Operating Instructions; Balancing A Stereo System; Range; To Adjust For Amplitude Balance In - McIntosh C20 Owner's Manual

BALANCING A STEREO SYSTEM

The ultimate in stereo performance and listening
enjoyment is obtained through the proper balancing of
the stereo system. A properly balanced stereo system
must be in phase. Each channel must be equal in loud-
ness and similar in frequency response. When the
proper balancing of the Mclntosh Model C20 Stereo-
phonic Pre-amplifier is accomplished, the stereo system
will remain balanced throughout all modes of operation.
To properly balance the Mclntosh C20 proceed as
follows: A familiar recording, either stereo or mono-
phonic, should be used in balancing the stereo system.
1. Turn the INPUT SELECTOR to PHONO 1 M.
2. Turn each RECORD COMPENSATOR control to
RIAA.
3. Turn the BASS and TREBLE controls to 0.
4. Turn the MODE SELECTOR to STEREO.
5. Turn the BALANCE and PHASE controls to O.
6. Turn the HF CUTOFF FILTER to the FLAT posi-
tion.
7. Turn the LOUDNESS control to FLAT.
8. With the controls set in this manner, a mono-
phonic signal of equal amplitude will be fed to each
side of the pre-amplifier.

TO ADJUST FOR AMPLITUDE BALANCE IN

THE TREBLE RANGE
Do not use the C20 BALANCE control for this pro-
cedure. The C20 BALANCE control is used to adjust
for any unbalance in the source material, the phono
cartridge, and the tape machine.
1. Adjust the BASS tone control to its full counter-
clockwise position.
2. While the recording is playing, alternate the
MODE SELECTOR between L and R positions. Adjust
the gain control on the input to the power amplifier
until the loudspeakers are of equal loudness.
When using the Mclntosh MC240 Twin 40 Watt or
MC275 Twin 75 Watt Dual Stereo Power Amplifier and
connecting the C20 to the stereo input jacks, merely
rotate the BALANCE control on the MC240 or MC275
until the loudspeakers are of equal loudness.
TO ADJUST FOR BALANCE IN THE BASS RANGE
1. Adjust the TREBLE tone control to its extreme
counterclockwise position.
2. Adjust the BASS tone control to its extreme
clockwise position. For an additional boost, if desired,
10

OPERATING INSTRUCTIONS

rotate RECORD COMPENSATOR control marked BASS
to the TAPE position.
ing this procedure. The bass sound will predominate.
In some installations it may be necessary to reduce the
volume to prevent acoustical feedback.
and listen carefully to the low-frequency response.
the back panel and establish balance by advancing the
controls, one more than the other.
pendent of the front panel tone controls and will adjust
only the low-frequency balance. This arrangement
leaves the front panel controls free to correct over-all
tone balance in the program, correcting for recording
or playback environment.
bass response when the C20 is adjusted for normal
playback, turn both LOW FREQUENCY TRIM controls
fully counterclockwise. Then bring the system into
balance by advancing only the trim control correspond-
ing to the loudspeaker producing less bass response.
response than you desire, the LOW FREQUENCY TRIM
controls may be turned fully clockwise. The system is
then brought into balance by reducing the bass re-
sponse on the loudspeaker producing the greater bass
amplitude.

ADJUSTING PHASE

RIAA. Set the MODE SELECTOR to STEREO.
way between the loudspeakers.
in front of you. Rotate the PHASE control from 0° to 180°.
If the source of sound is not directly in front of you in
0° position reverse the leads to one loudspeaker. The
PHASE control corrects phase in source material when-
ever necessary.
the stereo sound seems to come from both sides of
the room instead of being distributed between the
loudspeakers, adjust the PHASE control to 180°. This
listening effect is due to reproducing sound that is out
of phase from one channel to the other. You will find
some records differ from others in this respect and
some tapes differ from others.

LISTENING TO A STEREO RECORD

instructions, the C20 is ready for use. To listen to
stereo records, proceed as follows:
The music will have an unnatural tone balance dur-
3. Switch the MODE SELECTOR between L and R
4. Adjust the LOW FREQUENCY TRIM controls on
The LOW FREQUENCY TRIM controls are inde-
If your loudspeakers produce more than adequate
If your loudspeaker systems produce less bass
1. Rotate both RECORD COMPENSATOR controls to
2. Adjust BASS and TREBLE tone controls to 0.
3. Stand approximately 10 feet in front of and mid-
The source of sound should appear to be directly
If after having made this system phase adjustment,
Upon completion of the connecting and balancing
1. Set the MODE SELECTOR to STEREO.
2. Set the PHASE switch to 0°.