# Easy Music Everywhere.  Audio Amplifier - Part 1


While in high school, I bought a really cool rack mount amplifier at a garage sale.  It was branded [Queon](http://vedge.org/hw/queon/), and had lots of inputs - it was great.  It was supplemented during my university years with an 8-track player/amp combo, acquired from Value Village.  The Queon met its end when a roommates' cat knocked over a vessel of water that had been rested on top of the amp.  The 8-track player/amp combo met its end in a post-university move.

I'm not an audiophile, and have been using PC speakers ever since.  They sound OK, but:

- The volume control always seems to fail
- The permanently wired connections seem to fail
- Sometimes, it is nice to listen to the radio
- The bluetooth connectivity of little portable speakers is pretty handy
- DLNA / Airplay / Google Casting functionality is also pretty neat

So what I want is an amp for some bookshelf speakers that have been sitting unused.  My ideal amp:

- has a volume control
- has a minimum of 4 inputs (PC, radio, Bluetooth, DLNA or alternative)
- has a remote
- is smaller rather than bigger

As most people are looking for home theater systems, there's not much around that meets this criteria.  I have looked at inexpensive amplifiers from Amazon, such as the Lepai LP-2020, but it only has a single input.  I came across a place called [Shenzen Audio](http://www.shenzhenaudio.com/), which had all sorts of neat audio products, but it's hard for me to order something >$100 from completely unknown brands.  The [Teac AI-301DA](http://www.teac.com/product/ai-301da/) is what I want, but more than I'm willing to pay - I can sacrifice on audio quality and power.

So, I'm going to put together my own.  I'm going to pick an off-the-shelf [amplifier module](https://www.adafruit.com/product/1752), and connect it to an audio switch, add a micro-controller to control the inputs and volume.  I'm even thinking of adding an "auto-input" switch, which tries to auto-switch to the intended input (there must be a reason amps don't do this - I'll find out when I try).

I'm sure I just don't know how to search, but I'm surprised how little I could find about such circuits.  The best article I read was "[How-To: Make a solid-state A/V switcher](https://www.engadget.com/2007/03/13/how-to-make-a-solid-state-a-v-switcher/)" on Engadget, but I wanted to avoid soldering surface mount components.  There are many switching chips out there, I found it challenging to pick out a basic one.  I also considered just using a mechanical switch, but decided I wanted the option of using a remote.

Finally, I decided to use an [older design using a chip called a 4066](http://www.electroschematics.com/2140/stereo-switch/).  A number of forums indicate that the audio quality of designs using this chip is poor, but I tried it out - it sounded fine to my ears.  It will be hard to tell for sure until it's done, but there's always an opportunity to replace it in future revisions.