Gain question

[Rbloom659]

Hello,

Anyone care to explain what the term "gain" refers to in a conventional 2 channel stereo power amplifier? Why a separate gain control for each channel? Is gain related to volume or power output? Thanks for any light shed on this.

 

[RhapsodyInBlack]

in your case, gain is essentially volume...it sounds like the gain control is the only type of control you have on it. gain is basically defined as an increase in voltage, current and/or power. Most audio mixers have both a gain control for the input signal and a volume control for the output signal and the gain would be the ration between the two.

 

[Rbloom659]

OK, so it controls the input from the preamp? Some amps have no such controls, so what is the advantage? Why a separate one for each channel? Wouldn't that make one channel louder if set at different levels?

Thanks again -

Robert

 

[jaxvon]

Yes, it would make one channel louder if set at different levels. I would think there are separate controls for each channel so you can tweak your levels to perfection. Sometimes things aren't quite right, and being able to tweak one channel can help you perfect your sound (among many other things).

As far as purpose goes, some people might not be satisfied with the level of output from their preamp, so they turn the gain up. Conversely, someone might think their preamp outs are "too hot", so they want to limit the amount of gain the amp applies to the signal before sending it to the speakers. These controls are very common on live sound amps (like Crowns) due to the need for tweaking the sound at each venue.

 

[MDS]

Receivers/Amps have a maximum 'rail voltage' they are capable of producing. If you look at the specs for an amp it will often say something along the lines of '1 Vrms for maximum output' - meaning if it is fed 1V and its maximum gain is used, it will produce its rated output power.

Now if you use a source component that outputs 2 V and the gain on the amp were set to its maximum, then when the volume control is turned up near its maximum, the amp will clip. [The rail voltage will always swing between 0 and its max - the gain control of the amp in combination with the volume control of the pre-amp is what allows the voltage to be between 0 and max]. So as Jaxvon said, gain controls are provided to deal with those situations or when each channel requires slightly different gain settings to balance the sound from each channel.

One thing to remember to help visualize this is that the volume control does not actually 'turn up' the volume as you increase it. In reality, a volume control is an attenuator and the further you turn it up, the less it attenuates the signal. When it is at its max, the full 1V or whatever it is of the source component is sent to the amp and the amp applies its gain setting to get to the final output power.

 

[Snarl]

Gain: Increase in level or amplitude.

 

[Megalith]

Sorry to bump such an old thread, but it would be in my best interest to leave the preouts at 0db and adjust only the gain in order to achieve the volume I need, right.

Bumping my preout to +10 would allow me to attain the volume I need with a lower gain setting, meaning less noise, but I would probably introduce distortion with such a high setting, correct.