SchickeRIAA: A phono preamp based on a nearly forgotten Linsley Hood design
A project on Elektor Labs caught my eye as a turntable fan: SchickeRIAA, a phono preamp for MC cartridges in a compact through-hole build. It is based on an older design by John Linsley Hood, in which the RIAA equalization is not a passive network but is moved into the negative feedback loop of the amplifier stage.
The input is a THAT 1510 instrumentation amplifier with a linear gain of 40 dB. It also inverts the phase, so the whole chain ends up with no phase inversion. The equalizer stage that follows uses an OPA227, which the author chose for its low 1/f noise and very high open-loop gain. At 20 kHz the gain is 1, so no extra pole is needed for high-frequency correction. The lowest frequencies, such as the rumble from warped records, are already filtered out before the high-gain RIAA stage.
The power supply is especially interesting for home builders: there is an external transformer, a Delon voltage doubler on the board, and a regulator. An earlier version used a 317/337 regulator pair with a zener reference, while the current one uses an actively feedback-controlled regulator and a modified constant-current source built from two bipolar transistors.
I like that an old concept has not simply been copied but carefully rethought with modern components. The project was published in July 2026 and updated again in early August, and the schematics are on the project page. The final capacitor values are not given in the text, so it is worth checking the documentation and the discussion there.
Source: Elektor Magazine
The input is a THAT 1510 instrumentation amplifier with a linear gain of 40 dB. It also inverts the phase, so the whole chain ends up with no phase inversion. The equalizer stage that follows uses an OPA227, which the author chose for its low 1/f noise and very high open-loop gain. At 20 kHz the gain is 1, so no extra pole is needed for high-frequency correction. The lowest frequencies, such as the rumble from warped records, are already filtered out before the high-gain RIAA stage.
The power supply is especially interesting for home builders: there is an external transformer, a Delon voltage doubler on the board, and a regulator. An earlier version used a 317/337 regulator pair with a zener reference, while the current one uses an actively feedback-controlled regulator and a modified constant-current source built from two bipolar transistors.
I like that an old concept has not simply been copied but carefully rethought with modern components. The project was published in July 2026 and updated again in early August, and the schematics are on the project page. The final capacitor values are not given in the text, so it is worth checking the documentation and the discussion there.
Source: Elektor Magazine
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