SIST EN 60094-5:1999

SLOVENSKI STANDARD
SIST EN 60094-5:1999
01-april-1999
Magnetic tape sound recording and reproducing systems -- Part 5: Electrical
magnetic tape properties (IEC 60094-5:1988)
Magnetic tape sound recording and reproducing systems -- Part 5: Electrical magnetic
tape properties
Systeme für Tonaufzeichnung und -wiedergabe auf Magnetband -- Teil 5: Elektrische
Eigenschaften von Magnetbändern
Systèmes d'enregistrement et de lecture du son sur bandes magnétiques -- Partie 5:
Propriétés électriques des bandes magnétiques
Ta slovenski standard je istoveten z: EN 60094-5:1993
ICS:
33.160.30 Avdio sistemi Audio systems
SIST EN 60094-5:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN 60094-5:1999

---------------------- Page: 2 ----------------------

SIST EN 60094-5:1999

---------------------- Page: 3 ----------------------

SIST EN 60094-5:1999

---------------------- Page: 4 ----------------------

SIST EN 60094-5:1999

---------------------- Page: 5 ----------------------

SIST EN 60094-5:1999

---------------------- Page: 6 ----------------------

SIST EN 60094-5:1999
CEI
NORME
INTERNATIONALE IEC
94-5
INTERNATIONAL
édition
Première
STAN DARD
First edition
1988-03
Systèmes d'enregistrement et de lecture du son
sur bandes magnétiques —
Cinquième partie:
Propriétés électriques des bandes magnétiques
Magnetic tape sound recording and reproducing
systems —
Part 5:
Electrical magnetic tape properties
© IEC 1988 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun any form or by any means, electronic or mechanical,
y compris la photo- procédé, électronique ou mécanique, including photocopying and microfilm, without permission in
copie et les microfilms, sans l'accord écrit de l'éditeur writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
V
PRICE CODE
International Electrotechnical Commission
IEC
MeniayHapontlaa 3neKTpoTexHHVecKae KoMHCCHa
Pour prix, voir catalogue en vigueur
• • For price, see current catalogue

---------------------- Page: 7 ----------------------

SIST EN 60094-5:1999
3 –
94-5(1) © IEC –
CONTENTS
Page
FOREWORD 5
5
PREFACE

SECTION ONE - GENERAL
Clause
9
1.1 Scope
9
1.2 Object
SECTION TWO - TECHNICAL REQUIREMENTS AND INFORMATION CONCERNING TESTING CONDITIONS
9
2.1 Standard atmospheric conditions
9
2.2 Mechanical characteristics of tape transports
13
2.3 Electrical characteristics of test equipment
Calibration tape 15
2.4
2.5 Reference tape 15
2.6 Bias 17
2.6.1 Reference bias 19
19
2.6.2 Conventional test bias
SECTION THREE - PARAMETERS TO BE MEASURED
Bias ratio 23
3.1
3.2 Maximum output level 25
3.3 Relative tape sensitivity 31
3.4 Reference level to bias noise ratio 33
33
3.5 Signal to bias noise ratio
35
3.6 Reference level to d. c. noise ratio
37
3.7 Reference level to print ratio
39
3.8 Erasing attenuation (under consideration)
41
3.9 Uniformity variations
43
3.10 Drop-out annoyance
SECTION FOUR - INFORMATION TO BE SUPPLIED BY THE MAGNETIC TAPE MANUFACTURER
47
4.1 Recommended form for published data
57
APPENDIX A - Equipment noise correction
59
APPENDIX B - Measuring means
63
APPENDIX C - Intermodulation distortion measuring equipment

