Elekit TU-8450 preamp kit

The TU-8450 is Elekit’s purpose-built tube phono preamplifier kit: a full phono stage supporting both MM and MC cartridges, followed by a two-tube 12AU7 line stage, in the same compact form factor as the TU-8400 it was designed to partner with.

Phono stage: CR-type RIAA

Most phono stage designs apply the RIAA equalisation curve using negative feedback within the amplification circuit itself — convenient, but a design compromise. The TU-8450 uses a CR (constant resistance) equaliser instead: a passive RIAA network placed between two stages of amplification. Achieving the equalisation curve this way is more demanding to implement, but it does so independently of the amplifier’s gain characteristics. The result is RIAA accuracy of ±0.5dB from 20Hz to 20kHz — which gives your cartridge a genuinely straight shot at the groove.

The phono stage supports MM (47kΩ input impedance, 36dB gain) and MC (100Ω, 63dB gain), switchable on the rear panel. Two 2068DD op-amps handle the active amplification, and they’re socket-mounted — rolling alternative op-amps is a matter of pulling one and pressing in another.

Line stage: 12AU7

The line stage uses two 12AU7 tubes — ECC82, E82CC, ECC802, and 6189 are all pin-compatible — delivering 13.6dB of gain with a frequency response that extends from 5Hz to 200kHz at the −3dB points. Residual noise comes in at 20μV.

The 12AU7 is one of the most widely rolled tubes in audio for good reason: a deep catalogue across NOS and current production, meaningful sonic differences between varieties, and none of the fragility of the more exotic types. The TU-8450 gives you two sets of sockets to explore.

Hum rejection and power supply

A low-flux-leakage R-core transformer keeps magnetic interference out of the signal path. The DC heater supply for the 12AU7s and a FET ripple filter for the B-power supply work together to keep the noise floor genuinely low — important when a 63dB-gain MC phono stage is sitting one board away from everything else.

Upgrade paths

The PCB is designed with room to grow. Coupling capacitor positions accept components up to 36mm × 20mm (0.47μF, rated above 200V), which covers most of the boutique film capacitor options builders like to try. A REC-OUT terminal is also included, feeding a recording device directly from the phono stage output.

The natural partner to the TU-8400

The TU-8450 was designed alongside the TU-8400 power amp kit, sharing the same compact footprint. Positioned together they form a complete amplification chain from cartridge to speaker — in both function and appearance. If you’re building around a TU-8400, the TU-8450 is the intended other half.

Kit variants

The TU-8450 is available in three configurations. The Standard kit includes the complete kit with 2× 12AU7 tubes. The Standard kit (no tubes) ships without the 12AU7s, for builders sourcing their own. The Enhanced kit is SCA’s upgraded build configuration, with components selected for optimal performance in the available PCB footprint.

All three ship as a kit for self-assembly. Build assistance is available — see the Build service for details.

Specifications