EP 060 Neutral speaker design. The Speakers That Have No Sound

Aug 11

4 min read

Updated: Sep 1

What does a neutral loudspeaker actually sound like? According to Russell Lenehan of Lenehan Brothers, the ideal loudspeaker should contribute as little character of its own as possible. It should reproduce the incoming signal accurately, reveal the character of the amplifier and source, and prevent the cabinet from becoming an unwanted second instrument.

That philosophy sounds straightforward, but it creates one of HiFi’s most uncomfortable questions: if an accurate loudspeaker exposes a harsh or heavily compressed recording, is the speaker doing its job - or reducing the listener’s enjoyment?

The System One black loudspeaker is neutral and the cabinet is made from phenolic-resin. — Lenehan Brothers

Neutral speaker design - what does it mean?

A neutral loudspeaker aims to reproduce the recorded signal without adding an obvious tonal colour, resonance or flattering character of its own. No loudspeaker is perfectly neutral: its drivers, crossover, enclosure, radiation pattern and interaction with the listening room all affect the final sound. Neutrality is therefore a design goal rather than an absolute condition.

Russell’s practical definition is that a relatively neutral loudspeaker should allow the rest of the system to remain audible. A valve amplifier may sound softer, fuller or more spacious; a Class A, Class AB or Class D amplifier may present music differently. The speaker should reveal those differences instead of imposing the same signature on every system.

This is the meaning behind the provocative claim that Lenehan loudspeakers “don’t have a sound”. It does not mean they produce no sound. It means the designers are trying to minimise the sound contributed by the loudspeaker itself.

Why cabinet resonance matters

One of the central challenges in loudspeaker design is cabinet self-noise: sound produced by the enclosure in addition to the intended output of the drivers. Cabinet panels can store and release energy, vibrate or resonate. Some designers use controlled enclosure behaviour as part of a loudspeaker’s voicing. Lenehan Brothers takes the opposite approach and tries to make the cabinet as inert as practicable.

That decision has consequences. A heavily damped, rigid enclosure can be expensive, difficult to manufacture and costly to ship. It may also require materials and machining methods that are unsuitable for mass production. For Lenehan Brothers, however, reducing cabinet contribution is fundamental to hearing the drivers and the signal rather than the box.

Why use phenolic-resin composite cabinets?

The System One Black cabinet discussed in the episode uses a phenolic-resin composite reinforced with layers of organic material such as paper or cotton. Phenolic resin is familiar in an earlier form as Bakelite, but the layered composite described by Russell is designed to provide greater strength and internal damping than resin alone.

Why retain a solid-timber front baffle?

Internal of a neutral loudspeaker designed to be as inert as possible for sound accuracy — Lenehan Brothers internal

The enclosure is not entirely composite. A sculpted solid-timber baffle provides the visible furniture-quality finish and forms part of the mechanical design. This combination reflects a recurring theme in the interview: handmade construction does not exclude modern precision. Close-tolerance CNC machining and hand assembly can serve different parts of the same product.

Graphene-coated magnesium drivers: benefits and problems

Russell describes the material as rigid, fast and well damped internally. The graphene coating also protects the magnesium, addressing corrosion associated with earlier uncoated magnesium cones. However, a stiff metal cone does not behave perfectly throughout its full frequency range. It develops a strong breakup region that must be controlled.

Andrew notes the raw driver’s uneven on-axis response and prominent peak around the upper midrange/lower treble region. Russell acknowledges that the breakup behaviour was a major crossover-design challenge.

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Why the crossover is not necessarily simple

A design intended to let the drivers “speak” might appear to call for the simplest possible crossover. Russell rejects that assumption. The crossover must integrate the drivers smoothly, manage rapid amplitude and phase changes, and suppress the magnesium cone’s breakup behaviour.

QUOTE

On neutrality - "If the room's not mucking up the sound, the sound you get from a pair of our speakers will be exactly what you get from your system". Russell Lenehan

Wide dispersion, toe-in and the listening room

Lenehan Brothers favours relatively wide treble dispersion rather than deliberately narrowing radiation through a horn or waveguide. Russell argues that the drivers should radiate broadly and that the loudspeaker should then be positioned to suit the room. This approach makes setup important.

Accuracy versus enjoyment: the real argument

The most valuable disagreement in the episode concerns recordings that are compressed, aggressive or poorly balanced. A revealing loudspeaker may make those faults obvious. A warmer, less revealing or more characterful design may make the same music more enjoyable.

Andrew argues that listeners cannot change the master of a favourite album. If a particular type of system makes that music more pleasurable, choosing it is legitimate. Russell agrees that this is not “wrong”; it is simply a different design intention and a different part of the market.

This means accuracy and enjoyment are not universal opposites, but neither are they guaranteed to coincide for every listener, room and recording. A neutral loudspeaker can offer consistency, transparency and insight. A voiced loudspeaker can prioritise a particular presentation. The right choice depends on what the listener values and what music they actually play.

What is the future of HiFi listening?

For Russell, headphones, streaming and mobile listening do not eliminate the value of a dedicated home music system. Listening at home creates a different mental space from watching television, scrolling online or consuming music while travelling. In an increasingly congested life, focused listening may become valuable precisely because it is simpler and less visually demanding.

The takeaway

A loudspeaker cannot literally disappear from the reproduction chain, and perfect neutrality does not exist. Yet “a speaker with no sound of its own” remains a useful design ideal. It forces attention onto cabinet vibration, driver behaviour, crossover integration, dispersion, room interaction and every compromise between measurement and musical pleasure.

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