Microphone Guide

This microphone guide gives a brief overview of the various microphone types that could be used with Overtone Analyzer, along with their respective advantages and disadvantages.

Disclaimer: The information presented here is intended as a general introduction to microphones and cannot replace advice from a qualified audio professional. Before you buy a specific microphone, you should also consult other sources of information such as specialist stores and reviews in dedicated publications and websites.

Things to consider

When chosing a microphone for use with Overtone Analyzer (or most other purposes), various aspects will guide the suitability of a specific model. Here we will consider Performance, Convenience, and Price.

Performance

The performance of a microphone includes its sensitivity, frequency range, frequency response curve, and sound quality. The frequency range is the range of frequencies that the mic responds to. Cheap computer mics may range from 100Hz to 14000Hz, while a professional condenser mic may pick up frequencies as low as 15Hz and as high as 20000Hz.

The frequency response curve indicates how differently the microphone responds to different frequencies. Most microphones are more sensitive to certain frequencies than others.

For example, here is the frequency response curve of the Shure SM58 microphone. This is a very popular stage microphone for vocalists. As you can see, the response drops notably for frequencies below 200Hz. It stays fairly flat between 200Hz and 2000Hz, but then it has a large bumb for frequencies higher than 2000Hz. This means the microphone will be more sensitive to those higher frequencies, and that will affect the sound of the recording.

Frequency curve of Shure SM58 dynamic microphone
Figure 1: Frequency curve of Shure SM58 dynamic microphone

For comparison, here is the response curve of the Behringer ECM8000 measurement microphone:

Frequency curve of the ECM8000 measurement mic
Figure 2: Frequency curve of the ECM8000 measurement mic

In comparison to the SM58, the curve of this mic is almost totally flat between 50Hz and 20000Hz.

The sound quality of a mic is fairly subjective and very hard to quantify. If you want a dedicated mic for Overtone Analyzer, chose one whose response curve is as flat as possible. If you want the mic for other types of recording as well, you might want to try out various mics to see how you like their sound.

Another aspect of the performance characteristics of a mic is directionality. Some mics will pick up any noise in the room, while others are highly focused in one particular direction. For example, stage microphones are designed to record only the sound of the person directly in front of them to prevent feedback, so that they can be used even on a loud stage.  This can be an advantage over an omni-directional mic when you are using Overtone Analyzer in the same room as a noisy computer. On the other hand, you might have to hold such a microphone extremely close to your mouth, which can be inconvenient when you would rather record unobtrusively with a mic standing in the background.

Computer noise can be a large problem when using Overtone Analyzer (and generally when you are recording with your computer). Ideally you are using a very quiet computer, and you have a microphone that is either highly directional, or otherwise very far away from the computer. So a long cable can be inconvenient to carry around, but it allows to increase the distance between the mic and the computer and thus to minimize interference of the computer noise.

 

Convenience

For this discussion the convenience of a mic includes factors such as size and weight, robustness, and compatibility.

Size and weight are mostly important if you are using a laptop, for example to record your voice lessons or during workshops. Obviously it is less convenient to carry around a heavy studio mic in its own carrying suitcase with thick cables and perhaps even a microphone-stand, compared to the integrated mic of the laptop. A small but mediocre mic that you have always with you can be more valuable than a high-performing mic that you generally have to leave at home because it is too heavy or too fragile.

This brings us to robustness, another consideration mainly for mobile users. There seems to be an inverse relation between price and fragility of a mic, which means that very expensive mics tend to be more fragile than very cheap ones. But mainly this depends on the type of the microphone. Computer mics and dynamic stage mics tend to be very sturdy and can easily be dropped or thrown into a bag without taking any damage. Condenser mics, in contrast, have a large, microscopically thin membrane inside that can be damaged even from a single drop. That's why they often come in their own carrying case.

If you are not mobile but use Overtone Analyzer mainly with a stationary computer, those considerations of size, weight and robustness are less important.

