Ramsey 2013 Catalog - page 20

Audio Amps & Accessories
The UAM2 is probably the neatest audio kit to come along in quite a
while! It uses the latest amplifier technology to bring you clear, crisp, high-
power audio without any of the heat which is normally generated!
Lesson time: This is what is called a class “D” amplifier or as the media calls it, a
“Digital” amplifier. Instead of operating like a classic class “A” or class “AB” amplifier which
leaves transistors biased on all the time, losing energy whether they are producing audio or not,
the class “D” amplifier only produces power into the load of your speaker! This means that the amplifier device can deliv-
er a full 20 watts of power without getting so much as warm! Now it gets even better... The entire 22 watt amplifier
device is a single SMT component! YES, I said SMT or Surface Mount!
We designed the amplifier around the device to provide all the necessary interfaces, inputs and outputs in a convenient
mounting package. Audio input is standard unbalanced line level at 10K brought out to an RCA jack. Speaker output is
brought out to convenient board mounted screw terminals. The amplifier has selectable gain of 12dB, 18dB, 23.6dB, and 32dB. This is selected via board jumpers. A amplifier shut-
down terminal is also brought out to the Euroblock. You can use that to switch the amplifier on/off by taking it to ground.
The UAM2 runs on 8-18VDC, and is brought out to a standard 2.1mm power jack AND two terminals on a Euroblock. Therefore if you’re hardwiring it, you don’t need to use a plug
from a separate power supply! Full rated output will be achieved at 18VDC, but will operate all the way down to 8VDC! And that means it works great in a vehicle at 12VDC! Just
think of the applications!
The entire amplifier board is 2.6” square and can be easily installed inside your speaker enclosures, or other components. We made it even easier with a unique board that can be
“snapped” out into a small circle to be double face tape mounted directly to the back of a speaker! And however or wherever it’s mounted there is no concern for heat, ventilation,
or the need for a heatsink!
This IS a Surface Mount (SMT) kit, so you will need fine tweezers, magnifier, and a decent fine tip soldering iron! See assorted tools and accessories in the tools section.
(Who ever
imagined 20 watts in a single SMT device; I still remember fighting with vacuum tubes to get 20 watts!)
20 Watt Audio Amplifier Module Kit
18VDC Switching Power Supply, 1.7A
20 Watts from one SMT package!
Super efficient Class D design!
Super clean output!
No heat/heatsink concerns
Audio Output:
20W max
102dB into 8 ohms
Total Harmonic Distortion:
Less than 1%
Audio Input:
Line level 10K unbalanced
Gain Adjust:
4 input gain settings
Auto short to ground shutdown
Auto short to Vcc shutdown
Auto short shutdown
Auto thermal shutdown
Power Input:
8-18 VDC, 2.1mm connector
(18VDC for full rated output)
2.6” square, 1.43” diameter
22 Watts..And NO Heat!
Subminiature 20W Amplifier
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 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 21 watt outputs! This can also be bridged to an extremely effi-
cient (87%!) single channel (mono) 42 watt amplifier.
And at 42 watts, you’re probably already wondering about the heatsink requirements to dissipate 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! For a quick tutorial on Class D amplifiers, see the description of the
UAM2 above!
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 Euroblock terminals. No more concerns about having a matching input connector or plug or
whether it’s balanced or unbalanced! Audio speaker output is brought out to simple screw terminals. It doesn’t get much easier than that. Logic connections to ground are also pro-
vided 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.
As a result of customer requests, we have also designed this amplifier circuit into a complete 42 watt stereo amplifier system! Check out the UAM4SYS on the next page, it’s a com-
plete system amplifier in a compact aluminum case. Gives you the performance of a component system amplifier with no heat and in a compact form factor!
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.
back to the components, power supplies, and heatsinks it used to take to get 40 watts!)
42 Watt Audio Amplifier Module Kit
18VDC, 3.3A Switching Power Supply, 100-240VAC, 50/60Hz
The EXTREME big brother of the UAM2 in stereo!
2 independent 21W 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!
Audio Output:
2 x 21W stereo mode, 8 ohms
1 x 42W mono mode, 4 ohms
91dB into 8 ohms, 22Hz-22kHz
Audio Input:
Balanced, unbalanced, hi-Z
Gain Adjust:
Jumper settings, +22dB,
+25dB, +29.5dB, +36dB
90dB at 1kHz
Up to 87%
Short circuit, thermal overload
Programmable thermal flag
Auto short shutdown
Auto thermal shutdown
Power Input:
10-18 VDC, 2.1mm connector
(18VDC for full rated output)
2.5” square
42 Watts, 87% Efficient,
No Heat, All On A 2½” Board!
Subminiature 42W Stereo Amplifier
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