Presto Electro

I found my camera in my underwear drawer the other day. It had been missing for kinda a while, so I couldn't really remember what the last thing I photographed was. I fired it up, and was greeted with the gleaming, smiling face of this guy:

As you can probably imagine, this is not a face that is easy to forget… I knew I had seen it before, but I couldn't quite place it. So I skipped to the next picture:

NOW I had it, the Flaming Lips show!!! I forgot I brought my camera along for the show and promptly buried it in socks when I got home. Finding these pictures made me start to reminisce about the Flaming Lips show… It was amazing. The music was great. The surrounding crowd was awesome. And it cost exactly zero dollars.

…And this weekend, Denton did it AGAIN! But bigger, better, and for three days straight!!!

Last weekend was Jazzfest. Jazzfest is a three-day festival celebrating the tremendous amount of art and jazz in Denton and the surrounding area. It was epic. 200,000 people descended upon Quakertown Park to enjoy hundreds of artists of all sorts of media. You could spend a whole day just wandering around, checking out all of the paintings, sculptures, drawings and the like. I almost did on Sunday! I spent a good hour taking in the sights, but I had to get back to catch the UNT African Drumming and Dance Ensemble. (African Music is one of the few genres that can compete with Math Rock when it comes to poly-rhythms, so there is no way I was going to miss UNT's ADDE)

On the Friday before, I spent almost all of my time on the UNT Showcase Stage. This was where all of the UNT bands played, and I really only wanted to see UNT bands anyway. We're a legendary jazz school! It would be almost sacrilegious to go elsewhere for awesome jazz. My favorite band of the night was definitely the UNT Latin Jazz Ensemble. These guys were so awesome that loads of people hopped up out of their seats to dance to the ridiculously catchy Cuban beats.

And once again, The City of Denton and the myriad Jazzfest sponsors aimed it right at the typical student budget: 7 Stages, over 2,200 performers (Including headliners like Chick Corea, Brave Combo, Jimmie Vaughn and The 1 O'clock Lab Band) and countless visual artists of all kinds for exactly zero dollars. I love this city

As many of you know, I am a member of all sorts of environmentally friendly, earth-conscious groups: Slow Food, Engineers Without Borders, and The North Texas Energy and Environment Club are the most active of the bunch. And they are all pretty big fans of the same planet. Ours. Earth.

So for Earth Week I was a busy, busy boy. I was routinely triple-booked, and everything I was invited to was EXTREMELY COOL! It was not easy picking and choosing where to be at any given time this week. Check out my extremely complicated schedule for earth week:

(I nearest-neighbor resized it on purpose for censoring purposes because I am a photoshop PRO)

Upon closer inspection, I was actually quadruple-booked in some places. Sheesh. And I didn't even get involved (on an organizational level) with the bulk of the earth day celebrations! Check out this list of Earth Day Goings-On that I had nothing to do with on the main campus:

There were also a ton of events at Discovery Park, too. But I can't find hide nor hair of the poster for those events. On Earth Day proper (April 22^nd) there was a totally awesome Earth Fest at Discovery Park. It was at lunch time, and the main campus' Earth Fest was at dinner time, so if you really wanted to (and believe me I wanted to) you could've gone to both, and ate like a KING all day. I was (understandably, I hope) pretty beat by Thursday, so I went home and indulged in a nap during the main-campus earth-fest. But I did go to the Discover Park Earth Fest!!! Here is photographic proof:

Don't worry, I haven't joined the Federal Service they just had totally rad out-door laser tag at Earth Fest! They also fed us some excellent barbeque, and snow cones and ice cream. And while we were eating in the picnic area (which is in FULL BLOOM this spring, by the way) there was even a band providing some nice background music. Very classy. I am sure more pictures of the event will surface, so stay tuned! Hopefully there won't be too many more of me running around with a lasergun like some kind of lunatic…

Denton is a city with a lot of unusual sights. From the day-glo orange messenger trucks of Frenchy's Lawn & Tree Services to the immaculately-restored Denton County Courthouse:
But when I first moved up here, I was always the most struck by the façade of Recycled. On paper, a pink building with lavender trim sounds like something a Disney princess would live in, but in real life it really works out great!
This is largely thanks to the fact that Recycled is actually a recycled Opera House that was built in 1899. To add even more recycle-y-ness, the Opera House was built out of the bricks from the Denton County Courthouse that was condemned in the 1870’s. There are bricks in that building that are upwards of 150 years old!

