Allnic AUT-2000 step-up transformer

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Allnic AUT-2000
Allnic AUT-2000 step-up transformer

The Allnic AUT‑2000 is a step‑up transformer (SUT), designed to boost the output of a Moving Coil cartridge for use with a Moving Magnet phono stage. It sounds like a terribly old‑fashioned concept – phono stages with adjustable gain for all bar the most insanely low MC outputs have been available for decades. And yet, the SUT steadfastly refuses to die.

There is very good reason for their continued survival – the sound they help make when used in context. Creating the 20dB or more of gain required to augment an MC electronically (using active components) can introduce small amounts of intermodulation distortion across the whole audio spectrum, but doing the same electrically (using a transformer) is more benign with often just extremely small amounts of signal attenuation and harmonic distortion, both of which depend on the size of the transformers and mostly effect the bottom end of the frequency spectrum. The Allnic AUT‑2000 uses oversized Nickel/permalloy core transformers – one per side –claimed to deliver high‑levels of input signal saturation, and the transformer windings are in a five‑section ‘sandwich’ layout, which is claimed to lower inductance leakage. These transformers sit on silicone elastomer pads on the solid aluminium block base‑plate. Vibration shouldn’t be an issue in this part of turntable replay, but in reality, anything that can be done to minimise undermining these tiny signals at this stage is vitally important.

The AUT‑2000 has four gain‑level settings, each with its own tap from the transformer: +22dB, +26dB, +28dB, and +32dB . Almost regardless of cartridge load, the secondary load resistor in the output stage means any MM phono stage connected to the AUT‑2000 ‘sees’ a near‑perfect 47k Ω load. Rather than use a slightly different secondary load resistor on each tap, Allnic doesn’t tweak the output of the AUT‑2000, and as a result there is some mild attenuation at the frequency extremes on all the settings apart from the +26dB  setting. However, as this attenuation is at worst –1.5dB and at best –0.2dB, this is a practical solution to keep extraneous wiring to a minimum. This arrangement of loading and settings will make the AUT‑2000 compatible with an extremely wide range of cartridges; super low output and weird moving coil loads that will challenge the AUT‑2000 will challenge anything apart from dedicated SUTs designed for that specific cartridge (such as Audio Note’s Io), and are thus really beyond the scope of this test.

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