6.4 Subwoofers¶
Pair of 8" infinite baffle marine subwoofers with RGB LED lighting, mounted symmetrically in the rear quarter panels.
Type: 8" Infinite Baffle Marine Subwoofer
Model: M6-8IB-S-GmTi-i-4
Manufacturer: JL Audio
Product Page: M6-8IB-S-GmTi-i-4
Quantity: 2 (pair)
Mounting: Rear quarter panels (one per side, above wheel wells, firing inward)
Power Source: Amplifier Channels 1+2 bridged @ 4Ω → Sub A; Ch 3+4 bridged @ 4Ω → Sub B (one dedicated bridged pair per sub)
Specifications (per sub)¶
| Spec | Value |
|---|---|
| Power Handling | 200W RMS @ 4Ω |
| Impedance | 4Ω SVC |
| Sensitivity | ~85 dB @ 1W/1m |
| Voice Coil | 2" |
| Overall Diameter | ~9.5" |
| Mounting Depth | ~4.25" |
| Weight | ~7 lbs |
| Warranty | 3 years |
Wiring Configuration¶
Each sub runs on its own dedicated bridged channel pair on the JL Audio MV800/8i — Sub A on Ch 1+2 bridged, Sub B on Ch 3+4 bridged, both at 4Ω. This is an exact RMS match to the sub's 200W @ 4Ω rating, with no series compromise and independent per-sub gain/EQ/delay via the amp's onboard DSP.
| Wiring | Per-Sub Load | MV800/8i Output | Per Sub | Safe? |
|---|---|---|---|---|
| Bridged @ 4Ω per sub | 4Ω | 200W | 200W | ✅ 100% of RMS rating |
| Parallel both on one pair | 2Ω | n/a (bridged minimum is 4Ω) | n/a | ❌ Below bridged minimum |
Wiring path (per sub, both pairs identical):
Total amp output 400W into the pair (200W per sub) — exact RMS match, no headroom waste from series resistance, independent gain trim per side if the L/R quarter-panel locations end up acoustically asymmetric.
Infinite Baffle Requirements¶
- Minimum air volume: 0.75 cu ft per sub (1.5 cu ft pair)
- Installation type: No dedicated enclosure required
- Ideal location: Rear quarter panels above wheel wells, firing inward into cabin
- IB chamber: Rear cargo area / behind quarter trim (effectively unlimited volume in an LJ)
Features¶
- Transflective RGB LED lighting (via MLC-RW)
- Gunmetal trim ring with titanium sport grille
- Marine-grade construction
- Mica-filled polypropylene cone
- Synthetic rubber surround
Wiring¶
| Connection | Wire | Notes |
|---|---|---|
| Sub A (+) / (−) | 14 AWG | From amp Ch 1+2 bridged to Sub A voice coil |
| Sub B (+) / (−) | 14 AWG | From amp Ch 3+4 bridged to Sub B voice coil |
| LED | 20 AWG | RGB from MLC-RW (one tap per sub) |
Standard speaker wire (no XM-WHTMFC needed for subwoofer audio). No series jumper between subs — each sub returns directly to its own bridged channel pair.
Why Two 8" vs Single 12"¶
The single 12" M7-12IB option (600W RMS, 14" overall diameter, 7.94" mounting depth, requires 3+ cu ft IB chamber) was ruled out for LJ-specific install reasons:
- Mounting depth: 7.94" of basket depth makes most LJ panels impractical — cage tubes, wheel wells, and tailgate clearance all conflict.
- Single-sub asymmetry: harder to integrate cosmetically vs symmetric L/R 8" pair.
- No matching 12" M6: JL doesn't make a 12" M6-IB (M6 IB line tops at 10"), so the pair option doesn't exist at 12".
Tradeoff accepted: total sub output is 400W (2× M6-8IB on dedicated bridged pairs of the MV800/8i @ 4Ω each) vs ~580W for a single M7-12IB. About 70% of the single-12" output, but symmetric L/R placement, independent per-sub DSP, and a feasible mounting depth in the LJ quarter panels win out. Acceptable for a soft-top Jeep where wind noise dominates at highway speed anyway.
Outstanding Items¶
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Build Tasks¶
- Confirm exact mounting locations in rear quarter panels (clear of cage tubes and rear seatbelts)
- Verify quarter panel material can support sub weight + mounting torque (may need backing plate)
- Source M6-8IB-S product image (
docs/jeep_lj/images/jl-audio-m6-8ib-s-gmti-i-4.jpg)