---------------------- Page: 8 ----------------------

SIST EN 60094-5:1999
94-5(1) © IEC — 5 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
MAGNETIC TAPE SOUND RECORDING AND REPRODUCING
SYSTEMS
Part 5: Electrical magnetic tape properties
FOREWORD
The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the
1)
National Committees having a special interest therein are represented, express, as nearly as possible, an international consen-
sus of opinion on the subjects dealt with.
rnational use and they are accepted by the National Committees in that sense.
2) They have the form of recommendations for inte
In order to promote international unification, the I E C expresses the wish that all National Committees should adopt the text
3)
of the IEC recommendation for their national rules in so far as national conditions will permit. Any divergence between the
IEC recommendation and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
The I E C has not laid down any procedure concerning marking as an indication of approval and has no responsibility when an
4)
item of equipment is declared to comply with one of its recommendations.
PREFACE
This standard has been prepared by Sub-Committee 60 A : Sound Recording, of I E C Technical Committee No. 60 : Recording.
The text of this standard is based on the following documents :
Six Months' Rule Report on Voting
60 A (CO) 88 and 88 A
60 A (CO) 71
60A(CO)116
60A(CO)114A
Full information on the voting for the approval of this standard can be found in the Voting Reports indicated in the above table.
IEC Publication 94 and its supplements are under revision. The new IEC Publication 94 will be issued in several parts, of
which this is Part 5.
It will have the following parts :
Part 1: General conditions and requirements
General: electrical requirements for the magnetic tape recording and reproducing systems; mechanical requirements for
the magnetic tape; tape identification; programme identification (Fourth edition, 1981).
Part 2: Calibration tapes
Minimum requirements for calibration tapes for making adjustments and comparative assessments of the reproducing
performance (First edition, 1975).
(First edition,
Part 3: Methods of measuring the characteristics of recording and reproducing equipment for sound on magnetic tape
1979).
Part 4: Mechanical magnetic tape properties
Characteristics to be specified and relevant methods of measurement. Equipment to be used to determine the mechanical
properties of magnetic tapes (First edition, 1986).
Part 5: Electrical magnetic tape properties
Characteristics to be specified, methods of measurement and equipment to be used for the determination of the electrical
properties of magnetic tape for analogue sound recording and reproduction (object of this standard).

---------------------- Page: 9 ----------------------

SIST EN 60094-5:1999
IEC — 7
94-5(1) ©
Part 6: Reel-to-reel systems
Mechanical requirements and dimensions, including reels, hubs and relevant track allocations (First edition, 1986).
Part 7: Cassette for commercial tape records and domestic use
Mechanical requirements and dimensions, including track allocation (First edition, 1986).
Part 8: Eight-track magnetic tape cartridge for commercial tape records and domestic use
Mechanical requirements and dimensions, including track allocation (First edition, 1987).
Part 9: Magnetic tape cartridge for professional use
Mechanical requirements and dimensions, including track allocation (First edition, 1988).
Part 10: Time and address codes (First edition, 1987)
Part 11: Address code for compact cassettes (First edition, 1988)
The following IEC publications are quoted in this standard:
Publication Nos. 50 (806) (1975) : International Electrotechnical Vocabulary (IEV), Chapter 806: Recording and reproduc-
tion of sound and video.
94-1 (1981) : Magnetic tape sound recording and reproducing systems, Part 1: General conditions and
requirements.
94-2 (1975): Pa rt 2: Calibration tapes.
94-6 (1985) : Part 6: Reel-to-reel systems.
94-7 (1986) : Part 7 : Cassette for commercial tape records and domestic use.
94-8 (1987) : Part 8 : Eight-track magnetic tape cartridge for commercial tape records and domestic
use.
9: Magnetic tape cartridge for professional use.
94-9 (1988) : Part
386 (1972) : Method of measurement of speed fluctuations in sound recording and reproducing
equipment.
651 (1979) : Sound level meters.

