原创 Building a BADASS display (Part 1)

A few weeks ago, I went to the the EE Live! 2014 conference and exhibition. Whilst waiting for my plane at San Jose International Airport, I was ambling around seeing what there was to be seen when I passed one of those "Cool Electronic" booth-type stores that tempt you with products you didn't even know you wanted.

In this case, one item that really caught my eye was a cylindrical Bluetooth loudspeaker, about 10" tall, whose entire surface formed a spectrum analyser display based on tri-coloured LEDs. "Ooh, Shiny," I thought. I was, of course, captivated. As I've mentioned before, if you show me a flashing LED, I'll show you a man drooling.

Eventually, I managed to drag my eyes away. "That's interesting. How much might it be?" I said to the young lad behind the counter. Without looking up from his very important texting, he grunted "$199.95." (He was obviously a man of few words who liked to make each one count.) Well, Mother Maxfield didn't raise any fools (apart from yours truly, of course). "It's not that interesting," I thought to myself, so I thanked him for all of his help and strolled on my merry way.

The problem is that now my head is full of visions of mega-cool LED displays. Actually, that's the least of my problems, because I'm a digital logic designer by trade. I really know very little about the audio side of things, so I would be grateful for any advice anyone cares to offer.

My first move was to bounce over to YouTube to see what was out there with regard to audio spectrum analysers. The first one I saw looked sort of interesting.

One thing I like is the two alternative display modes—either solid bars or just showing the "top of the envelope," as it were. One thing I don't like is the fact that the bulk of the display is formed using only blue LEDs, with a couple of red LEDs at the top of each column.

The next video I saw was of a rather tempting coffee table display. The main thing of interest here was the way in which its creator starts off by varying the colour of the LEDs from left-to right, with red at one end of the frequency spectrum, blue at the other end, and green in the middle, as opposed to having the colours vary with amplitude as in the first video.

Actually, it's really worth watching the above video all the way through, because there are a lot of very interesting effects that make you (well, me) squirm in my seat with desire.

But wait, there's more, because I next ran across this little beauty. As you will see, this little scamp boasts a cornucopia of LEDs (32 x 32). On the downside, they are once again fixed in colour, with blue on the bottom, green in the middle, and red on the top.

The thing that really caught my eye in the above video is what I think of as the "trailing dot effect." This is where a vertical bar on LEDs "collapses" leaving the uppermost pixel (LED) illuminated, and this uppermost LED then slowly "falls" until it's "overwritten" by the next pulse of sound (is there an official/technical name for this effect?).

I cannot help myself. Quite apart from the fact that these things look so cool, I think I can have hours... days... weeks... months of fun playing with different algorithms and display modes.

My plan is to build what I am tentatively calling "Max's BADASS Display." What do you mean, "What does BADASS stand for?" I would have thought that was obvious; it stands for Bodacious Acoustic Diagnostic Astoundingly Superior Spectromatic, of course. I'm so excited about this, that I'm already planning on entering it in one of the Gadget Smackdown sessions at EE Live! 2015.

Now, I don't want to spoil your fun, so I'm going to leave you to ponder this a little. I will be posting another blog tomorrow (Part 2) telling you what I'm thinking of building and where I'm going with this little beauty. In the meantime, any suggestions—including links to other cool YouTube videos—will be very gratefully received.