Photo by Matt Botsford on Unsplash
Our podcast neighbor from the MyMac Podcasting Network, Guy Serle, is our guest for episode 349 of Geekiest Show Ever. He will educate us about the value of good recording hardware and best practices. Follow us for additional tips and conversation on Twitter @GeekiestShow.
Here are Guy’s notes:
Important Things to Remember About Audio
- Garbage in, garbage out. You can’t fix bad audio “in post.”
- Each person’s voice is different and no microphone is “one size fits all.”
- What the hell do all those specs mean? It can be bewildering, but let’s try to take some of the mystery out of it by using the specs of pretty much the industry standard microphone, the Shure SM58. It’s a dynamic mic which we’ll talk more about later.
- Frequency Response (SM58 – 50Hz-15kHz)
- Most microphones frequency response falls into a range of 20Hz to 20kHz though some manufacturers like to brag about ridiculous ranges like 10Hz to 25kHz. The reason why that doesn’t matter is because nearly no humans can hear outside the 20Hz to 20kHz range. There is some variation based on how far away you are and what direction you speak into a microphone, but the variance “typically” doesn’t matter as long as you are close to zero axis or speaking directly into the capsule of the microphone.
- Sensitivity (SM58 – -54.5 dBV / Pa (1.88 mV)
- I read up on this and apparently you need a degree in the University of Made-Up words to understand it. It involves voltage, impedance, Pascals, and sound pressure when speaking into a microphone. I think someone created fuzzy math just so Sound Engineers can put their hands on the chin and nod as someone says things about it so they don’t look stupid.
- Noise Levels (SM58 – less than 5dB)
- The equivalent noise states the self-noise of the microphone either as an A-weighted RMS-level or as an ITU-weighted peak-level….
- Got that? Me neither. The take away is the lower the noise level pretty much is better across the board.
- Frequency Response (SM58 – 50Hz-15kHz)
- Distortion
- Distortion is bad. Total Harmonic Distortion should be under 1%
- Max SPL or Sound Pressure Level – (SM58 – 94dB SPL)
- Sound above 150dB can be very painful to human ears. Large jets taking off generate about 100-120dBs of noise (hopefully less than 80dBs in the cabin) and for some reason microphone makers test their mics at these kinds of levels. MaxSPL is a rating of how loud a sound can you put into a microphone with it distorting. Larger the number the better I guess though if your recording sounds above 150dBs the bigger question is why?
- Rated Output Impedance (SM58 – 150 Ohms)
- Nearly all professional-grade studio/live microphones are designed with low output impedances. Professional preamplifiers are typically designed with high enough input impedances to obey the 10x rule of thumb. So the best preamp for the Shure SM58 would be one with an input impedance of around 1500Ohms. There’s really no way for the average person to figure all that out so audio interface and mixer makers do that for you. Basically the lower the impedance USUALLY is better…but not always.
- Try not to use one microphone with two people using some kind of 360 degree polar pattern. You have no idea where that other person’s voice has been. Also look at point 2. It’s very hard to adjust one microphone for two different voices. If there’s going to be two people recording, get another microphone.
- Understand the differences between the various polar patterns and why they exist.
- Cardioid which is more sensitive in the front and less on the sides. It should reject almost all sound from behind. If you look at the pattern in looks much like a butt. For a single mic user, this should be the pattern you use. There are also variations that tighten or loosen the pattern, but they do much the same thing.
- Super or hyper cardioid which has much more focus on the front of the mic with more rejection on the sides and less in the back. This can be good or bad depending on the mic as that rejection may also remove qualities of your own voice that you like.
- Wide Cardioid which as the name states has a slightly wider front facing pattern. Good for micing up a group of people singing.
- Omnidirectional. This is not a Batman villain, but a polar pattern that tries to be equally sensitive all the way around the microphone. I have never found a practical use for this pattern myself, but this is what some use to record more than one person.
- Figure 8 is a polar pattern that has a high front and back sensitive range while rejecting sound from the sides. Good for two people recording that are facing each other which unless you have to is a terrible way to record.
- Cardioid which is more sensitive in the front and less on the sides. It should reject almost all sound from behind. If you look at the pattern in looks much like a butt. For a single mic user, this should be the pattern you use. There are also variations that tighten or loosen the pattern, but they do much the same thing.
- USB is not a type of microphone!
- Know the differences between a Condenser and Dynamic Microphone
- Condenser microphones are much more sensitive than dynamic microphones.
- Condenser microphone will pick up the sound of a fly fart. OK, not really true, but they do pick up keyboard noise, external fan noise, air conditioners, chair squeaks, table bumps, kids yelling…outside your house…on the next street, and so on.
- Condenser microphones ALWAYS require some kind of power.
- If a condenser microphones attaches via a 3.5mm (like a headphone connector) jack, don’t buy it.
- Don’t buy ANY microphone that attaches via a 3.5mm jack.
- Dynamic microphones need a LOT of gain.
- Dynamic microphones “typically” have better background noise rejection than condenser microphones which is why most live events are done with dynamic microphone.
- What is Phantom Power and why do I care?
- Phantom Power (typically measured as 48Volts DC) is what’s used to power the inner pre-amp of condenser microphones which is why they need so little gain going out as compared to their dynamic cousins. That sensitivity comes at a cost of picking up a LOT of typical background noise that you might not even realize is there…until you have to figure out a way to get it out of your recording…which can be hard with occasional terrible results. Dynamic microphones don’t need or use Phantom Power, however it also won’t hurt them so if your interface or mixer has Phantom Power and it’s turned across every mic input, don’t worry. Your dynamic microphone will be fine. If you have a ribbon mic though it will be destroyed by Phantom Power. Those kinds of mics are really old school and expensive. They usually need pre-amps with a LOT of gain and unless you’re really into mics, don’t bother getting one.
Check out more of Guy’s content at VertShark.com
Twitter: @Macparrot or @vertshark
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Guy’s Podcasts: MyMac Podcast, Mac to the Future Livecast: Wednesday at 8PM EST on Facebook, and the weirdly wonderful Guy’s Daily Drive
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