---------------------- Page: 10 ----------------------

SIST EN 60094-5:1999
– 9 –
94-5(1) © IEC
MAGNETIC TAPE SOUND RECORDING AND REPRODUCING
SYSTEMS
Part 5: Electrical magnetic tape properties
SECTION ONE – GENERAL
1.1 Scope
This standard applies to non-perforated magnetic tape used for professional and domestic
analogue sound recording and reproduction.
1.2 Object
The object of this standard is to list and define the characteristics, methods of measurement
and equipment necessary to determine the electrical properties of magnetic tapes. It will also
enable users of magnetic tapes to compare the technical product data of different manufacturers,
produced in accordance with this standard.
SECTION TWO – TECHNICAL REQUIREMENTS
AND INFORMATION CONCERNING TESTING CONDITIONS
Standard atmospheric conditions
2.1
+5
Ambient temperature 2 °C
—5
Relative humidity 60 ± 15 %
Where necessary the tests shall be preceded by a period of conditioning to ensure that the test
specimen has reached equilibrium with the environment.
2.2 Mechanical characteristics of tape transports
a) Tape speed
The tape transports shall be capable of operating at the mandatory rated tape speed specified
in Table I.
TABLE I
Rated tape speeds
Tape application Speed (cm/s)
Professional 6.30 mm wide tapes 38.1 ± 0.2%
Domestic 6.30 mm wide tapes
9.53 ± 0.2%
Domestic 3.81 mm wide tapes 4.76 ± 0.2%
Other tape speeds may be required when additional optional information is given.
The tape speed fluctuations (wow and flutter) shall be not more than 0.15 % when measured
in accordance with I E C Publication 386.

---------------------- Page: 11 ----------------------

SIST EN 60094-5:1999
IEC – 11 –
94-5(1) ©
b) Tape widths
Tape transports shall be capable of accommodating tape widths of 6.30 mm and/or 3.81 mm
with tolerances as specified in IEC Publication 94-1.
In addition tape transports may be used to accommodate the other tape widths and track
allocations specified in IEC Publication 94-1 or IEC Publications 94-6 to 94-9.
c) Tape guides
Tape guides shall be such as to ensure stability of measurement without affecting the inherent
characteristics of the tape.
d) Tape tensions
The tape tensions at the recording and replay heads shall be 1.0 ± 0.4 N for 6.30 mm wide
tapes and 0.5 ± 0.2 N for 3.81 mm wide tapes.
It is recommended that pressure pads should not be used.
e) Heads
For details see Table II and Appendix B.
TABLE II
Type of head
Replay
Erase Record
All tests All tests
All tests
Country
Type
of origin
of tape Track Gap Gap Track Relative part
Track
configuration configuration length length configuration of I E C
(µm) (gm) Publication 94
Two track
Professional Full Full 7 (A
3 A 6 Germany
y
width (B) ( ) two channel
mm wide width 18
Figure 8
Nos. 1 and 2
Full Full 7 (A Four track
Domestic
Japan
2 A 6
p
two channel
6.30 mm wide width width 2 (B) ( )
Figure 9
Nos. 1 and 3
4 (A 1 A Four track
Domestic Full Full
7 Japan
p
3.81 mm wide width width 1,5 (B) ( ) two channel
Nos. 1 and 2
A = mandatory
B = optional (for use when additional information is given at the discretion of the tape manufacturer)
Tape wrap
f)
The total angular displacement of the tape around the head. The tape wrap shall be 6 ± 2°
around each head.
(0.105 ± 0.035 rad)
The heads shall be set or adjustments provided so that :
the face of the head contacting the tape is parallel to the corresponding faces of the
i)
guides,
ii) the head is positioned so that the tape wrap is symmetrical with respect to the gap ;
the head gap alignment can be set accurately and rigidly. If the tape under test has a
iii)
coating thickness greater than that of the reference tape being used, the wrap symmetry
with respect to the gap shall be adjusted for maximum short wavelength response.

