Choosing & Buying Microphones

Microphones – “Good” and “Bad”

As you will see in the next few posts, there are many ways to classify microphones. You can categorize them by type: dynamic, ribbon, and condenser. You can also group them by directionality: omni, cardioid, and figure 8. Some people would also group them as “good” and “bad.” Of course, we all want good microphones and would like to avoid the bad ones, but the answer to the question is extremely subjective.

Usually, the question implies, “What is the cost of” a good microphone. The answer to that is $100. The Shure SM57 is probably the most popular microphone used in recording studios. It appears in almost every studio’s mic locker, and usually in multiples. The SM-57 retails for around $100. The answer is also $3500. This is the cost of a Neumann U87, which appears in all major studios and has been used on countless hit songs. So, it isn’t about price.

Astatic Corporation in Conneaut, Ohio, built a little green bullet-shaped crystal microphone in the 1940s called the JT-31. Crystal microphones are rarely used today because of their poor frequency response and distortion. The JT-31 was used as a Public-Address and communications microphone. It sounded terrible by today’s standards but became extremely popular among blues harp players. It was lightweight, cupped in the hands easily, and distorted the sound (in a pleasing way) when played through a tube amplifier. So if you are a harmonica player, it is a good microphone. So, “good” depends on your use.

The Neumann U87AI is a $3500. microphone. It has a self-noise level of 12 dB(A). The $250. RØDE NT1, which sells for about $250. has a self-noise of only 4.5 dB(A), which is 7.5 dB better than the Neumann. This is a significant amount. If you need a quiet microphone, buy the RØDE. “Good” depends on what specification is essential to you.

I could go on here, but I hope you can see that what is “good” is very subjective. Much depends on what your needs are. In general, microphones of any type, condenser, dynamic, and ribbon, at the very bottom of the price range, have compromised build quality and poor quality control. But that changes quickly as the microphones go up in price. Because of modern manufacturing methods and the precision of computer-controlled machines, the cost of manufacturing a great microphone has diminished considerably. Plus, the economies of scale kick in as the home recording market has exploded in the past 25 years, and the volume of quality recording microphones has increased exponentially as well. As an electrical engineer, I don’t see anything in the build or components of most microphones that justifies a price of over $1500.

The differences in quality between a $500. microphone and a $3500. microphone are subtle. But there is intangible value in knowing you are buying the best. There is considerable psychological value in using the model of microphone that studios have used for years to record many classic hits. And what is that intangible value? Significant since many people are willing to acquire microphones for over $1500.

Consider this, a $40. crystal-controlled Timex watch is four times as accurate as a $3500. Rolex. But some people gladly spend for the Rolex because it offers them something more than the ability to keep precise time.

It’s About the Music (Not the Equipment)

There are no "Magic Microphones".

My friend, Bill, had a problem with his guitar amp and since I had a tube tester, I told him to bring it over, and I would test the tubes, and hopefully be able to get it working again. We got to talking about how some people upgrade the tubes, replace the capacitors and tweak everything to get the “perfect” sound. Then he said, “All they do is mess with the equipment, but never play any music.” It’s about the music. It’s about the music.

Now, some people are into recording because they love working on equipment and the recording part is almost incidental. I get that, and it’s perfectly OK, as long as it’s not an excuse to avoid the hard work of producing something creative and of lasting value.

Equipment is only a means to an end, and what matters most is the creative process and the end result.

A high-end German microphone is not going to fix a voice that needs training and practice.

More plug-ins, better preamps and whatever other equipment you lust after is not going to make up for inexperienced engineering and failure to spend lots of time learning your craft.

More effects and more tracks cannot fix a poorly arranged song.

I have a friend, Paul, who plays upright bass in a trio with two guitar players. They all sing. They needed a demo and were going to come into the studio, but we had trouble scheduling a time. They finally decided that since they were producing a demo to get more work, a mono demo would be adequate and they decided to record with a single mike. They spent their time balancing their mix and making it sound good in that one mike. I’m sure they’ll have a more than acceptable demo, and they probably honed their performance techniques a bit in that process. It’s about the music. The people who are booking them for a live gig really don’t care about how their demo was recorded or what mike they used.