The last aspect of convenience is compatibility with your sound card. While computer mics with a 3.5mm plug can be directly connected to a normal sound card or laptop, professional mics usually have an XLR connector and require a dedicated professional sound card. So in addition to the microphone, you may also have to get a new sound card, which adds extra price, weight, cabling, and set-up time.

Price

This is fairly obvious. All other things being equal, the price should be as low as possible.

Microphone Types

There are countless subcategories, but the ones we will discuss here are the following:

  1. Computer Mics
    1. Integrated Laptop Mics
    2. Free standing
    3. Headsets
  2. Professional Mics
    1. Dynamic
    2. Condenser
    3. Professional Headsets
  3. USB Mics

Computer Mics

Integrated Laptop Mics

The only good thing that can be said about integrated mics is their high convenience. As a laptop user, you always have it with you. However, in terms of performance, they should be avoided as much as possible. In most older laptops that we have tested, the integrated mic would pick up a lot of noise from the laptop's hard drive and fan. Newer laptops sometimes have directional microphones that are much better at filtering out that noise, but even then their frequency range is not very good.

Free standing computer mics

This is generally your most inexpensive option, and while you shouldn't expect much quality or durability, microphones such as the Trust MC-1200 are totally sufficient for basic exercises with Overtone Analyzer. For as little as 6.95 Euro, they offer outstanding value for money, and they work with your existing sound card. The downside is that the sound quality is not very good, and that they are not directional, which means they will pick up any noise in the room.

Trust MC-1200 free standing computer mic
Figure 3: Trust MC-1200 free standing computer mic

Headsets

Headsets are headphones with an attached computer mic. They also start at under 10 Euro, and at that price level the quality will be similar to a free standing mic: not very good, but adequate for some voice exercises. A big advantage of the headset over the free standing mic is that the distance to the mouth can be held constant, which makes it much easier to compare different recordings. More expensive models will provide better sound quality. However, these mics are usually designed for voice conferencing, not for measuring sound, so their frequency range may not be good enough for picking up fine details in the higher harmonics, or in very low frequencies.

Laptec Stereo Headset
Figure 4: Laptec Stereo Headset

Professional Mics

While computer mics are mainly for voice conferencing and general purpose sound input, professional microphones are serious tools for the professional sound technician and recording engineer. They come in a variety of forms for many general and special applications, but you will find two main categories: Dynamic and Condenser Mics. This refers to the way the microphone converts sound into an electric signal.

Professional mics cannot be directly connected to a standard sound card because they usually require an XLR socket. So if you want to get a such a mic, you probably also need to buy a new sound card (which can be an internal card for the desktop, or an external USB or Firewire card that can also be used with laptops).

Dynamic Mics

A dynamic microphone is like a miniature loudspeaker working in reverse. The diaphragm of the mic is attached to a coil of fine wire, which is positioned in the magnetic field of a permanent magnet. When sound enters the microphone, the sound wave moves the diaphragm, which will in turn move the coil in the magnetic field, producing a varying current in the coil through electromagnetic induction.

Shure SM58 dynamic microphone
Figure 5: Shure SM58 dynamic microphone

Dynamic mics usually have a very non-linear frequency response curve, and they are generally not as accurate as condenser mics. However, they are extremely resistant to moisture and to mechanical abuse. That's why they are mostly used for live vocals on the stage. They also tend to be relatively inexpensive (compared to professional condenser mics). The Shure SM58 costs about 99 Euro, but you will also need an XLR cable (~5 Euro) and a sound card with XLR input (starting at 100 Euro), and perhaps a microphone stand (~20 Euro).

For working with Overtone Analyzer, a professional dynamic mic is not a great choice, because their frequency response is so non-linear, and because the same or less money can buy an excellent USB condenser mic (see below). The only reason to use a dynamic mic for working with Overtone Analyzer should be that you already have one, or if ruggedness is a major concern, for example to work with children, where it is likely that the mic will often be dropped.

Condenser Mics

Condenser microphones have a diaphragm that acts as one plate of a capacitor. As incoming sound moves the diaphragm, those vibrations will cause changes in the distance between the plates. The resulting change of capacitance is converted into an electrical signal by various means.

