Work

[ruadmaa]

This may seem like a rather simple question for beginners but it is not. I saw this very question posted at another forum and nobody could come up with a suitable answer. For example, when the treble control is turned up, does it increase frequency response? Exactly what is the amplifier/receiver doing when these tone controls are used. If increasing treble increases frequency response does turning it down decrease frequency response?

 

[markw]

Short of a technical explanation,

They don't increase "frequency response". They simply boost or cut the amplitude of a range of the auio spectrum.

For instance, assume your amp puts out a range of 20hz to 20khz flat (+- 0 decibles). A bass control would boost or cut the bass range, starting from from around 250 or so and increasing gradually until it reaches it's maximum boost/cut of 10 db or so at 20 hz. A treble control may start at 10khz and have it's maximum effect at 20 khz.

One thing to be aware of is that for each 3db increase, you double the draw on an amp. So, if you apply 9 db of boost, you're calling for 8 times the power you would be using at 1000 khz.

Picture an equalizer with all itis controls in the middle. Now, if you boost or cut a range, the way the slides looks would approximate that action.

If you want a technocal explanation, I'll try to fine and post some links to that but you may want to brush up on your basic electronics first.

 

[ruadmaa]

Thank you markw. That is a better explanation than I had previously seen. No need to get into the heavy electronic theory.

 

[MDS]

The manual for a receiver usually lists the center frequency for the tone controls; eg. mine says +/- 12 dB, 50 Hz for Bass and +/- 12 dB, 20 kHz for Treble. How much of the frequencies above and below the center frequency are affected would be determined by the Q of the tone control (same principle as an equalizer - the Q affects the 'width' of the surrounding frequencies that are affected). The Q is not listed, so who knows...