QS400.4 2-Ohm 4-Channel Full-Range Amplifier

The QS400.4 is a compact 4-channel full-range car audio amplifier built around efficient Digital Class D Brazilian technology and rated at 4 x 100 watts TRUE RMS. Stable down to 2 ohms, the QS400.4 lets you wire multiple speakers and split power cleanly across four channels, making it an easy, affordable way to bring real power to a factory or entry-level system. With a regulated power supply and an efficiency rate of 80 to 90 percent, the QS400.4 delivers consistent output while staying easy on your vehicle's electrical system.

Efficiency is the whole point of the QS400.4. Its regulated power supply constantly delivers power, and that high 80 to 90 percent efficiency means the QS400.4 packs a lot of clean output into a small aluminum heatsink instead of wasting energy as heat. The compact chassis measures just 4 inches wide by 5.40 inches long by 2 inches tall, so the QS400.4 tucks into places larger amplifiers cannot, whether that is under a seat, behind a panel, or in a tight custom rack, freeing up space for the rest of your build.

The QS400.4 is also flexible. Its wide frequency response means you can run the QS400.4 on subwoofers, midbass, midrange, full-range speakers, phenolic and titanium drivers, and super tweeters, which makes it a genuine do-it-all amplifier for the vast majority of daily builds. Need more punch on a pair of speakers? The QS400.4 bridges two channels for double the output, delivering 2 x 200 watts RMS with a minimum 4-ohm impedance per bridged channel.

KEY BENEFITS

• 4 x 100 watts TRUE RMS certified output gives you honest, usable power
• 2-ohm stable across all four channels lets you wire multiple speakers flexibly
• Digital Class D Brazilian technology keeps it efficient and cool-running
• Regulated power supply delivers an 80 to 90 percent efficiency rate for steady output
• Compact 4" x 5.40" x 2" chassis makes it easy to mount anywhere
• Bridges to 2 x 200 watts RMS for more power on a pair of speakers
• Wide frequency response lets it drive subs, midbass, midrange, and tweeters
• Small aluminum heatsink keeps the amplifier easy on your vehicle's electrical system

TECHNICAL SPECIFICATIONS

• Model: QS400.4 (QS Series)
• Type: 4-channel full-range car amplifier
• Class: Digital Class D
• RMS Power: 4 x 100 watts TRUE RMS (full-range certified)
• Bridged Power: 2 x 200 watts RMS (min 4 Ohm per bridged channel)
• Impedance Stability: 2 Ohm stable (4-channel)
• Efficiency: 80-90% (regulated power supply)
• Dimensions: 4" W x 5.40" L x 2" H

INSTALLATION & COMPATIBILITY

The QS400.4 is designed to drop into almost any daily build. Its 2-ohm stability lets you run pairs of speakers per channel or wire a flexible speaker layout, while its small footprint means it mounts easily under a seat, behind the dash, or in a tight amp rack. Feed the QS400.4 clean power and ground with proper-gauge wiring, use quality RCAs from your head unit or a line-out converter, and set the gain by ear or with a meter to keep the output clean.

For a full system, many installers run the QS400.4 on their front and rear speakers or bridge it for stronger front-stage output, then add a monoblock for a subwoofer. Because it covers such a wide frequency range, this amplifier also works well driving pro-audio midrange and compression tweeters in louder SPL builds where efficiency matters. Whatever the layout, the efficient design of the QS400.4 helps you get the most out of your electrical system without constantly straining it. For anyone stepping up from a factory head unit, it is one of the simplest ways to add clean, controlled power to four speakers at once without resorting to a bulky, power-hungry amplifier.

FAQS

• How much power does the QS400.4 make?
  The QS400.4 is rated at 4 x 100 watts TRUE RMS certified at full-range output, and it bridges to 2 x 200 watts RMS on a pair of channels at a minimum 4-ohm load.
• Is the QS400.4 2-ohm stable?
  Yes. It is stable down to 2 ohms across all four channels, which lets you wire multiple speakers and divide the power per channel.
• What can I run on the QS400.4?
  Thanks to its wide frequency response, it can drive subwoofers, midbass, midrange, full-range speakers, phenolic and titanium drivers, and super tweeters.
• How big is the QS400.4?
  It has a compact chassis measuring 4 inches wide by 5.40 inches long by 2 inches tall, so it mounts easily in tight spaces.
• Is the QS400.4 efficient?
  Very. It uses a regulated power supply and Digital Class D design for an 80 to 90 percent efficiency rate, which is easy on your vehicle's electrical system.
• Can I bridge the QS400.4?
  Yes. You can bridge two channels of the QS400.4 to double the output to a pair of speakers, delivering 2 x 200 watts RMS at a minimum 4-ohm impedance per bridged channel.