Simply tube based RIAA circuit

[Ayot]

Hey guys,

After a short restoration of very old DD Japanese TT, I decided to build simple MM RIAA preamp based on triodes. Preamp will be used only with Grado Gold cartridge (input load 47k, output 5mV at 1kHz).

Several months ago, I bought a PCB from 8audio.com, but I have some doubts. Can you please, have a look on that circuit and let me know, if that network is correct? I have no experience with RIAA networks and cannot judge. Maybe you got any other comments to that circuit. It looks for me very Dynaco like. I'll appreciate any comments.

--
Ayot

 

[kevinkr]

The network is the correct topology if not ideal, can't vouch for the values.

R6 should be about 360 ohms, not the 360K cited.

Nothing particularly great about the design which is very similar to the designs extant in the 1960s.

 

[rayma]

if that network is correct?

You'd have to calculate or simulate it to see how well it conforms to the RIAA curve.
The input capacitor certainly should be 100pF rather than 100nF.

 

[Ayot]

You'd have to calculate or simulate it to see how well it conforms to the RIAA curve.
The input capacitor certainly should be 100pF rather than 100nF.

Can you recommend some kind of calculator for Liphitz RIAA inverse network? As far as I recognized, most important elements for that are R2, R4, C6, C7 and R9. Am I correct?