The outside is brilliant, but the inside is where Recycled really shines. The place is filled with an absolute labyrinth of shelves. You’ve really got to see it to understand, but they have a photo gallery on their website that hints at the layout of the place.
Once you get over the novelty of walking around a human-sized mouse-maze, the substance starts to sink in. Every shelf, every wall, is covered in REALLY COOL BOOKS! Recycled has sections on every subject imaginable. Art books, sheet music, science books, literature, nonfiction, metaphysics, yachting, farm upkeep, public records, poetry, picture books… the list goes on. If you want a book on some vague topic, Recycled almost certainly has a section for that.

If you’re not much of a reader, there is still plenty of awesome to be had. Recycled also boasts really big CD and record collections. I’ve found a lot of really great gently-used CDs here, and it is the only record store I know of that has a Local Denton Music section.

There’s also a Jazz section that is bigger than any Jazz section I have ever seen in my life. There’s almost more Jazz than pop at Recycled, and that warms the cockles of my heart.

In my last article I mentioned Denton’s uncanny ability to have all of that small-town flavor without that bitter small-town aftertaste. Today I’d like to upgrade all the adjectives in that sentence and talk about the metropolis-sized charms of modern-day Denton.

When I was living in the suburbs, north of Dallas, there was never anything nearby to do. If a band came to the metroplex, it was always a minimum of half an hour away, and parking was always a disaster (and expensive). In the end it usually took more time to GO to the show than it actually did to see it in the first place. This resulted in me and my friends seeing a lot less shows than we wanted to.

Everything changed when I moved to actual, real, down-town Dallas. Bands would come to the metroplex and I could WALK to the shows! I was two minutes away from almost every single venue. I saw a TON of shows. My weekend plans almost always involved a trip to one of the many Dallas venues because hey, why not?

The trouble is, down-town Dallas is also a crime-ridden and scary disaster of a place sometimes. My car got broken into a LOT while I was down there, and I was constantly exposed to crime and vagrants and all sorts of endemic big-city problems. I figured that was just how cities were. You take the good with the bad, and try not to notice the fact that your cheap apartment isn’t so cheap when you have to replace your driver’s side window every three months.

But then I moved to Denton! There is ALWAYS a cool band playing out here, and there are a million different places they can do it. There are traditional venues peppered throughout the city (mostly near the square though) and then there are house shows on top of all of that.

Last Saturday Camera Obscura came to Hailey’s and played an amazing show. It was their first time to come to Denton, and they had nothing but great things to say about it. (Of particular note was their praise of Denton’s own Old Fashioned Ice Cream Shoppe, Beth Marie’s.) My facebook was exploding with comments leading up to it because all of my friends spent the money they were saving for summer on show-tickets--Irresponsible! But it was so worth it.

My favorite thing about Denton is its ability to be a small town and nothing like a small town at the same time. This Saturday the planets aligned just so and the best parts of both worlds shined through simultaneously. Today I'll cover the small town bit, because it's my favorite.

I've always been stuck in either a big gross city or a totally unimpressive suburbia, so the small townish bits of Denton are a constant source of joy to me. On one of the first days after I moved here, I managed to "strand" myself on the main campus after the buses had stopped running to Discovery Park.* (See Footnote!) I was really bummed about it for about two minutes, and then I realized that the entirety of Denton is about 4 miles across, and a half-hour walk can get you pretty much anywhere in the city. It was a beautiful night, and the walk home was actually quite pleasant, if a little long. The little things like that are an unending source of novelty for me. Small towns are so much more convenient than big ones! Where I grew up, if I somehow wound up (assuming-I-was-) stranded at my old high school, it would have been a long, LONG walk along an extremely busy highway.

At this point I think we can all agree that yesterday's amplifier was pretty much terrible. It had way too much signal distortion and not enough common sense. Now that I've learned what I did wrong, I can apply this knowledge to future projects. Or current projects, as the case may be.

