McIntosh 20W 2 Brochure

Page 1

77mm -;mme¢

Power output: 20 watts continuous; 0 watts instantaneous
peak.

Power output: 25 watts intermittent; 50 watts instantaneous
peak intermittent.

Elliciency: final stage 60% at 20 watts, 70% at 28 watts.

Gain: Basic Antplllier todb. 70d!) with pro-amp, 90db maxi-
mum with transformer.

Frequency range: 20 to 20.000 cycles + or - .05db, 10 to
100,000 cycles -i~ or ~- 3db.

Distortion: less then V§°/o 20 to 20.000 cycles tor 20 watts
output.

Intermodulation Distortion: less than 1% 20 to 20.000 cycles
(or instantaneous peak power to 40 watts.

Noise level: BOdb below lull output, 65db when pro-amp
used.

Damping factor: 10 or better. Can he made infinite or gen-
erator resistance negative if required.

Input Impedance: 100.000 ohms, with transformer 50, 250,
600 or 20,000 ohms.

Output impedance: 4, 8, 16, 32 or 600 ohms balanced-
connection to actal plug.

Tube Complement: Rectifier i-5Y3, Amplifier l-l 2AX7. 2-615.
2-6V6G.

Dimensions: consists at 1 unit BV- " x 6%" x 5%".

Weight: complete amplifier 27 lbr., shipping weight 30 lbs.
Power Consumption: 70 watts zero signal output 117 volts,
60 cycles line power input. 115 watts at 20 watts output.

the McIntosh arnpllfler circuit is lundarnentally new. It provides practically 100% coupling between
primary windings of the output transformer, by winding the primary wires together or bifilarly. Static mag-
netic fields due to DC plate current are cancelled and the AC fields add in phase in the McIntosh circuit.
Because of this, the high oflicieney of class "B" amplification can be used for the that time with high quality
performance. Wave form distortion due to switching transients between each half of the class B" amplifier
is eliminated at any audio frequency. the output tubes may be considered to use the some winding or to
"take turns" on a single winding instead of the conventional condition of 1 primary for each tube.

The McIntosh has an inherent large advantage over conventional circuits. By bringing the output tubes
electrically four time: closer together the impedance is V4 that ol the conventional circuit. The coupling to
the secondary is improved by a similar lactor of A to 1 since the primary to secondary turns ratio has been
reduced 2 to i. The Mclntosh "take turn" primary therefore has id to l advantage over the conventional
"push pull" primary.

lhe 'r'z cathode, V: plate loading provides a lead back lactor at lZdb which with an additional loop
load baclr ofiers the lowest distortion, most stable power amplifier made. low impulse distortion has required
a number at circuit consideratlans including the billlar choke drive coil as indicated In the schematic diagram.
This prevents the usual bias changes due to transient or impulse program material.

The circuit permits the maximum possible eficiency of wide band amplifiers and yet operates at lull
output with substantially less than 1% distortion at all frequencies 20 to 20,000 cycles.

Creative Audio Assouates
150 SOUTH HARRISON SWEET
EASY ORANGE. ttEW mist!
ORMIGE 66229