MC INTOSH C20
Stereo tube preamplifier
FRONT PANEL : anodized gold and black crystal. Upper line : Mode selector (rev / stereo / L / R / m left / m right) - Balance - Phase (0° - 180°) HF cut-off filter ( flat / 9 KC / 5 KC) Aural comp (flat 5) Volume. Lower line : input selector (aux- tape- tuner 1- 2 phono 1 stereo/mono phono 2 stereo/mono tape hd 1-2). Record compensator : bass treble. Bass and treble controls. Rumble tape jack tape compare push-buttons. Tape jacks.
PANNELLO FRONTALE : in anodizzato oro e cristallo nero. Linea superiore : Mode selector (rev / stereo / L / R / m left / m right) - Balance - Phase (0° - 180°) HF cut-off filter ( flat / 9 KC / 5 KC) Aural comp (flat 5) Volume. Linea inferiore : input selector (aux- tape- tuner 1- 2 phono 1 stereo/mono phono 2 stereo/mono tape hd 1-2). Record compensator : bass treble. Controlli bass e treble. Pulsanti rumble tape jack tape compare. Ingressi tape.
No anodized bar in the middle line. Loudness term substitutes aural comp.
Ultima versione : assenza della barra centrale in anodizzato. Dicitura Loudness anzichι Aural comp.
REAR PANEL. In the upper line : main output, tape output, left and right low frequency trim inputs (tape monitor,aux,tape,tuner 1,tuner 2). In lower line: 4 AC outlet (1 unswitched for tape machine or turntable, colored red; 3 switched, colored black- total capacity 600 w max), Bright/Pilot/Dim selector, Phono 1 inputs ( xtal/ceramic low and high magnetic) Phono 2 inputs ( xtal/ceramic low and high magnetic), tape head 1 (low and high), tape head 2 (low and high).
PANNELLO POSTERIORE. Sul livello superiore : main output, tape output, left and right low frequency trim inputs (tape monitor,aux,tape,tuner 1,tuner 2). Sul livello inferiore : 4 prese di alimentazione AC (1 unswitched per tape o giradischi, colore rosso, 3 switched, colore nero - capacitΰ totale 600 w max), Bright/Pilot/Dim selector, Phono 1 inputs ( xtal/ceramic low and high magnetic) Phono 2 inputs ( xtal/ceramic low and high magnetic), tape head 1 (low and high), tape head 2 (low and high).
Top view open
(from the original Mc Intosh brochure)
Selects any one eight program sources including Tape, Tuner 1 and Tuner 2, Auxiliary, Phono 1 and Phono 2,Tape Head 1 and Tape Head 2. Each phono input has two switch positions, one for stereo the other parallels the stereo cartridge for Monophonic records.
Reverse: connects left channel to right speaker, right channel to left speaker, corrects for left-right reversal of program.
Stereo: (normal Stereo mode selector position) left channel to left speaker, right channel to right speaker.
Left: left channel to left speaker no program to right speaker.
Right: right channel to right speaker, no program to left speaker.
M Left: left channel only to both speakers. M Right: right channel only to both speakers.
Separate bass and treble compensator switches including " R I A A , " "LP," "Tape-Head," flat position for microphone and other positions for monophonic records. (Turning "TREBLE" control to "TAPE" gives flat response. Turning "BASS" to "O" gives flat response.)
Treble: boost 13 db at 20,000 cycles attenuate 18 db at 20,000 cycles.
Bass: boost 16 db at 20 cycles, attenuate.20 db at 20 cycles.
To balance for unequal program source: Turning control to left reduces right channel to No Output Turning control to right reduces left channel to No Output.
Reverses phase in the left channel to correct for speaker or program phasing.
HF Cut-off Filter:
Three positions providing (1) no filter action for normal use, (2) 9 KC cut-off, and (3) 6 KC cut-off to suppress record noise and hiss.
Compensates for the Fletcher- Munson hearing characteristics as program loudness is reduced.
Suppress low frequency disturbances such as rumble.
Front panel jacks, push button switch controlled to permit the addition of a portable tape recorder without disrupting the equipment permanently installed.
To permit instantaneous monitoring of tape before and alter recording.
Low Frequency Trim Controls:
On the back panel. Compensate for unequal response at low frequencies due to position of speakers or differences in speaker efficiency. Provides 6 db boost at 50 cycles starting from 500 cycles or 8 db cut at 20 cycles starting from 200 cycles.
Main Output: 2.5V with rated input 2 output jacks in parallel for each channel
Tape Output: 0.25V with rated input 1 output jack for each channel - Left plus right output: 2.5 volts from source impedance of 23.000 ohms
Voltage Amplification: Low level inputs to Main Output: 1,000 to 1 (60db) at 1000 cycles
Low level inputs to Tape Output: 100 to 1 (40db) at 1000 cycles
High level inputs to Main Output: 10 to 1 (20db)
High level inputs to Tape Output: 1 to 1 (0db)
Tape Monitor input to Main Output: 10 to 1 (20db)
A.C. Aux. Outlets: 1 unswitched for tape machine or turntable. colored Red; 4 switched, colored Black
Power Requirements: 117 volts 60 cycles A.C. 35 watts
Size: 155/8" wide by 51/8" high. Overall depth of chassis behind front panel is 1213/16".. The space required in front of cabinet panel for the thickness of the panel and knobs is 1Ό".
Weight: Chassis only 18 pounds. In shipping carton 28½ pounds.
Frequency Response: ±0.5 db 20 to 20,000 cycles
Distortion: Less than 0.2% at rated output, 20 to 20,000 cycles
Hum and Noise: High level inputs: 85 db below rated output
Low level inputs: less than 2 microvolts et input terminals
Input Sensitivity and Input Impedance:
Auxiliary: 0,25 volts 470.000 ohms
Tape: 0.25 volts 470,000 ohms
Tuner 1: 0.25 volts 470,000 ohms
Tuner 2: 0,25 volts 470,000 ohms
Phono 1: 2 to 10 millivolts 47,000 ohms for low output cartridge
10 to 70 millivolts 47,000 ohms for hi output cartridge
0.1 volt 220 mmf in series with 47,000 ohms for Xtal or Ceramic
Phono 2: Same as phono 1
Tape Head 1: 2 to 10 millivolts 47,000 ohms for low output head
Tape Head 2 : Same as tape head 1
Tape Compare (Monitor): 0.25 volts, 115,000 ohms
Are available on request the owner's and service manual with schematics.
Sono disponibili a richiesta il manuale di istruzioni e di servizio con gli schemi.