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Патент USA US3088751

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May 7, 1963
D. E. JOHNSON
3,088,741
APPARATUS FOR BALANCING THE OUTPUTS OF A STEREOPHONIC
PHONOGRAPH PICKUP CARTRIDGE
Filed April 13, 1959
FIG.
FIG. 7
INVENTOR
DONALD E. JOHNSON
|
BY
W
ATTOR EY
ice
assam
Patented May 7, 1963
2
not be equally transmissive to signals from the proper
3,088,741
APPARATUS FOR BALANCING THE OUTPUTS
OF A STEREOI’HONIC PHONOGRAPH PICKUP
CARTRIDGE
Donald E. Johnson, Couneaut, Ohio, assignor to The
Astatic Corporation, Conneaut, Ohio, a corporation of
Ohio
Filed Apr. 13, 1959, Ser. No. 805,8Q6
15 Claims. (Cl. 274—23)
The present invention relates generally to the art of
recording and reproducing sound and more particularly
to the provision of apparatus for balancing the outputs of
channels. The component parts of a stereophonic phono
graph pickup cartridges, including the groove engaging
tips, are quite small and may very easily be misaligned
when the pickup cartridge is being assembled. All of the
above variables effect the balance between the outputs of
a stereophonic phonograph pickup cartridge. It is a
monumental and almost impossible task to adjust these
variables with an absolute degree of accuracy.
Thus,
10 reproducing systems of the prior art have been inherently
unbalanced and it has been next to impossible to obtain
balanced outputs from the stereophonic phonograph pick
up cartridge.
It is the prime or ultimate object of the present inven
.a stereophonic phonograph pickup cartridge.
tion to provide apparatus for .adjustably balancing the
As will be understood by those skilled in the art, the 15 outputs of a stereophonic phnograph pickup cartridge.
most Widely accepted system for recording binaural or
Another object of the invention is to provide apparatus
sterephonic sound involves the simultaneous recording of
of the character above described which may be employed
two channels of sound or intelligence in a single record
groove or trace. The two channels may be cut as a lateral
with an originally non-adjustable sterephonic phonograph
pickup cartridge to balance the outputs thereof.
A further object of the invention is the provision of
apparatus for balancing the outputs of existing stereo
phonic phonograph pickup cartridges with a minimum of
channel and a vertical channel in the single groove or
may be cut into the opposite slanting side walls of a
ninety degree V-shaped groove or trace and these chan
nels are modulated in directions downwardly at angles of
modi?cation of the recording system and with a mini
forty-?ve degrees with respect to the surface of the record
mum of expense.
25
disc. This latter method of recording binaural or stereo
A still further object of the invention is to provide ap
phonic sound is commonly known by the designation
paratus of the character described which is of highly im
“45-45” in the art and is the system which is now en
proved and highly simpli?ed construction and which is
joying substantial commercial success. The apparatus of
characterized by its low cost and ease of use.
the present invention will be described in connection with
The above, as well as other objects and advantages of
the 45—45 system of recording and reproducing binaural 30 the invention, will become more readily apparent from
or stereophonic sound.
consideration of the following speci?cation and accom
One of the main reasons that the 45-45 system has
panying drawing wherein there are disclosed certain repre
been widely accepted is that the two channels of recorded
sentative embodiments constructed in accordance with the
sound or intelligence are substantially balanced with re
teachings of the invention.
35
spect to each other. That is, both channels in the walls of
In the drawing:
the groove or trace are inclined at the same angle with
FIGURE 1 is a fragmentary side elevational view,
respect to the surface of the record disc, both channels
partially in section, of the front end portion of a phono
are disposed equally on opposite sides of a neutral vertical
graph tone arm assembly embodying apparatus for balanc
center line, both channels may be made to contain sub
ing the outputs of a stereophonic phonograph pickup
stantially equal sound or intelligence over equal frequency
cartridge associated therewith;
ranges and in general all essential parameters are equal
FIGURE 2 is an underside plan elevation of the ap
whereby the two channels are inherently balanced. Of
paratus
shown in FIGURE 1;
course, each of the channels may be separately .and indi
FIGURE 3 is an end sectional view taken along the sec
vidually modulated as is desired. However, if the same 45 tion line III—-III of FIGURE 2;
sound or intelligence is recorded in both of the channels
FIGURE 4 is a fragmentary side elevational view, par—
the modulations or undulations therein will be equal and
tially in section, depicting the rear end portion of a phono
in this sense the 45—45 system is said to be balanced.
