Dynamic Microphone Is Too Quiet – Quick Fixes For SM7b, SM58 etc


Dynamic microphones are very useful, and they can be used in many applications. I started off my home recording doing pretty much everything on my Shure SM58 and even now I use my Shure SM7b for almost everything.

I love dynamic microphones as they are the most versatile of all microphones and are often used for both live music performances and studio recording.

However, due to the fact that these microphones are so versatile, they tend to be used for everything, and they sometimes encounter problems when used for some purposes. Many people experience the issue of a dynamic microphone such as a Shure SM7b or SM58 that is too quiet; why does this happen, and how do you fix it?

Low volume output from a dynamic microphone is usually due to low gain levels, poor microphone placement, and the lack of supporting hardware such as a preamp. Dynamic microphones need higher gain levels than other mics, perfect placement, and a good preamp to produce good volume output.

Dynamic microphones are very tough, and they are straightforward to use. There are many types and brands of dynamic mics, and they do not usually run into any problems. However, when a dynamic microphone seems to be too quiet for what you need it for, this can be a severe issue. Let’s look at what may cause a dynamic mic to not be loud enough and some of the solutions to this problem.

What Could Cause A Dynamic Microphone To Be Too Quiet?

It is better to have a good quality sound at the input than having to try and fix it after the signal has already been transmitted. Recording vocals or an instrument too quietly and then trying to boost it afterward often leads to a lot of unwanted background noise and sub-par results.

For this reason, it is important to have a good sound level from your microphone regardless of the purpose that you are using it for.

A common problem when using a dynamic microphone is a low volume sound level from the microphone.

There are a few reasons for this problem, but below is a list of the most commonly encountered causes for a dynamic microphone that is too quiet:

Low Gain Levels

Dynamic microphones are not usually powered microphones, and so they do not need to have phantom power sent to them.

This means that this type of mic is not very sensitive, which is usually a good thing, as these microphones are best suited for use in live situations when the microphone should be as quiet as possible. Better than condenser microphones for example.

Due to the lack of sensitivity in most dynamic microphones, the gain on the channel that is being used for the microphone must be turned up quite high, sometimes higher than you may expect, depending on the interface or console that the microphone is run to.

Low gain levels will mean that the microphone is not driven enough for it to pick up sound clearly, especially if the microphone that is used is a low-quality mic or if the interface or console that the mic is run to is not very powerful.

Low gain settings will result in a low volume output from a dynamic microphone.

Low Volume Sound Source Or Poor Mic Angle

Dynamic microphones are not the most sensitive pieces of hardware, and the diaphragm in the microphone itself that picks up the sound is relatively small.

These mics are means to be used in noisy environments, and the small size of the dynamic microphone diaphragm, as well as the omnidirectional polar pattern of the mic, means that if the sound source that the microphone is receiving is not close to the mic, or not in front of the mic directly, it will not be picked up very well, resulting in a low volume at output.

The polar pattern of the Shure Sm7b is very directional so won’t pick up sound from behind very well

Due to the nature of the dynamic microphone and the fact that it is intended for use in relatively noisy environments, if the volume of the sound source that the microphone is receiving is not loud, the microphone will have trouble picking up the sound, resulting in a low output volume.

Lack Of Correct Supporting Hardware

Many people do not realize that using a dynamic microphone well, and using it to the best of its ability, requires some extra hardware, whether the microphone is being used for live music, speaking, or even for recording purposes.

These microphones need to be used correctly, in conjunction with the correct supporting hardware, in order for them to function at their best and transmit the best possible audio signal.

One of the most important pieces of supporting hardware for using a dynamic microphone is a microphone preamp.

Without a preamp, the gain on the console or interface that the microphone is connected to will have to be tuned up very high, making the microphone very difficult to use and even more challenging to control and mix well.

Not having the correct supporting hardware for using a dynamic microphone well is a bigger problem than most people realize.

How To Solve These Problems

If there is nothing physically wrong with the microphone or any of the other components in the signal chain, then the above problems all have simple solutions.

Here are some ways to improve the volume output from a dynamic microphone:

Low Gain Levels

Low gain levels causing a low volume output is a simple problem to fix.

Many people are nervous to use gain control, and many people think that turning the gain up will result in signal problems such as distortion.

You may find yourself having to crank the gain right up to hear a dynamic mic through an interface.

The reality is, dynamic microphones need high gain levels in order to function well.

Turning the gain up on the channel that the microphone is plugged into will significantly increase the volume output of the microphone.

These mics need to be pushed a little in order to function well, and pushing the gain up on a dynamic microphone will not cause distortion or signal problems unless the gain is pushed up too far.

The gain can be increased on the interface or console that the mic is run to, or the gain can be increased on the recording in the recording software that is used.

Higher gain levels will result in more useable volume levels from a dynamic microphone. So if your interface can be pushed then don’t be afraid to crank up the gain.

Low Volume Sound Source Or Poor Mic Angle

The nature of dynamic microphones and the way they are built means that they are not very sensitive, and they are unidirectional.

This means that if the sound source that you are using the microphone to transmit is not directly in front of the mic and close to the mic, the output volume from the mic will sound very low.

The microphone should be placed less than 4 inches (about 10cm) away from the sound source or even closer if possible. This will allow the microphone to receive the sound from the source more effectively.

The volume of the sound source should also be sufficiently loud to be received well by the microphone. If the sound source is very low, the output from the microphone will be very low as well.

THE BEST SOLUTION: Lack Of Correct Supporting Hardware

You may find that even when you have the gain on your interface turned up as far as it will go, you still can’t get a good level signal from a microphone like the SM7b. This was the issue I had and this is the solution that helped me the most.

To solve this there is a simple solution but it involves buying another bit of gear. You will need a microphone preamp to boost the signal some more.

Using a microphone preamp is the best way to increase the signal quality, strength, and gain from a dynamic microphone.

Some mic preamps are able to increase the gain of the signal without creating more noise in the signal; this means that there is a noiseless volume increase for the microphone output.

A mic preamp such as the SE Electronics DM1 Dynamite is the perfect preamp to use for a dynamic microphone. I bought one of these and use it with my Shure SM7b and it’s fantastic. It boosts the signal nicely and doesn’t create any unwanted noise or distortion!

This preamp provides an above-average gain increase, which is perfect for dynamic microphones. This preamp adds +28dB of transparent, noiseless gain regardless of the connected load, which makes it ideal for using for recording or for live.

The DM1 Dynamite is an inline preamp, which means that it fits very easily into your signal chain, and the slim form factor of this preamp makes allows it to be used in even the most basic of at-home setups without getting in the way of anything.

Using a good preamp like this is the best way to increase the volume of your dynamic microphone and maintain the signal quality from the microphone simultaneously.

Conclusion

Low volume from a dynamic microphone is a prevalent problem, especially if the microphone is not used correctly or if it lacks the correct supporting hardware.

The main reasons for low output volume from a dynamic microphone are low gain levels, incorrect mic placement or mic angle, and the lack of supporting hardware such as a microphone preamp.

Dynamic microphones require high gain levels to function well due to their design. They are also unidirectional microphones, so the placement of the mic is crucial.

Using a preamp such as the SE Electronics DM1 Dynamite preamp is the best way to increase the volume output of a dynamic microphone.

Set your gain levels high, make sure your mic is close to the sound source, and use a good preamp, and you will find your dynamic microphone will have a loud, clear, noise-free, easy to work with an output signal that will exceed your expectations!

Rob Wreglesworth

Rob has come to terms with the fact he will probably never be a famous rock star....but that hasn't stopped him from writing and recording music in his home studio. Rob has over 15 years experience of recording music at home.

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