---------------------- Page: 12 ----------------------

SIST EN 60094-5:1999
– 13 –
94-5(1) © IEC
2.3 Electrical characteristics of test equipment
a) Reproducing characteristic
The reproducing characteristic of the test equipment used shall give a flat frequency response
when reproducing the relevant calibration tape specified in I E C Publication 94-2.
b) Recording characteristic
The recording chain shall be adjusted to obtain constant current in the recording head over
the specified audio-frequency range.
The third harmonic distortion of both recording and reproducing chains shall be less than
throughout the measuring range, for signal levels which enable the maximum output
0.02 %
level to be obtained from the tape under test.
The weighted system noise (including hum) generated by the recording and reproducing
12 dB below the combined value of weighted system and tape noise.
chains should be at least
If this condition cannot be achieved a corrected noise value may be derived from the equip-
ment noise correction curve (see Appendix A).
Bias and erase requirements
c)
kHz or
The signal applied to the bias and erase heads shall be equal to a frequency of 80
0.05 % .
higher with an even harmonic distortion content of less than
A higher bias frequency is necessary when optional measurements are made at duplicating
tape speeds.
d) Output level meter
The meter used for all measurements shall be of the r.m.s. (square law) type specified in
I E C Publication 651.
e) Equipment for noise measurement
Bias noise shall be measured using a weighting network with the characteristics specified
i)
651.
for the A curve in IEC Publication
In addition, the weighting curve and quasi-peak meter specified in CCIR Recommenda-
may be used.
tion 468-3
D. C. noise shall be measured using a high-pass filter with the characteristics specified in
ii)
Sub-clause 3.6.
Drop-out annoyance equipment
f)
For the name and address of the manufacturer of suitable equipment see Appendix B.
Intermodulation distortion equipment
g)
Suitable measuring equipment is described in Appendix C.
h) Third harmonic distortion equipment
Third harmonic distortion shall be measured using a frequency analyzer or a filter.
i) Uniformity measurement equipment
The characteristics of the measuring equipment shall be in accordance with those specified in
Sub-clause 3.9.

---------------------- Page: 13 ----------------------

SIST EN 60094-5:1999
– 15 –
94-5(1) © IEC
Calibration tape (IEV* 806-05-58)
2.4
A magnetic tape on which signals have been recorded, corresponding to a specified characteris-
tic, used to calibrate a reproducing chain.
Note. — A different calibration tape is required for each tape speed.
The type of calibration tape used for the purposes of this standard shall be stated and its format
shall be in accordance with I E C Publication 94-2.
Tape widths shall be in accordance with IEC Publication 94-1.
(IEV 806-05-59)
2.5 Reference tape
An unrecorded magnetic tape with specified characteristics, selected as a reference to enable
comparison with other magnetic tapes, or to measure characteristics of magnetic tape recorders.
Reference tapes shall be provided on the basis of a primary standard issued from an agreed
2.5.1
carefully measured batch of the tapes listed below, and shared among all member national stan-
dards organizations.
Primary reference tapes shall be periodically reviewed to ensure they are compatible with tape
recorders currently available in the various categories covered by this standard.
The measurements on these primary reference tapes shall be certified by the issuing national
2.5.2
Members National Standards Organization
standards organization and verified by a second I E C
able and prepared to do so.
The National Committees of the I E C prepared to verify I E C primary reference tapes listed in
2.5.3
table III, are the United States of America, the Netherlands, Japan, Germany, Canada, the
United Kingdom and Czechoslovakia.
It should be noted that no issuing country may verify its own I E C primary reference tapes.
If any national standards organization has no facilities for carrying out these measurements, it
may delegate this task to a qualified laboratory in that country.
(See Table III page 17.)
Any member country may, at its own discretion, either purchase or manufacture copies to be
2.5.4
used as secondary standards, provided these were certified by their own or another I E C member
shall
national standards organization. Copies of reference tape not conforming to this procedure
be classified as IEC reference tapes.
not
All IEC secondary reference tapes shall be calibrated and issued with correction factors for
2.5.5
sensitivity, bias ratio and maximum output level, expressed relative to the values of the corre-
sponding characteristics of the primary reference tape.
The relative parameters of these secondary reference tapes shall have tolerances very close to
the I E C primary reference tape.
* International Electrotechnical Vocabulary (IEV) [IEC Publication 50].

