McIntosh C-20 (1959-1963)

McIntosh C20

La veste estetica del pannello anteriore è assolutamente unica ed affascinante, non solo per l'ampia dotazione di controlli ma anche dal solo punto di vista estetico. Il pannello dorato incornicia due riquadri neri realizzati in cristallo, che all'accensione si illuminano di una tenua luce che lascia intravedere gli indici delle manopole della riga superiore. All'estrema destra troviamo la manopola di accensione e del volume, sottolineata da tre pulsanti neri e dalle uscite di registrazione. Il notevole numero diingressi e di modalità di funzionamento hanno fato del C20 uno dei preamplificatori stereo che sono diventati un riferimento assoluto.

Per quanto riguarda le valvole le scelte sono varie in quanto vengono impiegate, per il segnale, le arcifamose 12AX7A/ECC83; la raccomandazione è di usare valvole di qualità visto l'importanza dell'apparecchio; la 6X4, valvola raddrizzatrice, è abbastanza facile da reperire anche di marchi famosi ed affidabili.

"Simplicity, flexibility, and beauty have been integrated by careful engineering and design in the McIntosh C-20 Stereo Compensator. The greatest listening pleasure in stereo or monophonic reproduction is assured as a result of over a year of careful and diligent research in hte requirements of a new preamplifier designed for stereo. Full stereo flexibility has been provided plus built in protection for your investment in monophonic records. McIntosh has designed in the C-20 Stereo Compensator the necessary features required to give the finest monophonic reproduction the keenest listener may require. Complete satisfaction is yours in monophonic and stereophonic with the McIntosh C-20 Stereo Compensator."

"The C20 is the only Stereo Control Console that has enough flexibility to control all program sources.

The C20 is the only Stereo preamp with enough record compensation for the valuable Monophonic as well as the new Stereo records.

The C20 has the most complete facilities for tape recording, playback, dubbing and monitoring.

The C20 has by far the simplest yet complete control of tone balance.

The C20 is by far the easiest to mount and still give professional appearance.

The C20 is produced from three years of careful thorough research and development"

CONTROLS

Input Selector: Selects any one of eight program sources including Tape, Tuner 1 and 2, Auxiliary, phono 1 and 2, Tape Head 1 and 2. Each phono input has two switch positions, one for stereo, the other paralleles the stereo cartridge for Monophonic records.

Mode Selector:

Reverse; connects left 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 speaker

M Right; right channel only to both speaker

Record Compensator: Separate bass and treble compensator switches including RIAA, LP, Tape-Head, flat position for microphone and other positions for monophonic records. (Turning TREBLE control to TAPE gives flat response. Turning BASS to 0 gives flat response.)

Tone Controls:

Treble: Boast 13 dB at 20,000 Hz, attenuate 18 dB at 20,000 Hz

Bass: boost 16 dB at 20 Hz, attenuate 20 dB at 20 Hz

Balance Control: To balance forunegual programsource. Turning control to left reduces right channel to No Output. Turning control to right reduces left channel to No Output

Phase Control: Reverses phase in the left channel to correct for speaker program phasing.

HF Cutoff Filter: Three positions providing (1) no filter action for normal use, (2) 9KC cutoff, and (3) 5KC cutoff to suppress record noise and hiss.

Loudness Control: Compensates for the Fletcher-Munson hearing character stics as program loudness is reduced.

Rumble Filter: Suppress low frequency disturbances such as rumble.

Tape: Front panel jacks, push button switch controlled to permit the addition of a portable tape recorder without disrupting the equipment permanently installed.

Tape Monitor: To permit instantaneous monitoring of tape before and after recording.

Low Frequency Trim Controls: On the back panel. Compensate for unequalresponse at low frequencies due to position at speakers or differences in speaker efficiency. Provides 6 dB boost at 50 Hz starting from 500 Hz or 8 dB cut at 20 Hz starting from 200 Hz.

ELECTRICAL:

Frequency Response: 20 - 20,000 Hz ±0.5 dB

Distortion: Less than 0.2% at rated output, 20 -20,000 Hz

Hum and Noise: High level inputs - 85 dB below rated output, Low level inputs, less than 2 microvolts at input terminals

Input sensitivity and impedance:

Aux, Tape, Tuner 1, Tuner 2; 0,25 volts at 470 kohm,

Phono 1 and 2: 2 - 10 millivolts at 47 kohm for low output cartridge, 10 -70 millivolts 47 kohms for hi output cartridge, 0,1 volt 220 mmf in series with 47 kohms for Xtal or Ceramic

Tape Head 1 and 2: 2 to millivolts 47 kohms for low output head

tape Compare (Monitor): 0,25 volts, 115 kohms

Main Output: 2,5 V with rated input 2 output jacks in parallel for each channel.

Tape Output: 0,25 V with rated input 1 output jack for each channel

Left plus right output: 2,5 volts from source impedance of 23 kohms

Voltage Amplification: Low level inputs to Main Output: 1,000 to 1 (60 dB) at 1000 Hz

Low level inputs to Tape Output: 100 to 1 (40 dB) at 1000 Hz

High level inputs to Main Output 10 to 1 (20 dB)

High level inputs toTape Output 1 to 1 (0 dB)

Tape Monitor Input to Main Output: 10 to 1 (20 dB)

A.C. Aux. Outlets: 1 unswitched for tape machine or turntable, colored Red; 4 switched, colored Black

Power Requirements: 117 volts 60 Hz, A.C. 35 watts

Size: 15⅝" W x 5⅛" H. overall depth of chassis behind front panel is 12" The space required in front of cabinet panel for the thickness of the panel and knobs is 1¼".

Weight: Chassis only 18 pounds. In shipping carton 28,5 pounds.