graph tone arm assembly comprising a second embodi
In order to realize the inherent ef?ciencies of the
ment of apparatus for balancing the outputs of a stereo
balanced 45—45 system it is necessary to provide a stereo
phonograph pickup cartridge;
phonic phonograph pickup cartridge which is capable of 50 phonic
FIGURE 5 is an underside plan view of the apparatus
converting the balanced mechanical undulations of the
shown in FIGURE 4; and
two channels into proportionally and equally balanced
FIGURES 6 and 7 are enlarged sectional views taken
electrical impulses or outputs. As will be explained be
along the section lines VI-—VI and VII—-VII, respec
low, prior art apparatus is incapable of reproducing the 55 tively, of FIGURE 5.
balanced channels of recorded sound or intelligence as
I have found that the teachings of my invention may be
balanced electrical impulses or outputs.
embodied in a number of constructional form. Experi
In providing a stereophonic phonograpgh pickup car
mental work has been conducted on apparatus for ad
tridge for reproducing 45—45 stereophonic or binaural
justing the angular relation between. the stereophonic
record discs it is, according to prior art teachings, cus 60 phonograph pickup cartridge and the tone arm and such
tomary to employ two separate transducer elements and
apparatus is depicted in FIGURES 1-3 of the drawing.
to connect them to a single operatively disposed groove
Also, the teachings of the present invention may be im
engaging tip by coupling means. Various elastomeric
plemented by providing means for tilting the tone arm
clamping and damping pads are employed to support the
and the stereophonic phonograph pickup cartridge
transducer elements and the inherent characteristics of 65 mounted therein with respect to the surface of the record
each of these pads, its placement, the cement holding it
disc to achieve the desired balanced outputs. This em
and the degree of compression applied thereto may ma
bodiment is shown in FIGURES 4—7 of the drawing.
terially effect the response of the transducer element as
Referring now to the drawing, and initially to FIG
URES 1-3 thereof, there is shown a forward end portion
slightly with respect to their comparative transducing 70 of a phonograph tone arm 10 which, in accordance with
the usual practice, is mounted at its rear end, not shown,
e?iciencies. The coupling means may not be equally
for free swinging movement across the surface of a rec
compliant to signals from the off-side channels .and may
.sociated therewith.
Also, the transducer elements vary
3,088,741
4
3
arm and suitable knurled and internally threaded knobs
ord disc 11. The tone arm 10is generally channel shaped
and hollow and mounted in the enlarged forward end
32 and 33 are threadably received over the upwardly
projecting ends of the screws. Encircling the bosses 27
and 28 are a pair of tensioned coil springs 34 and 35
whose one set of ends bear against the underside of the
tone arm and whose other set of ends engage the pair
of transversely spaced mounting cars 22 and 23 of the
mounting bracket 21. It ‘will thus be seen that the coil
portion 12 thereof, in a manner to be more fully ex
plained, is a stereophonic phonograph pickup cartridge
14. The stereophonic pickup cartridge 14 may be of any
well known construction, such as, for example, is fully
disclosed in the co-pending application of Henry J. Cvetko
and Maurice M. Palo, Serial No. 782,571, ?led Decem
ber 23, 1958, entitled “stereophonic Phonograph Pickup
springs 34 ‘and 35 forcibly press the cars 22 and 23 into
Cartridge,” which is assigned to the assignee of the pres 10 engagement with the headed ends 31 of the screws 29
and 30.
The stereophonic phonograph pickup.
When the phonographpickup cartridge is mounted in
cartridge 14 comprises an operatively disposed groove
the manner illustrated in FIGURE 3 of the drawing—that
engaging tip 15 which is adapted to track the continuous
is ‘when equal lengths of the screws 29' and 30' are disposed
groove in the record disc 11 and the pickup cartridge
is also equipped with a second groove engaging tip 16 15 below the top wall ‘of the tone arm-the center line 25
of the stereophonic phonograph pickup cartridge is dis,
which may be adapted for playing different kinds of
p-osed along and coincides with the axis of symmetry 26 of
record discs.
the enlarged forward end portion of the tone arm. How
The stereophonic phonograph pickup cartridge is
ever, turning of eitherv of the, knurled knobs 32 and 33 in
rigidly but releaseably secured in a generally tubular
either direction will effectively change the relative lengths
holder 17 that is provided with a transversely extending
of the screws disposed below the top wall of the tone arm
operating arm, 18.and a plurality of rearwardly pro—
whereby the stereophonic phonograph pickup cartridge
jecting output terminals 19. The output terminals 19 are
assumes a tilted position with respect to the axis of sym
connected to suitable amplifying and speaker apparatus,
metry 26 of the tone arm. Thus, the tilted or rotational
not shown, by means of the twisted leads 24} extending
the length of the phonograph tone arm 10. The ar 25 position of the, pickup cartridge with respect to the tone
ent invention.
