Kaskode One Rev 1.1
22
2.2.2
Selecting the MC Step-up Ratio
The goal of the MC transformer is to take the small output voltage from moving coil type
cartridges and scale the voltage such that it is suitable for the input of the MM phono preamp
input.
The Kaskode One has selectable 1:5, 1:10 and 1:20 transformer step-up ratios for 60dB, 66dB or
73dB total gain respectively. The best way to select the correct step-up ratio is to calculate the
approximate output voltage from the transformer. Simply multiply the desired step-up ratio by the
MC cartridge nominal output voltage (V
MC
). The output voltage for the MC cartridge should be
stated by the manufacturer.
𝑉
𝑀𝐶
× 𝑆𝑡𝑒𝑝𝑢𝑝 𝑟𝑎𝑡𝑖𝑜 = 𝑉
𝑜𝑢𝑡
Equation 2: MC voltage after step-up
The MC transformer ratio should be selected such that V
out
in the range of 3-7mV.
For example
A manufacturer specifies the output of a MC cartridge as:
0.5mV (500uV) @ 5cm/s
A setup ratio of 1:10 would yield and output voltage of 5.0mV (5000uV). This is in the
recommended range of 3-7mV.
The actual output voltage will likely be a little bit less than this due to the resistive loss of the MC
step-up transformer. It is suggested to use Bandwidth Audio MC cartridge calculator, available from
www.bandwidthaudio.com
, for more accurate analysis of the output voltage.
