Audio Note (UK) Celebrates 35 Years of the Oto with Oto SE 35 Anniversary Edition

First introduced in 1991, the Oto holds a unique place in Audio Note (UK)’s history. Conceived by founder Peter Qvortrup and designed by Andy Grove, it was the first amplifier to be fully developed and manufactured in-house by the company. While Audio Note was already well known for the Ongaku, the Oto demonstrated that its single-ended valve philosophy could be realised at a more accessible level, without abandoning the company’s emphasis on musical engagement.

Peter Qvortrup says the amplifier’s longevity reflects Audio Note (UK)’s wider design philosophy: 

When I set Andy the challenge to design a single-ended pentode version of the Oto in the early 90s, single-ended amps were a big outlier. The Oto and now the Oto SE 35 stand as a testament to our philosophy on timeless quality audio design. We still maintain and service our customers’ Oto’s, making sure they’re good for years to come. This is what true longevity looks like, and that will never change.

For Andy Grove, the original Oto SE design came together unusually quickly. Rather than emerging from extended modelling or iteration, the circuit topology fell into place almost immediately, relying on careful calculation and reference to valve datasheets rather than prolonged simulation.

Anyone who is engaged in creative work like design, architecture, composition and songwriting will know when what you have in front of you fits together harmoniously. It looks right, feels right, and you know it IS right.

Grove recalls designing the amplifier in 1991 at his parents’ kitchen table in Suffolk, before the first prototype was built with fellow engineer Claus Molgaard and demonstrated shortly afterwards. The listening session, he admits, was a tense moment, but one that ultimately confirmed the design was sound.

While the Oto has undergone incremental evolution over the years, the Oto SE 35 represents a more fundamental rethink. Prompted by a special customer request and informed by recent work on Audio Note (UK)’s Meishu amplifier, Grove decided it was time for a deeper revision.

I decided it was time to give the Oto SE a complete makeover. The result is an amplifier with a more realistic ‘bass kick’, the kind of physical presence you feel when you are in the room with a kick drum or a bass guitar.

The anniversary edition introduces a new in-house-designed output transformer, a redesigned power supply incorporating a choke with optimised time constants, and targeted updates to the power amplifier board. The phono stage has also been revised, with increased sensitivity allowing the removal of the line stage previously required in earlier phono versions. According to Grove, this improves phase integrity and reduces noise, while revised internal wiring, shielding and a new in-house mains transformer contribute further gains across the amplifier.

Despite the technical changes, Grove is clear that the Oto SE 35 is not intended to reinvent the amplifier’s character.

It remains an all-round musical, fun-to-live-with amplifier, but it can now summon a serious amount of attitude when the recording demands it.

Reflecting on the milestone, Grove adds that turning 35 wasn’t a bad experience, and the Oto SE appears to be enng it too!

The Oto SE 35 integrated amplifier and the P1 SE 35 stereo power amplifier are available to order now through authorised Audio Note (UK) dealers. Prices start from £5,950 for the Oto SE 35 and £4,830 for the P1 SE 35.

For more information visit Audio Note