This article discusses how you can tell if a Dynamic Microphone is broken or damaged and general tips to take care of them.
Dynamic mics, also called moving coil microphones, are usually strongly built and last long. Some of them, like SM58 and SM57 are quite renowned, not just for their sound but also for their durability, reliability, and material strength, due to which they are also preferred for on-stage and live settings.
However, a heavy electronic impulse, a strong physical hit, corrosion, or moisture may damage the electronic device. Hence, even after being less sensitive compared to a condenser or a ribbon type, a dynamic mic still has a chance to break. In this post, we will discuss different tests by which you can examine if your mic is impaired or not.
How to tell if Dynamic Mic is broken?
Examine it Physically
The most direct method to test if the electronic gear is broken is to inspect it visually for any wear and tear on its outer body or covering.
After that, you can take a look at its capsule, detach it if possible, and check the internal parts, like a diaphragm, voice coil, and magnet.
These are the essential transducer parts, as they vibrate to convert mechanical energy (acoustic waveforms) into electrical energy. The diaphragm, voice call, and magnet may need to be separated, so I advise you to take this measure only if you know how to put them back together.
Further, you can check the housing of the device, which would contain a relay if the mic has an on/off switch, which should direct the signal to the XLR points using the hot (red), neutral (yellow), and ground (black) cables. It’s always a good idea to check these cables to see if they are not damaged, in good condition, and not soldered to the wrong place or component.
You can also go for the flapping test, wherein you flip the microphone or shake it back & forth, and if you hear any flapping while you rock it, it’s a sign of damaged machinery.
Monitor the recordings
Record yourself or an instrumentalist using the mic in focus, and hear if it distorts at certain frequencies or creates any noise, hiss, or buzzing sounds. Try to record different dynamics of the sound sources, and check if the device responds differently to these dynamics.
If it sounds dull, has a poor frequency pick up, and has an unusual echo or distortion, all these are signs of a broken microphone.
Frequency Response Test
Frequency response is the sensitivity of a mic over a range of frequencies, and its expected curve over the human hearing range (20-20 kHz) is provided by every manufacturer. For example, having a flat frequency response means that the mic catches each frequency with the same amplitude and energy.
So you can compare the expected and current responses of the mic because when its machinery is damaged, this rating and curve change.
So at some frequencies, there may be minor fluctuations, and some random variation is desirable, but if the mic is damaged, some frequencies will have abnormal differences in amplitude, resulting in noise or distortion at those frequencies.
Hence, this test is the best and the most common way to determine if the mic is not functioning properly. Any frequency analyzer or an EQ with a decent visual display will give you a general picture of the mic’s frequency response.
Alternatively, in your DAW, you can also compare the EQ curves of different mics recording vocal or instrument takes, with performances as close as possible with both the mics.
Impulse Response Test
Each mic has different and unique feedback or reaction to impulses and transient of any sounds. A proper impulse response test may involve a lot of high-grade tech and equipment, but here’s what you could do. You can mic a snare drum or any percussive sound and listen for yourself. A damaged mic will react slowly to the transient, affecting the sonic quality.
Alternatively, you can compare the waveforms of the recordings of your mic with a properly functioning mic. The waveform of the broken mic will show a late or uneven response to impulse sounds. In this also, it’s best to record a drum, percussion, or percussive vocals like rap vocals.
A lot of times the mic may not be damaged, and the buzz or any inconsistencies you hear could be because of the cable. So it’s good to try changing the XLR cables or the interface or mixer cables you use. The noise problem could also be due to the noisy computer fan.
Also, if you suspect something is wrong with your mic, check other hardware and software like the interface, mixer, your computer’s internal audio drivers, fan, and even your DAW settings.
You can also check if the right microphone is selected in the recording system or computer and if the right gain and level for the mic are set. Lastly, make sure while you’re performing, you are holding the mic close to the sound source, as a dynamic mic is not good at catching off-axis sounds.
What can damage a microphone?
Factors like repeated or frequent mechanical stress, humidity, corrosion, overheating, dust, smoke, and intense electric flow can cause a dynamic mic to damage or break. That said, dynamic mics are usually designed to be not sensitive to these parameters and are created to be rugged, robust, and long-lasting.
There’s a common misconception that phantom power destroys it; however, phantom power can only damage the device if it’s turned on before plugging the mic. In that case of carelessness, you may cause permanent damage. However, it’s not surprising that some dynamic transducers even survive that.
Eventually, after years of overuse also, a mic can get harmed. The overuse can cause some internal components or wiring to function differently and hence be a cause of destruction. Lastly, too much gain or feedback can also cause impairment during a performance or show.
We have seen various ways to tell if there’s something wrong with your moving coil recording device, and there are plenty of reasons why it could shatter. Hence, it’s important not to mishandle your audio equipment. One tip is to ensure you do gain staging before recording yourself or your instrumentalist.
In addition, it’s important to bring the gain down and turn off the input of your interface or mixer before and after plugging the mic cable(s) into it. It’s also important to have your room earthed, so the cables don’t catch any electric shocks or impulses that may lead to a device injury. Having good quality cables always is a great idea.
Lastly, if you’re not very well versed with the tech, there’s always an option to consult a professional or a technician who could help you with this. Dynamic mics are electronic devices that work on complex circuits and transistors, which may require special equipment to examine and fix. Hope this article was of help.
Shaurya Bhatia, is an Indian Music Producer, Composer, Rapper & Performer, who goes by the stage name MC SNUB, and is also 1/2 of the Indian pop music duo, called “babyface”. A certified Audio Engineer & Music Producer, and a practicing musician & rapper for more than 6 years, Shaurya has worked on projects of various genres and has also been a teaching faculty at Spin Gurus DJ Academy.