Marantz 8B (1962)

Model 8B Dual Thirty-five, Stereophonic Power Amplifier

In this ultra-linear high performance amplifier, Marantz offers you all the beauty of contemporary design. With its optional grille snapped into place, the kodel 8B presents a smooth, uncluttered appearance consistent with the precision of its contemporary electronics. All connections are made in the rear to permit neat installation. Wherever you place the Model 8B its beauty will attract, its name will enhance, its performance will satisfy and endure.

The Model 8B is essentially two 35 watt amplifiers on one compact chassis. Built-in metered adjustments assure balanced performance of both channels.

Power Output per Channel: 35 watts (70 watts peak) "Ultra-Linear" operation. Nearly 20 watts of excellent Triode operation can be obtained by altering two connections inside chassis.

Response (at 35 watts): Within 0,2 dB from 20 cps to 20 kc (equivalent of ± 0,1 dB). Within 1 dB from 15 cps to 40 kc into "Grid" input. At 0,5 watt: ±1 dB from 3 cps to 40 kc. Response has been deliberately rolled off approx. 7 dB at 100 kc to control transient response. Subsonic Filter in standard "Input" alowly rolls response off below 20 cps (less than 1 dB at 20 cps: -10 dB at 3 cps. etc)

Distortion (THD at 35 watts): Less than 0,1% at midfrequencies. Less than 0,5% from 20 cps to 20kc. Intermodulation distortion at 35 watts equivalent (70 watts peak): Less than 0,5% (60 cps/12 kc, 4:1): (I.M. messurement of typical amplifier: 35 W. equiv. 0,5%; 30 W equiv. 0,28%; 20 W equiv. 0,17%; 10 W equiv. 0,11%). Distortion below 35 W is largely of second order, and reduces rapidly with signal level.

Inverse Feedback and Stability: 20 dB of overall feedback. Great care has been taken to ensure stability and low distortion under widely varying loads, both resistive and reactive, such as are encounterd in loudspeaker systems. Power supply surges are balanced out of signal channels providingexcellent recovery from strong transients. Will not oscillate under any condition of open circuit capacitive load.

Motored Tests and Adjustments: Built-in meter and test switch provide accurate adjustment of each output tube bias. This makes the use of matched tubes unnecessary.

Adjustable Dynamic Balance (located subchassis) pre-set at factory.

Damping Factors: Greater than 20 from 20 cps to 20 kc (instructions given for optional insertion by the customer of two additional resistors to provide damping factors of 2, 11, or 0,5)

Output Connections: 4, 8 and 16 ohms

Input Sensitivity(for 35 watts): 1,3 volts RMS into 250K

Hum: Better than 100 dB below 35 watts containing proportionatelylittle of high orer harmonics.

Power Supply: The use of Silicon rectifiers, three telephone quality electrolytics and choke, provide excellent regulation, and thorough filtering, together with long life.

Power Requirements: Design center: 117 volts, 60 cycles. Range: 105 - 125 volts, 50/60 cycles.

170 watts of zero signal; 250 watts of maximum signal.

Tube Complement: 2 x 6BH6, 2 x 6CG7, 4 x EL34/6CA7

Dimensions: 13½ x 7¼ x 10½ inches (wide x high x deep)

Weight (shipping): 55 lbs