Onkyo M-510

Very well remembered Mozilla-esque & Gargantua-esque heavyweight powerhouse which needs two people to be lifted : 63 kilos.

Able to output 2x 1,2kW at 1 Ohm, one might imagine this having been aimed at PA reinforcement for deaf audiences but, in fact, the circuit's engineering are very much fine-tuned and almost microscopic.

The secret inside lies in the two secondary transformers : these are "In Phase" transformers which echo the Signal In-Phase Filters of the Integra P-308 high-end preamplifier. In Phase transformers are to cope with the reactive load of loudspeakers, and not only their resistive aspect.
Real Phase transformer are inserted between the positive and negative charging currents of the the power-supply and the capacitors : as the positive and negative currents pass through the transformer's two windings, unwanted peaks and dips cancel each other out - in phase !

Otherwise, the Grand Integra M-510 is real dual-mono amplifier : two power cords and two toroidal power transformers !
A fifth and common trafo is used for the meters and out-of-the-signal-path circuitry such as speaker relays. Each channel benefits from two 33,000µF / 100V capacitors - for a 99,000µF total...
Each channel's power board holds 7 pairs of (I believe Sanken) transistors, 28 in toto. Gargantua-esque indeed.

The front flap hides the speaker selector (A, B, A+B), variable input pots, dimmer, and meter range selector (x1 or x0,1).

Looks-wise a bit heavy-handed and tacky and not really discrete with its 27cm in height, but, hey - you can't be Gargantua and look like Minnie the Mouse !


This post was originally made possible thanks to Henrik who loaned a very informative USA catalog ; my own lavish japanese dedicated catalog and "technical leaflet" will follow for an update.