arm may be adjusted whereby its axis 25 lies along a
plane 37 tilted to the right with respect to the 'axis of sym
rangement is such that the undulations in the two .chan
nels. in the groove of the record disc that are sensed by
the operatively disposed groove engaging tip 15 are con
metry 26 of the tone arm or alternately, along a plane 38
which is tilted to the left with respect to the axis of sym
verted by the transducer elements of the pickup cartridge,
not shown, into proportional electrical impulses. or out 30 metry 'of the tone arm, for example.
As described ‘above, the stereophonic phonograph pick-.
puts that may be evidenced across pairs of the output.
up cartridge responds to a pair of signals, each of which
terminals 19.v One output is provided for each of the
is separately recorded on an opposite side wall of a single
two channels recorded in the groove of the record disc
11.
‘record groove or trace.
The electrical impulses or outputs ‘are then con
When the outputs of the cart
ducted by the leads 24} to the associated amplifying and 35 ridge 14 are not balanced and absolutely equal for equal
undulations in both of the channelslthe unbalance in the
speaker apparatus whereby the same are ampli?ed and
outputs of the pickup cartridge may be corrected by ma
nipulating the knurled knobs 32 ‘and 33 to change the rela
reproduced as audible sound.
The holder 17 for the stereophonic phonograph pickup.
cartridge 14 is journaled for rotation in, a generally U
shaped holder 21 whereby the pickup cartridge may be
40
tive angular disposition between theaxis 25 of the phono
graph pickup cartridge vand the axis of symmetry 26 of the,
turned over conveniently upon manipulation of the lever
tone arm.
18 to place the groove engaging tip 16 in operatively
disposed groove engaging relation as is well known in
the art. This is shown in FIGURE 3 of the drawing.
The U-shaped mounting bracket 21 is provided with a
pair of outwardly directed and transversely spaced mount
This in effect changes the angle of attack of or engage
men-t between the operatively disposed groove engaging
tip and the two channels in thecontinuous groove and the
surface of the record disc. Thus, the operatively disposed
groove engaging tip is positioned in better driven relation
with one orthe other of the channels in the groove of the,
ing ears 22 and 23. The above described structure is
record disc whereby the outputs of, the stereophonic pho
well known in the art and, in accordance with present day
nograph pickup cartridge are equally balanced.
practice, suitable vertically extending screws are placed
Unbalanced outputs may result from unequal forces be:
through the ears 22 and 23 and are securely tightened to 50
ingapplied to the pickup cartridge by the tone arm 10,
hold the mounting bracket rigidly against suitable mount
from structural faults in the pickup cartridge. and from in-.
ing bosses provided in the enlarged forward end portion
herent differences in the properties of the component parts
of the tone arm. The disposition and mounting of the
thereof. Any and all unbalance in the outputsof the
component parts is such that the axis 25 of the stereo
phonic pickup cartridge is angled downwardly with re 55 stereophonic phonograph pickup cartridge may be cor
rected and compensatedfor by changing the angle of at
spect to the surface of the record disc 11 and the longi
tack between the operatively disposed groove engagingvtip
tudinal axis of the tone arm and coincides with the
vertical physical axis of symmetry 26 of the enlarged
and the channels of the groove in the record disc as abovev
described.
In accordance with the teachings of the present in 60 A further advantage of the above described apparatus
is that the pickup cartridge is resiliently mounted by the
vention, I provide a pair of downwardly depending mount
springs 34 and 35. The springs 34 ‘and 35 are tensioned
ing bosses 27 and 28 on the underside of the top wall of
forward end portion 12 of the tone arm 10.
the tone arm which are somewhat shorter than those of
to such an extent that the ears 22 ‘and 23 of the holder,
21 are maintained in tight engagement with the headed
the prior art. The bosses 27 and 28 are transversely
spaced with respect to each other and are preferably inte 65 ends 31 of the screws 29 and 30 during normal use of the
tone arm and the stereophonic phonograph pickup cart
grally molded or otherwise formed with the tone arm.