If you are just learning guitar, you don’t need a $10,000 classic Martin. A $200 beginning guitar will work just fine. And remember, a guitar player who has been honing his craft for 30 years is going to produce some fantastic music out of that $200 beginner’s guitar, and a 2nd-year guitar student on a $10,000 Martin is still going to sound like a beginner.

So, it’s really about balance. Find some good music and musicians to record, learn your craft well, and then worry about the fine points of the equipment. We are at a unique place in the evolution of recording technology in that professional quality recording equipment is available at such a low price point that equipment purchase is no longer a large barrier to building a small or home studio. However, just because the gear is capable of great results doesn’t make those results automatic. Like mastering any instrument, learning how to produce good recordings takes lots of practice and time. Purchasing better equipment is no short cut to the process, any more than acquiring a Steinway is going to instantly make you an accomplished pianist.

So, don’t worry too much about that classic German microphone at the beginning. Once you’ve honed your craft for a while, getting better preamps and microphones will be another incremental step in improving your product. No “magic microphone” is going to let you skip the years of learning and practicing.

Dynamic Microphones and Room Noise

Are dynamic microphones better at rejecting room noise than condenser mics? The short answer is “no.” There is also another misconception that condenser microphones have a better “reach” than dynamics; that is, they pick up distant sounds better. There is no such thing as “reach.” All microphones pick up sound the same way at a distance according to the Inverse Square Law, which we will discuss later.

But there are a couple of caveats. First of all, you need to be comparing microphones with the same pickup pattern. An omnidirectional microphone picks up more room noise than a cardioid. Also, a condenser microphone may have a better low-frequency response than a dynamic and pick up a little more low-frequency rumble.

First, there are a couple of terms you need to understand. The first is the signal-to-noise ratio, which is independent of microphone sensitivity. So if you are talking or singing into a microphone with the gain properly so that your meter is peaking around “0” dB, and you stop singing or talking and the meter reads -40 dB, the signal-to-noise ratio is 40 dB. In other words, the signal-to-noise ratio is how much louder the desired signal is than the background noise. In this case, the limiting factor on the signal-to-noise ratio dB room noise. In a very quiet room, the limiting factor in establishing the signal-to-noise ratio is the noise generated by the microphone and the preamplifier.

The other term is the Inverse-Square-Law, which states that the intensity of sound drops by 6 dB for each doubling of distance from the source to the microphone. Again, this is true for condenser microphones, dynamic microphones, and your ears. It’s a fundamental law of physics.

So, if you are one inch from the mike capsule and move to two inches away, the microphone output drops by 6 dB. If you move from two to four inches away, the signal level drops another 6 dB., and if you go from four to eight inches away, your signal drops another 6. But, the distance between the noise and the microphone hasn’t changed, and the noise level is constant. However, since your voice level has dropped by 18 dB, and since you moved from 1 inch to 8 inches away from the mike, you’ll need to increase the gain of the preamp by 18 dB to get your voice to be peaking around 0 dB. And by doing that, you raised the noise level by 18 dB.

So, one reason that a dynamic microphone might seem less sensitive to noise is that your lips are usually right on the microphone, maybe an inch away from the capsule since there is usually a built-in foam pop filter in the microphone. With a condenser, since you usually need to use a pop filter, you might be six to eight inches away from the capsule.

So, effectively you get a better signal-to-noise ratio because you can get closer to the dynamic. If you stay 8 inches away from both microphones, the signal-to-noise ratio should be about the same.

Which Microphone Will Make My Song “Radio Ready”?

Old time radio with a musical staff graphic.

I saw this post on one of the recording forums a while back, and I think it raised a good question, but not in the way the person posting it had intended. “What microphone should I buy to make my recordings “radio ready?”

