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Shure SM81 Microphone Review

November 26, 2023

We continue to review Shure SM81 microphone of the core "SM" product line from Shure. Today we take responsibility for covering higher budget mics, it is time to take a look at more professional stuff. Here we'll talk about Shure SM81, a microphone for instruments that will satisfy most sound engineers and (what is more important) most musicians and singers no matter what instrument and style they perform. So, ladies and gentlemen, let us introduce to you the Shure SM81 Condenser Instrument Microphone, and allow us to begin with its specs, as usual.

Best Price on Shure SM81 Microphone

The Shure SM81 is a professional-grade cardioid condenser microphone for recording musical instruments, with wide frequency response and low self-noise.

Shure SM81 box case Classic Package

Shure SM81 Specifications

  • Microphone Type: Condenser
  • Form Factor: Pencil
  • Polar Pattern: Cardioid
  • Diaphragm Size: 10mm
  • Frequency Response: from 20Hz up to 20000Hz
  • Impedance: rated at 150Ω (85Ω actual) recommended minimum load impedance: 800Ω
  • Sensitivity (at 1,000Hz): open circuit voltage: -45 dBV/Pascal (5.6mV) (1 Pa = 94dB SPL)
  • Output Clipping Level: 800Ω ohm Load: -4dBV (0.63V) / 150Ω ohm Load: -15dBV (0.18V)
  • Maximum SPL (at 1,000Hz): 800Ω ohm load: 136dB (attenuator at 0) 146dB (attenuator at -10) 150Ω ohm load: 128dB (attenuator at 0) 138dB (attenuator at -10)
  • Self-Noise: 16dB typical, A-weighted & 19dB typical, weighted per DIN 45 405
  • Hum Pickup: 3dB equivalent SPL in a 1 mOe field (60Hz)
  • Signal-to-Noise Ratio: 78dB (IEC 651) at 94 dB SPL - S/N ratio is the difference between 94dB SPL and equivalent SPL of self–noise A-weighted
  • Overvoltage and Reverse Polarity Protection: max. external voltage applied to pins 2 and 3 concerning pin 1: +52 Vdc / reverse polarity protection: 200mA max. (diode-clamped)
  • Connector: 3-pin XLR male
  • Power Requirements: 11 to 52 Vdc, 1.2mA (requires phantom power)
  • Housing: steel construction with vinyl metallic paint finish and stainless steel screens
  • Size: L 212mm x W 23.5mm at the widest point
  • Net weight: 230 grams (without cable)
Shure SM81 polar pattern

Overall Build & Design

As always, Shure please us with outstanding design. The monolithic structure is used here not only for caching your eye with its simplicity but also to simplify the working process. Stainless steel construction looks expensive and moreover, it looks durable, you can be sure, that you will be able to break this mic only in case you really want it and you, fortunately, have a gas burner in your studio. Shure SM81 microphone is also designed to operate over a wide temperature range and humidity, which once again shows its reliability

Now to knobs and switches. To knob and switch, to be precise. The switch under the grille is an attenuator and the knob in the center of the body is a low-frequency response selector, but we will talk about them later. All you need to know in the "design" part is that they are useful. Reasons in the "Sound" section.

Shure SM81 package

As for accessories, mount parts, and cases – there will not be any problem with it. Shure took care of it (as they always do). SM81 package bundle is furnished with a classic Swivel Holder and foam Windscreen to eliminate all flaws of the human voice and wind noise (in case you want to record vocals with this mic or to use this microphone outdoors), also package bundle includes a storage case as you can see on picture above and attenuator-switch lock. Yeah, a good microphone is an expensive treat.

As an optional accessory, we recommend buying an A53M shock mount clip designed for Shure SM81, which reduces mechanical vibrations & noises by more than 20 decibels. Another great accessory for this mic is the OnStage MS7701C Tripod Stand, which proved to be excellent in reliability and available in two color schemes (black and chrome) + we have a great article on microphone stands, so you'll have no problem finding the perfect microphone stand for your instrument mic.

Sound Quality & Features

One of the most important sections of our Shure SM81 review is sound quality & features, and we'll go into more detail here.

The sound characteristics of this model are strongly above average, but the more important thing is that Shure allows us to customize some of them. Nearly linear frequency response of the SM81 can be changed by using the built-in switch of low-pass characteristics (which is located on the mic housing / Three selectable variations: flat, 6dB, or 18dB/octave roll-off). This is a great feature if you want to saturate your recording with low frequency or cut it. Handy stuff, especially for recording instruments!