ridge. , However, if the pickup cartridge is ‘subjected to
The bosses have vertical bores extending therethrough
an excessive vertical force, due to operator carelessness in
which are adapted to loosely receive the ends of elon
dropping the tone arm, for example, the springs 34 and
gated and threaded screws 29 and 30. The headed ends
31 of the screws 29 and 30 are received below the trans 70 35 will be further compressed to absorb this force. The
arrangement is such that the pickup cartridge is better
versely spaced and projecting ears 22 and 23 to carry
adapted to withstand excessive vertical forces and this is
and support the mounting bracket 21, the holder 19 and
an important safety feature.
the stereophonic phonograph pickup cartridge 14. The
Considering now the embodiment shown in FIGURES
screws 29 and 30 are sufficiently long whereby their
threaded ends project above the top wall of the tone 75 4-7 of the drawing, there is shown the rear end portion
3,088,741
5
6
40 of a tone arm which is supported for universal pivotal
movement by mounting means, to be hereinafter more
fully described, from a mountnig board 41. The mount
ing means comprising a base assembly 42 which is secured
to the mounting board 41 by a nut 43 threadably received
on the lower end portion of the base assembly. An inner
pivot tube 43 is journaled in the base assembly 42 and it
phonograph pickup cartridge are not matched and are not
absolutely equal, the unbalance may be corrected lby ap
establishes a vertical ‘axis ‘44 about which the tone arm
most, the user need only procure a new tone arm with its
propriately manipulating adjustment knob 58 to properly
tilt the tone arm.
One important aspect of the invention is the ease with
which present and prior art reproducing systems may be
modi?ed to include the apparatus described above.
At
associated adjustment knob and block or knobs, coil
may be laterally pivoted. Secured at the upper end of the
pivot tube 43 is a rearwardly extending plate 45 which 10 springs and elongated screws.
Another important aspect of the present invention is
has a pair of downwardly depending ears 46 and 47
the extreme simplicity of the apparatus. The same is
formed along the edges thereof. A transversely extending
adapted to be readily manufactured at a relatively loW
pivot pin 48 spans the ears 46 and 47 and establishes a
cost whereby it may serve the mass market.
horizontal axis represented by the line 49 about which the
It should be apparent that I have accomplished the
tone arm 40 may pivot vertically.
objects initially set forth by providing improved apparatus
The transversely extending pivot pin 48 is snugly re
for balancing the outputs of a stereophonic phonograph
ceived in an aperture 50‘ in the inner side wall of the tone
pickup cartridge. Although two representative embodi
arm and the end of the pivot pin projects outwardly be
ments of such apparatus have ‘been disclosed, many
yond this inner side wall. In the outer side wall of the
tone arm 40 there is provided a vertically elongated
changes may be made therein without departing \from the
clear teachings of the invention. Accordingly, reference
aperture 5-1 through which projects the headed end por
tion of the transversely extending pivot pin 48.
should be had to the following appended claims in deter
To further and radjustably secure the tone arm to the
transversely extending pivot pin 48 a block 53 of resilient
and relatively hard material is mounted on the transversely 25
mining the true vscope and intent of the invention.
I claim:
-
1. Apparatus for balancing the outputs of a stereo
extending pivot pin 48 intermediate the ends thereof and
phonic phonograph pickup cartridge of the type adapted
inwardly of the ears '46 and 47. It will be noted that the
block 53 is mounted adjacent the ear 46 and the outer side
wall of the tone arm and is offset a substantial distance
for use in reproducing two channels of sound recorded
on opposite sides of a single groove and having a stylus,
comprising means to support said cartridge to maintain
from the vertical axis 44 de?ned by the pivot tube 43.
The block 53 extends through an aperture 54 in the plate
said stylus and record groove, and means to move the
a predetermined transverse angular disposition between
45 and has a socket 55 formed in the upper surface there
of. Snap ?tted in the socket 55 is a ball 56 which is
cartridge with respect to said support and thus to adjust
the transverse angular disposition of said cartridge in
mounted at the end of ‘an elongated threaded portion 57
a plane extending normally with respect to the center line
of adjustment knob 58. The elongated threaded portion 35 of said groove.
