well remembered Mozilla-esque & Gargantua-esque heavyweight
powerhouse which needs two people to be lifted : 63
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.
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 ; these transformers are to avoid the phase shift between
voltage and current in the amp-to-speaker signal path.
Most pronounced around the speaker's resonance frequency, this phase-shift
also happens between the voltage and the charging current in the
amplifier's power supply ; these charging currents may start fluctuating
along the low-frequencies contained in the musical signal. Out-of-phase
charging currents can generate electromagnetic flux which in turn
often induces voltages of the same incorrect phase in the nearby
driver stage (through which the audio signal passes) ; the problem
is then, naturally, sent to the loudspeaker... muddy bass and blurry
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 !
You can see the schematic of the Real Phase system by clicking the
"more" button below - click
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.
Linear Phase Switching is included
for true waveform linearity (see the Integra
P-308 page on TVK for details) and an elaborate complex protection
circuitry kicks in if necessary - 1,2kW per channel can transform
your fragile tweeters into live frisbees.
cool "waiting monitor" flashes some leds geometrically
while a dimmer allows to switch off the VU meters' lamps ; gold-plated
terminals and solid wood sideburns give the ultimate in reliability
and looks, respectively. Both the variable and direct inputs are
single-ended, though. The front flap hides the speaker selector
(A, B, A+B), variable input pots, dimmer, and meter range selector
(x1 or x0,1).
The Onkyo Grand Integra M-510
was lavishly displayed in a "Big New Sound" section in
Stereo Sound #73 (winter 1985), and was seen in many a japanese
Onkyo ad, often accompanied by the Grand
Scepter GS-1 horn loudspeaker. However, this golden Grand
Integra now remains... quite invisible.
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 !