[PStamler]

On Tuesday, June 5, 2018 at 9:21:14 PM UTC-5, wrote:
PStamler, Phil:

I guess the question to ask is, on Uncle Joe's
1970 color Philco, is the volume located in the
input stage, or the power amp side?

Same for the volume on a stereo receiver in
the home.

On Uncle Joe's Philco, the volume is located between the input stage (which, to simplify, extracts the audio and video signals from the mixture coming into the antenna terminals) and the power amplifier.

On home stereo receivers there may be a line-input amplifier which receives and maybe processes the audio signal (tone controls and the like); the volume control is usually located between this input Aamplifier and the power amplifier. Other stereo receivers don't have an input amplifier; the line input feeds directly into the volume and balance controls, and the signal then goes to the power amplifier. There are variations; for example, the tone controls may come after the volume control. But in all cases the volume control is upstream from the power amplifier.

Thekma you may be confusing all this with "power soaks", which are high-powered attenuators placed between the power amplifiers of guitar amps and their speakers, allowing players to crank the amp and overload it while maintaining a safe-and-sane volume level. That's useful in recording studios, and it's sometimes used in playing smaller clubs, so the lead guitarist can get a nice dirty sound without flattening the customers against the back wall. I've never seen power soaks used outside of guitar-amp applications, though; certainly your Adcom amp doesn't use one. In the Adcom, on the models with a volume control, the signal feeds directly into the volume control, and then goes to the power amp. That's true of most professional power amps, although some (as you've noted) don't have any level control. Those are usually used either in conjunction with a preamplifier/control center, which contains its own volume control, or an electronic crossover, which also contains volume controls for the different frequency bands.

Peace,
Paul