Tone Controls on Yamaha Amp - Questions

Can someone please help me understand what happens when I turn the bass or treble knob up or down on my amp?

The manual says for Bass, it boosts/cuts (20 Hz) by +/- 10 dB and the turnover frequency is 400 Hz.

For treble it says it boosts/cuts (20 kHz) by +/- 10 dB and the turnover frequency is 3.5 kHz.

What I am trying to understand is does that mean when I turn the bass knob, does that mean I am boosting or cutting the bass at 400 Hz or 2o Hz? And if so, how does that affect the surrounding frequencies?

And same question for treble, does it mean turning the treble knob means that I boost or cut the treble at 3.5 kHz or 20 kHz and if so, how are the surrounding frequencies affected?

Thanks in advance.

 

The bass knob starts to boost/cut at 400 hz and reaches its max at 20 hz. The treble starts boosting or cutting at 3.5khz and reaches its max at 20 khz. Boost/cut will be about zero at the turnover frequency and rise or fall from there.

 

The turnover frequency is the point bass or treble begins to take effect. So if the bass boost is +10dB at 20Hz, the boost at the turnover frequency would be apprx +1dB to +3dB.. depending on the curve. The turnover point depicts the "knee" in the response curve... where the response begins to become significant. Bass and treble do not turn on or off like a switch at a certain point. It's a gradual transition. So, to answer your question, the bass and treble are slightly affected at the turnover frequency.

 

First of all, thanks a ton for your post. As I am new to a lot of this, it brings up more questions for me:

So the bass knob on my amp allows me to increase or decrease the bass at 20Hz by 10dB?

And if I got that right, why is the turnover frequency (400Hz) significant? When you say slightly affected, that suggests to me it would be less significant than the +10dB at 20Hz. Or am I missing something?

Also, what happens to the frequencies between 20Hz and 400Hz? Is the curve something like this? (Can't find one for a Yamaha amp, but as a guideline, I thought this might be helpful.)

 

The graph describes what happens between, for example looking at bass boost, this Fisher 500C maxes at +10dB at 50Hz, but half the boost +5dB at 250Hz. The turnover point is at apprx 400Hz at about +2dB. When you set the bass control at a lower setting, the curve isn't as extreme. The typical turnover points on most pre-amps are: Bass at 400Hz, and treble at 2.5kHz. The turnover points can be different on certain makes and models. High end pre-amps tend to control more of the frequency extremes, which may have turnover points at 100Hz and 10kHz... and only 6dB max boost (((or))) no tone controls. Yamaha tends to be on the conservative side, more like 200Hz and 5kHz turnover and not as much total boost or cut.

It is never a good idea to crank the bass and treble to their extremes, since any recording needing that much would be a very lousy recording. If the listener feels the need to boost or cut, usually only 2 to 3dB will be fine. (extra margin designed in because some people are simply bass and treble "happy") Back in the 70's I knew a few people who cranked the bass and treble all the way up, and were happier listening to music that way. If more than 6dB boost or cut is needed for the music to sound right, then something's very wrong with the system, the room acoustics, or the recording.

 

Not really relevant and I might be mistaken (frequently am) but I thought Yamaha gear (at least from the late 80's through late 90's) was +\- 5dB on the bass/treble?

I spent a good number of years with a Yamaha retailer and seem to remember using that as a selling feature.

But it could been Luxman.

 

Checked my manual again and it is indeed +/- 10dB on bass and treble.