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CTA Classroom - Phantom of the Power
by Mike Sessler, ChurchTechArts.org
Today we're going to continue our series on the electrical side of sound. Last time, we tackled ground loops; their cause and a few solutions. This time around, it's phantom power. Phantom power is one of those often misunderstood aspects of sound. It's one of those things that's really not that complicated once you get it, but up to that point it's a bit of a mystery. So today we take the mystery out of phantom power.
Why Use It?
The first question we need to ask is why use phantom power at all? Strictly speaking, we don't need to, as the only reason we need phantom power is to power condenser microphones. Take all the condensers off stage and you can shut off phantom power forever. But most of us like to use the occasional condenser mic or active DI, so phantom power is necessary. Some condenser mics and active DIs will run on a battery, but if you don't have to power something from a battery, you shouldn't (you know it's going to die at the most inopportune time). It should be noted that it is only condenser mics and active DIs that require phantom power; for all other sources, it's best to turn it off if you have the option to do so on a channel by channel basis.
Phantom power moving from the console to the mic, audio goes the other way. In basic concept, anyway.
What is it?
New Americans with Disabilities Act Standards for Hearing Assistance
In 2010, the US government modified the standards for the Americans with Disabilities Act (ADA) with respect to public assembly spaces and the quantities of receivers and hearing aid compatible receivers. All Assembly Areas are required to comply with the ADA.
So what is an Assembly Area by definition? According to Section 219.2 of the 2010 ADA, an Assembly Area is: A building or facility, or portion thereof, used for the purpose of entertainment, educational or civic gatherings, or similar purposes. For the purposes of these requirements, assembly areas include, but are not limited to, classrooms, lecture halls, courtrooms, public meeting rooms, public hearing rooms, legislative chambers, motion picture houses, auditoria, theaters, playhouses, dinner theaters, concert halls, centers for the performing arts, amphitheaters, arenas, stadiums, grandstands, or convention centers.
So where does that leave houses of worship or churches?
Read more: New Americans with Disabilities Act Standards for Hearing Assistance
Crown Amplifier Warranties Extended
Beginning with Infocomm 2011 (announced June 14, 2011), the Crown CTS, MAi, and ITech amplifier series warranties have been increased from 3 years to 5 years, with a no-fault warranty! Also, the advance replacement policy has been increased from 90 days to 1 year.
A "no-fault" warranty means that if your amplifier needs to be repaired for any reason, it will be fixed at no charge to you during the warranty period. Blow up it after using it in a rainstorm - it's covered. Have a huge feedback surge that tanks your speakers and your amps. The amps are covered. These provisions apply only to Crown CTS, MAi and iTech amplfiiers.
And if you have a problem within the first year, Crown won't fix your amplifier. You'll simply get a replacement amplifier in its place, in advance.
Both programs add a lot of value to the purchase of a new Crown amplifier. Chalk up one more reason to choose Crown. MAi Series amps are available on our website, but we're restricted from advertising CTS and iTech amplifiers. Please call for more information and pricing on iTech and CTS Series amplifiers from Crown.
CTA Classroom - Ground Loops
by Mike Sessler, ChurchTechArts.org
The topic for today's post comes from a reader, Jonathan Mould. He wanted to know more about the electrical side of sound. This is an interesting topic because sound is both electrical and physical. Sound systems turn physical movement of air into electrical signals, then process and amplify those signals (sometimes changing them into streams of 1s and 0s and back), and finally turn those amplified signals back into physical air movement. It's all kind of crazy when you think of it that way.
I started this post thinking I could tackle three topics and realized that even a cursory explanation of ground loops would take a whole post. So, you're witnessing the beginning of a series here. First up, Ground Loops.
Ground Loops
To understand ground loops, one must first understand electricity. A full explanation is beyond the scope of this article, but here's a brief description. Standard 120 volt circuits consist of three leads; a hot (current carrying) lead, a neutral (the return) and a ground. To vastly over-simplify, the electricity leaves the panel on the hot lead, travels to the appliance, does some work and returns to the panel on the neutral. The ground is properly called a safety ground and serves one basic function—to send any electricity right back to a safe place (the earth) if anything goes wrong inside the appliance. This is a preferred outcome (as opposed to sending said accidental electricity through your body to the earth).
Electrons go from the panel, to the appliance, do some work and then back to the panel on the neutral leg. This is vastly simplified, OK?
Electricity always wants to get back to ground, or earth, and will always take the path of least resistance. Should there be a short inside an appliance, the chassis of said appliance could become energized. If you touched it and happened to be providing a good path to ground, that current will flow through you. Since it only takes about 20 milliamps to stop your heart, it's very possible that a short like that could kill you. This is why we never...
CTA Classroom - Set Auxes to Post
by Mike Sessler, ChurchTechArts.org
Last week, Chris Huff had a great post over at Behind the Mixer that explained the differences between pre- and post-fader aux mixes. He said, quite correctly, that you generally want monitor mixes to be pre-fader, and FX sends to be post-fader. I totally agree with that, and run my auxes that way almost all the time.
This post is going to be about when it makes sense to break those rules. Keep in mind that this is a compliment to, not a criticism of Chris's post. But first let's review. You generally want monitor mixes to be pre-fader because you don't want changes made to the house mix affecting the monitor mix; most of the time. Every once in a while, however, that's exactly what you want. Let's look at some examples.
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