About: CT Sounds HYDRO-8 8" 300W RMS Shallow Mount Subwoofer

CT Sounds is proud to introduce the hydro shallow mount subwoofer series after completing a rigorous R&D process spanning 2 years! Our goal was to engineer a 300-watt 8” shallow-mount subwoofer with a mounting depth below 3.5” that was suitable for both sealed & ported enclosures. To achieve this, we focused on the EBP (Efficiency Bandwidth Product). As a general rule, EBP < 50, is used only for sealed enclosures, EBP 50 - 100, is used for both, and EBP > 100, is used only for ported enclosures. EBP = FS/QES.

Our 1st prototype utilized a 50.8 mm voice coil & 30 oz magnet resulting in a high QES rating of 1.05 and low EBP of 44.1. The 2nd prototype utilized a 44.7 mm voice coil & 30 oz magnet resulting in a slightly lower QES rating of 0.843 and a slightly higher EBP of 54.8. After the 1st and 2nd prototypes, we determined a larger motor assembly was needed to provide a more controlled electrical system (lower QES). This led us to invest in a custom-tooled basket (used in the final prototype) to keep the mounting depth below 3.5”.

The 3rd and final prototype uses a 44.7 mm voice coil & 40 oz magnet resulting in a reduced QES rating of 0.577 and a balanced EBP of 80.07. In testing, we ran into mechanical noise due to the larger motor assembly and voice coil in a confined space. Therefore, we invested in a custom-tooled cone to maximize the excursion capability by creating an equal distance between the cone, spider, and bottom plate. The result is an 8” shallow-mount subwoofer that is extremely responsive in both sealed & ported enclosures.

Product Highlights:  

• RMS Power: 300 Watts
• MAX Power: 600 Watts
• Voice Coil Configuration: Dual 2 Ohm (D2) or Dual 4 Ohm (D4) 
• Use Cases: Sealed & Ported Enclosures

Specifications: 

• Product Type: Car Subwoofer
• Subwoofer Size: 8"
• Voice Coil Configuration: Dual 2 Ohm (D2) or Dual 4 Ohm (D4) 
• RMS Power: 300 Watts
• MAX Power: 600 Watts
• Voice Coil Type: 1.75 Inch - 4 Layer High-Temperature Copper Voice Coil
• Magnet Type: Y35
• Bottom Plate Type: Low Carbon Iron
• Surround Type: Dual White Stitched Competition Mega Foam Surround
• Cone Type: Composite Paper with 3% Carbon Fiber Reinforcement
• Tinsel Lead Type: Single Braided Flat Copper Tinsel Leads
• Terminal Type: 12 Gauge Push Terminals
• Basket Type: Stamped Steel
• Spider Material: Poly-Cotton Blend

Thiele/Small Parameters: 

• Qes: 0.577 (D2) | 0.668 (D4) 
• Qms: 6.549 (D2) | 6.083 (D4) 
• Qts: 0.531 (D2) | 0.602 (D4) 
• Fs: 46.20 Hz (D2) | 47.47 Hz (D4) 
• Vas: 10.298 L (D2) | 10.427 L (D4) 
• Mms: 82.895 g (D2) | 77.535 g (D4) 
• Cms: 0.143 m/N (D2) | 0.145 m/N 
• Re: 3.9 Ω (D2) | 6.4 Ω (D4) 
• Bl: 12.751 Tm (D2) | 14.880 Tm (D4) 
• Le: /
• Sd: 227 cm² 
• Xmax - Single Way (mm): 8 mm 
• Xmax - Single Way (cm): 0.8 cm 
• Vd (Sd*Xmax): 181.6 cm² 
• SPL: 84.48 dB 

Subwoofer Measurements:

• Cutout Diameter: 7.51"
• Overall Diameter: 8.77"
• Mounting Depth: 3.26"

Box Specifications:

• Displacement: 0.02 ft3

Box Recommendations:

• Sealed: 0.35 ft3
• Ported: 0.875 ft3
• Tuning Frequency: 36 Hz
• Port Area: 14 in2

*Enclosure recommendations do not account for subwoofer, bracing, and port displacement.