The microphone has a 10dB attenuator to mute a bit of instrument if it is needed (good news for drummers).

SM81 has a cardioid polar pattern which means that only direct sounds will be recorded, this microphone also has a really powerful output level and low distortion over a wide range of impedances. A lot of people on the internet claim that this mic is really good for recording acoustic guitar and that is all. That is not true because there are dozens of factors that influence subsequent recordings and we are not going to name them here.

Don’t forget about the phantom power. Shure SM81 is working with a phantom power range from 11 to 52Vdc. We don’t recommend using this mic with phantom power lower than 48Vdc as it’ll cause small deformation of your sound, whereby the sound will not be so clear at all frequency ranges.

Shure SM81 Frequency Response

Preparing Shure SM81 review we could not pass by the frequency response of this mic. The main feature of SM81 – is frequency response. It’s not curved over the frequency range as seen in the picture. Shure SM81 is designed with flat frequency response for accurate reproduction of sound sources. You'll hear/record your instrument or sound source exactly as it sounds without additional saturation.

Shure SM81 frequency response

Here you can check out some audio samples recorded with Shure SM81

Among all the audio samples, we liked the way the violin was recorded the most. After trying out this microphone in our studio and in the process of writing the Shure SM81 review, we've made sure - this mic, without any doubt, is designed for recording instruments and it fulfills its task 110%. You can also listen to the recorded speech through the Shure SM81 mic (the latest audio sample).

Shure SM81 Acoustic Guitar Recording (audio example) #1
Shure SM81 Acoustic Guitar Recording (audio example) #2
Shure SM81 DrumKit Recording - Floortom (audio example)
Shure SM81 DrumKit Recording - Racktom (audio example)
Shure SM81 DrumKit Recording - Hi-Hat (audio example)
Shure SM81 DrumKit Recording - Overhead (audio example)
Shure SM81 DrumKit Recording - Snare Top (audio example)
Shure SM81 DrumKit Recording - Snare Bottom (audio example)
Shure SM81 Piano Recording (Spaced Pair audio example)
Shure SM81 Piano Recording with Scarlett Focusrite 2i2 (audio example)
Shure SM81 Violin Recording (audio example)
Shure SM81 Speech Recording (audio example)

Shure SM81 vs Shure KSM137 vs Rode NT5 vs AKG C451 B

Of course, our review on the Shure SM81 can't do without comparing it to other mics. The Shure SM81 competes with three mics (Shure KSM137 / AKG C451B / Sennheiser e914) in the general price range of 350 to 450$ and we will also compare the Shure SM81 with the cheaper Rode NT5 microphone. Well, let's cut to the chase.

Shure SM81 vs Shure KSM137

Shure SM81 vs Shure KSM137

One of the main competitors of the SM81 microphone model is also a microphone from Shure manufacturer. The Shure SM81 and Shure KSM137 are both cardioid condenser microphones designed for recording instruments and both cost about the same. They also have about the same frequency response and low-freq cutoff capability. Comparing these two microphone models we would like to point out that the Shure KSM137 is a more modern microphone and compared to the Shure SM81 it has a more flexible switchable attenuator - (0 dB, 15 dB, and 25 dB) for handling extremely high sound pressure levels. While the Shure SM81 has only 0dB and 10dB attenuation. The Shure KSM137 also has a quieter noise floor, higher SPL overload point, and higher output level.

In summary, we can note that the Shure KSM137 wins this comparison. As the microphone is more modern and overall we can say that the Shure KSM137 is an engineering reimagining of the SM81 microphone to stay in the competitive market of new recording devices.

Shure SM81 vs Rode NT5

Shure SM81 vs Rode NT5

Another competitor of the Shure SM81 in the instrumental microphones class is Rode NT5. Both microphones provide great recording quality and they have similarity in technical specifications. But they also have some differences & advantages over each other that make them unique, for example, the frequency response of SM81 is flat on the whole frequency range, while Rode NT5 has some uplifts in the frequency range (but these uplifts are also flat). Another difference is that Shure SM81 has a three-position low-frequency controller and 10dB attenuator, while NT5 doesn’t have these features.

