A Question About Volume Controls Types


My previous preamp's volume knob had a definite low point and high point. When it was powered down I could rotate the volume up to the maximum setting and if I left it there and switched the preamp on, it would of course come on at full volume.

I'm trying to understand how the volume control works on my McIntosh MA252 integrated amp. When it's turned off and I spin the volume control up, there's no end point; it just free wheels. After I've done that and I power it up, the volume is exactly where it was during my last listening session.

Can someone explain how they work so differently?
route-66
It most likely uses an optical encoder.  It could also use a sweep contact encoder ....
The encoder translates the right or left motion into volume up or volume down to a microprocessor that manipulates the output either in the digital domain or often through a resistive ladder like in many Conrad Johnson preamps.  
That looks like a nice amp. How does it sound ? 
One control is entirely analog and that is what you are adjusting.
The other is digitally controlled, and remembers what its setting was last time it was operated. The control itself is simply a counter wheel and can spin as much as you like. When on, the circuit counts the notches that have gone by as you advance the control and makes the change in volume.
Thanks for all the answers!

@oddiofyl This amp sound so much better than the Counterpoint SA3.1 preamp/Adcom GFA555 amp combo that I had been using for over 30 years. I still have a tube front end with a solid state output stage like before, but this integrated amp is a real step up for me.

I have one more question if you don’t mind; are there any advantages with one type of volume control over the other?
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Maybe somebody else can tell if there's an advantage with one type of volume control over another?
I have one more question if you don’t mind; are there any advantages with one type of volume control over the other?
Well, with the regular type volume control, it's probably a potentiometer which is basically a variable resistor and typically these continuously contact a resistive plate, which can wear out and become statick-y over time. The other type is a stepped attenuator, with discrete contact positions which attenuate the signal using a set of resistors. These contacts are discrete steps so at any position the knob is connected to two contacts, one at the input...then the signal passing through a set of resistors, and going to the output contact position. The possibility of wear and tear is less.
Maybe somebody else can tell if there's an advantage with one type of volume control over another?
Digitally controlled controls often employ a chip that does the actual volume control change. Because of that the resistive elements often are not to the same quality as an analog control. I feel that analog controls are the best way to go and are better than digitally controlled and all-digital volume systems. But analog controls vary widely too; the best are actually switches with fixed resistors as mentioned above.
I've always liked the tactile feel of a knob vs. push buttons ...  my last preamp had digial volume...I hated it and regretted selling my Mc C15 for that unit.

My c-j Classic 2SE has an analog pot, no remote which is fine by me.  My NAD M51 has a digital volume control, and honestly it is one of the best I have ever heard and is super smooth and has fi e increments, 100 steps.  

So it doesn't matter how its done as long as its done well.  
Thanks for all the help Guys!