Audio Database

The

McIntosh C29 a price point -- unknown (1970 in-the-earlies ?)

Description
 
The preamplifier which succeeded the amplifier technology of C28 and C32.

An input selector is used as a double silver contact, and is structurally made strong.
Moreover, the operation of the network shielded in each high-level input and the short switchpoint which grounds an unnecessary input is kept from a signal being fed back between input circuits.

Newly developed IC and OP amp were carried in the Phono equalizer, and low-distortion low-noise-ization of a difference input circuitry is realized to it.
In order to fully demonstrate the low-noise effect, the part with little error is adopted as a feedback circuit.

IC headphone amplifier of 0.1% or less of a distortion is developed and adopted as headphone amplifier.
It makes it possible to operate dynamic type headphone to a two-line concurrent.
A sound volume can be adjusted in the volume only for headphone.

The switching is using the push-button and, as for picking, the switchpoint is directly attached to the printed circuit board.
Since the input/output circuitry to each tape deck is shielded, it removed the direct-current leakage from a partner's tape deck, and has reduced the pop noise generated at the time of a switching, and the it1 noise.

The original high precision step type Attenuator of a mac company is adopted as volume control.
It consists of the controls and Volumes OFF which divided a span of 70dB into 32 steps.

A loudness control is controllable with the "Loud" thumb on a succession variable target.

In order that a power transformer may remove a hum and may raise an SN ratio, it is shielded by Mie with a copperplate, a silicon-steel board, and metal casing.
In the Output voltage of 24V, by a 3,000-micro F capacitor, monitor amplifier is supplied, and the voltage by which full wave rectification was carried out pressures 18V partially from this Output voltage, and supplies a voltage stabilizer and an OP-amp circuitry through IC voltage control circuitry.

By the feeling ability outlet circuit of an electric current (SCR adoption), if the player operates, the power source of a preamplifier will also be in ON status.
If a player is come by off, a power source will also be in an OFF status.
It is also possible to turn OFF this functionality itself.

Rear
Phono Power

Rating of a mode
Form Stereo preamplifier
Frequency characteristic 20Hz-20kHz+0 -0.5 dB
Distortion 0.02% or less (at the time of 20Hz - 20kHz, and an Output power)
Input sensitivity/impedance Phono1, 2:2mV (1kHz) / 47kohm (65pF)
AUX, Tuner, Tape1, 2:0.25V/250kohm
MIC: 2.5mV / 500kohm
A hum and a noise AUX, Tuner, Tape1, 2:IHF 100dB, 90dB (with no auditory sensation weighting)
Phono1, 2:IHF 90dB, 80dB (at the time of a 10mV input)
An Output voltage/impedance Main output: 2.5V / 10kohm (at the time of a rated input)
Tape output: 0.25V / 10kohm (at the time of a rated input)
Headphone and Line output:0.75V (8ohms), 2.5V/600 ohm
line feed character-HF filter 50Hz or less, 7kHz or more (12 dB/oct)
Voltage amplification (decibel)
Input Main Tape Headphone, Line
AUX, Tuner, Tape1, 2 : 20dB 0dB 30dB
Phono1, 2 : 62dB 42dB 72dB
MIC: 60dB 40dB 70dB
The semiconductor used Transistor: Two pieces
IC: Nine pieces
Silicon diode: 11 pieces
light emitting diode: Eight pieces
SCR: One piece
LDR: One piece
Bass control + 20dB--20dB (20Hz), an 11-step switching
Treble control + 18dB--18dB (20kHz), an 11-step switching
Volume control 0dB--70dB, a succession variable
Power source AC120V, 50Hz/60Hz
Power consumption 45W
Dimensions Main unit: Width 375x height 122x depth of 330mm (pan nowait-lock included)
Front panel: Width 406x138mm in height
Weight 8.6kg (at the time of an original packaging: 14.1kg)