The main advantage of the Rode NT5 is its price of 219$, while SM81 is more expensive at 100-250$ (there are currently good deals available on Amazon for the Rode NT5 microphone, for the price of the Shure SM81 you can get a matched pair of Rode NT5s and other very favorable bundles). The classic package bundle is similar, except for one detail: SM81 comes with a storage case, and Rode NT5 comes with a zipped pouch. You can listen to comparison audio examples of these mics and choose for yourself which one will be better for you (first playing Shure then Rode).

Shure SM81 vs Rode NT5 (First SM81 then NT5)

Shure SM81 vs AKG C451B

Shure SM81 vs AKG C451B

The Shure SM81 and AKG C451 B are very often compared on sound engineer forums and favor the AKG C451B microphone more. And it is not for nothing that AKG C451B is favored more, as the microphone is more modern compared to Shure SM81 and is a reincorporation of the legendary C-451 E/CK-1 capsule from 1969. AKG C451 B has a more flexible three-position attenuator - 0dB, -10dB, -20dB and controlled bass cutoff on frequency response - flat, 75Hz, 150Hz. The frequency response of AKG C451 B is very similar to Shure KSM137.

Our editorial team also favors the AKG C451 B more than the Shure SM81. You can also see comparisons of these two microphones on the Internet and YouTube. The AKG C451B sounds slightly better and has better features at the same price as the Shure SM81 (but at the moment the AKG C451B may cost a bit more). Here's a pretty good deal on the AKG C451B on Amazon.

Shure SM81 vs Sennheiser e914

Shure SM81 vs Sennheiser e914

Shure SM81 is the least compared to the Sennheiser e914 because the e914 is not a popular model among Sennheiser instrument microphones, even though it has similar characteristics and price to SM81. The Sennheiser e914 microphone model was sold in a rather small number of copies, but the microphone itself turned out to be of very high quality and with excellent sound and characteristics. Most likely Sennheiser did not spend resources on marketing promotion of this model.

Well, let's move on to a detailed comparison. Sennheiser e914 has a more flexible attenuator of 0, -10, and -20 dB while Shure SM81 only has an attenuator of -10 dB. Frequency Response is also slightly different between the microphones. The e914 has small uplifts in the 5k to 15k Hz range, which can affect the additional coloration of the upper frequencies of the recorded instrument. The Shure SM81 has a flat frequency response that does not color the sound over the entire range. Both microphones also have a three-position bass roll-off/cut-off, linear switch.

The only advantage of the Sennheiser e914 is that it has a more modern microphone and a more flexible attenuator. But it does color the sound a bit at high frequencies (sometimes this can be an advantage, sometimes a disadvantage, it's up to you).

Summarizing the comparison

Summarizing our comparison we would like to note that the most preferable microphone is AKG C451B, but at the same time, it is the most expensive of all. And the best price-quality is Shure KSM137. But it should be noted that all the microphones compared in our review are of very good quality and we recommend all of them for purchase, especially if you can find a good discount on them.

As you may have already realized from our Shure SM81 review, the distinctive feature of this model is its flat frequency response, compared to all competitors.

Three Reasons to buy:

  1. Flat frequency response allows you to pick up clear raw sound from the instruments. This feature will help to process recorded instruments a lot easier during mixing.
  2. Price / Quality. For 349 dollars you get an essential microphone for your studio, in case of recording any instrument. Once you decide to record acoustic string instruments, organ, piano, keys, woodwinds, brass, violins, choir, drums, percussion, etc., this is your choice.
  3. Compared with the other instrumental microphones Shure SM81 has a built-in three-position low-frequency filter: flat, 6 dB/octave rolloff, 18 dB/octave rolloff).

Final Verdict on Shure SM81

It becomes more and more difficult to make fair and objective reviews as the microphones we taking a look at are more expensive and professional. There are some things that we can say without a doubt. When you are looking for a mic in this price category, you should realize that the quality of sound will be greatly influenced by your instruments, devices, and recording space. If everything is okay SM81 is one of the best choices for you, at least because of the engineering quality of Shure masters and good reviews in media and from professionals in the audio recording industry.

We hope you enjoyed our Shure SM81 review. If you have any questions or suggestions, please feel free to write in the comments section below. We'll be happy to answer them all.

And the most important thing: follow your heart, young padawan.

May the music force be with you.

  • Good sound quality
  • Durable overall build and construction
  • Built-in attenuator and low-frequency filter
  • Low self noise
  • Wide & Flat frequency response
  • The microphone is quite outdated and there are more interesting competitors on the market at the moment. We recommend looking at the Shure KSM137 microphone instead.
Our Score

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