Technical Description - McIntosh MC257 Owner's Manual

Technical Description

McIntosh Laboratory, the company who introduced
the world's first amplifier that could be called "High
Fidelity", has done it again. The McIntosh engineering
staff has created a Power Amplifier without compro-
mise, using the most advanced McIntosh circuit design
concepts.
The MC257 has a continuous average power output
rating of 250 watts and with a peak output current of
25 amperes per channel; making this one of the most
advanced amplifiers available today. The distortion
limits for the MC257 are no more than 0.005% at
rated power output for all frequencies from 20Hz to
20,000Hz. Typical performance at mid frequencies is
less than 0.002%. The true distortion readings on the
MC257 are so low, it takes special measuring tech-
niques to make accurate readings. The MC257 can
deliver the best possible performance from any type of
high quality loudspeaker system. Refer to figure 15.
Creating an amplifier with this level of perfor-
mance did not come easily. Many months of design,
testing and measuring were required. Extensive con-
trolled listening tests, the ultimate form of measuring,
were made before the final design was accepted.
Design Philosophy
The design philosophy incorporated in the MC257
involved several different techniques, all based on
sound scientific logic. Every stage of voltage or cur-
rent amplification must be as linear as possible prior
to the use of negative feedback. McIntosh engineers
know how to properly design negative feedback cir-
cuits so they contribute to the extremely low distortion
performance expected from a McIntosh Amplifier.
The typical McIntosh owner would never accept the
approximately 100 times higher distortion of many
non-feedback designs. Refer to figure 16.
12
Figure 15