All Spectrum Electronics hobby kits, components, semiconductors, test and measurement, tools and supplies -   
  Catalog » Kits » All Kits » UAM2 » Reviews My Account  |  Cart Contents  |  Checkout   
20 Watt Audio Amplifier Module Kit
$49.99 $29.99
by William Kuhn Date Added: Sunday 21 February, 2010
Just finished building this. Took about 2 hours (maybe less), and it worked as advertised. Ramsey did an excellent job all around. Here are a few comments to help you if you're thinking about getting one of these (which you obviously are if you're reading this;-)

First of all, the kit I received looks even better than the picture. The top of the board is now classic green soldermask, with white silkscreen printing. It also had nice gold coated pads (colorwise at least) to solder to, rather than the tinned look in the photo. It is a very high quality PC board.

The build went quite smoothly, but I confess that I have experience with surface-mount parts, and I have the proper tools (small-tip iron, small diameter solder, good tweezers, and optical aids). One nice thing is that the SSOP integrated circuit was already soldered. While this may disappoint you initially, it is essential - as the chip has 25 mil or less pitch on the pins, and would be virtually impossible to solder well without a microscope, etc.

All the other parts you have to install/solder yourself. This is a good learning project if you are new to surface mount soldering - BUT - be very careful. Read the manual carefully, including the soldering instructions. It is critical especially in light of the fact that SMD capacitors do not have values printed on them. Thus, if you get them mixed up, you're in trouble. Stay organized and don't separate the parts from the bags they come in as you build. Put the unused caps back on or in the bag as you take them out of the "tape" they come in. In short- take your time, as the manual says.

With the right tools, soldering was pretty easy - as they provide good pad size for all but a couple of components (which were therefore a little tricky).

So how well does it work? I powered it up slowly with my variable voltage supply to avoid blowing things if something was wrong. Fortunately I had no difficulties. The current stayed low as I turned the supply up. A good sign. With that "smoke test" passed, I applied some signals, first from my audio sig-gen, and then from my IPOD. It worked exactly as advertised. Great volume/power, and the chip barely gets warm (I think there is a metal tab under it that sinks heat to the ground-plane on the board. Otherwise, even at 90% efficiency, a Watt or two would be dissipated and it would get toasty). Works well from about 8 volts to 18 volts. I tested mostly at 12v, but ran it up to 16V and at high volume was drawing around 0.8 Amps at peak points of the music. So that's about 12 Watts into the speaker. Very loud. I'm sure it will hit 20W at the 18V end of the spec, as advertised...

Haven't had a chance to look at audio distortion yet. The output waveform is hard to interpret on a scope, as the squarewave is dominant. A look at the radiated spectrum shows a 267 kHz fundamental and tons of harmonics out to about 30 MHz, and then quite clean after that (except for a blob around 76 MHz). So if you're not worried about using AM radios or ham radios and such in its vicinity, it seems to be a great amp...

Rating: 4 of 5 Stars! [4 of 5 Stars!]
Back Write Review

Add to Cart

Shopping Cart more
0 items
Quick Find
Use keywords to find the product you are looking for.
Advanced Search
Manufacturer Info
Ramsey Electronics
Other products
Notifications more
NotificationsNotify me of updates to 20 Watt Audio Amplifier Module Kit
Tell A Friend
Tell someone you know about this product.
Reviews more
20 Watt Audio Amplifier Module Kit
Just finished building this. Took about 2 hours (maybe less) ..
4 of 5 Stars!
What's New? more

MoPower UPS V2 INA219 ADD-ON
Resistor Color Code Chart and Ohms Law Formula Wheel Chart
Shipping Info
Terms and Conditions
Credit Application / NET30 Accounts
Contact Us

Contact Us

Van Nuys, California

Copyright © 2004-2017 All Spectrum