“Without love and magic, it’s impossible to make a musical reproducer.” - Alain Pratali
My aim with this blog post is to introduce you to Alain Pratali and his brand, Aurai loudspeakers. I have been in the business since 2003, and a music/audio lover since the 80's. No other speaker I have heard, and that I can reasonably afford, has connected me to the music like Aurai. I hope with this information you can come to appreciate the design genius of Alain Pratali, and perhaps become curious enough to listen to a pair of their Z165 or Z215 speakers in your own home.
About the Founder, Alain Pratali
Chief designer, and owner Alain Pratali is a retired naval captain and electromechanical engineer by trade. He spent 35 years in audio (so far), some of his more notable accomplishments were the design of the Oracle Audio 1000 and 2000 CD players and amplifiers for Jacques Reindeau.
The Oracle Audio CD1000
Also prior to Aurai and the Z series, Alain had a very successful run of loudspeaker designs done for Simon Lee (formerly of April Music) in South Korea. Alain designed the 8” 2 way M1 tower and M3 Bookshelf speakers. Both of these designs feature a proprietary high frequency driver designed by Alain at the time. It was the success of the Simon Audio speaker designs, and this driver that prompted Alain to start Aurai Audio in 2019.
Design Philosophy
Proper Time Domain behavior of a loudspeaker unlocks the emotion in music.
- Excellent impulse response and in-phase transients are the key to Alain’s designs. Alain believes getting the time domain information correct unlocks the emotional content of the music. Measurements help chase down the desired emotional response, but in and of themselves are only part of the magic of loudspeaker design.
- For Alain, the woofer must be able to have a bandwidth of at least 65Hz to 3300Hz with minimal directivity. This means the critical vocal range is handled by a single driver.
- Driver membranes must also be lightweight, with minimal ringing or resonances that would force the designer to add more parts in the signal path to tame the output of the driver.
- Higher Efficiency designs are easier to drive, more sensitive to the input signal, tend to have greater dynamic expression and resolution when paired with a proper crossover.
Tackling the Time Domain in the Crossover
In the Z series loudspeakers, first order (minimum phase) crossovers are implemented, and if a steeper slope is needed, compounding first order crossovers keeps time and phase alignment correct through the drivers passband while providing a steeper slope.
Time Domain and Time Alignment
To further ensure proper time domain behavior, the low and high frequency drivers in the Z series are physically time aligned. Meaning, that their projected sound waves emanate from the speaker arrive at your ears at precisely the same time.
Driver Selection
Alain has chosen to work with the French Company Supravox, known for their wide-band driverss. Aurai’s proprietary woofers use cast frames and motors from Supravox, with custom machined pole pieces, spiders, voice coils, and cones. They also incorporate phase plugs to flatten the response and control dispersion further.
For the high frequencies, all of Aurai’s designs revolve around the proprietary and extremely low-mass .12g dome tweeter, loaded in a donut style horn/waveguide. It’s based on a Western Electric 555 motor with a floating Altec diaphragm. The tweeter’s origins date back nearly 50 years. There is no glue, the coil heat-seals directly with the membrane for no loss of energy or the finest signal. The assembly nests in a support optimized for performance, bandwidth and finally, a custom horn/waveguide machined out of Delrin.
"First impressions? "What an incredible tweeter!"...This was one hellaciously fast and responsive HF unit. It dug deep into the finest upper harmonics...This unknown French tweeter was superior to the far heavier but famous Mundorf AMT in our regular monitors. It was superior to the inverted ceramid Accuton dome in our Albedo Aptica Two-way towers. It most reminded me of a Raal ribbon, albeit with a higher energy density and more color...I thought this dome tweeter to be second only to Michael Borreson's high-tech, ultra-costly ribbon which I'd heard in this room the year prior..." Srajan, Sixmoons
To attenuate the output level of the high frequency driver, energy robbing resistors in series with the signal are not necessary. Rather, additional magnetic force is added to the base magnet, reducing the output level without mucking up the signal. It is pure genius. Nothing extra is added to the signal path of the crossover circuit.
Enclosure
All Z-series are constructed out of baltic birch ply for it’s stiffness and superior sound to MDF. The unusual depth of the Z series enclosures help reduce the energy from the rear wave of the driver by increasing the distance between the driver and the rear of the enclosure. For the Z215, the long enclosure helps to form the Tapered Quarter Wave Tube design, with the larger opening on the back of the enclosure.
Crossover
12 awg Jantzen copper/wax foil inductors are used on the low frequency drivers, as they have the most natural dynamics, tone and sound. Owners have a choice of Duelund, Miflex, Jupiter or Rike capacitors on the high frequency driver. Only 3 parts are necessary in the Z165 crossover. The elegant simplicity of the design is a testament to the excellent engineering of the Aurai drivers.
The Future
Aurai plans the introduction of a subwoofer in 2024. This will be a 4th order bandpass design based off of their design experience with the Lieutenant loudspeakers. The subwoofers are not designed to plunge the ultimate depths, but for control, excellent impulse response, and output down to 27 Hz.