Фонокорректоры — Engström M-Optic

The M-Optic is a valve phono stage from Engström, the Swedish electronics maker established in 2008 and known for its MONICA line stage and M-Phono. It was built around optical pickups such as those made by DS Audio, as the optical counterpart to the M-Phono. It was launched at High End Vienna 2026.

Key specs that matter

The input stage is a specially specified Lundahl transformer that converts the photodiode current from the cartridge into voltage. Gain comes from parallel-connected 6922 valves, followed by a separate 6922 equalisation stage. A second Lundahl transformer provides a balanced output. Inputs and outputs are available on both RCA and XLR. Supplies are separate per channel, and the unit uses three power transformers, two chokes and seven regulated supplies. Internal magnetic shielding is double-layered. Engström had not published gain or measured figures in the launch material.

Engineering and use context

An optical cartridge does not generate voltage from a coil. An LED and a photodiode detect the movement of the cantilever, and the photodiode delivers a current that varies with the groove. The output follows the displacement of the stylus rather than its velocity, so it rises towards low frequencies compared with a magnetic cartridge and needs its own equalisation. Engström uses a transformer to convert the current to voltage, and the transformer's behaviour naturally reduces the unwanted low-frequency rise, while also keeping the two channels in precise phase alignment. Connecting 6922 valves in parallel increases transconductance and lowers noise, which matters at the low levels of a phono signal. The dedicated equalisation stage then produces a flat response. The output transformer converts the signal to balanced form and isolates the phono stage from the next component. Separate supplies for each channel prevent one channel's current demands from modulating the other, and chokes in the supplies add filtering beyond what capacitors alone provide. The double magnetic shielding protects the transformers and low-level circuits from the fields of the power transformers inside the same case.

Pairing

The M-Optic works with optical cartridges from DS Audio and others using the same principle. It pairs with Engström's MONICA line stage through balanced connections.

Alternatives

Engström's M-Phono handles conventional MM and MC pickups with valves.