Onkyo M5100 Discrete Output Stage Amplifier 110 Watts Per Channel Excellent
Late 1980s-90s Vintage Onkyo M5100 Power Amplifier With Discrete Output. Sanyo called this "Discrete" as in they used Sanken 2SC3855's NPN and complimentary pair 2SA1491's PNP transistors rather than a monolithic power pack (STK-XXX) - that was in common use by many manufactures in Japan at the time. The output caps are Nichicon. This is one of Onkyo's Delta Line Powers Supply and typical large Power Transformer, although for some reason its listed on the front of the unit. (see photos). Cash Sale, No Holds, Call or Text.
Condition: This amp was tested on 4/14/22 and found to be in good working order. The amp is in excellent physical condition (perhaps mint), and per the service manual (copy included) meets all critical output specs (RMS). The center bar on the front is an AC Power On Indicator, not a level indicator. To the left is the Protection Circuitry Overload Indicator, comes on briefly during start up during normal operation. The amplifier has spring loaded rear speaker terminals, better than most this style, for up to two pairs of speakers. These can be selected from the front panel. Both A &B Speakers have Green LED on indicators. No output transistors have been replace, and no one but DALAUDIO has been in the unit. If I kept the amp, which I thought about, we would replace the spring loaded speaker terminals on the back, with 5 way banana style connectors. Not a terribly difficult or super expensive upgrade.
My thoughts: The amp was tested and sounds very clean, and dynamic, with output
consistent with its THD rating. This amplifier is rated to 110 watts per channel. Actually I was quite surprised how it sounded, very dynamic soundstage, and seemed to have ample headroom for my larger Vintage POLK SDA 2's which we use for auditions as I am most familiar with them. (Sensitivity: 92 dB - Suggested Amplification: 10-500 watts). So based on sound and condition, I raised the price. Its a nice name brand, made in Japan and its a fair price for the quality.
Note 1: The amp make a small thump (scope shows a low frequency sine thump) likely filter cap discharge, that can be heard through the speakers if its powered-off with any source active. Simple solution is to turn down everything and turn preamp off first.
Note 2: We have a matching 1990s Onkyo P-3300 Preamp and a Onkyo tuner that is also available, let us know if interested.
Specifications from the Service Manual.
- Power output: 110 watts per channel into 8Ω (stereo)
- Frequency response: 5Hz to 100kHz
- Total harmonic distortion: 0.09%
- Damping factor: 40
- Input sensitivity: 1V
- Signal to noise ratio: 100dB
- Dimensions: 17.2" W x 6.25" H x 11.4"D