The SD-3 series is Sundown's premier sealed box offering. They started off this design knowing that the majority of sealed box applications today face a depth restriction. Each SD-3 model was designed to have the lowest depth possible while still maintaining a large window of mechanical cushion (about 2” p-p maximum mechanical travel for all models). We do not consider the SD-3 an “ultra-shallow” but they are as shallow as possible and feature several techniques to reduce the effective depth required
As mentioned above; the SD-3 series effectively requires less depth than other woofers that are more physically shallow. First, they have a completely solid pole and thus require no room for air venting behind the motor. This allows the motor to be completely flush against the back wall of the enclosure. Secondly the entire SD-3 series features an inverted rubber surround – this reduces the space required in front of the woofer to about 1” total (we suggest 1.25-1.5” when possible for the best sound). So, despite not being an “ultra-shallow” woofer they have an effective total depth requirement of about 2” less than most traditional woofers of an equal depth.
The SD-3 series truly is a world-class sound quality woofer with low mounting depth, small box requirements, and a reasonable price. This line features an under-hung motor topology – this means that the voice coil is shorter than the top plate so the amount of winding in the gap doesn’t change at all over the center portion of stroke – in this case featuring a 1” thick top plate and 1/2” long 8-layer copper voice coil. This allows for 0.57" (14.5mm) linear excursion one-way while maintaining an extremely flat BL curve. The large inverted rubber surround & high-stroke spider also allow for a very even compliance curve over the full range allowed by the SD-3 series. To further reduce distortion a large Magnet ID faraday ring has also been included
Sundows borrowed some technology from their large high-excursion woofers and incorporated a hyper-extended pole-piece into the SD-3 line. This helps to prevent voice coil rocking & related damages at high levels of stroke – since the SD-3 has such a soft suspension and shallow depth it would be more prone to this without the hyper-extended pole. But, thanks to Sundown's extensive experience in building high-stroke subwoofers they were able to incorporate the ideal solution.
Product Features:- Sundown Audio SD-3 8 D4 8" 300W RMS Dual 4-Ohm SD Series Subwoofer
- Power Handling:
- RMS Power = 300-watts
- Voice Coil Configuration: Dual 4-Ohm
- Xmax = TBA
- Under-Hung low distortion motor topology
- Solid pole piece with chamfered edges
- Black Aluminum 2.5” voice coil former for superior heat dissipation
- High Temperature 8-Layer copper voice coil wire
- Large aluminum faraday ring (Magnet ID)
- Spring Loaded Terminals
- Stitched-On Tinsel Lead Wires
- Optimized for small sealed enclosures 0.25-0.33 cubes sealed
- Inverted Rubber Surround to reduce front-mount depth
- High strength cast aluminum frames
- Xmax = TBA
- DC Resistance (Re): 6.1 Ω
- Resonance Frequency (Fs): 46.4 Hz
- Equivalent Volume (Vas): 5.8 L
- Electrical Q Factor (Qes): 0.67
- Mechanical Q Factor (Qms): 3.97
- Total Q Factor (Qts): 0.57
- Force Factor (BL): 16.4 NA
- Moving Mass (incl. Air Load) (Mms): 100.7 g
- Suspension Compliance (Cms): 0.12 mm/N
- Sensitivity: 81.2 dB 1w / 1m
Box Recommendations:- Sealed: 0.4 cu. ft.
- Ported: N/A
- Displacement: 0.10 cu. ft.
- Depth: 4.75 in
- Outside Diameter: 8.375 in
- Cutout Diameter: 7.375 in
- Recommended Tuning: 32 Hz
- Recommended Port Area: 8 - 12 sq. in
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