Gain vs Volume....a question?


Please excuse me for asking, what might be obvious to all but me, but I am curious. Can someone explain to me (a non-tech) what the difference is between cartridge gain settings and the actual volume control on the pre-amp.
rwd
I might disqualify to answer but English was never my strong suit & I don't follow instructions too well either! :-)

>>cartridge gain settings
The amount of gain you will be providing to the signal coming from the cartridge. You can multiply the cartridge output signal level by this gain number (not in dB but after you convert it to a linear number) & this will tell you the max. signal that you will able to feed your phono pre with.

>>the actual volume control on the pre-amp
The portion of the total available gain that you are actually using to listen to music. In most cases, the user rarely uses all the available gain in his/her system to listen to music at reasonable volume levels.
It is important to have much more gain than you are going to use as this ensures that the signal is within the linear operating range of the electronics being fed with this (music) signal. I.E. you are above the min. sensitivity of the electronics.

Hope that this complements TWL's post.

There is the aspect of hitting the max. input level of the electronics. You didn't ask for that, so I won't answer either.

Rick,

Gain setting is like a car’s transmission box. Preamp volume control is like the gas pedal.
Sugarbrie;

Thanks for the post. It looks like you did a lot of work for us as I think you had to copy it, word for word.
In simple terms, gain is a ratio and volume is what you hear. For example, say that "gain =10". Take two sounds - a gunshot and a whisper. If you multiply each by 10, the whisper will have a higher volume and be easier to hear whereas the gunshot will have enough volume to seriously damage your ears. Both sounds are increased by the same proportion or gain. But a gain of 10 will not take a whisper to that of a gunshot - you will need a series of gain stages in between.

Front end audio equipment is a series of gain stages. The cartidge has a gain setting, but not enough to drive an amplifer, and in most cases not even a preamplifier. So the chain is cartridge, phono preamp, preamp, and amplifer.

The volume control adjusts the gain within the preamp from zero gain to the maximum gain of the preamp. The strength of the source signal will ultimately determine the audible volume for a given volume (gain) setting.
Just to add a couple more simplistic thoughts to the already excellent discussion from an absolute layman’s perspective, "volume control" generally can be achieved by two basic means, either attenuating (that is reducing) the signal that comes into the control or by amplifying it (which I have understood as adding gain). An active preamp is called that because the volume control can do both of these things--it can both reduce the signal from the input level towards zero and it can (because it has an amplification stage) amplify the signal above the input level. A "passive" preamp, on the other hand, is passive because it can only reduce the input level -- it will not have an amplification stage at all.

For most sources, the output level of the signal (which is the input at the preamp) is relatively high. Which is to say that at zero gain at the preamp (no attenuation or amplification of the signal) the volume level will be relatively loud. (Which is how passive preamps/volume controls can work -- based on the assumption that the volume associated with zero gain will be louder than you ever want or need, therefore attenuation or reduction of the signal level can provide all of the volume control range you would ever want).

Compared to just about every other source out there, however, the output signal that comes off of a vibrating pin scratching across a rotating platter of vinyl is tiny. So tiny that, without additional amplification, the signal would be too weak for a volume control designed to provide a useful range for things such as CD players to do much anything useful with at all. Thus, in order to jack the tiny output from a typical phono cartridge up into the range the your average preamp volume control was designed to operate in, you need some additional amplification. This is why a phono preamp is a separate or additional piece of equipment (or stage in your existing preamp) from your plain vanilla preamp -- it independently amplifies the signal coming from the cartridge up into a range useful for your average volume control. The gain level of the cartridge dictates how much more work the phono stage will have to do to get the signal up into this useful range. Did my layman’s understanding screw that all up horribly?