AC1800KD1 (v2)
Class-D Monoblock Amplifier — AC Series
◆ AC Series · Class-D Monoblock · 2026 Edition AUNEX AC1800KD1 — 1800W RMSClass-D Monoblock Car Amplifier | 1-Ohm Stable The AUNEX AC1800KD1 is a compact, full-power Class-D monoblock amplifier engineered for high-output subwoofer systems where verified performance matters. Rated...
1,800W
RMS @ 1Ω
105dB
SNR
4-Layer
PCB
Individually bench-testedEvery unit verified against Aunex quality standards before shipping.
2-Year Warranty — Direct from Aunex1-Year Limited Warranty via authorized dealer.
Professional Installation RecommendedContact your nearest Aunex authorized dealer.
POWER OUTPUT·
RMS·
VERIFIED @ 14.4V DC
AC1800KD1
CLASS-D MONOBLOCK
1 OHM
1800 W RMS
2 OHM
1200 W RMS
4 OHM
650 W RMS
DIMENSIONS (W×H×L)
5.70 × 2.02 × 11.43"
144.92 × 51.2 × 290.4 mm
VOLTAGE RANGE
9 – 17V DC
THE AUNEX STANDARD
COMPACT.
CLASS-D.
UNCOMPROMISED.
The car audio industry has a power inflation problem. Most amplifiers on shelves today are marketed with numbers measured under ideal lab conditions — optimistic test frequencies, burst measurements, and load tolerances that no real install will ever replicate. The result is a watt figure that looks impressive on a box and disappears the moment you turn the key.
We built the AC1800KD1 to end that conversation. Every unit is independently tested at rated power under real-world operating conditions. 1,800W RMS at 1 ohm — measurable, repeatable, and printed on the box without an asterisk. This is the amplifier for anyone who has ever been burned by inflated specs.
“What’s on the box is what comes out of the terminals — no inflated peak numbers, ever.”
— THE AUNEX POWER PROMISE
Channels1
RMS Power @ 4Ω650 Watts
RMS Power @ 2Ω1,200 Watts
RMS Power @ 1Ω1,800 Watts
THD< 1.0%
Efficiency @ 4Ω84%
Signal-to-Noise Ratio> 105 dB (±3 dB)
Frequency Response10 Hz – 250 Hz
Input Sensitivity250 mV – 10 V
Crossover Slope24 dB / Octave
Low-Pass Filter45 Hz – 250 Hz
Bass Boost0 – 18 dB @ 45 Hz
Subsonic Filter10 Hz – 50 Hz
Operating Voltage9 – 17 V
Idle Current1.38 A
Fuse (Included)200 A
Height2.05" / 52 mm
Width11.46" / 291 mm
Depth5.71" / 145 mm
Weight6.26 lbs / 2.84 kg
Canales1
Potencia RMS @ 4Ω650 Watts
Potencia RMS @ 2Ω1.200 Watts
Potencia RMS @ 1Ω1.800 Watts
THD< 1,0%
Eficiencia @ 4Ω84%
Relación señal-ruido> 105 dB (±3 dB)
Respuesta de frecuencia10 Hz – 250 Hz
Sensibilidad de entrada250 mV – 10 V
Pendiente de cruce24 dB / Octava
Filtro paso bajo45 Hz – 250 Hz
Refuerzo de graves0 – 18 dB @ 45 Hz
Filtro subsónico10 Hz – 50 Hz
Voltaje de operación9 – 17 V
Corriente en reposo1,38 A
Fusible (incluido)200 A
Altura2,05" / 52 mm
Ancho11,46" / 291 mm
Profundidad5,71" / 145 mm
Peso6,26 lbs / 2,84 kg
Canaux1
Puissance RMS @ 4Ω650 Watts
Puissance RMS @ 2Ω1 200 Watts
Puissance RMS @ 1Ω1 800 Watts
THD< 1,0 %
Efficacité @ 4Ω84 %
Rapport Signal/Bruit> 105 dB (±3 dB)
Réponse en fréquence10 Hz – 250 Hz
Sensibilité d’entrée250 mV – 10 V
Pente de croisement24 dB / Octave
Filtre passe-bas45 Hz – 250 Hz
Renforcement des basses0 – 18 dB @ 45 Hz
Filtre subsonique10 Hz – 50 Hz
Tension de fonctionnement9 – 17 V
Courant au repos1,38 A
Fusible (inclus)200 A
Hauteur2,05" / 52 mm
Largeur11,46" / 291 mm
Profondeur5,71" / 145 mm
Poids6,26 lbs / 2,84 kg
- 01 — Remote Level Control: Surface or flush mount. Keep cable away from power wires and moving parts.
