The PTT6.5W04-NFA-01 is the standard stroke 6.5" bass-midwoofer from the PURIFI woofer family. It incorporates similar breakthrough technology, but due to a reduced excursion limit the efficiency is improved over the PTT6.5X04-NFA-01 long stroke woofer.
PURIFI PTT6.5W04-NFA-01 bass-midwoofer
PURIFI is a fresh company that designs and manufactures extreme 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 performance degrading aspects for both amplifiers and transducers. Thanks to this understanding the PTT6.5W04-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 (PTT6.5X04-NFA-01) and a 6,5" passive radatior available. Looking for similar performance, but something smaller? Take a look at the 4" PTT4.0W04.
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 by a large degree.
PURIFI developed mathematical models for the motor system, suspension, cone and surround. These models allowed for optimization of each distortion mechanism separately. This systematic approach reduced all distortions mechanisms and keeps intermodulation distortion low. The result makes that the PTT6.5W04-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 | Improvement |
Low force factor modulation | Current through the voice coil is not distorted by cone movement. Gives undistorted midrange regardless of excursion |
Constant force factor over excursion - Bl(x) | Prevents amplitude devotions of midrange output during 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 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 allows more current to flow on a similar drive voltage. This gives a higher sensitivity and is preferred in most applications. If you have an amplifier that is not comfortable with low impedance loads or have specific requirements, such as parallel woofers, the PTT6.5X08-NFA-01 might be more favorable.
Q: Why is this surround odd shaped?
A: This is the PURIFI Natural Surround. Conventional surrounds 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 complex sound wave. We are told that the Natural Surround is also called ‘wormy’ by insiders.
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