The Nightshade v.4 is the premium 3 inch coil “ultra-high excursion” subwoofer in Sundown Audio’s lineup. The 10, 12, 15, and 18” models feature their custom tooled and patented cast-aluminum frames (US Patent Numbers D691596, D691597, D691598, and D741841).
Sundown Audio makes these new platform frames to an all new, patent-pending (Application US20170339501A1 and US Patent Number D791740S1), neodymium based motor structure featuring a hyper-extended pole and extreme clearances (allowing up to 4″ p-p travel before mechanical bottom). The Nightshade v.4 features an enormous 45mm (1.77”) magnetic gap to ensure the coil is always under control. This motor drives a 3″ diameter 4-Layer Flat Wire Aluminum Coil with an extremely long winding (3.15” long) wound on a thick aluminum former to incredible levels of excursion. They use 100% American made voice coils, each motor is hand assembled in North Carolina by their team, and the final assembly of the parts into a complete product is also done there, in-house, with high strength US made adhesives.
The Nightshade v.4 features the longest coil of any 3” coil speaker they have made to date. Due to the extremely powerful motor of the Nightshade v.4 they could take advantage of an extremely long 4-layer coil – the 4-layer coil keeps the mass and inductance down while allowing them to use such a long coil for incredible linear x-max while the powerful motor allows them to achieve the level of BL they desired. The Nightshade v.4 has a full 25% more motor force than the v.3 model while shaving off over 30 pounds of weight!
With the introduction of the new light-weight motors they also incorporated several new cooling / thermal management features to push the power handling up to an enormous 3000-watts RMS:
1) The motor utilizes N48H Neo (heat treated). The entire motor would need to be nearly 250 degrees F before the magnet is affected in any way. This is nearly 40 degrees more than is required to boil water.
2) The Neo magnets are sandwiched between two aluminum plates which meet the air gap along their inner edge. These plates help carry the heat away from the gap and thus the magnets and voice coil. The bottom aluminum plate is cooled by the air going in and out of the holes around the motor. The top aluminum plate is cooled by the air-flow from the spider going in and out of vented spacer ring. These plates also serve as very effective shorting rings. The NS v.4 has the lowest inductance of any large woofer Sundown Audio have ever produced. Furthermore, their Neo magnets themselves do not directly come into contact with the “air gap” of the woofer like most Neo-Radial designs; meaning they will never be directly adjacent to the extremely hot voice coil. Instead, a flux distribution ring separates them from the magnetic gap.
3) That brings us to the vent ring itself (mounted between the frame and the motor). For the NS v.4 they developed and tooled solid cast aluminum vent rings. Thus allowing heat to more easily move through the aluminum “top plate” and into the vent ring and thus finally into the frame itself. Their “Sundown” frames are MASSIVE chunks of aluminum (e.g. Heat-Sinks) with the 18” frame being a full 10 pounds of metal!
4) Now let’s discuss the “active” cooling of the coil. As most people are aware a solid pole piece necessarily forces all of the air under the dust cap across the former as the woofer moves back and forth thus resulting in quick heat dissipation from the aluminum former. This air can then easily escape the side vent-holes of the motor and be exchanged with cooler air. Additionally; the “Sundown” frames feature a “closed base” design which forces all the air movement from the spider to go through the vent ring creating a high velocity air stream across the top part of the coil. This type of cooling is used on everything they make from the SA series on up and has proven incredibly effective for the close to 9-years they have done it this way.