RECORD INDUSTRY ASSOCIATION OF AMERICA, INC.

BULLETIN E 3

STANDARDS FOR STEREOPHONIC DISC RECORDS

October 16, 1963

A. Introduction
A true stereophonic disc record has two distinct orthogonal modulations derived from an original live recording in which a minimum of two separate channels are employed.
B. The Stereophonic Groove
1. The stereophonic groove shall contain two channels of information recorded as orthogonal modulations of a single groove.
2. The 45 degree-45 degree system is the standard. In this system the two mutually perpendicular axes of modulation shall be symmetrically disposed with respect to a normal to the disc surface.
3. The right hand information channel, as viewed by the listener, shall appear as modulation of the out side wall of the groove.
4. When equal in-phase signals are recorded in the two channels they shall result in lateral modulation of the stereophonic groove shall produce equal in-phase acoustical signals.
5. The stereophonic groove contour shall be as recommended in RIAA Dimensional Standards for Disc Phonograph Records, Bulletin E 4.
C. Characteristic
1. For stereophonic disc records the RIAA Standard Recording and Reproducing characteristic shall be standard.
D. Reproduction Recommendations
1. The desirable tip radius of the reproducing stylus for stereophonic disc records is 0.5 mils.
2. The reproducing stylus motion shall be tangent to, or lie in a plane which passes through the record center, and which is inclined at a nominal angle of 15 degrees, clockwise, to a normal to the record at the stylus tip, as viewed from the record c enter.

DIMENSIONAL STANDARDS
DISC
PHONOGRAPH RECORDS
FOR HOME USE

Bulletin No. E 4

RECORD INDUSTRY ASSOCIATION OF AMERICA

These are dimensional standards to facilitate equipment design and assure interchangeabliity. They are not intended to indicate or imply quality or performance levels.

RECORD INDUSTRY ASSOCIATION OF AMERICA, INC.
ONE EAST 57TH STREET
NEW YORK CITY 22


R. I. A. A. DIMENSIONAL CHARACTERISTICS
33 1/3 RPM PHONOGRAPH RECORDS FOR HOME USE

7" Records10" Records12" Records
Outside Diameter6 7/8" + 1/32"9 7/8" + 1/32"11 7/8" + 1/32"
Thickness
a. Flush Design
.075" + .010" -.015".075" + .010".075 + .010"
b. Contour Design
(See drawings)
Fig. 2; Fig. 3Figure 1Figure 1
Center Hole Diameter(Same as 10")0.286" + 0.001" -0.002"(Same as 10")
Lead-in Spirals.
a. To start at record edge
b. Grooves per inch
c. Contour to be same as recording grooves
NOTE: In addition, there shall be at least one complete unmodulated groove at recording pitch.
(Same as 10") 16-32(Same as 10")
Margin Diameter, the outer set-down limit of reproducing stylus6 25/32"9 23/32"11 23/32"
Diameter of Outermost Groove at Recording Pitch6 5/8" max.9 1/2" max.11 1/2" max.
Recording Groove Contour
a. Included Angle(Same as 10")90 degrees + 5 degrees(Same as 10")
b. Bottom Radius(Same as 10")0.00025" max.(Same as 10")
c. Width--Monophonic(Same as 10").0022" -- .0032"(Same as 10")
d. Width--Stereophonic--Instantaneous(Same as 10").0010" min.(Same as 10")
Minimum Inside Diameter of Recording4 1/4"4 3/4"(Same as 10")
Runout of Recording Grooves Relative to Center Hole(Same as 10")0.050" max.(Same as 10")
Note: This figure does not imply that a record having this degree of run-out would be acceptable from a quality standpoint. It does provide, for instance, a limit for the maximum sensitivity or a velocity trip when combined with the pitch of spirals between individual bands.
Lead Out Spiral(Same as 10")2 to 6 grooves/inch(Same as 10")
Note: The number of grooves per inch shall be so chosen that the spiral contains at least one complete revolution. (11/1/61)
Stopping Groove, Closed Concentric Circle
a. Diameter3 7/8" + 0 - 5/64"4 3/16" +- 1/32"(Same as 10")
b. Width(Same as 10")0.003" -- 0.006"(Same as 10")
Direction of RotationClockwise, when observer faces side of record being played.
Rotational Speed(Same as 10")33 1/3 RPM(Same as 10")
Crossover spiral SpiralThe number of grooves joining successive bands on a record shall not be less than 16 per inch.


