What is a Cloudlifter, and do I really need to buy one with my Shure SM7B for my podcast rig?

What is a Cloudlifter, and do I really need to buy one with my Shure SM7B for my podcast rig?

The short answer: probably!

The long answer:

By virtue of their 'passive' electronic design, dynamic mics generally have much lower output level than condenser mics, sometimes up to 28dB less depending on the microphone. This means the preamp of the mixer/audio interface it's connected to needs to do a lot more work in order to bring the level up enough for use in recording, broadcast, or loudspeaker reinforcement. That said, most dynamic mics have enough output gain to work well with most audio inputs - but even among dynamic mics, the SM7B has a particularly low output with a sensitivity of -59dBV (1.12mV), compared to the iconic SM58 with a sensitivity of -54.5dBV (1.85mV). 

Shure's "Find An Answer" database has this to say about the SM7B specifically:

When selecting a preamp for the SM7B for speech, make certain the preamp has a minimum 60 dB of gain. Here's why:
  1. With an acoustic input of 84dBSPL - typical speech level at 3 inches, the output level of the SM7 is -69dBV.
  2. The mic preamp must increase the mic signal level up to about 0dBV - line level.
  3. -69dBV of mic signal, increased by +60dB of preamp gain, equals an output level of -9 dBV. Not quite to the 0 dBV level, but close enough to work with most line level inputs."
Most modern microphone preamps found inside mixers and audio interfaces provide added gain of only 40 to 50 dB, mostly due to the popularity of condenser microphones with very high output gains - these condenser mics don't require terribly powerful preamp circuitry, because even a basic mic preamp can provide them with a relatively high voltage 'phantom power' to amplify their audio signal before it it is actually sent down a cable to the input. While fine for condenser and high-gain dynamic microphones, the 40-50 dB provided by the average preamp is not enough gain to bring the SM7B signal up to line level.  Even if your preamp does claim a maximum Mic Input analog gain of say, 60dB (such as the QSC TouchMix series), note that this is the MAXIMUM gain that preamp can deliver, while the SM7B requires 60dB as a MINIMUM - you effectively have no way to bring that level up or down, and you'll be pushing your preamps (which may or may not have desirable sonic coloring, depending on their quality) to their limit just to reach a level the mic can function at. 


So, what to do? Enter the Cloudlifter. It's a very popular and cost-effective phantom-powered in-line preamp by Cloud Microphones that provides 25-28 dB of very sonically-transparent ("clean") additional gain. It's so popular in fact, that many retailers sell the SM7B and Cloudlifter as a package deal, and we highly recommend this combination for most applications where the SM7B is being used to capture speech. I specify speech here, because one advantage of the SM7B (and dynamic mics generally) is it's ability to tolerate very high SPL sources without overloading the internal circuitry or distorting (note that high SPL signals from a dynamic mic can still distort at the preamp level, and both the mic AND preamp must be rated to handle them!).
So if you're using the SM7B to record a jackhammer or a plane taking off, skip the Cloudlifter, double-check your preamp specs, and record away!


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