Clean Channel Volume Low

[wikwox]

I have a Fender Pro 185. Two twelves, 185 watts and a reputation for peeling paint if you don't watch the volume. Channel two, the dirty side is loud and easily keeps up with the band with master on 3 and drive at about 5. The clean side sounds good but I have to keep it at 5, seems to me thats higher than it should be. I have replaced the "bass" pot on this channel, the shaft was snapped off, and I lubed/cleaned the rest of the pots. What are probable causes for lowered volume? On a tube amp I would look at the power tubes but obviously thats not the case here. Everything inside the amp looked good, clean and where it should be. Any ideas?

[J M Fahey]

Your amp is fine.
The "number" on the pots is only a reference number, does not mean a given power output.

[joecool85]

Your amp is fine.
The "number" on the pots is only a reference number, does not mean a given power output.

I agree, it's just the way the amp was designed.

[wikwox]

Your amp is fine.
The "number" on the pots is only a reference number, does not mean a given power output.

I agree, it's just the way the amp was designed.

So your saying that even though the amp seems to turned half way up it's no reference to the power of the amp?

[armstrom]

Your dirty channel likely has significantly more gain than the "clean" channel. That's how all analog amps achieve "dirt" in the sound. Lots of gain and then some manner of clipping after the high gain. Digital/DSP based amps are an entirely different story and can use all sorts of techniques to introduce "grit" into the sound.

The volume control(s) in MOST amp circuits (not all, but most) are simple variable voltage dividers. They are not increasing the amplification of any stage in the amp. This is known as passive volume control. Active volume controls exist but are less common in guitar amps since messing with the gain of an amplification stage can cause other issues in the signal. So typically the gain of a given stage in the amp (preamp, poweramp, pre-pre-preamp, whatever...) is set at design time and the input signal to that stage is simply attenuated to achieve lower volumes.

So don't think of your amp as being "half way up" think of it as "reducing the signal to the power amp by half". (no, being on 5 out of 10 does not mean half signal.. but it works for this example.)

So, if your clean preamp has less gain to begin with (trying to avoid clipping and other gnarly distortions) then cutting that signal "in half" compared to cutting the dirty channel signal "in half" before feeding it into the power amp must be quieter.

Couple all of that with the fact that distorted sounds have a psychoacoustic effect of "sounding louder" than a clean signal at the exact same SPL and I'm sure you can account for the difference in volume you're hearing.

So, to sum up all that nonsense rambling... I agree with the others, your amp is fine There's a reason the amp has an independent volume control for each channel. If they were equally as loud for any given setting then they would have just given you one for both channels
-Matt