57 of the adjustment knob 58 is threadably received in a
2. Apparatus according to claim 1 characterized in that
vertically disposed aperture 59 formed in the top wall of
said stereophonic phonograph pickup cartridge is mounted
the tone arm 40 and the vertical axis of the adjustment
in a tone arm, and said means to adjust comprising means
knob 58 is offset laterally with respect to the vertical
to change the angular disposition of said cartridge in a
axis 44 de?ned by the pivot tube 43. It should be evident
plane extending generally normally with respect to the
that upon proper turning movement of the adjustment
center line of said tone arm.
knob 58, forces may be brought to bear on the trans
3. Apparatus according to claim 1 characterized in
versely extending pivot pin 48 to cause an inward or out
that said stereophonic phonograph pickup cartridge is
ward tipping of the tone arm. Thus, if the adjustment
mounted in a tone arm, means mounting said tone arm
knob 58 is rotated in ‘one direction from the position 45 for pivotal movement at a point spaced from said stereo
shown in FIGURE 7 to effectively increase the length of
phonic phonograph pickup cartridge, and said means
the elongated threaded portion '57 of the adjustment knob
mounting comprising means to ladjustably tilt said tone
58 disposed between the 'block 53 ‘and the inner surface
arm and said stereophonic pickup cartridge en masse in
of the top wall of the tone arm, the tone arm will be
tilted with respect to the axis 49 of the transversely ex~ 50 a plane extending normally with respect to said center line
of said groove.
tending pivot pin 48 with the outer side wall of the tone
4. Apparatus according to claim 1 characterized in that
arm disposed above the inner side wall thereof. A line
said stereophonic phonograph pickup cartridge is mounted
interconnecting the side walls of the tone arm and lying
in a tone arm, means mounting said tone arm for pivotal
along the axis '49 with the parts disposed as shown in
FIGURE 7 may now extend along the line 60.
Converse
ly, if the adjustment knob 58 is rotated in the other direc
tion the length of the elongated threaded portion 57 of
the adjustment knob 58 disposed between the block 53 and
movement from a support at a point spaced from said
stereophonic phonograph pickup cartridge, and said means
to adjust comprising means to tilt said tone arm and said
stereophonic phonograph pickup cartridge en masse with
respect to said support.
the inner surface of the top wall of the tone arm will be
5. Apparatus for balancing the outputs of a stereo
decreased to tilt the tone arm in the opposite direction. 60
phonic phonograph pickup cartridge of the type adapted
The above mentioned line interconnecting the side walls
‘for use in reproducing channels of recorded intelligence
of the tone tan-n may then be coincident with the line
from channel means, said stereophonic phonograph pickup
61 whereby the outer side wall of the tone arm is disposed
cartridge comprising channel ‘sensing means, and means to
below the inner side wall thereof. Manipulation ‘of the
adjust and retain the angular disposition of said channel
adjustment knob 58 will cause tipping of the tone ‘arm
to change the angle of attack between the operatively dis
posed groove engaging tip of the stereophonic phonograph
pickup cartridge mounted in the outer free end of the
tone arm and the two channels in the groove of a record
sensing means in a plane extending normally with respect
to said channel means to change the angle of attack be
tween said channel sensing means and said channel means,
a tone arm, means mounting said stereophonic phono
graph pickup cartridge in said tone arm, and said means
disc.
70
mounting comprising said means to adjust whereby the
The mechanism ‘above described comprises a second
embodiment of the invention and is particularly adapted
for use where the phonograph pickup cartridge is non
adjustably and rigidly secured in the free end of a tone
arm. If outputs from the two halves of the stereophonic 75
‘angular disposition of said stereophonic phonograph pick
up cartridge in a plane extending generally normally with
respect to the center line of said tone arm may be adjust
ably varied.
3,088,741
phonic pickup cartridge comprising channel sensing means,
6. Apparatus. according to claim.5 characterized in
a tone- arm,- means mounting» saidv stereophonic pickup
cartridge, in said .tone arnnmeans mounting said tone arm’
forqpivotalmovement from a support at a point spaced:
fronrsaid stereophonicpickup cartridge,_ and said means
that said means mounting. comprises a. bracket having a.
pair of outwardlyextending and transversely spaced, ears,
said stereophonic pickup cartridge being mounted in said.
bracket, a pair of headed elongated screws extending ver
tically through said ears whereby said ears rest on the
mounting comprising meansdtoadjustably tilt saidltone,
armabout its longitudinalaxis and .to retainsa-id ‘tone arm’:
in tilted :positionzwhereby the, angle of attack between said;
channel sensing means and, said channels maybe adjust-.
headed portions .of said: screws, said tone arm, having a
top wall,- said-screws projecting above said top *wall, inter:
nally threaded knobs. threadably received on the ends of
said screws projecting above said top wall of said tone 10. ably varied; said tone ,arm comprising-a top walLand-a
pair of transversely spacedvertically extending side Walla.
