~ RIAA–1 Configuration Calculator ~

Calculates the component values to make a passive 'lumped' C–R '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 becomes a 2 terminal type which develops an EQ 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 but 'perfect' amplifiers either side are not required as the network can incorporate a resistive source Rs if R1 is reduced by Rs and 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 will indicate components not required ~ Zero T1 and C4=0 not fitted ~ if any R=0 it should be shorted ~ if error is NaN infinity or negative try changing the 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 2CR 'current driven' networks are often used in negative feedback loops and have been for many years before transistors or op-amps ~ When driven from a 'low' output impedance and terminated into a low resistance feedback node [Rfb] 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 Rfb 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 and depending on the quality of the amplifier and the feedback topology used you may get acceptable accurate 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 valve 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 "