~ RIAA–2 Configuration Calculator ~

Correct replay equalisation is only obtained with correct source and load impedances suggesting 'perfect' amplifiers are required either side of the networks ~ However the voltage driven network can incorporate a resistive source Rs if R3 is reduced by Rs and any resistive load RL across the output will appear in parallel with Rs+R3 so R3 can be increased to accommodate RL

An adjustment of R3 alone can correct for Rs and RL and is often required in practice ~ After obtaining values for R4 C3 and C4 from your chosen R3 you can select a close standard value for C3 or C4 or maybe both rather than making non standard Cs ~ The default values here are more than accurate enough when R3 is adjusted for Rs and RL

T3  µs	T2  µs	T1  µs	Sig. Figures
ƒ=  Hz	ƒ=  Hz	ƒ=  Hz	Calculated –3dB corner frequencies for each T
The table below allows one component in each row to be changed to calculates the other 3 ~ It is possible to delete Time Constants and the 'errors' in rows and columns indicate components not used ~ Zero T1 and C4=0 not fitted ~ if any R=0 it should be shorted ~ NaN infinity or negative try changing the time order of Ts
R3  kΩ	R4  kΩ	C3  nF	C4  nF
R3  kΩ	R4  kΩ	C3  nF	C4  nF
R3  kΩ	R4  kΩ	C3  nF	C4  nF
R3  kΩ	R4  kΩ	C3  nF	C4  nF

The 2 terminal or current driven networks are often used in negative feedback loops and have been for many years long before transistors and op-amps because when driven from a lowish output impedance and terminated into a resistive load RL the current through the network has an inverse RIAA or RIAA record characteristic

The rising current with with frequency develops a voltage across RL which could be a cathode [or emitter] load or part of an op-amp feedback loop and reduces the gain of the amplifier in accordance with the RIAA or BS1928 ~ Depending on the quality of the amplifier and the feedback topology used you may get acceptable playback of vinyl records

I refer to the 2 terminal networks as current driven because that is how I often use them ~ Not in a feedback loop around a voltage amplifier but as the output load of a Transconductance amplifier which may be the collector of a transistor with un-bypassed emitter resistor or the anode circuit of Cascode or Pentode where the current develops the equalised output voltage across the network As shown here ΐ

" Can it be this sad design ~ Could be the very same "