- 02 — Clipping LEDs: Faint glow = 1–2% THD warning. Fully lit = 7%+ THD. Reduce gain immediately.
- 03 — Bass Boost: 0–18 dB @ 45 Hz. Re-adjust Input Gain after any Bass Boost change.
- 04 — Subsonic Filter: 10–50 Hz safety cutoff. Use the 75% rule: tuning freq × 0.75 = filter point.
- 05 — Low-Pass (LP) Filter: 50–250 Hz. Recommended 80–100 Hz for most subwoofer setups.
- 06 — Phase Switch: 0° (standard) or 180° (reversed). Choose whichever produces the fullest bass.
- 07 — Input Gain: Not a volume control. Matches head unit output to amp input. Set with Clipping LED method.
- 08 — RCA Inputs: Balanced inputs reject common-mode interference (alternator whine, etc.).
- 09 — Speaker Terminals: 16–8 AWG. Loosen → strip ½" → insert fully → tighten.
- 10 — +12V Terminal: Up to 4 AWG. Run direct to battery. Fuse within 18" (457 mm) of battery.
- 11 — Remote Turn-On: Switched +12V source. Head unit blue/white wire or any ignition-switched circuit.
- 12 — Ground: Same gauge as +12V. Short as possible to bare chassis metal. Use a star washer.
Gain Setting Method
Set head unit ~75% → raise gain slowly → back off the instant the Clipping LED flashes → never leave LED on during normal playback.Warning
Always configure the Subsonic Filter before playing music. Unfiltered ultra-low frequencies will destroy subwoofer voice coils.| Symptom | Probable Cause | Action |
|---|---|---|
| Does Not Power On | Blown fuse | Check in-line fuse at battery and both onboard fuses. |
| Loose REM wire | Confirm +12V on REM terminal when stereo is on. | |
| Poor ground | Verify clean bare-metal ground connection. | |
| Protection Mode | Speaker short | Disconnect all speakers → power on → check wiring. |
| Thermal overload | Improve airflow — do not enclose the chassis. | |
| Impedance too low | Check total speaker load vs. amp minimum rating (1Ω). | |
| Protect at High Volume | Voltage drop | If <11V under load, upgrade battery or power wire gauge. |
| No Sound | Head unit muted | Check volume and mute status on source unit. |
| RCA cable fault | Try a known-good RCA cable. | |
| Gain too low | Rotate Input Gain clockwise. | |
| Distorted Sound | Gain too high | Reduce gain until distortion disappears. |
| Low charging voltage | Charging system must maintain 12.5–14.4V. | |
| Subs out of phase | Check speaker polarity — a reversed sub cancels bass. | |
| Engine Whine | Ground loop | Use a single common ground point for amp and head unit. |
| EMI on RCA | Reroute RCA cables away from power wires. | |
| Sound Cuts on Bumps | Loose connections | Tighten all terminal set-screws firmly. |
Coverage
- Direct from Aunex2 years from date of purchase
- Authorized Dealer1 year from date of purchase
- WhoOriginal US purchaser
- WhatDefects in materials and workmanship
Exclusions
- Physical DamageMisuse, neglect, accidents
- Seal/SerialBroken warranty seal or altered serial number
- InstallationImproper install, static, or electrical interference
- LaborRemoval or reinstallation costs
Claim Process
- Step 1Contact Customer Service for remote troubleshooting
- Step 2Provide dated proof of purchase
- Step 3Obtain a valid RMA — do not ship without one
- Step 4Return in original or equivalent packaging
Key Notes
- FusingOnly the specified amperage fuse is covered
- EnvironmentNot for excessive heat, moisture, or dust
- WiringInstaller responsible for proper wiring practices