Purifi Audio PTT5.25X04-NFA-01

The PTT5.25X04-NFA-01 is a specialized midrange speaker from the Danish manufacturer Purifi Audio, known for its innovative and high-performance audio technology. The focus of this midrange speaker is on improved efficiency, neglect of the modulation of the force factor and extremely low magnetic hysteresis distortion. With its innovative PURIFI Natural Surround technology, it guarantees robust long-throw performance and undistorted sound in the midrange range. In addition to this 4-ohm version of the PTT5.25X04-NFA-01, there is also an 8-ohm version.

• Negligible force factor modulation and surround radiation distortion
• Low magnetic hysteresis distortion
• "Real" long-stroke performance: Distortion remains low over the entire stroke
• Unadulterated midrange performance
• Developed and manufactured in Denmark

The challenge

Speaker drivers are known to cause a large, if not the largest, amount of distortion in an audio signal chain. Reducing this distortion is challenging because fine-tuning to improve one part (e.g. harmonic distortion) often results in a deterioration of another part (e.g. intermodulation distortion). This distortion is composed of several separate distortion mechanisms. By carefully mapping and fully understanding these mechanisms, PURIFI has managed to improve overall performance to a great extent.

A completely new perspective on driver design

PURIFI developed mathematical models for the motor system, suspension, cone and surround. These models made it possible to optimize each distortion mechanism separately. This systematic approach reduces all distortion mechanisms and keeps intermodulation distortion low.

• The mechanism improvement modulation with low force factor
• improvement
• The current through the voice coil is not distorted by the membrane movement. Ensures an undistorted midrange regardless of the deflection
  
• Constant force factor over the deflection - Bl(x)
• Prevents amplitude deviations of the midrange output during large excursions (sometimes called "rumble")
• Low distortion due to surround radiation Low magnetic hysteria distortion
• Reduces harmonic and intermodulation distortion caused by the surround
• Reduces harmonic and intermodulation distortion caused by magnetic traces from the previous cycle

• PTT NFA woofer series
• nominal diameter 13.3 cm
• load capacity (QMW) 250 W
• Sensitivity (SPL at 1m / 2.83V) 85.7 dB
• DC resistance (Re) 3.8 Ω
• resonance frequency (Fs) 29 Hz
• overall quality (Qts) 0.26
• Membrane area (Sd) 85 cm2
• equivalent volume (Vas) 13 L
• Maximum deflection (Xmax) 9.8 mm
• Cone / Diaphragm Material Proprietary Fiber Mix