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Damping

RockerAlex

Inspired
No matter how many times I read the explanation of this parameter I can never fully understand what if means ... Can somebody explain to me why the bass becomes so overpowering with this set to 0?
 

Rex

Legend!
Damping is a power amplifier's ability to control the movement of a loudspeaker.

Ideally, you want the cone of the loudspeaker to exactly follow the signal that's coming out of the amp. But that never exactly happens. The speaker cone and voice coil have inertia, and they want to, for instance, keep moving forward when the signal is telling them to start moving backwards. If an amp has a lot of damping going on, it can more tightly control the speaker, and the sound and feel will be tighter. If the amp doesn't have much damping, it will sound and feel looser and spongier.

The thing about damping is that it has its strongest effect at frequencies close to the resonant frequency of the speaker. For guitar speakers, the resonant frequency is in the bass region. So zero damping means loosely-controlled bass.
 

Thomas Larsson

Experienced
The correct name of damping would be "negative-feedback" . Most amps sends an ouf of phase signal from the speaker output back to the power-amp-input to "correct" what has "gone wrong". It makes the output signal more similar to input-signal. Pentods properties is among other things to keep the current constant. That means that if the impedance of the speaker raises it will cause the signal voltage to increase as well. That is a big difference to solid most state amps.

Speakers have nominal impedance around 300-1000 Hz or something. (for example 8 ohms)
The bass-resonance is around 50-150 Hz for most guitar cabs. ( 30-40 ohms )
The impedance also raises with frequenzy and gets 4-5 times as high at 20kHz (30 -40 ohms)

So:
With no damping you will get a scooped sound.
More bass and also more high end .
You will also get more smooth powertube distortion.

With lots of damping you will get a stiffer narrower power amp sound. In fact it sounds more like a solid state power amp with high dampings.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Note that when you set Damping to 0 that Presence becomes a Hi-Cut so if you have the Presence turned up you'll lose high end when you turn Damping to 0.

Also, Depth does not work at a Damping of 0 since Depth modifies the feedback and there is no feedback.
 

RockerAlex

Inspired
Note that when you set Damping to 0 that Presence becomes a Hi-Cut so if you have the Presence turned up you'll lose high end when you turn Damping to 0.

Also, Depth does not work at a Damping of 0 since Depth modifies the feedback and there is no feedback.
Thanks for the clarification Cliff. :)
 

Rex

Legend!
The correct name of damping would be "negative-feedback" ...
Lots of great info in your post, though I would clarify that "negative feedback" isn't the correct name of damping. Rather, negative feedback is a way to increase damping. Even amps with no negative feedback at all have some damping.

Lots of nice, juicy details in your post.
 
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