Предусилители — Extraudio XP5 MKII

The XP5 MKII is a line preamplifier from Extraudio, a company that has designed high-end audio systems in the Netherlands since 2008. It belongs to the Origin line and uses vacuum tubes in pure Class A. According to Extraudio, the MKII revision brings 21 changes over the first XP5, among them a revised input impedance and circuit topology, more power supply capacitance, shorter signal tracks, a finer volume control and longer remote battery life through new firmware.

Key specs that matter

Two 6922/ECC88 dual triodes run the voltage-gain and cathode-follower stages. Nominal gain is 11 dB. The rear panel carries four RCA line inputs, one balanced XLR input and a processor or home theatre bypass input in both RCA and XLR form, plus one RCA and one XLR output pair. Maximum output is 8 Vrms on RCA and 16 Vrms differential on XLR. Extraudio quotes 20 Hz to 20 kHz within 0.05 dB, 1 Hz to 1 MHz at -1 dB, THD below 0.003% at 1 kHz and 2 Vrms, 100 dB(A) signal-to-noise, 102 dB(A) dynamic range and 88 dB channel separation. Input impedance is about 82 kohm on RCA and 40 kohm differential on XLR, and output impedance is about 50 ohm. The aluminium case measures 44 x 12 x 40 cm and weighs 15 kg.

Engineering and use context

Each input is switched by a dedicated audio relay into a single valve gain stage, and the volume control sits after the gain circuit. It is a motorised ALPS Blue Beauty logarithmic potentiometer with 128 microcontroller-managed positions. The high-voltage B+ supply is regulated and filtered in several stages with parallel reservoir capacitors and polypropylene bypassing, and the valve heaters run on DC. The analogue supply is built in a double dual-mono layout around a sand-core transformer, while digital and control circuits get their own isolated transformer. Symmetrical C0G/NP0 filtering on the inputs, a buffer protection circuit and an AC input filter block EMI and RF interference. The circuit boards are four-layer and gold plated, the chassis panels are 6061 aluminium, and the front has no display - only an input knob with six LEDs, a volume knob and a power button. Idle draw is about 20 W and standby below 0.5 W.

Pairing

Extraudio names its XP-A1500 dual-mono power amplifier as the partner designed alongside the XP5. The RCA and XLR outputs work independently, so the maker suggests feeding two power amplifiers, or one stereo amplifier plus two subwoofers. Recommended loads are 20 kohm or higher on RCA and 10 kohm or higher on XLR. An optional MM/MC phono module can be fitted at extra cost, and the RC2 remote charges from a standard USB charger.

Alternatives

The Extraudio XP3 is an earlier pure Class A preamplifier from the same maker.