---------------------- Page: 14 ----------------------

SIST EN 60094-5:1999
– 17 –
94-5(1) © IEC
TABLE III
I E C primary reference tapes
Tape Reference
Country
Width
speed batch Use Type Description
of issue
(mm)
(cm/s) number
Professional
19.05 A 342 D B Germany — Fe2O3
6.30
38.1 6.30 MT 82472 A United States of America — Fe2O3
United States of America — Fe2O3
76.2 6.30 MT 82472 B
Domestic
4.76 3.81 R 723 DG A Germany IEC I Fe2O3
IEC II
4.76 3.81 U 564 W A Germany CrO 2 (Revision 1986)
4.76 3.81 CS 301 A Japan IEC III Double Layer Fe 2O3 + CrO2
IEC IV
4.76 3.81 E 912 BH A Japan Metal Pigment
4.76 C 264 Z B Germany — Fe2O3
6.30
9.53 6.30 C 264 Z A Germany — Fe2O3
Germany — Fe2O3
19.05 6.30 C 264 Z B
A = mandatory
B = optional (for use when additional information is given at the discretion of the tape manufacturer)
3.81 mm wide domestic tape types, IEC I, II, III and IV, are described in Table V.
Note. —
2.5.6 The reference tape used for tape measurements shall have a known sensitivity, distortion (for
professional tapes), maximum output level (for domestic tapes), and bias characteristics, and is
required for the following purposes :
to determine the conventional test bias for domestic tapes and to serve as a reference for bias
a)
ratio for professional and domestic tapes ;
b) to determine the relative tape sensitivity of the tape under test ;
to determine the correction factor for maximum output level at 10 kHz arising from tolerances
c)
in measuring equipment. (See Sub-clause 3.2: "Result".)
2.5.7 In order to ensure matching of mass produced domestic recorders and tapes, alignment of
recorders shall be such that compatibility with the relevant I E C primary reference tapes is
obtained.
2.5.8 All reference tapes are to be used in conjunction with the time constants specified for the
relevant tape speed in I E C Publication 94-1 and Table IV contained in this standard.
2.5.9 The width and thickness of the reference tape shall be in accordance with IEC Publication 94-1.
Note. — See Appendix B for the names and addresses of the manufacturers of primary standard IEC reference tapes.
2.6 Bias
Definitions :
Biasing
The conditioning of the magnetic medium during recording by superimposition of the wanted
signal upon that used to produce a high frequency alternating magnetic field.

---------------------- Page: 15 ----------------------

SIST EN 60094-5:1999
94-5(1) © IEC – 19 –
Bias current
A high frequency alternating current passing through the coils of a recording head which
produces the biasing magnetic field.
2.6.1 Reference bias
Reference bias is the value of bias required for the primary reference tape.
Reference bias for professional reference tapes (tape speeds of 76.2 cm/s, 38.1 cm/s and
a)
19.05 cm/s)
Preferred method :
Reference bias shall be determined by finding the value of bias current which will produce
minimum third harmonic distortion at a frequency of 1 kHz, from the primary reference tape,
when it is recorded to the reference level contained on the relevant calibration tape.
This value approximately corresponds with maximum sensitivity at 1 kHz.
Alternative method :
Alternatively, it can be determined as the higher of the two bias currents, at which the output
at 10 kHz is a known amount below the obtainable maximum.
The alternative method may be used for a specific IEC standard recording head, provided it
produces the same bias current as the preferred method.
(tape speeds of 19.05 cm/s, 9.53 cm/s and
b) Reference bias for domestic reference tapes
4.76 cm/s)
Preferred method :
Reference bias shall be determined by finding the value of bias current which is necessary to
produce the specified maximum output level at 315 Hz (1 kHz for 19.05 cm/s tape speed),
with a third harmonic distortion content of 3 %, from the relevant primary reference tape.
The absolute values of maximum output level at 315 Hz (1 kHz for 19.05 cm/s tape speed) for
the primary reference tapes are derived from the specified difference between their maximum
output levels at 10 kHz and 315 Hz (1 kHz for 19.05 cm/s tape speed), and are listed in
Table IV.
Alternative method:
Alternatively, it can be determined as the higher of the two bias currents at which the output
at 6.3 kHz is a known amount below the obtainable maximum.
The alternative method may be used for a specific I E C standard recording head, provided it
produces the same bias current as the preferred method.
The maximum output levels listed in Table IV are absolute values obtained from the primary
reference tapes, and are specified by the primary reference tape manufacturer in accordance with
Sub-clause 2.5.2.
All maximum output levels are expressed relative to the reference level contained on the
relevant calibration tape, using the I E C standard heads specified as mandatory in Table II.
2.6.2 Conventional test bias
The value of bias current used to measure the tape under test.

