Our 1961 series utilizes a 5.5” woofer that is built around the same core fundamentals as its bigger brother, the 1723 series. The cone body is the same, using long fiber pulp paper with our proprietary coating that ensures covering a wide frequency range from the deepest bass to well above 1500Hz without any hint of cone resonance. The cone material also makes it inherently self-damped which gives a natural sound without coloration throughout the frequency band.
The entire surround of the driver is designed to follow the same curvature as our waveguide, so the speakers are recessed into the cabinets and have a smooth NBR rubber surround that also acts as a gasket and smoothens out the curvature to meet the face of the baffle. The looks are just like we do on our 1961 Subwoofers and 1723 Subwoofers, except here it is a single integrated piece in the woofer design.
Modeling
While many brands may advertise FEA design and modeling, usually this only refers to the basic magnetic circuit. Arendal Sound has taken the science of transducer modeling to another level. The motor topology is firstly designed to meet fl ux density and excursion requirements. Then the materials and geometry are fine-tuned to minimize fl ux modulation and stabilize the inductance vs. both position and current. Lastly, the voice coil stroke or BL(x) shape is optimized for zero-point centering and symmetry which are the final points for maximizing motor control over-excursion and minimizing distortions.
We use non-linear FEA modeling to analyze the compliance of both the spider and surround to achieve excursion requirements and optimize Cms(x) to compliment the motor. This translates to increased excursion and lower Distortions which equals maximum sound quality
We utilize Klippel Laser-based diagnostics. It’s a tool often misunderstood, but when used properly in conjunction with component design, a woofer’s design can be dialed in. Klippel testing basically serves to confirm the initial FEA modeling and accuracy of part tooling and offers the diagnostic abilities to allow our engineers to refine the initial designs until final goals for excursion, linearity, stability, and distortion are met.
Material selection and design
Distortion is closely related to how far the cone and motor have to move for a given volume level. Size presents its own engineering challenges and the motor, suspension, and diaphragm all must be delicately balanced to be able to cover the critical midrange frequencies without coloration.
We utilize low-carbon steel specifically chosen for its ability to carry more flux in the magnetic circuit.
The vented T-yoke is CNC milled to final dimensions to ensure tight tolerance, proper fit and prevent flux-robbing losses often found in typical motor assemblies. Vents in the aluminium bobbin as well as the T-Yoke, vents in the basket under the spider and in the cone body all together reduce physical and thermal compression, maintaining a hugely dynamic response. This continuous exchange of air mitigates thermal compression and increases the woofer’s overall power handling capability. Second, the airflow relieves asymmetric compliancy and noises (ie, distortion) due to non-linear compression and rarefaction of air typically trapped under the dust cap and spider. Typical vented pole designs will be limited in effectiveness due to the lack of airflow volume. Meaning, at the highest power and excursion where the airflow is needed most, the pole vent alone will not be sufficient.
Aluminium voice coil wire is chosen for its weight to conduction properties and lower sensitivity to temperature change, compared to copper. This results in higher efficiency and lower thermal compression. The driver also has a large linear excursion of 13mm peak to peak and a very low inductance design to maximize sound quality, bass response and extension.
We use copper shorting rings to reduce inductance, increase frequency bandwidth and lower distortion.
Symmetrical suspension consists of critical components such as the NBR surround, Poly-cotton spider material with progressive roll geometry, and integrated tinsel leads. All combined to create very high excursion capability with an exceptionally linear suspension. Again, this contributes to high output and low distortion at all operating frequencies.
