The new Etude 5 has been introduced to fill a need; “many listeners love the coherence and impulse
response of a single driver loudspeaker, but…”

The Etude Philosophy

Is recreation of the live musical event in the listening room using wide-band balanced mode radiator drive units to deliver essentially all fundamental musical instrument and vocal frequencies, with minimal electrical components between the amplifier and the loudspeaker.The most crucial aspect is avoidance of any drive unit output overlap/crossover in the aurally sensitive 2-3 kHz range; this is the Achilles heel of the majority of the majority of historic and current loudspeaker designs. Adhering to these criteria results in preservation of the attack component of a musical note and the harmonic and temporal coherence associated with listening live.

The Etude loudspeakers are designed around the latest generation of wide-band drive units known as balanced mode radiators (BMR). There are numerous published descriptions of how these operate; though in essence they act as a conventional pistonic drive unit at low frequencies and then change to radial bending wave drive units at higher frequencies. The transition from pistonic to bending wave, and the number of bending modes (nodes), are carefully engineered parameters. The balanced mode aspect greatly increases the frequency range of BMR drive units to the extent that one appropriately loaded 120 mm diameter (6.5 inch chassis) BMR drive unit can deliver useful output down to 20 Hz (depending on room dimensions and positioning) all the way to slightly beyond 20 kHz. No other wide-band drive unit can achieve this range in such an even-handed manner. The loudspeaker latterly described is the Curvi-BMR (see Curvi website).

The first Etude loudspeaker was the Etude 1, this was developed in 2010 in collaboration with Christien Ellis of CE Electroacoustics and uses two 85 mm BMR drive units in a 10 litre sealed enclosure. The prototype was reviewed by Paul Messenger in Hi Fi Critic (2010, 4(4), pp. 30-31) where he found that “…the Etude 1’s freedom from crossover effects really pays dividends, delivering an almost electrostatic-like coherence through the midband”. (see legacy material on the Etude 1)

In parallel with the Etude 1 development, further experiments were conducted with the objective of extending the frequency range beyond 20 kHz, increasing bass output / extension and maximum output level. The second Curvi prototype cabinet was used as a test bed and was fitted with two 85 mm BMR drive units; one firing forward, the other firing upward. These units were loaded by the 2.4 m transmission line and directly driven, though the upper unit was later fitted with a shunt capacitor to limit high frequency output. The bass was augmented using two Jordan JX92S mounted on the rear of the cabinet such that the line was driven about 1/3 along its length. The bass units contribute to output below 100 Hz. The high frequency extension was bolstered above 5 kHz by a ring radiator tweeter. This “Etude X” prototype sounded effortlessly powerful, very smooth and coherent. At low frequencies, the two Jordan bass units were well damped and did not modulate the motion of the two BMR units. Simulations confirmed the latter effect and validated the line sharing – “common time base” concept. The only problem with the prototype was high frequency output from the upper BMR unit blurring of stereo images, this was cured using the shunt capacitor.

These observations led to the design of the Etude 5 prototype back in 2012-13. There have been several key iterations of the design including changing the positions of the bass units and tweeter, rigid circumferential mounting of the BMR array and trial and implementation of high quality passive components in the filters

The new Etude 5 has been introduced

to fill a need; many listeners love the coherence and impulse response of a single driver loudspeaker, full range electrostatic or magneto-dynamic panel, but cannot live with the large physical size, limited bandwidth and colouration/uneven frequency response, particularly in the case of some classic folded horn speakers. Maximum loudness limitation is also a problem with some direct radiating single drive unit loudspeakers.

The Etude 5 addresses these issues head on, via use of a line array of four 85 mm balanced mode radiator (BMR) wide-band drive units which are driven full range via a parallel LCR baffle step equalisation network, as is the case with the Curvi-BMR loudspeakers. The BMR drive units are mounted on a machined aluminium baffle and are clamped in place circumferentially via 4 mm brushed stainless steel bezel. Frequency extremes are bolstered by a ring radiator tweeter which starts to contribute to high frequency output at 5 kHz and extends output to 40 kHz. The low frequency end of the spectrum is underpinned via a pair of side mounted force cancelled 200 mm 75 mm voice coil Morel woofers, contributing to bass output from 100 Hz, and substantially filling in below 50 Hz, down to an in-room 20 – 25 Hz. Fundamental, and most harmonic, frequencies of the majority of musical instruments and vocals are therefore covered with no interruption by the BMR line array, this provides unrivalled, speed, coherence and transparency. The line array also provides excellent stereo imagery, which is sharpened thanks to the tweeter. A novel feature of the Etude 5 is that the BMR array and the force cancelled woofers share the same transmission line, simulations have shown that modulation of the BMR units by the woofers at low frequencies is not significant. Sharing the line provides excellent bass speed and timing due to the woofers and the BMR units driving the same column of air – the “time-base” is the same for both sets of drive units. Rigid mounting of the BMR units and circumferential support of their chassis contributes substantially to the quality of transient response.

As taste and room acoustics vary; the depth of the baffle step filter notch and tweeter output are variable via solderless connections. All filter components are of high quality and include Falcon, Jantzen and Mundorf inductors (including a 1.8 mm thick wire air-cored inductor from Mundorf or Jantzen for the baffle step notch filter). Capacitors are from Mundorf and Jantzen. Parallel thick film resistors are used in the baffle step notch filter and tweeter attenuation; a parallel resistor network gives improved dynamics and allows one resistor to be soldered in place whilst the other is solderless swappable to enable changes in the resistance value. Connection to the amplifier is via a single pair of large high quality binding posts.

The 25 mm higher density exterior grade MDF cabinet (with 36 mm thick baffle) is coupled to the floor via an 8 mm laser cut and forged steel base, equipped with bespoke spikes. The forged profile allows the cabinet to sit low in the plinth, thus maximising stability.  For enthusiasts with listening rooms with excitable suspended floors, or floors with poor acoustic insulation, the Clipaudio Mute Point isolation bases are highly recommended at £1200 / pair supplement.

The most recent design is the Etude High Sensitivity Bipole (EHSB), developed in collaboration with
Danny Baty of Super Natural Audio. I have been working with Danny, the designer and
manufacturer of a 2.3 W single ended triode amplifier, amongst other superb valve audio
electronics, for some years now. He needed a loudspeaker sensitive enough to use with his
amplifier. The EHSB is the result – for the first time, horn-like sensitivity (slightly more than 100
dB/W total output) is combined with the speed and coherence of BMR drive units and truly
extended bass (to below 25 Hz), thanks to inverse tapered transmission line loading.


Etude 5 gains top HiFi Pig Reviewer Award