McIntosh C29

Commentary

A preamplifier that takes over the amplifier technology of C28 and C32.

The input selector is a double-silver contact for structural robustness.
In addition, a shielded network at each high-level input and a short switch to ground unwanted inputs prevent feedback of signals between input circuits.

The Phono equalizer incorporates a newly developed IC and OP amplifier to achieve a low distortion and low noise differential input circuit.
In order to fully realize the low-noise effect, parts with less error are used for the feedback circuit.

We have developed and adopted an IC headphone amplifier with a distortion factor of 0.1% or less as a headphone amplifier.
It is possible to operate two dynamic headphones at the same time.
The volume can be adjusted with the headphone volume.

A pushbutton is used for switching, and the switch is mounted directly on the printed circuit board.
Since the input / output circuits to each tape deck are shielded, DC leakage from the other tape deck is eliminated, and pop noise and click noise generated during switching are reduced.

The volume control uses a high-precision step-type attenuator developed by Macintosh.
It consists of a control that divides the 70 dB range into 32 stages and volume OFF.

The loudness control can be controlled continuously and variably with the "Loud" knob.

The power transformer is triple shielded with copper plate, silicon steel plate and metal case to remove hum and improve the S / N ratio.
For 24 V output voltage, a 3,000 μ F capacitor is used. The full-wave rectified voltage is supplied to the monitor amplifier. 18 V is divided from this output voltage and supplied to the constant voltage circuit or OP amplifier circuit through the IC voltage control circuit.

With the current sensitive outlet circuit (SCR), when the player operates, the power of the preamplifier is also turned on.
When the player is turned off, the power supply is also turned off.
This function itself can also be turned off.

Model Rating

Type	Stereo preamplifier
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.5 dB
Distortion factor	0.02% or Less (20 Hz to 20 kHz, Rated Output)
Input Sensitivity / Impedance	Phono1, 2 : 2 mV (1 kHz) / 47k Ω (65 pF) AUX, Tuner, Tape1, 2 : 0.25V/250k Ω MIC : 2.5mV/500k Ω
Hum and noise	AUX, Tuner, Tape1, 2 : IHF 100 dB, 90 dB (without acoustic compensation) Phono1, 2 : IHF 90 dB, 80 dB (at 10 mV input)
Output Level / Impedance	Main output : 2.5V/10k Ω (at rated input) Tape output : 0.25V/10k Ω (at rated input) Headphone, Line output : 0.75 v (8 Ω), 2.5V/600 Ω
LF-HF Filter	50 Hz or Less, 7 kHz or More (12dB/oct.)
Voltage amplification factor (dB)	Input Main Tape Headphone, Line AUX, Tuner, Tape1, 2 : 20dB 0dB 30dB Phono1, 2 : 62dB 42dB 72dB MIC: 60dB 40dB 70dB
Semiconductor used	Transistor : 2 IC : 9 Silicon Diode : 11 LED : 8 pcs SCR : 1 LDR : 1
Bass Control	+ 20 dB ~ -20dB (20 Hz), 11-step switching
Treble Controls	+ 18 db ~ -18dB (20 khz), 11-step switching
Volume control	0 dB ~ -70dB, continuously variable
Pwer	120 VAC, 50Hz/60Hz
Power consumption	45W
External dimensions	Body : Width 375x Height 122x Depth 330 mm (Including Panlock) Front Panel : 406 mm W x 138 mm H
Weight	8.6 kg (Packed : 14.1 kg)