Denon PM-750 DC amplifier restored

DENON is a respectable audio brand born in 1939. Starting with professional audio gea, it added Hi-Fi components production in 1971. The word DENON is in fact a contraction of  "Japan Denki Onkyo".  "Denki" means electrical and "on" is the shortcut to "Onkyo" meaning "acoustics".

After some serious introductions on the professional audio and awards by the musical industry, here we are in 1983 with this amplifier. We are facing a high quality piece of equipment. Back in the day only the finest dealers had DENON gear, and it was a good bet as for quality equipment, they were still less pricey than Luxman.

By chance this example is a silver one, with a real smooth visual impression (the black models look too modern).

Lots on technology is on board. We are on the DC conception period (Direct Current concept, to get lots of clean current to the output, competitors like Marantz, Harman/Kardon were exploiting the same concept). The output stage is equipped with what DENON calls the "Unique zero cross linear bias circuit" (the what?). The purpose of this design is "to eliminate the switching distortion caused by the cutoff of the power transistor and to achieve both the quality of class A amplifiers and the high efficiency and high output of class B amplifiers". Among other benefits, we have a direct source switch to bypass all equalisation, MM/MC capability, rec monitor… all signs of a top of the range piece.

In short both quality and power are present. So is the weight. And Man, this amp sings! Powerful, warm and clean, the bass is responsive, the mids are rich and the highs like crystal. As usual with Japan-born amps, you have the feeling the power written on the specs card is too modest to be true. 

The listening let us very happy, as we think that this piece can drive anything beautifully, from the laziest speakers to the most cascading digital sources. It may not look overly vintage, but the point is the sound it delivers.

We had the chance to pick this example from a careful non-smoking user (with a reason for sale being: i have other ones - the same ones in fact…).

This model tends to be very sensitive when warming a bit, and entering security mode with age. Renowed specialist LaboDiva just did a great job in refurbishing the main board soldering stage, the protection relay and overall command overhaul. The Denon is now ready for years of pleasure.

Finished in silver.

Fully cleaned, tested, deoxydized and sanitized unit.

Perfect working condition, see the photo gallery for potential cosmetic signs of patina and age.