Condenser mics are the most common type of mic that you will find in studios because they have the best frequency response and sensitivity, and they tend to reproduce sound across the entire frequency range more evenly. However, they are much more sensitive to moisture and to mechanical stress. They are also more sensitive to loud sounds.

A Large Diaphragm condenser micThe Behringer ECM-8000 measurement mic
Figure 6: A Large Diaphragm condenser mic
Figure 7: The Behringer ECM-8000 measurement mic

Condenser mics can be further classified into Large and Small Diaphragm Microphones.

Large Diaphragm Microphones have a capsule diameter of over 2.5cm and usually have a higher sensitivity than small diaphragm mics. They are also the largest and most fragile type of mic because they are so easily damaged, and they are very sensitive to moisture.

Small Diaphragm Microphones have a capsule diameter of less than 2.5cm. They are more compact, more robust, lighter, and also tend to have a more neutral frequency response curve than large diaphragm mics.

Condenser mics normally require a powered XLR input. Even if your sound card has an XLR input, you need to check that it is suitable for condenser mics and provides 48V phantom power. Condenser mics start at about 60 Euro, but they can cost several thousand Euro. A suitable sound card with a powered XLR input starts at about 140 Euro.

A condenser mic with the appropriate sound card is by far the best solution for working with Overtone Analyzer (and for most other recording work), at least when it comes to the performance of the mic (sensitivity, accuracy, frequency curve, sound quality). The downsides are the high price, less robustness, large weight and size, and the need for an external sound card with extra weight and lots of cables.

Professional Headsets

These are head-mounted microphones designed for recording live vocals. Very often they are wireless, although models with wires are available. They start at 150 Euro, but most cost at least 300-500 Euro.

Shure WH-20 Professional Headset
Figure 8: Shure WH-20 Professional Headset

A professional headset could be a consideration if you plan to record yourself during a voice lesson or some other situation where you don't want to pay much attention to the recording and the microphone, but for dedicated analysis work with Overtone Analyzer a good condenser studio mic is probably better.

USB Microphones

USB Microphones are a hybrid between professional mics and consumer mics. They offer an integrated solution that has a microphone and a sound card all in one device that connects directly to your computer's USB port. There are both dynamic and condenser mics with a USB connection on the market, and all considerations regarding the differences between those two microphone types still apply. However, for working with Overtone Analyzer the USB condenser mics are the most interesting type because they offer an excellent combination of convenience, performance, and price.

The Samson C-01U USB Condenser Microphone
Figure 9: The Samson C-01U USB Condenser Microphone

The great thing about those mics is that they offer the performance of an (entry-level) professional condenser mic, but they don't require a new sound card. Starting at 69 Euro for the Samson C-01U, and about 100-250 Euro for various other models, you get a condenser mic that is dramatically better than a computer mic connected to your sound card without having to buy or carry an extra XLR-capable sound card.

While the USB condenser mics are quite a bit heavier than a small computer mic, they are still fairly portable because they only have one USB cable. For working with Overtone Analyzer, a USB condenser mic can be an excellent choice if mobility and price are a consideration, but sensitivity is also required.

Summary and Conclusion

  • If you just want to experiment a little bit with Overtone Analyzer, almost any microphone at your disposal will be sufficient to get started, including the cheapest computer mics and headsets. A headset might be better because it keeps the distance between the mic and the mouth more constant and therefore produces recordings that are easier to compare. Just don't expect any frequency response below 100Hz.
  • If you need better quality but want an uncomplicated, affordable solution, get a USB condenser mic. Good models are the USB condenser mics from Samson and MXL.
  • If you want even more quality, get a professional condenser mic. You will need a sound card that has XLR inputs and provides phantom power, such as the Emu Tracker Pre (144 Euro). If you want the microphone mainly for use with Overtone Analyzer, get a dedicated measurement microphone such as the Behringer ECM-8000 (53 Euro).
  • If you also want to do other recording work as well, be sure to read more reviews and ask audio professionals about your intended usage to find a microphone that meets your needs and your budget.