INSTALLATION for C-8S
The C-8S Professional Audio Compensator with Stereo Control is a
complete C-8 Compensator with the addition of a "STEREO MODE SELECTOR
SWITCH," "STEREO BALANCE" and ganged dual "VOLUME CONTROLS".
Shipped with the C8s are two 6 foot shielded leads and one 3 foot shield-
ed lead. These will be used in interconnecting the system.
To interconnect the C-8 and C-8S for monaural-stereo reproduction,
complete the following procedure. Use the C-8 for the left channel
and the C-8S for the right channel.
(A.)
The C-8 Is first modified as follows:
1.) The heavy inter-unit cable connecting the C-8 to the power
amplifier Is disconnected at the amplifier end.
2.) With a pair of cutting pliers, remove pin #2 from the octal plug
of the inter-unit cable. In a monaural system pin #2 carries the signal
from the preamplifier to the power amplifier. In a stereo system the
signal must be obtained from the main output jack on the back of C-8.
3.) After removing pin #2 the inter-unit cable Is reconnected to the
power amplifier.
4.) On C-8's with serial #10600 and above the input marked "MIC" can
be simply converted to preamplification and equalization for tape heads
by cutting one wire on the input selector switch, (see figure B.)
On serial numbers below 10600 the conversion must be done at the factory
The cost of factory conversion is $5.00. Tape heads can, of course,
be used in "PHONO #1" on all C-8 compensators without any conversion.
For proper tape head connection see the top paragraph on page 4 of the
C-8 Instruction manual.
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(B.)
Now connect the program sources in the following fashion:
1.) Plug one end of the 3 foot shielded lead into the jack marked
"MAIN OUTPUT" located on the back panel of the C-8.
2.) The C-8 "VOLUME" control on the front panel is turned fully
clockwise. The changes in volume will be controlled by the C-8S ganged
"VOLUME" control.
3.) Insert the left channel phono cartridge lead in "PHONO #2" on the
C-8.
4.) If a tape deck is used for stereo playback, insert left channel
lead into "MIC" input of the C-8, serial #10600 and above, after conver-
sion as in section A, step #4 above. This input is terminated at 100,000
ohms. N.A.R.B. tape playback equalization is achieved by depressing the
Bass Compensation switch labeled "950", adjusting the "BASS" tone control
to - 1, and adjusting the "TREBLE" tone control to- 2.5.
If a stereo tape playback with preamplifiers is used, insert the
left output in the channel marked "TAPE".
(c.)
Next interconnect the C-8S:
1.) Plug the heavy inter-unit cable from the C-8S in the octal socket
marked "Pre-Amp" on the right power amplifier.
2.) The loose end of the 3' shielded lead (section B, step #1) from
the C-8 "MAIN OUTPUT" is plugged into the "LEFT STEREO IN" on the C-8S.
3.) Interconnect by means of one of the 6' shielded cables between
the jack marked "LEFT STEREO OUT" on the C-8S and the "0.5 VOLT" input
of the left power amplifier.
4.) Interconnect by means of the other of the 6' shielded cables between
the "MAIN OUTPUT" on the C-8S and the "0.5 VOLT" input on the right
power amplifier.
5.) Plug the A.C. cord from the C-8 into one of the auxiliary A.C.
receptacles on the C-8S.
6.) The A.C. cords from both power amplifiers can now" be plugged into
the auxiliary A.C. plugs on their respective preamplifiers. The on-off
switch on the volume control of the C-8S now controls turning on the
entire system.
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(D.)
Connect the program source equipment to the C-8S as follows :
1.) Plug the right channel phono cartridge lead into the C-8S input
marked "PHONO #2".
2.) Connect the output of the right channel tape head to the input
marked "TAPE HEAD". For N.A.R.B. equalization from a tape head, depress
the bass compensation switch labeled "950", adjust "BASS" tone control
to - 1, and "TREBLE" tone control to - 2.5.
3.) If a tape recorded with preamplifiers is used, plug the output of
the right channel into the input marked "TAPE".
4.) If a monaural cartridge is used, plug it into "PHONO #1".
5.) Connect a tuner output to input marked "TUNER",
(E.)
The balance of the stereo system will be maintained in all modes of
operation by following these system balancing instructions:
1.) Turn input selector switches on both preamplifiers to "PHONO #2".
2.) Turn the stereo "MODE" selector switch to "MON RIGHT".
3.) Adjust the "BALANCE," "BASS," and "TREBLE" controls to 12 o'clock.
4.) Adjust the RECORD COMPENSATOR" to RIAA settings.
5.) Adjust the "INPUT LEVEL CONTROL" on both compensator "PHONO #2"
channels totally clockwise. A monaural record is used for correctly
balancing the system. Turn up the volume control on the C-8S. With the
mode selector switch in "MON RIGHT" the same signal will be heard from
both loudspeakers.
6.) If the sound from each loudspeaker is not of equal loudness adjust
the control marked "GAIN" on one power amplifier until the sounds from
the loudspeakers are of equal intensity. Do not use the Balance Control
for this adjustment.
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7.) With th e monaural record playing , stand o n a line approximatel y 10
feet in fron t of and midway betwee n the loudspeakers . The main sourc e of
sound should appear to be directl y in fron t of you. If th e musi c sounds
are divide d the loudspeaker s are out of phase. Correct this by reversing
the loudspeaker lead s on one loudspeake r only. The power amplifiers now
are in phase and balanced . Do not chang e th e "GAIN" contro l on the
power amplifiers in any of th e following steps .
8.) Next balanc e for equa l tone quality o n each sid e by moving the
"MODE" switc h between "STERE O LEFT" and "RIGHT". Compare the hig h
frequency respons e on each loudspeake r first. Adjust the "TREBLE"'
tone control on one side only until the surface nois e from the recor d
on each sid e is of equal intensity .
9.) Next mak e a carefu l compariso n of low frequenc y response . Whil e
switching between "STERE O LEFT" and "RIGHT11 adjust th e "BASS" ton e
control on one compensato r until the bas s output is equa l from bot h
speakers.
10.) Remove the monaura l record . Next play a stere o record . Turn th e
C-8S volum e control up to room volume and adjust the "BALANCE" control
for balanced stereo results. The balanc e control is designe d to adjust
for unequal program sources, and maintain balanc e of th e system when
switching between "STEREO NORM " an d "REV".
Installation Precautions :
Caution mus t b e exercised in the installatio n to keep the groun d lead from
each channe l of the stereo cartridg e or stereo tap e heads separate to prevent
ground loops and hum .
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