PR5 Valve Phono Preamp
Are you interested in listening to vinyl records? If so, you need an RIAA Valve Phono Preamplifier.
An RIAA phono preamp boosts the small signals from your phono cartridge to a level that can power a stereo amplifier to full volume. It also applies the RIAA frequency correction, which reverses the frequency adjustments made during the record-making process. This ensures the sound from your system is accurate and clear.
You can pair it with any power amplifier. The Red Roo valve phono preamp kit is an ideal companion for the SE5 power amplifier or any other amplifier if you're looking to upgrade your system for vinyl playback.
Circuit Configuration. The valve phono preamp uses 12AX7/ECC83/7025 tubes arranged as two constant current draw (CCDA) amplifiers. Cathode followers drive the RIAA equalisation network to maintain RIAA accuracy as tubes age, and the circuit can drive any type of power amplifier or long/high-capacitance cables.
Dual Input Option. The valve phono preamp kit is equipped with two switchable moving-magnet (MM) phono inputs. Perfect if you've got two turntables and want to queue up tracks.
Moving-Coil Flexibility. For those with a moving-coil (MC) cartridge, convert one input to MC by adding two Lundahl cobalt-based amorphous core LL9226 step-up transformers to the PC board or using external step-up transformers (both at extra cost). This allows switching between an MC cartridge for critical listening and an MM cartridge for regular playback.
Step-up transformers provide a low-noise way to amplify the small signals of an MC phono cartridge without needing solid-state circuits in the audio path.
Compact Design. The PR5 valve phono preamp kit is very space-efficient, making it a great match for the SE5 stereo amp. It doesn't hog shelf space like other tube preamps that are often bulky and heavy.
User-Friendly Interface. The front panel boasts a solid-metal Balance knob and stylish toggle switches for power and phono input selection. On the rear panel, you'll find input and output connectors plus a turntable earth wire connection if needed. Blue LEDs illuminate the tubes when powered on (customisable to other colours).
Simple Assembly. The PR5 valve tube preamp is straightforward to assemble. For an easy build, choose the solderless kit with pre-assembled, tested PC boards. For a full DIY experience, opt for the full kit of parts that need soldering onto PC boards. The 'solderless' option saves time and ensures success. If you can handle a screwdriver, you can assemble the solderless version.
Power Supply Design. The power supply is uniquely designed to prevent mains power from entering the chassis. DC heaters and an earth-loop breaker help eliminate hum or buzz from the speakers due to power supply interference.
Caution is advised as the circuit contains dangerous voltages of up to 280V DC. The SE5 measures 154mm wide, 240mm deep, and 115mm high.
