The Isobaric Small Reds (ISRs) build on Dr Rod’s isobaric design experience at Linn with their Sara 9, Isobarik and Keltik loudspeakers (see Legend Story).   We have mounted two high quality 6.5″ bass drivers in isobaric configuration to achieve deeper bass in a relatively small standmount cabinet.  The result is usable bass to well below 40 Hz that is also very tight, fast ,detailed and harmonically rich.

The other drivers of the ISRs have also been equally carefully chosen as the drivers are the most important part of any loudspeaker. The ISR’s superb 90mm midrange unit (also used in the Tikandi Plus) is made in Germany from high srength Mg alloy coated on each side with very hard ceramic so that it remains pistonic well above 3 kHz. This results in extraordinarily low distortion through the critical midband region allowing these vital frequencies to come through crystal clear and without the hardness or muddle of many loudspeakers in this region.

We use a beryllium tweeter to give the same clarity in the treble – beryllium is the lightest, strongest metal so dome breakup (a major cause of distortion) is over 40 kHz, an octave above human hearing.  The tweeter has a superb magnet/voice coil structure as well as a suspension system that also gives very low distortion at its lower frequencies.

The cabinets have the best design features of ‘form follows function’ with the truncated pyramidal shape giving non-parallel sides to minimise internal reflections minimising cabinet resonances that blur timing; while the triangular front baffle which follow the size of the drivers minimise edge diffraction effects that blur the acoustic imaging.  Their cabinets are very solidly built in 18mm laminated MDF with constrained layer damping plus extensive bracing to minimise panel vibrations that can otherwise add erratically to the driver output and colour the music.

Thus the Isobaric Small Reds cover the full range of human hearing in a relatively small cabinet from deep bass to sparkling highs with very uniform frequency response with very low distortion to faithfully retain the tonal character of music and voices. And by minimising driver and cabinet resonances they have the fast, open natural sound that makes all Legend loudspeakers famous.

It was for these reasons that the Isobaric Small Reds were chosen as monitors for Sydney’s Fine Music 2MBS-FM radio station’s recording studio where full-range high fidelity is essential.

And the measurements by Newport Test Labs for Australian Hi-Fi showed that the Small Reds have “an extremely flat frequency response – varying by + & – 1 dB between 100Hz and 10kHz….. So far as the low-frequency performance is concerned, I don’t think I have ever seen such extended low-frequency response from any loudspeaker with the Small Red’s internal volume (and external dimensions) … ”  The full review of the original ISRs is given here  – but they are now even better!

Recently we made the ISRs ‘DEQX-active’ by replacing the passive crossovers with a DEQX preamp/processor to create a true state-of-the-art loudspeaker.  They are also designed and built in Sydney, making it a true Australian-made world-class system.

The DEQX preamp/processor separates out (crossovers) the bass, mid and high signals in the digital domain where it can be done much more accurately, and with steeper slopes while retaining minimum phase distortion, than in the analog domain by ‘passive’ crossover filters. In addition we measure each driver with a very high quality microphone using the DEQX processor and it also corrects for any remaining frequencies and phase non-linearities in-band.   The DEQX is a quality pre-amp, controlling volume and switching between analog and digital inputs.

Each low, mid and high output from the DEQX is connected its own amplifier that is then connected directly to each driver – this is what is meant by being DEQX-active.   It therefore requires 6 channels of high quality amplification – you can mix and match different types and power outputs for each driver to meet your tastes and budget.  But for the ultimate sound we recommend using DEQX amplifiers that have Hypex Ncore modules with very low distortion right across their frequency range – matching that of the ISR drive units!

However, the overall sound quality is also affected by your room. At various frequencies/wavelengths depending on room dimensions sound can resonate to form ‘standing waves’ that can give 10 dB or more of non-linearity at your ears. Although these standing waves should be reduced as much as possible by physical means (dispersion and adsorption) the DEQX processor can also help correct for them by measuring and applying inverse corrections, We will help you do this during set-up of your DEQX-Active ISRs.

The final output from the DEQX-Active ISRs is therefore extraordinarily accurate in both frequency and phase. The former leads to very natural tonal balance of all instruments, including voices; while the latter results in incredible speed and timing of your music plus superb imaging, both lateral and in depth.   Listening through Legend’s Active ISRs is just ‘like being’ there at the recorded performance.

We can arrange most paint colours and finishes from AS2700 including those below. Please contact us for details.

DEQX preamp/processor

DEQX-active ISR frequency response