Audio Note OTO SE 35 – Anniversary Edition of the Tube Integrated Amplifier

The British high-end audio manufacturer Audio Note (UK) has marked 35 years since the release of its Oto integrated amplifier by launching the Audio Note Oto SE 35th Anniversary Edition, which the company describes as the most significant modernization and improvement of the design in all those years. First introduced in 1991, the Audio Note Oto tube integrated amplifier holds a special place in the history of Audio Note (UK).

The concept proposed by Audio Note founder Peter Qvortrup and implemented by Andy Grove became the company’s first amplifier to be fully designed and manufactured in-house. Although Audio Note (UK) was already known for the Ongaku amplifier, the Oto proved that the philosophy of single-ended tube amplifiers could be realized at a more accessible level without sacrificing sound quality.

Peter Qvortrup notes that the amplifier’s long life reflects Audio Note (UK)’s broader design philosophy: “When, in the early nineties, I asked Andy to develop a single-ended pentode version of the Oto, single-ended amplifiers were a great rarity. The Oto, and now the Oto SE 35, symbolize our philosophy of timeless, quality audio design. We still service and repair our customers’ Oto amplifiers so they can serve for many years. That is true sustainability, and it will never change.”

Andy Grove brought the original Oto SE project to life very quickly. Instead of lengthy modeling and iterations, the circuit topology took shape almost immediately thanks to careful calculations and work with the tubes’ technical parameters. “Anyone engaged in creative work – design, architecture, composition, or songwriting – knows the moment when everything comes together harmoniously. It looks right, it feels right – and you understand that it really is right,” Andy Grove noted.

Grove recalls designing the Oto amplifier in 1991 at the kitchen table in his parents’ home in Suffolk, after which, together with engineer Claus Molgaard, the first prototype was created and soon demonstrated. The listening session, he admits, was a tense moment, but in the end it confirmed the validity of the concept.

Although the Oto amplifier gradually evolved over time, the Oto SE 35 is a more fundamental reworking. At customers’ requests and influenced by recent work on the Meishu amplifier, the company decided to carry out a deeper modernization. “I decided it was time to completely update the Oto SE. The result is an amplifier with a more realistic ‘bass slam’ – that physical sensation you feel when you’re in the same room as a kick drum or a bass guitar,” Andy Grove said.

The Audio Note Oto SE 35 35th Anniversary Edition received newly developed in-house output transformers, an improved power supply with a choke and optimized time constants, as well as updates to the output stage board. The phono stage has also been redesigned with increased sensitivity, eliminating the need for a line preamplifier that was required in previous versions. According to Grove, this improves phase integrity and reduces noise, while updated internal wiring, shielding, and a new mains transformer provide further improvements.

The tube integrated amplifier Audio Note Oto SE 35th Anniversary Edition will be presented at the Bristol HiFi Show 2026, taking place at the end of this week in Bristol. The recommended retail price of the anniversary edition in the UK is £5,950.