~ RIAA–1 Configuration Calculator ~

Calculates the component values to make a passive 'lumped' or 'all in one' RIAA replay equalisation network of my type RIAA-1 as shown in this pdf and below ~ With R1 connected parallel to C1 the 4 terminal network can be used as a 2 terminal type which develops a voltage across it or current through it depending how it is driven and terminated

Correct equalisation using this 4 terminal network is only obtained with 0Ω source and ∞Ω load so 'perfect' amplifiers are required either side of the networks but they can incorporate a resistive source Rs if R1 is reduced by Rs ~ A resistive load RL will appear in parallel with R1 so the value (R1–Rs) can then be increased to accommodate RL

Thus a single adjustment of R1 for this network can correct for both Rs and RL and is often required in practice where amplifiers have significant output and/or input impedance ~ It is also possible that the impedances of amplifiers either side of the 4 terminal network are such that R1 does not need to be changed

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
R1  kΩ	R2  kΩ	C1  nF	C2  nF
R1  kΩ	R2  kΩ	C1  nF	C2  nF
R1  kΩ	R2  kΩ	C1  nF	C2  nF
R1  kΩ	R2  kΩ	C1  nF	C2  nF

The 2 terminal or current driven networks are often used in negative feedback loops and have been for many years before transistors and op-amps ~ When driven from a 'lowish' output impedance and terminated into a  low resistance feedback node the Current through the network has the RIAA Record characteristic the inverse of  RIAA playback

The rising current with with frequency develops a voltage across R! which could be a cathode or emitter resistor or part of an op–amp feedback loop and reduces the gain of the amplifier in accordance with RIAA playback EQ ~ 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 as the load on the output of a Transconductance amplifier which could be the collector of a transistor with un–bypassed emitter resistor or the anode circuit of a Cascode or Pentode where the current develops the output voltage across the network wrt signal ground which may be the HT supply As shown here ΐ

" Made alive a worldly wonder ~ Often told but never seen "