New dielectric capacitors and one output transistor replaced. DC offset calibrated.

Restored/calibrated over 200 power amplifiers. Can’t keep them all. Electrical Engineer Oklahoma (GI bill), US Navy Electronic technician, was certified to repair nuclear submarine communication equipment..advanced soldering skill certificate. Goal is to restore these units and let others enjoy.

S&M in the model name stand for Stereo/Mono. As a stereo amplifier, the SM-70 delivers 25 robust watts per channel into 8 ohms, and at the flip of a rear-panel switch, the amp becomes a monoblock that can deliver in excess of 70 watts into 8-ohm loads

One balance input for bridged mode or use

RCA input jacks for either stereo or bridge mode.

Here is an affordable class A stereo power amp!

Simply outstanding sound quality. If u own a 8 ohm center channel run this amp in bridge mode/monitor mode. Or use it for left and right in stereo mode.

I can’t recall one sounding as good as this one.

Note to use in mono mode for center channel speakers need to be 8ohms. Bridge mode on any amp halves the speaker impedance in half. So 8 ohm speaker appears as 4 ohms to the power amp. Thus, 4 ohm speakers appear as 2 ohms. The heat is just too much on any amp in bridge for a 4 ohm speaker.

I had them setup driving my new b&w s3 floor speakers in mono/ bridge mode just blew me away.

The SM-70 features all-FET circuitry from input to output. Four output MOSFETS are used in each amplifier, with each device rated to handle 100 watts. A 140-watt toroidal transformer is standard equipment. The input sensitivity is very high, requiring only 1.35 volts peak to peak for full rated output.

The amplifier is a class-A design

Frequency Response:

20Hz to 30KHz +/- 0.5 dB

THD: under 0.05%

S/N Ratio: better than 90 dB stereo mode, better than 100 dB Balanced mono mode

Power Output:

Stereo Mode: 8 Ohm Load: 25 Watts rms × 2, 4 Ohm Load: 40 Watts rms × 2

Mono Mode: 8 Ohm Load: 80 Watts rms, 4 Ohm Load: 120 Watts rms

Minimum Load Impedence tolerated: 3 Ohms continuous, 2 Ohms intermittent

Input Impedence: 100k-Ohm

Input Sensitivity: 1 Volt rms for full output

Dimensions: 5″ × 11″ × 13″ (H × W × D)

24 lbs