Marantz PM-15

Not to be mistaken with the recent PM-15S1 - this is the original PM-15.

All elements that make the PM-15 are either copper-plated diecast aluminium or... copper-plated diecast aluminium. The chassis base is that at 3mm thickness (!) while the front, sides and knobs are extruded aluminium.

The 600VA transformer is fully shielded with a copper foil and most of the other elements such as power transistors, caps, chassis separations and screws are... copper-plated.
The PM-15 makes for a massive amount of copper : 32kg :-)


At the center of Marantz technology, then, were HDAM modules : Hyper Dynamic Amplifier Module. HDAM modules are op'amps built with discrete components :
2 FETs, 5 bipolars, 4 diodes and 10 resistors all rolled into a copper enclosure.

The moving coil part of the phono stage uses dual-differential circuit and discrete componentry in its first stage, HDAMs in its second ; the XLR input's buffer uses HDAMs with ten FET transistors around it ; the preamp stage is configured as balanced DC servo.
PCBs aren't double-sided but of the 70µ kind just the same.

The volume pot is a 3,3cm diameter 4-gang from Panasonic structured like Victor's JP-S7 or the Kyocera C-910 (among others) : acting on input gain and output level of the preamp output HDAMs at the same time for better linearity at low levels and even less noise.
Speakers' outputs are damped with two 4,7 Ohm self placed in series.

Added to the power supply is a CCNE circuit : a cap and precision resistor are added between the power transformer and the rectifying diodes and shielded into resin...
The two beer-size cans are 22,000µF / 80V ELNA caps made for Marantz.

Output stages are HDAM driven, of course, while the output devices consist of two pairs of Sanken bipolars per channel : 2SC2292 and 2SA1216 (Pc=200W / 180V / 17A).
Like all the amplifiers from the series (PM-99SE, PM-90, SM-80 etc), the PM-15 works in Class A/B so the first 20 or 30W per channel are in full Class A.

Look-wise a little heavy on heaviness (or leaning on a strong '57 Chevy bumper complex), sound-wise the PM-15 is... perfect.
I for one don't see any reasons to go beyond this level of quality : State of the Art as they say.


Now, abouth that other, more recent, PM-15...
If a glance at the guts of it tells more than many words, there is another way to look at this evolution : between 1993 and 2007, the price of copper has quadrupled and that of aluminium has tripled.

Simply put : building a PM-15 the way it was built in 1994 just isn't possible anymore.


The original PM-15 was in the supreme league and it still is. Despite a consequent pricetag, the PM-15 sold very well - very easy to find today.

If you want the same in (even) bigger mode, the rare sc-5, bb-5 and sm-5 trio is the way to go.