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Post by ozboomer on Mar 26, 2012 23:24:46 GMT -5
I've been using musical instrument amplifiers for a few decades now... but I've never really had to understand the differences between 'gain', 'volume' and 'master (volume)'. Having recently bought a Fender Mustang I amplifier, I now have access to Twin Reverb, Deluxe, etc amplifiers (albeit modelled versions)... and I need to understand some more about all these 'volume' controls. Is there a handy reference about that explains how these different controls work? My ears are not so flash that I can easily discern light distortion/overdrive so I'd like to know the 'right' way to use these controls. In my experiments so far, I've found that sometimes there is no sound at all if the 'gain' and/or 'volume' controls are on '0'.. but the sound is distorted as soon as the controls are put on '1'.. and there must be some way of sensibly setting the controls. I would have thought that the 'gain' control is something to do with the output from a pre-amp stage and as such, the sound shouldn't really be distorted until the control is past '6' or '7'... but this doesn't explain the function of the 'volume' control compared to the 'master (volume)' control. Would greatly appreciate any pointers... Thanks. John |
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Post by ashcatlt on Mar 27, 2012 0:31:52 GMT -5
As I understand it, most guitar amps are built such that the power amp section has a set level of gain. They don't give you a knob for that. But you want to be able to control the volume, and in many cases the amount of distortion added to the sound. There are really only three ways to do that.
1) Run the preamplifier at a set gain, and attenuate the input before it reaches that stage. There are a number of reasons that this isn't the best idea. Cant think of any amps which do this.
2) Adjust the gain of the preamp section. If I'm not completely mistaken, this is the way most amps with a single Volume control operate. In something like a master volume fender, this would be the channel Volume. It might also be labled as "Gain" or "Pre ". Usually turning this knob up will start to add preamp distortion, and - if the signal is not attenuated afterwards - power amp distortion.
3) You can attenuate the signal between the preamp and power amp stages. This usually wont be the only volume knob on an amp. This would be the Master Volume. On some amps, this might also be labled as "Post" or even mislabled "Post Gain". Given enough output from the preamp, this knob will adjust both the total output of the amp and the amount of power amp distortion picked up along the way.
How these things are implemented in a modeller can be a question. I'm always a bit frustrated working with models that have knobs where the original amp doesn't! Most seem to have Gain - which basically adjusts the amount of distortion - and Volume - which sets final output level. Some (my VAmps, and most of the VST modelers I have) also have a Master Volume after that. In these cases I like to believe (and believe I can hear) that the the Volume controls some of the simulated power amp distortion
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Post by ashcatlt on Mar 27, 2012 0:35:24 GMT -5
The real answer:
Turn the knobs till it sounds good and plays at an appropriate level!
Please excuse the second post. My mobile device fails at scrolling text boxes, and I don't feel like winding up the big machine.
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Post by reTrEaD on Mar 27, 2012 6:57:04 GMT -5
but I've never really had to understand the differences between 'gain', 'volume' and 'master (volume)'. They are all attenuators. The difference is where they are in the signal chain. Generally... Gain -> Volume -> Master High settings of gain and volume with a low setting of master will allow distortion without excessive volume. For a clean sound, gain will be set fairly low with a low to moderate setting of volume, adjust master to desired loudness. |
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Post by andy on May 7, 2012 11:21:35 GMT -5
Is there a handy reference about that explains how these different controls work? That may help, may be a bit vague. The way I look at it is that they are both volume controls at different points in the circuit, bearing in mind the meaning of the word 'overdrive'; that being that the cool sounds you get from dirty-ing up your guitar sound are from pushing more signal through electrical components than they were originally designed for. Also 'gain' is just a term for an increase in voltage, but in amps it is used to differentiate between 'internal' volume and actual output volume. Step 1: Guitar amps were originally designed to cleanly reproduce the sound of a pickup, but due to the limitations of the cranky old valve technology, they could only do this up to a certain point. If you turned your amp up too loud, they started sounded horrible and distorted. Step 2: That horrible distorted sound turned out to be pretty damn cool, but the volume that guitar amps became capable of producing (for the sake of staying cleaner) was so high that getting that distortion was impossible without playing at earsplitting volume. Hence the introduction of 'booster' pedals such as the famed Dallas Rangemaster. These meant that rather than turning your amp up so loud that it began to distort, you could push so much signal into your amp that the circuitry began to distort, and then use the volume to adjust the actual loudness. Step 3: With manufacturers no doubt feeling a bit daft that their amps only got the cool, fashionable rock sounds with a bit of outboard kit hooked in front, the 'master volume' amp was invented. This is essentially an amp with a built in booster. The 'gain' is how much signal is pushed into the circuitry, the volume is how much you get out at the end in actual percieved volume. This can be tested with any pair of dirt pedals- set the one to the right to a clean sound with the volume whacked up, and the one to the left to a kind-of-dirty-ish sound. With the dirty one on, it is a bit dirty. Kick on the clean but loud one, and the sound gets dirtier, but not necessarily that much 'louder'. Likewise, turn down the volume (on the clean boosting pedal or on your guitar), thereby lowering the voltage going into the pedal from the guitar, and things clean up again. In the context of an amp, you could get the power amp (volume) to distort, but it would be very loud, or you could get the pre-amp (gain) to distort, and then have the volume control available to keep any nearby ears happy. The belief that a distorting power amp sounds better than a distorting pre-amp is exactly what has given rise to the current slew of low wattage amps on the market, taking us back to Step 1 above, but for the very fact that the sound will be distorted before the amp gets ridiculously loud. Modellers are a bit confusing, as the amps modelled may only have had one volume control, and yet run through three different volumes on the unit. I have also noticed that the 'master volume' amps in my Pod don't always change characteristics as I bring up the 'channel volume', so digital modellers, for all their real world value, may not be the best place to truly get a grip on the gain/volume function. |
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