In Analog Systems Design last week I built a PROPER amplifier. As it turns out, a real amplifier has multiple stages designed to preserve and filter the audio signal in the most controllable way possible. Here's a flowchart for the one I built last week:

As you can see, a proper audio amplifier actually contains two amplifiers. And a few other components in between that I'll get in to a little later. To analyze this circuit, let's start from the end and work backwards:

• The Power Amplifier: This is very similar to the circuit I built in the last update. It takes a voltage signal and makes it louder. Nothing too fancy. A potentiometer attached to the feedback loop of this amplifier serves as a volume control knob. The input voltage comes from…
  
• The Equalizer: This summing amplifier takes the signals from each of the audio filters and combines them all into one single signal. Usually the gain on this amplifier is 1, or unity, indicating that it does not amplify or dampen the signals. It only combines them. Depending on the number of filters in the amplifier, the equalizer could have any number of knobs to dampen each frequency range. The frequency ranges are determined by…
  
• The Audio Filters: Low-Pass, High Pass, and Band-Pass filters can be employed in this section to split the sound in to bass, treble and mid-level chunks. My personal amplifier was designed to isolate bass notes with a (low-pass filter) and high notes (with a high-pass filter). A third, unmodified signal, was also sent to the equalizer for mixing purposes. The high- and low-pass filters only function correctly when the voltage input is large enough to interact noticeably with the capacitors. Most audio signals are not loud enough to do this on their own, so you've got to use…
  
• The Preamp: This amplifier doesn't have quite as much power or gain as the power amp. Its job is to take the tiny AC signal produced by the audio device, and amplify it before it gets sent to the filters. Some audio devices (like Carbon Microphones, for example) need a DC current in order to produce any kind of signal at all, but sending DC into this preamp would be bad-news-bears. High-DC currents could saturate the preamp very easily, which would result in a totally gross sound. So we need to remove the DC but preserve the AC with…
  
• The Coupler: Fortunately for all of us, DC voltage can be thought of as an EXTREMELY low frequency AC voltage. Imagine it as an alternating current signal with a period of ∞ and a frequency of 1/∞ (a.k.a. zero). The coupler is just a high-pass filter that passes almost every frequency except for extremely low ones. My coupler let every single frequency in the range of normal human hearing pass right on through.
  

This amplifier actually sounds pretty good! For testing purposes, we had to output the signal through a really small, tinny speaker that was about an inch in diameter, but it was still a lot nicer sounding than the mess I made with that op-amp so many years ago!

I apologize for the slow updates lately. This week was basically the perfect storm of exams and major projects. On the plus side, the exams all went great and I can add "Building a complete amplifier" (including pre-amp, audio filters, equalization, panning and power amplification) to my resume. And list of bragging rights.

As it turns out, amplifiers are a lot more complicated than I ever imagined. I tried to build one once when I was in high school, and it didn't turn out so great. For starters, the design centered around a 50 cent op-amp from radio-shack that really shouldn't ever be used anywhere near any sort of audio signal processing. I googled around and sorta half-figured-out that I could use an inverting amplifier configuration to amplify voltage signals.

So I did just that! I wired it up with a few resistors I took off of an old, broken VCR (of which there we about half a dozen to choose from in my room at the time) and the op-amp, and then I powered the whole mess with a wall-wart AC-to-DC adapter. I plugged my terrible guitar into this abomination of a circuit, and somehow nothing caught on fire. I plugged a pair of headphones into what I perceived to be the output, and out came the LOUDEST, most FIERCELY DISTORTED guitar sound I had ever heard. It was awesome.

Sure, I had completely failed in adequately amplifying the signal of my guitar, but instead I created a box that made my Squier sound like some kind of hideous beast out of hell. The trouble is, I couldn't really spend much time listening to it because it shredded my headphones pretty quickly. So where did I go wrong?

I've already outlined a handful of problems, but some of them were only implied. As it turns out, the source of the distortion (ignoring the distortion caused by my poor, rupturing headphones) was the AC adapter. Operational Amplifiers are supposed to have a bi-polar power supply: One positive voltage, and one negative voltage. My adapter was only giving it a +9 and a +0.

So the output couldn't give me any voltage at all when it was supposed to be putting out negative voltage. This brought out some weird clipping that REALLY got ugly if you played more than one note at the same time. Additionally, my headphones were linking Vout with ground, with only minimal resistance. In order for Vout to provide the appropriate amount of feedback current across Rf, the amp had to make Vout absurdly high. This elevated voltage made the incoming current cancel with the Vout/Rf current, but it also made Vout way louder than anyone could ever want.

I've still got that circuit bread-boarded in a box somewhere. I ought to get it out and see if I can fix it sometime. I've still got that old Squier… (because you can't even GIVE those things away…)