• The EXTREME big brother of the UAM2 in stereo!
• 2 independent 20W amplifiers in one SMT package!
• Super efficient Class D spread spectrum design!
• Built-in click and pop suppression!
• Balanced & unbalanced hi-Z inputs!
• Logic level mute and shutdown functions!
• Selectable gain from +22dB to +36dB!
• Built-in thermal protection!
• Programmable device shutdown with LED indicator!
• Runs cool, no heat sink required!
• All this on a 2½” square board!

When we released the UAM2, it became the most popular audio amplifier product in our history. The novel Class D design, providing a clean 20 watts in such a tiny package, set the hobbyist world on fire! And that’s a pretty tough task when it didn’t even produce any heat at its full output! Because of the popularity of the UAM2, we put the engineering staff into overdrive and the result is the brand new UAM4!

The UAM4 is the big brother to the extremely popular UAM2. It uses the latest spread spectrum amplifier technology to bring you clear, crisp, high-power audio without any of the heat which is normally associated with such an amplifier. It’s extremely clean Class D design produces two independent 20 watt outputs! This can also be bridged to an extremely efficient (87%!) single channel (mono) 40 watt amplifier. And at 40 watts, you’re probably already wondering about the heatsink requirements to dissapate the heat, right? Stop wondering, there’s no heat, so there is no heatsink required! And all that power is generated in a single SMT device the size of your thumbnail on a small 2½” square board!

The high impedance input is designed to use your choice of either a balanced line input or an unbalanced signal source using easy to connect Euro terminal blocks. Logic connections to ground are also provided to mute and/or shut down the amplifier. You can also enable the built-in over temperature signal to activate one of these controls automatically! Easy to use board jumpers offer selectable gain of +22dB, +25dB, +29.5dB or +36dB to match your input levels. Board jumpers also enable protection and shutdown options as well as stereo/mono/bridge mode. The amplifier also features built-in click and pop suppression to protect not only your ears and sanity, but your speakers and equipment! Power input for maximum rated output is 18VDC at 2.64A. Input voltage can be reduced to a minimum of 10VDC with reduced output. If required, use our switching power supply below which provides 18VDC at 3.3A with an input of 100-240VAC, 50/60 Hz. It doesn’t get much easier than that!

If you’re looking for an incredible stand-alone stereo (or mono) amplifier to build into your equipment, speakers, or application, the UAM4 is the latest and the greatest! Remember, this is an SMT kit so you will need tweezers, a magnifier, some pretty good eyes, and a fine tip soldering iron or station. Check out SMT related tools in our Tools section. (Think back to the components, power supplies, and heatsinks it used to take to get 40 watts!)

Specifications
Audio Output	2 x 21W stereo mode, 8 ohms 1 x 42W mono mode, 4 ohms
Signal / Noise	91 dB into 8 ohms, 22Hz-22kHz
THD+N	0.1%
Audio Input	Balanced, unbalanced, hi-Z
Gain Adjust	Jumper settings, +22dB, +25dB+29.5dB, +36dB
PSRR	90dB at 1kHz
Efficiency	Up to 87%
Protection	Short circuit, thermal overload Programmable thermal flag Auto short together shutdown Auto thermal shutdown
Power Input	10-18 VDC, 2.1mm connector (18 VDC for full rated output)
Dimensions	2.5" square