Reference Loudspeakers

I am building a pair of active three-way loudspeakers: a Purifi woofer, a Satori midrange and a Satori tweeter, each on its own amplifier channel with DSP, and two passive radiators for the lowest octave. No subwoofer, and no compromise on dynamics.

In progress1 log entry

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  1. Tweeter, Satori TW29BN-B
  2. Midrange, Satori MD60N-6
  3. Woofer, Purifi PTT6.5X04-NFA-01
  4. Two Purifi 6.5″ passive radiators, planned
  5. Hypex FA253: DSP and three amplifier channels
One speaker as a schematic: the crossover is in the DSP, and each driver has its own amplifier channel. Dashed: the passive radiators, still planned, and the box, not designed yet. Drivers roughly to scale.
Design
Active three-way, a pair
Woofer
Purifi PTT6.5X04-NFA-01
Midrange
Satori MD60N-6
Tweeter
Satori TW29BN-B, 4 Ω
Amplifier
Hypex FA253: three channels with DSP
Bass
Two Purifi 6.5″ passive radiators per speaker, planned
Subwoofer
None

Why build them

I already had good loudspeakers: Dynaudio Xeo 30s, and I liked how they sound. What I want now goes further: bass deep enough that no separate subwoofer is needed, dynamics with nothing audibly compressed, and enough resolution that nothing in a recording hides. The measure is not a number. It is music good enough to move you.

Three ways, three amplifiers

Each driver gets its own amplifier channel, and the crossover is not a network of coils and capacitors in the box but filters in a DSP before the amplifiers. The Hypex FA253 has three channels, one for each driver, and its DSP in the same module.

Band Driver
Bass Purifi PTT6.5X04-NFA-01
Midrange Satori MD60N-6
Treble Satori TW29BN-B, 4 Ω
TweeterMidrangeWooferRadiatorfrequency 400 Hzwavelength 85.8 cmplaying midrange

Why three drivers: at 40 Hz a wavelength is 8.6 metres, at 4 kHz 8.6 centimetres. An illustration with time slowed down very far; the field is two metres wide.

The lowest octave

One rule is set: no further active drivers. Passive radiators are allowed. A passive radiator is a cone with no motor, moved by the air in the box; tuned with the box, it lets a small woofer reach lower than it could alone. Each speaker gets two of Purifi’s 6.5-inch radiators; whether with aluminium or fibre cones is still open.

201001k10k0-12-24-36HzdBwoofermidrangetweetersealedwoofer / mid 350 Hzmid / tweeter 3.0 kHzradiators tuned 32 Hz

Drag the diamonds

Ideal filters and an ideal box, not the measured design: where the crossovers go is not decided yet. The sum runs flat through both crossovers, and the passive radiators hold the lowest octave before it falls. More in the log: The parts list.

Next

The enclosure and the crossover. Measurements, drawings and the first sound go in the log.

Log

  1. The parts list