arm‘, and a pair of coil springs encircling said. screws and
a transversely extending pivot pin spanning said side walls,
extendingbetween saidears and the underside of said top.
means supporting said pivotpin from said support, said
wall.
pivot pin being rigidly attached. to one’ of saidside walls,
7. Apparatus according to claim 5 characterizedin that
said tone arm further comprises a top wall, a pair. of 15,' an elongated aperturev in they other of said side walls
vertically extending members, said vertically extending
through'which said pin loosely. extends, and adjustment
members being connected with and carrying said stereo—
means o?setlaterally:fromsaid longitudinal axis of said
tonearm adjacent said other. side wall for adjustably
varying the distance between said top wall and said trans-_
phonic phonograph pickup cartridge on opposite sides of
the center line thereof, said vertically extending members
projecting through said top wall, and means to .adjustably
20
versely extending pivot pin.
and individually vary the lengths of said vertically ex
tending members disposed below said top wall of said tone
12. Apparatus according to claim 11 characterized in
that said adjustment meanscomprises a resilient and rela
arm.
tively hard block mounted on said tone arm adjacent said
other side wall of said- tone arm,.said block having a
8. Means for mounting a phonograph pickup cartridge
for. transverse tilting movement with respect to the center 25 socket in theupper face thereof, an adjustment knob hav
ing an elongated threaded portion, a threaded aperture
line of a tone arm having a top Wall comprising a pair of
in said-top wall, said-elongated threadedportion'being
vertically extending members, said vertically extending
threadably received in said aperture, said elongated
members being connectediwith andcarrying said phono
threaded portion having a b-all'fonned on oneend thereof,
graph pickup cartridge on. opposite. sides of and out
wardly of; the center line thereof,.said vertically extending 30. and said ball being seated in said socket.
13. Apparatus vfor mountin-g'a tone arm of the type
members projecting through said top Wall of saidtone
havingl'a top'wall- and a pair, of transversely’spaced ver
arm, and means to adjustably and individually vary the
ticallyextending sidewalls, a transversely extending pivot
lengths of said vertically extending members disposed
pin spanning said-side walls, said pivot pin being attached
below said top wall of said tone arm.
9. Apparatus according ‘to claim 8 characterized in that 35. to one of said side walls, and adjustable means adjacent
the other of said sidewalls for adjustablyvarying the
said mounting means further comprises a pair of ears
distancev between said top wall and said pivot pin to allow
projecting ‘outwardlyrfrom said phonograph pickup‘ car
adjustable tilting of said tone ‘arm about its longitudinal
tridge, said vertically extending members having headed
endportions, said vertically extending member extending
through‘ saidears whereby saidears rest on said headed
portions, and spring means biasing said ears into engage
m'entwith'said headed portions of said vertically extend
ing members.
axis.
40,
1
14. Apparatus according to claim 13 characterized in
that said adjustable means comprises a block mounted on
said pivot pin. adjacent said other side wall, a vertically
extending member connected with said block and project
ing through said top wall,'and means to adjustably vary
10. Apparatus for balancing the outputs of a stereo—
phonic pickup cartridge .of the typeadapted for use in 45 the length of said vertically extendingamember disposed
between said top wall and said-block.
reproducing channels of recorded intelligence, said stereo
15. Apparatus according to claimwl4 characterized in
phonic pickup cartridge comprising channel sensing means,
that-said block has ‘a socket ,formed therein, said block
a tone arm, means mounting said stereophonic pickup car
being,formedfromresilient and relatively ‘hard material,
tridge, in said tone- arm, means. mounting said tone arm
for pivotal movement from ya support at a point spaced 50. said vertically extending member-having a ball. at one .end
thereof, and saidball being seated- in said socket.
fromsaid stereophonic pickup cartridge, and said means
mounting comprising means to adjustably. tilt said tone
armxabout its longitudinal axis and to retain said tone
arm in tilted position whereby the angle of attack between
said, channel sensing means ‘and said channels may be
adjustably varied.
11. Apparatus for balancing the outputs of a stereo
phonic pickup cartridge of the type adapted for use in
reproducing. channels of recorded intelligence, said stereo
References Cited in the ?le, of this patent
UNITED‘ STATES PATENTS
2,568,671
2,582,9482,776,144
Vistain ______________ __ Sept. 13, 1951
Cairnes _' _____________ __ Jan. 22, 1952
Nichols ______________ __ Jan. 1, 1957
3,028,161
Siebert _______________ __ Apr. 3, 1962
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