LL1678 Lundahl MC-Übertrager Moving Coil Input transformer

Lundahl LL1678 compact MC step-up with 1:8, 1:16 and 1:32

The Lundahl LL1678 is a compact moving-coil input transformer with an amorphous core and three selectable turns ratios. It is particularly attractive for flexible phono DIY projects intended to support different cartridges or gain requirements.

Ratios of 1:8, 1:16 and 1:32 cover Denon, Lyra, Ortofon, Dynavector and many other MC cartridges. The LL1678 provides a value-focused alternative to the larger premium LL1931 and LL1941 models.

Suitable applications

• Switchable MC step-up stages for several cartridges
• Ortofon SPU, Cadenza and Quintet
• Denon DL-103 and DL-103R, Lyra and Dynavector
• Compact PCBs, external SUT enclosures and phono DIY

Technical specifications

Transformer type

Compact passive MC step-up transformer, one channel per component

Core material

Amorphous cobalt strip core

Winding wire

Standard copper wire

Step-up ratios

1:8, 1:16 or 1:32

Voltage gain

Approximately 18.1 dB, 24.1 dB or 30.1 dB

Cartridge load with a 47 kΩ MM input

Approximately 734 Ω, 184 Ω or 46 Ω without additional loading

Documented frequency response

Approximately 10 Hz to 90 kHz within ±1 dB with balanced input and output; approximately 10 Hz to 35 kHz in the documented unbalanced 1:8 arrangement

Dimensions

Approximately 30 × 23 × 15 mm

Weight

Approximately 27 g

Stereo requirement

Two LL1678 transformers are required for stereo

Flexible phono design notes

The three ratios support a very broad range of cartridges. A ratio selector should be mounted close to the transformers so that wiring remains short and the delicate MC signal is not routed through unnecessary cable length.

Primary grounding and the complete connection scheme must follow the Lundahl data sheet. Careful enclosure and grounding design are as important as the selected turns ratio at these signal levels.

Questions about choosing a flexible MC transformer

Which compact transformer suits an Ortofon Cadenza or Quintet?

The Lundahl LL1678 at 1:16 is a strong starting point. A 0.4 mV Cadenza Bronze produces approximately 6.4 mV and a 0.3 mV Quintet about 4.8 mV. A 47 kΩ MM input reflects approximately 184 Ω to the cartridge.

Which affordable Lundahl step-up transformer suits an Ortofon SPU Classic?

The LL1678 can be connected at 1:32 for an SPU Classic. A 0.2 mV output then becomes approximately 6.4 mV and the cartridge sees about 46 Ω from a 47 kΩ MM input. The larger LL1941 provides the same high ratios in a more elaborate premium construction.

Can I build a switchable SUT for several cartridges with the LL1678?

Yes, its three ratios are particularly useful for a switchable SUT enclosure. Both winding sides must be switched according to the Lundahl diagram, and very short wiring with reliable contacts is important for low hum and extended high-frequency response.

Is the LL1678 an affordable alternative to the LL1931 and LL1941?

Yes, it covers the combined ratio range of both premium models while requiring much less space. The premium transformers use Cardas OFC, larger cores and more elaborate construction. The LL1678 is therefore attractive when flexibility, size and budget have priority.