SPOTFIRE* PR5 Phono Preamp
The SpotFire PR5 is a vacuum tube RIAA phono stage designed for serious vinyl playback, compatible with moving magnet (MM) and, optionally, moving coil (MC) cartridges (via step-up transformers).
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.
The PR5 all-tube design preserves the analog warmth and harmonic texture while remaining accurate to the vinyl source. It's 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 provide a low-Z drive for long or high-capacitance cables.
Dual Input Option. The standard valve phono preamp kit is equipped with two switchable moving-magnet (MM) phono inputs - ideal for users with two turntables or tonearms.
Moving-Coil Flexibility. For those with a moving-coil (MC) cartridge, you can convert one input to MC by adding two optional Lundahl cobalt-based amorphous core LL9226 step-up transformers to the PC board, or by using two external step-up transformers (both at extra cost).
This allows switching between an expensive MC cartridge for your special vinyl's and a less-expensive MM cartridge for every-day use.
Step-up transformers provide a very 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 inside the case contains dangerous voltages of up to 280V DC. The PR5 measures 154mm wide, 240mm deep, and 115mm high.
Why Choose the SpotFire PR5?
- You want genuine tube sound with modern low-noise performance
- You want to listen to your vinyl as the artists intended - using tubes
- You prefer a phono stage that’s expandable, tweakable, and serviceable
- You run multiple turntables or plan to try MC cartridges in the future
- You value made-in-Australia engineering and support
SpotFire PR5 vs Other Phono Preamps
| Feature / Design Point | SpotFire PR5 | Typical Tube Kit | Solid-State MM/MC |
|---|---|---|---|
| Gain Structure | 12AX7 CCDA, high gain + cathode follower | 12AX7 high gain only | Op-amps or discrete transistors |
| RIAA Equalization | Accurate passive network | Often varies as tubes age | Digital or op-amp EQ |
| MM/MC Support | 2xMM standard, MC via Lundahl option | 1xMM only | MM/MC selectable (sometimes internal) |
| Tube Rolling / Customization | ✅ Easy (4x 12AX7) | ✅ Possible, often noisy or unusual tubes | ❌ Not supported |
| Output Drive Capability | ✅ Low-Z buffered output | ⚠️ Moderate output Z | ✅ Very Low-Z |
| Noise Floor | ✅ Very low (DC heaters) | ⚠️ Moderate hum and noise likely | ✅ Very low |
| DIY Friendliness | ✅ Solderless or full DIY | ⚠️ Full solder, poor instructions | ❌ Usually no DIY |
| Component Quality | ✅ High Quality, polypropylene film caps, gold tube sockets, | ⚠️ Basic component quality | ✅ Depends on brand |
| Power Supply | ✅ External 12V adapter (safe) | ❌ Internal AC transformer | ✅ Internal regulated or external adaptor (safe) |
| Price vs Sound | ⭐⭐⭐⭐½ – High value tube sound | ⭐⭐ – Looks good, mixed Quality | ⭐⭐⭐⭐ – Clean sound, less character |