Category Archives: Introduction to Performance Technology

FAQ for All My Courses

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Where can I find __________?

In general:

  • Howdy (http://howdy.tamu.edu) stores all syllabi and faculty curricula vitae (cv) to comply with Texas state law.
  • eCampus (http://ecampus.tamu.edu/) stores any materials that are sensitive because of academic integrity (e.g., tests, study guides), federal privacy law (e.g., grades), or intellectual property laws requiring limited distribution, as well as files needing other kinds of special handling (e.g., large file downloads).
  • This website will store most other materials not described above.

 

Where can I get help with __________?

  • For help with this website or any problems specific to this class only, e-mail your instructor.
  • For help with any facilities inside the College of Liberal Arts: click here
  • For help with eCampus, contact Instructional Technology Services: click here
  • For help with Howdy or TAMU internet connectivity, contact Help Desk Central: click here

 

What do you do at TAMU / What kind of music do you compose?

As a professor at TAMU, my job is to create new research and creative work, present it in internationally prominent venues to raise TAMU’s profile, and—since TAMU is a Tier One Research University—to bring students in on the intellectual frontiers I explore, as much as possible. (This course is taught with the assumption that this is why you are here.) Here is some of my work toward this goal.

 

What music do you find inspiring?

This is not because this course is about this music, and it’s not my goal to get you to like this music too. I just get asked about this occasionally. It’s a playlist, so skip around as you like.

 

 

 

Technology-Based Performers

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NOTE: Not every work you find at these links will qualify for your case study project, but these are sites where you will find many applicable works. Check the specific criteria for your case study in eCampus!

More About Voltage vs Current and Audio Impedance

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Voltage can be transmitted with little to no current because electromotive force and magnetic force are directly related. This is how we can send signals through outer space and how we can use magnets in microphones and guitar pickups to transmit sound electrically. So, voltage is important for these kinds of input transducers.

Because voltage can be created with little to no current, it is preferred for sending electrical power (V*I) over long distances. High voltage in power lines can be “stepped down” to 120V to increase current to meet the demands of appliances.

However, because voltage creates an accompanying magnetic field, if we transmit our audio signals at high voltage, they will interact more strongly with nearby magnetic fields along the way (e.g., other high voltage lines or devices). That is, our message won’t make it through in perfect shape.

Resistance decreases current, and when the current drawn by a device is constant, resistance makes voltage increase (like a thumb partially blocking the end of a water hose). Impedance is basically resistance, when considering AC circuits like those carrying sound waves. So, high impedance devices like electric guitar pickups and cheap consumer microphones send their signals with higher voltages and lower current than professional audio equipment. Their higher voltage means less power is needed for amplification, but the higher voltage signal is more susceptible to being affected by external electromagnetic interference. High voltage (high impedance) may be preferred when power is the main concern, but not when the quality of the signal—the message—is important.

So, it is preferred to send audio signals at low impedance, meaning high current and low voltage. Current is manipulated throughout a signal path in order to scale the voltage as needed to preserve the integrity of the signal represented by the voltage.

Device inputs are supposed to have impedance a about ten times as high as the impedance of the signal coming into it, sacrificing current in order to boost voltage while it is inside the device. This is like “zooming in” on the signal so the audio equipment can process it with greater precision.

As for actuators, transducers that convert electricity into sound, light, heat, movement, etc., it makes sense that power is needed: measured in Watts = Voltage * Current. So, they won’t work on little-to-zero current even if we can make high voltages as described above. Every device expects to draw as certain amount of current from a circuit. If the current is constant, specified by the device, then voltage scales the resulting power. Voltage is the answer tot the question, “How much?” in terms of loudness, brightness, speed, etc.

In short, you could say that voltage is the message, and current is the muscle.

Wrapping Cables

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Yes, there is a best way to wrap cables, and people like to talk or be snobby about it. It’s true that when you take proper care of your cables, it almost seems like they uncoil and re-wrap themselves on command—it’s hard to find such easy and effective ways to make your life happier. Here is one of many videos to demonstrate the over-under technique. Search for more if you want to find a different angle on the subject or if you want to be amazed at how long some people can take to explain this.

Notes

For cables 25ft and longer, the coils should be about forearm length. Shorter cables should have a smaller coil, but it should never feel tight. Very, very long and thick cables may feel more comfortable with a larger coil, but those should be exceptional cases. In your own studio, you may want to settle on one smaller size coil to use, so all your cables use one size or the other.

If you have a poorly-treated cable, some “cable therapy” may be in order. Here’s what I prefer to do:

  1. In a large space, throw out the cable to uncoil it in a straight line as much as possible.
  2. Run the cable tightly through your hands from one end to the other, twisting and massaging lumpy areas (with badly twisted wires inside) and keeping any naturally-forming coils ahead of you. Keep pushing them ahead, and they’ll work their way out the far end. Two points of caution:
    1. Don’t be too rough on your cable. You may need to let a couple rough spots pass and repeat this step before your cable behaves. Despite the wording used in one video above, truly forcing your cable into shape can do as much damage as mistreating it did.
    2. Avoid burning your hand by holding the cable too tightly and running the cable through it too fast.
  3. Wrap your cable using the over-under method. Roll the cable in your fingers to guide its natural twist to sit comfortably in wrapped coils. If a coil twists after you’ve wrapped it, back up and redo it. Fasten with velcro when you’re done.
  4. If your cable is still a little warped, massage the whole cable by grabbing it firmly like a steering wheel and twisting slightly to help all coils sit in their new form more comfortably. Inch your hands all the way around the coil bit by bit, massaging as you go.