I found
a good solution for the way too high gain of my Sugden A21SE amplifier or rather way too sensitive inputs (110mV). First I wanted to put an active attenuator between the preamp and the power amp boards inside the Sugden, but I discovered that with an input signal of 1.77 Vrms the pre-amplifier started to distort when the potentiometer was set to 2/3. My Meitner DAC even has 2.3 Vrms.
So attenuation of the signal must take place before the Sugden preamplifier.
I looked at the input circuit in the Sugden and determined that the input is a 475 ohm resistor in series with the 50 Kohm volume potentiometer. Only after the potentiometer does the Signal encounter a HF blocking capacitance.
That means that I can place a resistor attenuator at the input of the pre-amplifier board without any problems. I chose 10.2 Kohm in series and 475 ohm parallel. Seems to work fine. High frequencies such as 50KHz are also not attenuated. So with there resistance values I end up with a damping factor 22.5x. or -27dB.
now the potentiometer can be set to twelve o'clock while listening and the sound is still beautiful.
So attenuation of the signal must take place before the Sugden preamplifier.
I looked at the input circuit in the Sugden and determined that the input is a 475 ohm resistor in series with the 50 Kohm volume potentiometer. Only after the potentiometer does the Signal encounter a HF blocking capacitance.
That means that I can place a resistor attenuator at the input of the pre-amplifier board without any problems. I chose 10.2 Kohm in series and 475 ohm parallel. Seems to work fine. High frequencies such as 50KHz are also not attenuated. So with there resistance values I end up with a damping factor 22.5x. or -27dB.
now the potentiometer can be set to twelve o'clock while listening and the sound is still beautiful.