The flippant answer I gave in my head was, “Maybe you should skip the microphone and get some voice lessons.” In all honesty, I knew nothing about his vocal skills, but the nature of the question was a dead giveaway that he knew little about the music production process. The person posting was not happy with his recordings and felt that what he needed was a better microphone, and if he bought the right one, all of a sudden, his recordings would get some airplay. If it were only that simple!

Producing a song that is worthy of airplay first requires a great song and a quality arrangement. The performance needs to have something in it that stands out, and then the recording needs to meet the standard of other songs that get airplay.

A well-recorded song is mostly dependent on the skill of the engineer, then the recording space, and then the equipment used. Changing any one piece of equipment in the recording chain usually does not make any significant difference in the final product. I don’t think any song ever became a hit because of the specific microphone that the singer used.

Are microphone choices important, then? Of course, they are! As engineers, we spend significant time on choosing the proper microphone for a given vocalist and maybe even different microphones for different songs. Part of our job is to get the best recording we possibly can. But I don’t think any professional audio recording engineer is under the illusion that any microphone is going to make up for a lack-luster performance or a singer who hasn’t polished their craft.

The microphones and other equipment we use are the tools that help us create our magic. Having the right tools is extremely important. But, knowing how to use them is even more critical. Knowing the limitations of our tools is golden.

Which Is the “Best” Microphone?

Asking about a “best” microphone is a loaded question. It leads to another question, best for what?

In short, with 155 microphone manufacturers, there are likely many microphones that will work well on a given source. Ultimately, this is a question that you will need to answer for yourself. It depends on the source, how you want the source to sound, how it will fit in the mix, the instrument, the musician, and your room. That said, there are specific microphones or types of microphones used for particular sources, so finding out what those are might be a place to start.

For example, consider recording an electric guitar. I recently did an album for what might be called an alternative rock group. Instrumentation was drums, bass, electric guitar lead, electric guitar rhythm, keyboard, female lead vocal, and background vocals. Lead vocal and guitar were the featured instruments. We were trying to get the proper sound when miking the amp and set up four different microphones to test. We set up a favorite mic for guitar cabinets, the Shure SM-57 Dynamic. Then, as a test, A Blue Spark Condenser, an Electro-Voice ND-468 Dynamic, and a Studio Projects B1 Condenser. After listening, our uncontested choice was the Studio Projects B1 Condenser microphone; it blew away the SM-57.

So what did this tell me? It said to me that for this group, with this guitarist, with this guitar, with this amp, in my recording space, the Studio Projects B1 was the best choice. Also, the Studio Projects B1 will be on my list of microphones to try when I am recording an electric guitar.

Not long ago, I spent an afternoon in the studio with Lee Murdock, an artist I have recorded over 20 albums for. I wanted to compare a couple of small-diaphragm condenser microphones that I had recently acquired, a RØDE NT-55, and an older AKG C451EB, with my standard microphone for acoustic guitars, a Shure SM-81. Lee brought in a 6-string guitar, a 12-string guitar, and a classical guitar. We set the mics up about a foot above the 12th fret and made test recordings. All three mics performed in a way that matched their published curves. The SM-81 has a ruler-flat frequency response. The other two sounded a bit brighter, and their published curves showed a 2 dB boost in the 8 kHz. region. We agreed that all three mics made a great recording, and any of them could match the other with a little bit of EQ.

Of all uses, engineers probably spend the most time selecting a vocal microphone. Our ears are programmed to detect every nuance in the human voice, so this is a crucial choice, especially since the vocals are a vital part of most songs. If you search for which microphones were used by famous artists on their hit songs, you’ll find everything from Shure SM-58s to Classic Neumann U-47s and U-87s. When Dolly Parton was recording for RCA in Nashville, she used an Electrovoice RE-15 that they supposedly kept in a vault with her name on it. Michael Jackson reportedly used a Shure SM-7 on Thriller. Vocal mic choice is a long process and often results in not using the most expensive microphone.

In addition to how the microphone sounds, there are sometimes physical issues. Trying to position a large vacuum tube mic on a snare or tom will be next to impossible in most cases. And mics on the snare or toms might take a good whack with a drum stick, and it is better to take a hit on a $100. SM-57, which would likely survive, than on an $1800. Neumann KM84, which probably wouldn’t. Also, many microphones wouldn’t be able to handle the sound pressure level of being within an inch of a drum head.

