Mcintosh C2300 Manuel d'utilisateur télécharger pdf (Page 21)

Control Circuit is unacceptable for use in the C2300, as

it does not match the classic McIntosh Volume Control

Audio Taper. The C2300 incorporates electronic circuitry

together with sophisticated firmware to produce electroni-

cally the classic McIntosh Volume Control Audio Taper,

while maintaining the channel balance and freedom from

control noise.

The Volume Control on the Front Panel of the C2300 is

actually a special digital optical encoder. As the Volume

Control is rotated, a beam of Infra Red Light is picked up

by two internal sensors as a series of digital pulses. Refer

to the exploded view in figure

29. The number of and time

between pulses are counted by

a Microprocessor which in turn

controls the McIntosh designed

Precision Electronic Attenua-

tor that provides 213 steps in

0.5dB increments and maintains

the channel balance to within +

0.1dB.

With most Preamplifiers the Volume Control is placed

ahead of the Amplifying Circuitry providing large dynam-

ic range and freedom from input overload however, back-

ground noise level is higher at lower settings of the volume

control. By placing the Volume Control after the Amplify-

Technical Description

ing Circuitry there is lower background noise however,

a reduction in dynamic range and input overload is the

result. The only correct way to design a high performance

Preamplifier is with two volume controls. This provides

the benefits of wide dynamic range, freedom from Input

overload and a background noise level that actually goes

down as the volume control setting is reduced. The special

controlling circuitry for this dual volume control design is

known as the McIntosh “Dynamic Control Multiplexer”.

Meter and Circuitry

McIntosh solved the problems with ordinary meters in

the C2300. By developing electronic circuits the meters

are made to respond to short intervals with an accuracy

of 95%! To permit the eye to see such high speed motion,

the electronic circuits that drive the meter pointer are time

stretched. Special logarithmic circuitry allows the meter

to indicate a 60dB plus range, without resorting to a Meter

Range Switch.

Power Supply Circuits

To compliment the design of the C2300 there are fully

regulated power supplies. The special “R” core transform

ers supplies the necessary voltage/current for the low and

high voltage regulated circuitry.

Figure 29

Infrared

LED

Optical Disc

Sensors

C2300 Block Diagram

1 2 ... 16 17 18 19 20 21 22 23 24

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Mcintosh C2300 Manuel d'utilisateur Page 21

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