Our 1961 speakers are built around a 28mm synthetic soft dome with a custom designed, matching waveguide. This tweeter was designed for the 1723 series, and most of its design principles are transferred to the 1961 series. The soft dome itself is very lightweight, completely pistonic up to ultra-high frequencies, optimally damped, produced to exceedingly tight tolerances and specifically chosen for its sweet sound character and consistent frequency response. We basically utilize the same tweeter as in the 1723 series, but instead of a neodymium magnet assembly we opted for a less expensive ferrite magnet assembly that still makes the tweeter sound exquisite.The role of the waveguide is to take an already excellent tweeter and further refine its performance. The size and shape, although appearing to be rather simple, is in fact the result of painstaking modelling, testing and refinement. By precisely controlling the directivity over the entire frequency range of the tweeter, we are able to broaden top end dispersion that the tweeter naturally wants to beam straight ahead, and focus the frequencies at the lower end of the tweeter range that naturally want to spread out in all directions. This provides a more consistent polar response across the tweeter’s entire frequency range and a close match to the dispersion pattern of the mid-bass driver it is working with, simplifying the crossover design.

Design

Everything about this tweeter except for the diaphragm has been completely modelled, designed and tooled from scratch. The motor of this tweeter is a powerhouse, all bespoke designs by Arendal Sound and extensive FEA modelling and optimization through Comsol. As usual we use Klippel analysis to review all driver designs.The end result is a high performance, high power handling tweeter with very good bandwidth, low distortion and high efficiency.

• High temp polyimide CCAW wire.
• Underhung voice coil design.
• Ultra-low viscosity ferrofluid contributes to voice coil cooling and ensures the best possible transient response.
• Large aluminium heatsink/shorting ring reduces distortion and prevents thermal compression.
• Multiple vents for increased airflow and balanced compliance.

Waveguide assembly

The waveguide was designed specifically for the new 1961 tweeter and its new speaker applications. It’s a constant directivity, custom designed and tooled waveguide in ABS plastic material, thick and sturdy to avoid any resonance.To give the waveguide assembly that final touch in feel and look, we designed and tooled an NBR rubber ring that fits smoothly to the end of the waveguide shape, covering screw holes and showing off a subtly integrated Arendal Sound logo.The waveguide serves several purposes, augmenting tweeter performance to a level that no flat baffle mounted single dome solution could reproduce:

• Increased efficiency by controlling lower frequency dispersion – typically a 6dB gain.
• Very low distortion due to increase in lower end efficiency.
• Precise polar response control (constant directivity).
• Low crossover frequency (approx. 1 octave lower than without the waveguide).
• Excellent directivity transition from mid/woofer to tweeter.

Air flow venting

The air chambers, venting and damping materials found behind the dome and surround are optimized to create a very well controlled impedance with no secondary resonance peaks, which typically cause electrical phase shifts that present an awkward load for amplifiers and further smear the sound, adding a harsh character.