Behringer MIC2200 사용자 설명서

ULTRAGAIN PRO MIC2200 User Manual

1.2.2  What are audio dynamics?
A remarkable feature of the human ear is that it can detect the most wide 

ranging amplitude changes—from the slightest whisper to the deafening roar 

of a jet-plane. If one tried to record or reproduce this wide spectrum of sound 

with the help of amplifiers, cassette recorders, records or even digital recorders 

(CD, DAT etc.), one would immediately be restricted by the physical limitations of 

electronic and acoustic sound reproduction technology.
The usable dynamic range of electro-acoustic equipment is limited as much 

at the low end as at the high end. The thermal noise of the electrons in the 

components results in an audible basic noise floor and thus represents the 

bottom limit of the transmission range. The upper limit is determined by the 

levels of the internal operating voltages; if they are exceeded, audible signal 

distortion is the result. Although in theory, the usable dynamic range sits 

between these two limits, it is considerably smaller in practice, since a certain 

reserve must be maintained to avoid distortion of the audio signal if sudden level 

peaks occur. Technically speaking, we refer to this reserve as “headroom”—

usually this is about 10 - 20 dB. A reduction of the operating level would allow for 

greater headroom, i.e. the risk of signal distortion due to level peaks would be 

reduced. However, at the same time, the basic noise floor of the program material 

would be increased considerably.

Ear

M

icr

ophone A

mplifier

Po

w

er A

mplifier

Tape R

ec

or

der

Radio

Cassett

e

Rec

or

der

P/dB

140

120

100

80

60

40

Fig. 1.1: The dynamic range capabilities of various devices

It is therefore useful to keep the operating level as high as possible without 

risking signal distortion in order to achieve optimum transmission quality.

t

P/dB

+20

0

-20

-40

-60

-80

Clipping

Headroom

Operating level

Effective SNR

Noise floor

Fig. 1.2: The interactive relationship between the operating level and the headroom

A closer look at developments and trends in audio technology shows that tubes 

are enjoying a renaissance today, in a time when even amateur musicians are free 

to use digital effects processors and recording media, and ever more affordable 

digital mixing consoles are becoming a natural part of the equipment of many 

semi-professional studios. Manufacturers try with ever new algorithms to get the 

most out of DSP’s (Digital Signal Processors), the heart of any digital system.
Still, many audio engineers, particularly old hands often prefer using both old 

and new tube-equipped devices. As they want to use their warm sound character 

for their productions, they are ready to accept that these “little darlings” 

produce a higher noise floor than modern, transistor-based devices. As a 

consequence, you can find a variety of tube-based microphones, equalizers, 

preamps and compressors in today’s recording and mastering environments. 

The combination of semiconductor and tube technologies gives you the 

additional possibility of using the best of both worlds, while being able to make 

up for their specific drawbacks.

1.3.1  Tube history
Due to many patent litigations, it is difficult to determine exactly when the tube 

was “born”. First developments in tube technology were reported between 

1904 and 1906. It was a research task of that time to find a suitable method for 

receiving and rectifying high frequencies. On April 12, 1905, a certain Mr. Fleming 

was granted a patent for his “hot-cathode valve” which was based on Edison’s 

incandescent lamp. This valve was used as a rectifier for high-frequency signals. 

Robert von Lieben was the first to discover (probably by chance) that the anode 

current can be controlled by means of a perforated metal plate (grid)—one of 

the milestones in the development of amplification tubes. In 1912, Robert van 

Lieben finally developed the first tube for the amplification of low-frequency 

signals. Initially, the biggest problem was to produce sufficient volume levels, 

which is why resonance step-ups (though impairing the frequency response) 

were used to maximize the attainable volume. Later, the objective was to 

optimize the electroacoustic transducers of amplifiers in such a way that a broad 

frequency band could be transmitted with the least distortion possible.
However, a tube-specific problem is its non-linear amplification curve, i.e. 

it modifies the sound character of the source material. Despite all efforts to 

ensure a largely linear frequency response, it had to be accepted that tube 

devices produce a “bad” sound. Additionally, the noise floor generated by the 

tubes limited the usable dynamics of connected storage media (magnetic tape 

machines). Thus, a one-to-one reproduction of the audio signal’s dynamics 

(expressed as the difference between the highest and lowest loudness 

levels of the program material) proved impossible. To top it all, tube devices 

required the use of high-quality and often costly transducers and sophisticated 

voltage supplies.
With the introduction of semiconductor technologies in the field of audio 

amplification, it soon became clear that the tube would have to give way to 

the transistor, as this device featured an enormously enhanced signal-to-noise 

ratio, required a less complex power supply and yielded an improved frequency 

response. Plus, semiconductor-based circuits can be realized much more easily—

for less money.
Two decades later, the introduction of binary signal processing meant the 

beginning of a new era of recording media that provided plenty of dynamic 

response and allowed for the loss-free copying of audio signals. As digital media 

were enhanced, however, many people began to miss the warmth, power and 

liveliness they knew from analog recordings. This is why purists still today 

consider digital recordings as “sterile” in sound.