What’s Cooking @e-Gizmo- Episode 8: Going Audio!

As I mentioned in my earlier blogs, we figured it is time to expand our DIY products to include traditional analog electronics kits as well. The last few weeks, I busied myself designing audio amplifier kits. …Yes, you read it right, audio amplifier kits.

It’s not like the local hobby market has a shortage for this stuff. The local hobby market is indeed flooded with this stuff, that adding one more may seem to counter wisdom. But we at e-Gizmo has an important resources at hand that will set our kits apart from the rest.

Experience. We, or rather, I worked for at least 20 years designing among other things, O.E.M. audio products, distributed by a large  American electronics chain of stores bearing its brand. I was involved not just with design, but with almost every engineering aspect of the manufacturing lines, up to product quality assurance.

Equipment. Our lab is likewise properly equipped to do comprehensive audio test and qualifications. I am knowledgeable with industry accepted audio test procedures. Hence, you can be sure that the performance figures we will present with the product are gathered through actual tests and measurements, and not just copied from the IC device datasheet.

This will probably surprise you, but the actual performance of the product depends largely on the way the end product is designed and built. For example, even a high performance IC, if built on a poorly designed PCB, will not perform quite well. IC datasheet specifications indicate only how well the IC can perform, and cannot be used to assume that it performs as such. An actual measurement is required.

Introducing: e-Gizmo Audio Kit Product lines

These are what I came up with so far – our initial audio product offerings, and a preview of more to come:

Low Power 0.5W Audio Amplifier with On Board Loudspeaker

This general purpose low power audio amplifier will be a welcome addition to your electronics project building toolkit. Just hook it up on a 5-12VDC power source and it is ready to go. The amplifier has a built in loudspeaker, and the PCB functions as the front speaker baffle corner mounting holes.

Medium Power 5W + 5W  rms(sine average) 2 channel Audio Amplifier

This is a low cost, medium power stereo amplifier with sufficient output power for medium fidelity sound reproduction. You can use it to boost the music output of your personal players. When used to drive bookshelf loudspeakers, the sound output will be loud enough to fill every corner of a fairly large room with good fidelity music. You will find it quite useful as a test amplifier on your workbench.

20W+20W rms(sine average) BTL  Stereo Audio Amplifier

  
A 20W per channel stereo amplifier cut out for automotive applications. If you are thinking of building a DIY amplifier for your motorbike, you just found the right stuff. It has enough reserve power to impress your friends with its clean music power even in a noisy environment. The amplifier will work with supply voltage of 9-18VDC. Lower supply voltage results in lower power output capability.

The 20W Amplifier has a pretty good THD+Noise performance (0.05%) as actual measurement in our lab reveals. Frequency response is flat within the 20Hz-20Khz audio bandwidth. This qualifies it for use as a hi-fi home amplifier as well. A more elaborate measured data will be published with the product documentation of this amplifier.


Programmable Preamplifier and Tone Control

Still under development is a universal preamplifier and tone control module that can be incorporated with any audio amplifier. The preamplifier employs digital control to keep all signal paths within the board, hence minimizing noises, crosstalk, interference, and ugly wirings that typically plague DIY built audio equipment. Volume, Bass, and Treble control, even input selector, are all digitally controlled.

  
Probably, the most striking feature of this preamplifier is, the controller module (MCU board) is user programmable. It employs an AVR microcontroller with Arduino bootloader- yes, you can program it and add features if you want to using the all popular Arduino IDE environment! For example, you can add a Bluetooth module and have it remotely controlled using your Bluetooth enabled PC or android phone.

Future Prospects

As I am writing this blog, I am already looking for the next member of this series. A 40W to 60W Audio Amplifier is next in order, and with little encouragement coming from you, we will take a shot at the >100W heavyweight division.