One piece of information that frequently appears on the internet is that ‘condenser microphones have better sound quality than dynamic microphones’ or ‘condenser microphones are always better, so you should definitely buy a condenser microphone.’ In this post, we will extend upon these topics and take some time to learn about the criteria for a good microphone and how to choose one.
Link to Condenser and Dynamic mic document
Contents
The Criteria for Choosing a Microphone: What Makes a Good Mic?
Many people face difficulties when selecting a microphone. This is often due to a lack of understanding of how to read specifications and what criteria define a good microphone. Some recommend microphones with phrases like ‘microphones that suit men well’ or ‘microphones that are good for thin vocals,’ but these are not actually good directions for evaluating a microphone.
People often ask about ‘the best microphone for a certain type of voice,’ but this is subjective and varies according to personal preference. Of course, certain microphones might emphasize or weaken specific frequency bands (often referred to as their ‘color’), but this doesn’t mean they are a perfect match for every situation.
One important characteristic of a microphone is ‘transparency.’ A good microphone should accurately reproduce sound without imposing any desired color or effect. It is crucial to recognize that all equipment has evolved towards minimizing distortion. With this approach, users can precisely record the sound they want and add the desired color or effects in the post-processing stage.
In fact, selecting a microphone based on the voice is something I largely disagree with. This is because the tone balance of vocals changes depending on the direction of the arrangement.
Let’s delve into more detailed criteria for a good microphone in the next section.
Uniformity of Frequency Response
A good microphone should first and foremost have a uniform frequency response. It’s very common to have multiple takes and split recordings during a session. If the vocal timbre changes with each take, it can become quite problematic.
M49’s K49 dual diaphragm (right)
The differences in a microphone’s frequency response are largely related to the structure of the diaphragm. While this is sometimes seen in dynamic microphones, condenser microphones often use a dual-diaphragm structure to provide various directionalities (multi-patterns). Generally, a single directional pattern called ‘Cardioid’ is mainly used for vocal recording, but dual-diaphragm offers more than just multiple directionalities. It significantly improves the proximity effect associated with changes in distance from the microphone, ensuring that slight changes in the artist’s position or angle during recording do not cause significant differences in timbre.
Not all single-directional microphones have a single diaphragm structure. For example, the AT4047, while being unidirectional, utilizes a dual-diaphragm structure. However, all multi-pattern microphones use dual diaphragms.
“Frequency Bandwidth and Output THD
One of the key characteristics expected from a good microphone is a wide frequency bandwidth. Such microphones have less loss of the original sound and can reproduce sound more accurately. Additionally, they should have low THD (Total Harmonic Distortion), which means less distortion and indicates superior quality. (Similarly, it’s important to remember that while equipment with color can’t be made transparent, transparent equipment can be edited later to add color.)
Microphones use a balanced output method. They can be broadly categorized into those that convert unbalanced signals to balanced ones using a transformer and those that do not.
In microphones that use a transformer, the linearity of the signal is ensured. However, depending on the quality of the transformer, THD (Total Harmonic Distortion) can be excessively introduced at higher volumes.
Among microphones that do not use a transformer, those using DC coupled out can remove DC bias while simultaneously eliminating ‘near-DC’ components, i.e., low-frequency signals to some extent. This is applied like a low-slope HPF (Low Cut), resulting in a sound with reduced lows and emphasized highs.
Furthermore, transformerless microphones that use Tube or Bipolar Junction Transistor for Active Buffered Output roll off the ultra-high frequencies without inducing THD.
Please, No More Low-Cost Condenser Microphones…
We have just explored the general criteria for a ‘good microphone.’ First, the frequency response should be uniform; second, the frequency bandwidth should be sufficiently wide; and finally, the THD (Total Harmonic Distortion) should be minimal.
So why do I advise against buying condenser microphones?
Primarily, low-cost condenser microphones use a DC coupled out method for cost reduction. Such microphones often lose a lot of bass, resulting in an irrecoverable audio source. (Of course, higher-end models may operate in a way that only applies HPF (High Pass Filter) to the extreme low frequencies.)
Typically, flagship products from microphone manufacturers use a transformer or Fet-buffered out, among other technologies. Why is that? Even the Neumann TLM102, which costs over 1,000 dollars, uses DC coupled out. However, it’s worth considering whether this product truly represents Neumann’s quality. (Notably, it even has a single diaphragm.)
Even the SM57 and SM58, which are available for around 100 dollars, come with a built-in transformer. So, is it really necessary to spend 400 or 500 dollars on a condenser microphone with DC coupled out and a single diaphragm? In actual recording, it can be observed that such dynamic microphones often have a much better low-frequency response.
As mentioned in a previous document, sensitivity is also an important aspect that cannot be overlooked.
If one is considering buying such inexpensive condenser microphones, it is likely for a home recording environment. Unless it’s a professional studio with a booth environment, I recommend choosing a dynamic microphone. Especially the Blue baby bottle, often purchased for its attractive design, has a sensitivity of 39.8mV/Pa. If you don’t want to record the sound of footsteps from the next house, it might be wise to remove it from your shopping cart