A horn loaded speaker can have a sensitivity as high as 110 dB at 2.83 volts (1 watt at 8 ohms) at 1 meter. Source: Internet
Advertisement - The Electrician, 1st June 1934 Between the mid 1930s until the 1950s, 1000 ohms per volt became a de facto standard of sensitivity for radio work and this figure was often quoted on service sheets. Source: Internet
And if the movement resistance is 1000 ohms, for example, R1 must be adjusted to 4.525 ohms. Source: Internet
Again for the case of a hypothetical 1 mA, 500 ohm movement on a 1 ampere range, the shunt resistance would be just over 0.5 ohms. Source: Internet
As an example, a meter movement that required 1 milliampere for full scale deflection, with an internal resistance of 500 ohms, would, on a 10-volt range of the multimeter, have 9,500 ohms of series resistance. Source: Internet
An improved version of 1927 increased this to 13-ranges and 166.6 ohms per volt (6 mA) movement. Source: Internet