This is
another improved version of the old RIAA amplifier. This one is optimized for
+20dB at 20 Hz and -20dB at 20 kHz keeping
0dB at 1
kHz. Output impedance is high and should be followed with my line amplifier
which has cathode follower
input, it
cannot drive cables so keep it together with a line amplifier. If you have low
input impedance, add a cathode follower like
the output of my line amplifier. The output stage could also be replaced with a
SRPP or mu-follower. Output 0.95V at 4mV in.
I have done
some more tweaks. Change R6/R16 to 120k and R8/R18 to 160k. This will tweak the
curve even closer to 19.3dB
at 20 kHz
and -19.6dB at 20 kHz. Simulation shows 19.7dB at 20 kHz and -19.7dB at 20 kHz.
That’s not too bad with E24
resistors.
Further tweaks can be done, adjust the 20 Hz point with R6/R16 and the 20 kHz
point with C3/C7.
The low
frequency rolloff is 4.2 Hz with 120uF decoupling capacitors.
Link to simulation plot of the version on the
schematic before tweaks.
