PureShape SB26
Directivity polar plot
All measurements are real ones, performed with the ideal 25mm roundover return, taken at 1/24 resolution in a half-space presentation (±90°).
SPL
The loading effect provides much greater sensitivity in the low end compared to direct radiation in the low end.
Distortion
Its loading capacity allows operation at very low frequencies. The radiation restriction, combined with the reactive loading effect, reduces the tweeter’s required excursion to achieve a given SPL after equalization to a flat response,
leading to lower distortion.
Intermodulation distortion (IMD) is also reduced, since both harmonic and intermodulation distortions are strongly linked to driver nonlinearities, which generally increase with diaphragm excursion.
The driver becomes so efficient that most distortion components are buried in the measurement noise floor (around 0.01% here), making them effectively invisible on the 95 dB SPL distortion chart, making only a tiny rise in H3 visible.
How it competes versus Direct Radiation (no WG)
Mounting
We recommend a round-over return of around 25mm radius on each exposed side to eliminate midrange narrowing and beaming.
Mounting is done with the baffle using M4 screws into a rebate 10 mm large, 8 mm high, with 4 mm radius corners.
Users must remove the protective grille using a heat gun, or by carefully following the method shown in the photos. The grille must be gently pulled off a few millimeters at a time around the entire adhesive circumference. Be careful of the magnetic force when the grille is released.
To avoid applying lateral pressure on the driver’s surround during screwing, use a paper ring with an inner diameter greater than 50.5 mm. The ring will provide a 0.1–0.2 mm clearance around the entire surround, including its glued area.
Together with the waveguide’s centering system, it prevents lateral forces from being applied to the tweeter surround during screw tightening, eliminating the risk of permanently displacing the voice coil and causing rub & buzz.
The mounting operation is the sole responsibility of the client, and AudioHorn cannot be held responsible for any damage resulting from improper installation. In case of damage, Bliesma offers affordable repair services if the tweeter dome has not been damaged.
Then place the three centering pieces to align the tweeter. With the waveguide facing downward, keep the assembly well away from any metal objects, as the tweeter’s magnet is very strong and may attract them.
Hold the tweeter securely while lowering it into its final position. Once it is correctly seated using the centering pieces, tighten the three supplied screws. Leave the centering pieces in place.
