STEREO PREAMPLIFIER C11 GENERAL DESCRIPTION 1 TECHNICAL DESCRIPTION Mechanical Specifications 1 2 Electrical Specifications TABLE OF CONTENTS 2 FRONT PANEL FACILITIES 2 BACK PANEL FACILITIES 5 INSTALLATION 6 CONNECTING 8 A-C Connections Input Connections Output Connections Loudspeaker Phasing Connections Ground Connection OPERATING INSTRUCTIONS Balancing a Stereo System Adjusting Phase Listening to a Stereo Record Adjusting the Balance Control After the System has been Balanced Adjusting fo
C11 STEREOPHONIC PREAMPLIFIER GENERAL The Mcintosh C11 Stereophonic Preamplifier is a control center for any stereophonic sound system. To increase the enjoyment of stereo, this control center does four jobs with precise control. First, the control center amplifies weak electrical impulses. As the record rotates on the turntable, undulations in the grooves move the pick-up stylus approximately onethousandth of an inch, in any direction, from the rest position.
MECHANICAL Dimensions Chassis: 14½ inches wide; 4¾ inches high; 12 inches deep including connectors. Front Panel: 15¾ inches wide; 51/8 inches high Front Panel Mounting Space Required: 16 3 / 8 inches wide; 5¼ inches high SPECIFICATIONS Weight Chassis: 15 pounds Shipping Weight: 25 pounds Finish Anodized gold and black (front panel) ELECTRICAL SPECIFICATIONS Main Output 2.
INPUT SELECTOR INPUT SELECTOR TUNER 2 PHONO 1 TUNER 1 PHONO 2 TAPE MIC AUX TAPE HD Select any one of eight program sources with this switch: 1. AUX: any auxiliary service requiring flat amplification, such as a television set, is connected to the C11 through this position. 2. TAPE: any self-contained tape machine (tape machine having its own playback preamplifier) is connected to the C11 through this position. 3.
BALANCE BALANCE 0 LEFT RIGHT This two-positioned switch reverses the phase in the left channel to correct for loudspeaker or program phasing. POWER POWER ON The C11 is balanced for unequal program sources by this control. LEFT . . . turning the control to the left accents the left channel by reducing the right channel output. RIGHT . . . turning the control to the right accents the right channel by reducing the left channel output.
VOLUME VOLUME This continuously variable control regulates the volume for both channels. OUTPUT LEVEL CONTROLS Under the panel end caps are the thumb wheel OUTPUT LEVEL CONTROLS. The L OUTPUT is on the left-hand side. The R OUTPUT is on the right-hand side. BACK PANEL FACILITIES Figure 2. C11 Back Panel AC OUTLETS OUTPUT CONNECTIONS There are five AC outlets on the left-hand side of the rear panel. (See Figure 2.) These outlets have a maximum rating of 660 watt total.
HIGH LEVEL INPUTS These receptacles accept high-level program source connections as follows: TAPE MONITOR (COMPARE) . . . accepts a signal from a tape recorder with a monitor head and preamplifier. AUX . . . accepts any auxiliary service requiring flat frequency response, such as a T.V. set, tuner, tape recorder with its own playback preamplifier, etc. TAPE . . . accepts connection from a tape machine with its own playback preamplifier. TUNER 1 & TUNER 2 . . .
MAKING THE FRONT PANEL CUTOUT The panel is cut out using the "FRONT PANEL CUTOUT TEMPLATE." To position the template on the front of the panel, make two locating holes from the back (inside) of the panel using one of the mounting strips (½ inch by 3½ inches) as a measuring tool. Proceed as follows: Scribe a vertical center line through the exact center of the proposed cutout area from the top of the panel to the top surface of the shelf as illustrated in " A , " Figure 3.
inch thick. Secure the chassis with the proper length 10-32 machine screws, inserting them from beneath the shelf. Do not tighten the 10-32 screws until you have tightened the front panel screws. IMPORTANT: USE OF THE WRONG LENGTH 10-32 SCREWS MAY CAUSE ELECTRICAL SHORTING IN THE CIRCUIT. END CAP Attach the two metal panel end caps (packed with mounting hardware) on each end of the panel by sliding onto the pins. (See Figure 5.
The C11 provides eight separate program inputs controlled by the INPUT SELECTOR switch and one input for tape comparison or monitor. The input program connection should be made in accordance with Tables 1 and 2. Figure 7. C11 Input Connections (Back Panel) INPUT SENSITIVITY INPUT IMPEDANCE The tape monitor input accepts a signal from a tape recorder with a monitor head and preamplifier. 0.25 V 250K AUX The auxiliary input accepts any auxiliary service requiring flat frequency response, such as a T.
Figure 8. Turntables Feeding Low Level Input OUTPUT CONNECTIONS Two sets of outputs, located in the upper left-hand corner of the back panel, are provided. (See Figure 2.) The MAIN output connects to power amplifiers (Figure 9) and the TAPE output to feed a tape recorder. The MAIN and TAPE output jacks are fed from cathode followers.
treble response, turning it counterclockwise decreases the treble response. Use the controls to compensate for 3% tape speed for individual tape head characteristics. A left plus right output jack is next to the MAIN output. It is marked L+R. A monophonic signal can be distributed to other rooms by connecting a third power amplifier to the jack marked L+R. This amplifier is used to drive the monophonic loudspeakers. The cable connecting to this output should not have a capacity of more than 200 mmf.
ADJUSTING PHASE 1. Place the COMPENSATOR switch in the RIAA position. 2. Set the MODE SELECTOR to STEREO. 3. Turn the BASS CONTROLS and TREBLE CONTROLS to 0. Stand approximately 10 feet in front of and midway between the loudspeakers. The source of sound should appear to be directly in front of you. Alternate the PHASE switch between NORMAL and REVERSE. If the sound is not directly in front of you in the NORMAL position, reverse the leads to one loudspeaker.
4. The conductor's idea of tone balance at the time the recording was made. 5. The microphone frequency response characteristics. 6. The recording process influences. These factors can be considered as environmental influences. The BASS CONTROLS and TREBLE CONTROLS are designed to provide a degree of compensation for effects of environment. Listen to your system with each control set to zero.
EQUALIZATION CURVES 25 20 15 10 RESPONSE IN DB 5 0 -5 -10 -15 -20 -25 20 1KC 100 IOKC 20 KC 10 KC 20 KC FREQUENCY Figure 1 0 . Equalization curves. BASS AND TREBLE CONTROLS 20 15 10 RESPONSE IN DB 5 0 -5 -10 -15 -20 20 100 1KC FREQUENCY Figure 1 1 . Bass and treble controls.
RUMBLE AND HIGH FREQUENCY FILTERS 0 -5 R E S P O N S E IN DB -10 -15 -20 -25 -30 100 20 1 KC FREQUENCY Figure 12. R u m b l e filter and high frequency 10 KC 2 0 KC 10KC 20 KC filter. LOUDNESS CONTROL 20 15 RESPONSE IN DB 10 5 0 -5 -10 -15 -20 20 100 1KC FREQUENCY Figure 13. Loudness control.
Your C11 will give you many years of pleasant and satisfactory performance. If you have any questions concerning the operation or maintenance of this preamplifier please contact: Customer Service Mcintosh Laboratory Inc. 2 Chambers Street Binghamton, New York Our telephone number is 723-5491. The direct dial area code is 607. GUARANTEE Mcintosh Laboratory Incorporated guarantees this equipment to perform as advertised.
LABORATORY INC. 2 CHAMBERS STREET, BINGHAMTON, N. Y. Made in U.S.A. Phone-Area Code 607-723-5491 Printed in U.S.A.