---------------------- Page: 16 ----------------------

SIST EN 60094-5:1999
94-5(1) © IEC – 21 –
(tape speeds of 76.2 cm/s, 38.1 cm/s and
a) Conventional test bias for professional tapes
19.05 cm/s)
The conventional test bias used for the professional tape under test shall be derived in the
same manner as the reference bias for the relevant primary reference tape (see Sub-clause
2.6.1, Item a)). This bias value shall be expressed in terms of bias ratio (see Sub-clause 3.1).
b) Conventional test bias for domestic tapes (tape speeds of 19.05 cm/s, 9.53 cm/s and 4.76 cm/s)
The conventional test bias used for the domestic tape under test shall have the same value as
the reference bias derived from the relevant primary reference tape (see Sub-clause 2.6.1,
Item b)).
Conventional test bias is the bias value specified for use with the tests defined in this standard.
It is not necessarily the optimum bias ; this may be separately quoted in the manufacturer's
published data, together with any relevant test results and/or curves.
TABLE IV
Table of maximum output levels specified for domestic IEC primary reference tapes
Maximum
Time output level
Maximum
Tape Tape constant for 3% third
Reference output level
width speed Type (µs) harmonic distortion
batch number difference
(mm) (cm/s) (dB)
(dB)
t1 t2 315 Hz 1 kHz
10 kHz
3.81 4.76 IEC I R 723 DG 120 3 180 + 4.3 — — 7.7 12
3.81 4.76 IEC II U 564 W 70 3 180 + 4.3 — — 7.7 12
3.81 4.76 IEC III CS 301 70 3 180 + 4.4 — —7.6 12
3.81 4.76 IEC IV E 912 BH 70 3 180 +4.8 6
— —1.2
6.30 4.76 — C 264 Z 120 3 180 * — *
6.30 9.53 — C 264 Z 90 3 180 * —
6.30 19.05 — C 264 Z 50 3 180 —
* = under consideration
Note. — 3.81 mm wide domestic tape types IEC I, II, III and IV are described in Table V.
SECTION THREE – PARAMETERS TO BE MEASURED
Measurement conditions
a) For the purpose of this standard, all professional tapes shall be measured using their own
value of conventional test bias.
In addition, measurements may be made using a value of reference bias derived from the
relevant reference tape.
b) For the purpose of this standard, all domestic tapes shall be measured using conventional test
bias.

