Phonostages — Krell 300p Phono

The 300p Phono, named K-300p by its maker, is a transistor phono stage made by Krell Industries of Orange, Connecticut. It has one MC and one MM input, switchable from the front panel, and it was the only phono stage in Krell's 2023 line-up, alongside the Illusion and Illusion II preamplifiers and the K-300i integrated amplifier.

Key specs that matter

There are two RCA inputs, one for MC and one for MM, and the signal leaves through RCA and balanced XLR pairs. MC gain can be set to 62, 56, 50 or 44 dB, and MC loading to 10, 25, 47, 100, 249, 470, 825 or 1,000 ohm, with 47 kOhm as the default. MM gain is 36 or 30 dB, the MM input impedance is fixed at 47 kOhm, and capacitance can be set to 10, 20, 47, 100, 220, 330, 470 or 680 pF. RIAA accuracy is ±0.2 dB. Referred to 1 V output, signal to noise ratio is 77 dB A-weighted for MC at 62 dB gain and 87 dB for MM at 36 dB gain. Input overload is 3.4 mV for MC and 23 mV for MM, and THD at 1 kHz and 1 V output is 0.08% for MC and 0.06% for MM. Power consumption is 15 W. The unit measures 438 x 105 x 289 mm and weighs 4.5 kg, in black or clear anodised aluminium and steel.

Engineering and use context

Krell built the MC input as a hybrid discrete and integrated stage with paralleled low-noise transistors and a Burr-Brown SoundPlus op-amp, while the MM input uses a dual low-noise FET circuit. RIAA equalisation is passive, built from precision resistors and polypropylene film capacitors. The output stage is balanced and uses Krell's Current-Mode topology, which Krell says offers greater bandwidth than voltage-mode designs. A custom linear tracking regulator supplies the circuits with low noise and handles positive and negative signal swings symmetrically. All gain and loading settings are made on the rear panel, so the case never needs to be opened, and a rear switch sets the default input. The front panel carries an absolute phase button, and a switchable 14 Hz critically damped infrasonic filter reduces low-frequency acoustic feedback and warp signals. The chassis fits a standard rack shelf.

Pairing

Its XLR output suits balanced line stages such as Krell's Illusion and Illusion II preamplifiers. With eight MC load values and four gain settings, most moving-coil cartridges can be matched, and two turntables can stay connected, one on each input.

Alternatives

The Krell K-300i is the integrated amplifier that shares the K-300 designation in the same Krell line-up.