R. I. A. A. DIMENSIONAL CHARACTERISTICS
78 RPM PHONOGRAPH RECORDS FOR HOME USE

10" Records12" Records
Diameter9 7/8" + 1/32"11 7/8" + 1/32"
Thickness - Measured at 4 points, from outer edge, 90 degrees apart.0.080" + 0.010"0.090" + 0.010"
Diameter of outermost groove of recording pitch.9 1/2" + 0.02"11 1/2" + 0.02"
Center Hole Diameter0.286" + 0.001"0.286" + 0.001"
Minimum Inside Diameter of Recording3 3/4"3 3/4"
Eccentric Stopping Groove
(a) Diameter3 3/8"3 3/8"
(b) Run-out relative Center Hole0.250" + 0.015"0.250" + 0.015"
(c) Groove Shape
(1) Minimum Depth0.003"0.003"
(2) Contourapproximately same as music grooves.
Lead-in spiralAt least one complete turn between outer edge of record and recording pitch.
Lead-out spiral
(a)Nominal pitch1/8" (min.)1/8" (min.)
(b)Contour:approximately same as music groove.
(c)Depth:may vary to blend from music groove to eccentric stopping groove.
Shape of outer edge
(a) Semi-circular, or
(b) "V" Where "V" edge is used, it is recommended that it have:
(1) Included angle of 80 degrees + 10 degrees
(2) Edge radius of 1/64" (approx.)
(3) Apex of the "V" depart from the mid-plane between record faces by not more than, 0.010"


R. I. A. A. DIMENSIONAL CHARACTERISTICS
45 RPM PHONOGRAPH RECORDS FOR HOME USE

Outside Diameter6 7/8" + 1/32"
Thickness
a. Recording area, measured at 4 points from edge 90 degrees apart.0.026" min., 0.052" max.
b. Label area--see drawing of cross section (attached)
Center Hole diameter to be measured under the weight of the record on a tapered plug guage.1.504" + 0.002"
Lead-in Spiral
a. To start at record edge
b. Grooves per inch16-32
c. Shape to be same as recording grooves
Note: In addition there shall be at least one complete unmodulated groove at recording pitch.
Margin diameter, the outer set-down limit of the reproducing stylus6 25/32"
Diameter Outermost Groove at Recording Pitch6 5/8" + 0
Recording Groove Contour
a. Included angle90 degrees + 5
b. Bottom radius0.00025" max.
c. Width--Monophonic.0022"--.0032"
d. Width--Stereophonic, Instantaneous.001" min.
Minimum Inside Diameter of Recording4 1/4"
Runout of Recording Grooves Relative to Center Hole.050" max.
Note: This figure does not imply that a record having this degree of run-out would be acceptable from a quality standpoint. It does provide, for instance, a limit for the maximum sensitivity of a velocity trip when combined with th e pitch of spirals between individual selections.
Lead-out Spiral
a. Grooves per inch2-5
b. Contoursame as recording grooves except width may increase to 0.006"
Stopping Groove, Closed Concentric Circle
a. Diameter3 7/8" + 0
b. Width0.003"--0.006"
Direction of RotationClockwise, when observer faces side of record being played.
Rotational Speed45 RPM
Crossover SpiralThe number of grooves joining successive bands on a record shall not be less than 16 per inch.

Figure 4, 45 RPM 7" Dimensions
Figure 5, Optional interlocking serations for 33 1/3 and 45 RPM records

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