---------------------- Page: 17 ----------------------

SIST EN 60094-5:1999
– 23 –
94-5(1) © IEC
However if additional optional measurements are made using optimum bias for the tape
under test, the bias value shall be determined from the bias current which will produce the
same difference between its maximum output levels at 10 kHz and 315 Hz (1 kHz for
19.05 cm/s tape speed) as that specified for the relevant primary reference tape (see Table
IV). This bias value shall be expressed in terms of bias ratio (see Sub-clause 3.1).
It should be noted that the specified difference between the maximum output levels shall be
determined with measuring equipment having accurately calibrated electrical characteristics :
The "amplitude/frequency response" section of the calibration tape, used for adjusting the
1)
reproducing chain shall not vary from the absolute value, or if there is any deviation this
shall be known.
2) The reference level contained on the calibration tape used shall not vary from the absolute
value, or if there is any deviation, this shall be known.
The absolute values for 3.81 mm wide calibration tapes are represented by the calibration tapes given as
Note. —
samples to the National Committees of the IEC after the meeting in Prague in 1981, and identified as
"IEC (Prague) 1981". The absolute values for 6.30 mm wide calibration tapes are under consideration.
The characteristics of the IEC recording head shall be known.
3)
For the purpose of this standard, unrecorded tape used for commercial tape recordings may
c)
be measured in accordance with the requirements for domestic tapes, using optimum bias for
b) of section
the tape under test as defined in the " Measurement conditions " given in Item
Three.
In addition, the tape may be recorded at a tape speed typical of duplication use. Where this
option is exercised, results shall be shown at the mandatory tape speed and the recording
speed shall be quoted.
Measurements of the relevant parameters of tapes for professional use shall be made on
d)
6.30 mm wide tape.
Measurements on other tape widths, using track allocations in accordance with I E C Publica-
tion 94-6, are optional.
Measurements of the relevant parameters on tapes for domestic use shall be made on the
e)
appropriate width of 6.30 mm or 3.81 mm.
Unless otherwise specified, the parameters shall be measured using one inner track.
f) All measurements shall be carried out at the relevant tape speeds specified in Tables I, VI,
VII and VIII.
Unless otherwise specified, all measurements are to be carried out in accordance with the
g)
technical requirements stated in Section Two and the results shall be expressed in decibels as a
voltage or current ratio, for example :
201g(dB)V2
Bias ratio
3.1
Definition:
The ratio of conventional test bias current (for professional tapes) or optimum bias current (for
domestic tapes) required for the tape under test to the reference bias current required for the
primary reference tape.

---------------------- Page: 18 ----------------------

SIST EN 60094-5:1999
94-5(1) © IEC — 25 —
Method:
The values of bias current passing through the recording head for the reference tape and the
tape under test are measured. The ratio shall be calculated on this basis.
a) For professional tapes
The bias ratio shall be determined at a frequency of 1 kHz from the values of bias current
which correspond to minimum third harmonic distortion at reference level, from the tape
under test and the relevant primary reference tape.
b) For domestic tapes
If additional optional measurements are made using optimum bias (see Section Three :
"Measurement conditions", Item b)) for the tape under test, then its bias ratio shall be
determined from the bias current which will produce the same difference between its maxi-
mum output levels at 10 kHz and 315 Hz (1 kHz for 19.05 cm/s tape speed) as that specified
for the relevant primary reference tape (see Table IV).
Measurements :
a) For professional tapes 6.30 mm wide
Bias ratio shall be measured as indicated in Table VI.
b) For domestic tapes 6.30 mm wide
Bias ratio shall be measured as indicated in Table VII.
For domestic tapes 3.81 mm wide
c)
Bias ratio shall be measured as indicated in Table VIII.
Result:
The bias ratio of the tape under test is expressed in decibels relative to the reference bias
required for the relevant primary reference tape.
Maximum output level
3.2
Definitions :
Maximum output level
The maximum output level of a magnetic tape is the value of recorded level at which :
a) a specified percentage of distortion occurs, or
b) the magnetic tape has attained saturation.
Saturation (IEV 806-05-29)
The state of a ferromagnetic material subjected to an external magnetic field of such intensity
that the induced magnetization cannot be substantially increased by further strengthening of that
magnetic field.
Method A, mandatory :
The method for frequencies at and below 1 kHz is to measure the output level at which 3 %
third harmonic distortion occurs, i. e. :
Uf2
Amplitude of third harmonic component — 3% third harmonic
x 100
Amplitude of fundamental component Ufl distortion

---------------------- Page: 19 ----------------------

SIST EN 60094-5:1999
94-5(1) © IEC — 27 —
Output level
Ufi
Uf2
0 f2
fi
Frequency (linear scale)
684/87
Output signal spectrum.
FIG. 1. —
Method B, mandatory :
The method used for frequencies at and above 10 kHz is to measure the output level at which
the magnetic tape has attained saturation, i. e. the audio-frequency current is gradually increased
until the output level ceases to increase. The corresponding value of the output level is noted.
Method C, optional:
In addition, the output level for 5 % intermodulation distortion may be measured at any
frequency by recording a combination of two sinusoidal signals Uf
...