So in conclusion, the best microphone for an application depends on a lot of factors, and it is something that you’ll need to work out through experience.

Learn what the characteristics of each type of microphone are and their common usage. As you build your microphone locker, get different types of microphones so that you have choices that make a difference.

Read up on which microphones are usually used to record specific instruments. Experiment with other choices when you can. It is good to have your favorites for each instrument because there is rarely time during a recording session to experiment with every microphone that you will use.

Finally, remember there is no “best” microphone for any use. There is a range of microphones that will work on each source. Don’t be afraid to experiment and develop your personal favorites.

Growth of the Microphone Industry

The growth of the microphone industry and the growth of the home recording industry are entirely intertwined. The home recording revolution began in the 1970s with Tascam Model 10 console and Series 70 recorders. This equipment made home recording affordable and also spawned the opening of many small commercial studios. I opened my studio in 1973 and benefited from the new, lowcost, electret condenser microphones hitting the market.

At the beginning of the home recording revolution, there were only 10 – 15 manufacturers making studio-quality microphones. According to the Recording Hacks website, which contains probably the most comprehensive listing of studio-quality microphones on the web, over 151 manufacturers were making microphones for recording studios in January of 2020.

Frank Sinatra at Columbia Records recording on an RCA 44B ribbon microphone. — Frank Sinatra at Columbia Records recording on an RCA 44BX ribbon microphone.

The manufacturers got it right the first time. Classic microphones from the 1940s, 1950s, and 1960s were made exceptionally well and had a superb performance. The RCA 44BX and 77DX, AKG C12, Neumann U47, U67, and U87 are still very desirable today and bring high prices, not only because they are collectible, but because they always produce excellent results. These classic microphones were used on many hit recordings, not primarily by choice but because they were the only ones available. At that time, the selection of microphones was minimal.

Progress in microphone design over the past 75 years has been one of evolution rather than revolution, with only a few significant innovations.

The first notable innovation was the invention of the FET (field effect transistor). Condenser microphones required a preamplifier in the microphone body because of the high impedance of the capsule. A vacuum tube and the associated high-voltage and filament power supply were needed for that preamp. The FET allowed manufacturers to get rid of the large high voltage tube supply and miniaturize the components in condenser microphones. Vacuum tube condenser microphones were replaced by new FET microphones that were battery powered.

The next innovation was the implementation of phantom power to power the microphone over the standard 3-wire balanced cable. The expensive batteries became an option and soon disappeared as phantom power became the norm in the 1980s.

The innovation of the electret condenser microphones allowed for smaller microphones because their permanently polarized diaphragm eliminated the need for an external bias power supply. The elimination of the bias supply resulted in a cost reduction and a smaller microphone. Lavaliere microphones got more compact, and low-cost electret condenser microphones hit the rapidly growing home recording market. My first condenser microphones were a pair of Sony ECM-22P microphones I purchased in 1973. They still work well.

The steady progress in dynamic microphones and ribbon microphones was given a shot in the arm with the discovery of the metal compound, neodymium. Neodymium was discovered independently by General Motors and Sumitomo Special Metals in 1984. Magnets made from this metal are the material of the smaller magnets and higher outputs in dynamic and ribbon microphones because of their intense magnetic fields. Neodymium spawned a new generation of more compact ribbon and dynamic microphones.

During that time there was a continued improvement, re-design and re-engineering that produced a continuous forward movement in the quality and features of studio microphones.

Seventy-Five years of design experience plus precision CNC machining equipment automated the production of many microphone parts, bringing the cost down and providing considerably improved quality control. The takeaway here is that because of significantly increased sales volume and lower automated manufacturing cost; there is a greater variety of quality microphones with many options available at reasonable prices than ever before.

Microphones and Recording Techniques for Small and Home Studios.

Category Archives: Choosing & Buying Microphones