Print-through
Encyclopedia
Print-through is a generally undesirable effect that arises in the use of magnetic tape
for storing analogue information, in particular music
.
The proximity of layers of tape on the spools of a cassette or reel to reel
tape causes a weak imprint of magnetic information to be transferred to adjacent layers, effectively shifting a copy of the signal backwards and forwards along the tape. This can sometimes be heard as pre- or post-echo
. Thinner tapes (designed for longer running times, since more tape can be held on the same spool) are more prone to the effect than thicker tapes, and tapes held in storage for a long period or exposed to a weak magnetic field can show pronounced print-through. Digital
tapes are not affected in the same manner as the imprint is generally too weak to change the state of bits recorded on adjacent layers of the tape.
Print-through is actually used deliberately to mass-record prerecorded audio cassettes. In the duplicator
, an endless loop of high-coercivity
source tape is forced into close contact with blank tape and run across a "print-through head" in which a weak AC
high frequency sine wave
is used to transfer the information to the blank tape without erasing the source tape. This permits the tapes to be run at very high speed, speeding up production. However, audio quality using this method is not as good as when the signal is directly recorded onto the tape.
shields the signal against this distortion, however the linear audio and (depending on format) chrominance
signals of a video cassette may still print-through.
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
for storing analogue information, in particular music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...
.
The proximity of layers of tape on the spools of a cassette or reel to reel
Reel-to-reel audio tape recording
Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a reel, rather than being securely contained within a cassette....
tape causes a weak imprint of magnetic information to be transferred to adjacent layers, effectively shifting a copy of the signal backwards and forwards along the tape. This can sometimes be heard as pre- or post-echo
Echo (phenomenon)
In audio signal processing and acoustics, an echo is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single...
. Thinner tapes (designed for longer running times, since more tape can be held on the same spool) are more prone to the effect than thicker tapes, and tapes held in storage for a long period or exposed to a weak magnetic field can show pronounced print-through. Digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
tapes are not affected in the same manner as the imprint is generally too weak to change the state of bits recorded on adjacent layers of the tape.
Print-through is actually used deliberately to mass-record prerecorded audio cassettes. In the duplicator
Loop bin duplicator
A loop bin duplicator is a specialized audio tape machine used in the duplication of pre-recorded audio cassettes.- Analog Loop Bin Duplicator :...
, an endless loop of high-coercivity
Coercivity
In materials science, the coercivity, also called the coercive field or coercive force, of a ferromagnetic material is the intensity of the applied magnetic field required to reduce the magnetization of that material to zero after the magnetization of the sample has been driven to saturation...
source tape is forced into close contact with blank tape and run across a "print-through head" in which a weak AC
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
high frequency sine wave
Sine wave
The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. It occurs often in pure mathematics, as well as physics, signal processing, electrical engineering and many other fields...
is used to transfer the information to the blank tape without erasing the source tape. This permits the tapes to be run at very high speed, speeding up production. However, audio quality using this method is not as good as when the signal is directly recorded onto the tape.
Video recording
Since analog video is recorded by frequency-modulation of the video signal, the FM capture effectCapture effect
In telecommunication, the capture effect, or FM capture effect, is a phenomenon associated with FM reception in which only the stronger of two signals at, or near, the same frequency will be demodulated....
shields the signal against this distortion, however the linear audio and (depending on format) chrominance
Chrominance
Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...
signals of a video cassette may still print-through.