Grimm Audio PW1 – minimalist phono preamplifier

The Grimm Audio PW1 phono preamplifier stands out with its minimalist circuitry, aimed at preserving the integrity of vinyl playback. The PW1 minimizes the number of components in the signal path, allowing the music to flow with minimal interference. Each gain stage uses a single active component, while a carefully selected op-amp serves as a buffer to maintain signal quality. The “PW” stands for Phono Wizard, so the PW1 features a wide range of input adjustment options to suit the characteristics of the cartridge.

The Grimm Audio PW1 phono preamplifier uses FET field effect transistors due to their high input impedance and musical amplification characteristics. For the MC (moving coil) input, a specialized low-noise FET transistor was chosen, with noise levels of 0.7 nV/√Hz, resulting in a signal-to-noise ratio of ≥80 dB, which is excellent for vinyl. Grimm Audio admits that the PW1 exhibits higher harmonic distortion (<0.55%, mostly 2nd harmonic components) than some competitors, but this compromise avoids a "sterile" sound.

The Grimm Audio PW1 does not use an external power supply – it has a custom low-noise transformer from Amplimo “on board”. An aluminum chassis and copper sub-chassis further protect against electromagnetic interference.

The Grimm Audio PW1 phono preamplifier offers flexible settings for both moving magnet (MM) and moving coil (MC) cartridges. Gain options include an additional 10 dB for MM inputs and up to 77 dB for MC, allowing even ultra-low output cartridges to be used. Input impedance:

MM resistive: 47 kΩ;

MM capacitive: 47 pF, plus optional 47 pF, 100 pF, and/or 220 pF in parallel;

MC resistive: 47 kΩ, plus optional 33 Ω, 100 Ω, 330 Ω and/or 1 kΩ in parallel;

MC capacitive: 330 pF, plus optional 330 pF and/or 680 pF in parallel.

A sliding panel on the bottom of the enclosure provides access to detailed loading and gain settings, allowing audiophiles to fine-tune playback to match cartridge specifications. The capacitive and resistive load adjustments are suitable for both MM and MC cartridges. The Grimm Audio PW1 phono preamplifier is now available in Europe with a suggested retail price of €4,800.