I don't think I've ever seen a 100K ladder. Are you sure it's not a potentiometer type?
The term "ladder" is often misused to describe what is in fact a stepped potentiometer. A real ladder attenuator looks (in schematic form) like a ladder turned on its side, and has a constant input and output impedance. It has a minimum loss of 6dB when used between equal impedances. Ladders are usually available in 150/150, 150/300, 600/600 and like configurations. Like I said, I don't think I've ever seen a 100K ladder.
The Altec name lives on, but only as a manufacturer of consumer crap (e.g., computer speakers).