• Incl.Excl.
  • Customer Support



      PURIFI PTT6.5M04-NFA-01 Ultra Low Distortion Midrange

      € 355,33€ 429,95 4 In stock
      • -10% Order 4 for only € 386,96 per piece
      • -15% Order 6 for only € 365,46 per piece

      Buy now, pay later

      • 24h express shipping available
      • Same day shipping
      • In-house techniscal support
      • 45 days worry-free returns
      Request quotation
      Do you have a question about this product?

      Do you have a question about this product?

      Our employee is happy to help you find the right product

      Product description

      Dedicated midrange driver with enhanced efficiency. Negligible force factor modulation. Ultra-low magnetic hysteresis distortion. Utilizes PURIFI’s neutral surround technology.



      • A whole new take on driver design
      • PURIFI’s Natural Surround
      • Extreme low distortion over full excursion range 
      • Engineered and manufactured in Denmark
      • Excellent midrange performance
      • High power handling
      • Perfect balance between volume displacement and midrange efficiency


      Product Details

      PURIFI PTT6.5M04-NFA-01 Ultra Low Distortion Midrange


      The PTT6.5M04-NFA-01 has been optimized for Midrange use and achieves higher sensitivity as compared to the X- and W- versions of PTT6.5 product family. Furthermore, the M-version has a slight redesign chassis. Please observe the 2D drawings in the datasheet. The driver achieves astounding performance with ultra-clean distortion specifications.


      PURIFI is a fresh company that designs and manufactures extremely high-performance transducers and amplifier modules. Don’t let the freshness fool you; Their leadership team consists out of some well-respected audio technology pioneers. PURIFI developed a deep understanding of many performances degrading aspects for both amplifiers and transducers. Thanks to this understanding the PTT6.5W08-NFA-01 is the most refined bass-mid woofer from our woofer category.


      Besides this 4 ohm version, there is also an 8 ohm version, a long stroke version (PTT6.5M08-NFA-01), and a 6,5" passive radiator available.


      The challenge 

      Loudspeaker drivers are known to add a large, if not the largest, amount of distortion in an audio signal chain. Reducing this distortion is a challenge with the complication of fine-tuning to improve one part (e.g. harmonic distortion) often results in a degradation of another part (e.g. intermodulation distortion). These distortions consist out of several separate distortion mechanisms. By carefully mapping and completely understanding these mechanisms, PURIFI succeeded in improving the overall performance to a large degree.


      A whole new take on driver design

      PURIFI developed mathematical models for the motor system, suspension, cone, and surround. These models allowed for the optimization of each distortion mechanism separately. This systematic approach reduced all distortions mechanisms and keeps intermodulation distortion low. The result makes that the PTT6.5M04-NFA-01 is a compact 6.5” driver that parallels or even surpasses the bass performance of a low excursion, large surface driver, while it also excels in midrange performance.


      The mechanism


      Low force factor modulation

      Current through the voice coil is not distorted by cone movement. Gives undistorted midrange regardless of the excursion

      Constant force factor over excursion - Bl(x)

      Prevents amplitude devotions of midrange output during the large excursion (sometimes called ‘burbling’)

      Low surround radiation distortion

      Reduces harmonic and intermodulation distortion caused by surround

      Low magnetic hysteria distortion

      Reduces harmonic and intermodulation distortion caused by magnetic traces left by the previous cycle



      Q: Should I go with this 4 ohm or with the 8-ohm version? 

      A: Both woofers have similar distortion performance and the T/S parameters are alike. The 4 ohm coils of this PTT6.5W04-NFA-01 allow more current to flow on a similar drive voltage. This gives higher sensitivity and is preferred in most applications. If you have an amplifier that is not comfortable with low impedance loads or has specific requirements, such as parallel woofers, the PTT6.5M08-NFA-01 might be more favorable.


      Q: Why is this surround odd-shaped?

      A: This is the PURIFI Natural Surround. Conventional surroundings create distortion as they deform. The shape of the Natural Surround reduces cone edge resonances and distortion. It might be odd-looking, but form follows function here. A more detailed look shows that the surround actually represents a complex sound wave. We are told that the Natural Surround is also called ‘wormy’ by insiders. 

      Show more


      Article number
      Nominal Diameter
      Power Handling (RMS)
      250 W
      Impedance (Z)
      4 Ohms
      2.83Vrms/1m 93.2 dB
      DC Resistance (Re)
      3.9 Ω
      Voice Coil Inductance (Le)
      0.26 mH
      Resonant Frequency (Fs)
      55 Hz
      Mechanical Q (Qms)
      Electromagnetic Q (Qes)
      Total Q (Qts)
      Diaphragm Mass Inc. Airload (Mms)
      17.8 g
      Mechanical Compliance of Suspension (Cms)
      0.47 mm/N
      Surface Area of Cone (Sd)
      132.7 cm2
      BL Product (BL)
      8.1 N/A
      Compliance Equivalent Volume (Vas)
      11.7 L
      Maximum Linear Excursion (Xmax)
      +/- 3.9 mm
      Driver's Mechanical Losses (Rms)
      1.47 kg/s
      Cone / Diaphragm Material
      Proprietary Fibre Mix

      Show more


      0 from 5Based on 0 reviews
      Review this product

      There are no reviews written yet about this product..

      PTT6.5M04-NFA-01 Ultra Low Distortion Midrange
      € 355,33
      € 429,95
      PTT6.5M04-NFA-01 Ultra Low Distortion Midrange
      4 In stock
      Add to cart
      Compare 0

      Add another product (max. 5)

      Start comparison

      By using our website, you agree to the usage of cookies to help us make this website better. Hide this messageMore on cookies »