Optimizing Phono Stage with Phono Termination Plugs

Moving Magnet (MM) - For MM pickups the terminating capacitance is very important for high frequency response. The terminating capacitance combined with the MM pickup's inherent inductance will form a damped resonance circuit. This resonance extends the high frequency response.

If capacitance is too low, the circuit will not resonate and the frequency response will roll off in the 7-10 kHz range. If capacitance is too high, the resonant circuit will peak in the 7-10 kHz range, causing the response to sound overly sharp while simultaneously rolling off high frequencies. Correct capacitance will create a linear frequency response as shown in the drawing below.

The total capacitance required will depend on each individual pickup and will be specified in the included documentation from the manufacturer.

Note: The 91E has an input capacitance of 100pF. The cable from the pickup to the amplifier could be estimated at an additional 100pF. If more capacitance is required, this is accommodated by inserting the needed phono termination plugs as needed into the load sockets.

Moving Coil (MC) - For MC pickups, terminating resistance is not critical as regards frequency response. However, it will influence output level and signal-to-noise ratio.

The total resistance required will depend on each individual pickup and will be specified in the included documentation from the manufacturer.

Note: The 91E has a 1 kOhm input impedance.