Page 123 - Hi-Fi_News_-_December_2020 video

Physically, the M-2 power amp is an source of choice, Yamaha spared no ABOVE: Pictured stacked for illustration
imposing beast. Weighing in at 21kg, each expense when it came to the phono only – the M-2 power amp [below] produces a
side comprises a dedicated heatsink for the stage here, utilising a dual-FET circuit with considerable amount of heat and its perforated
output devices while the upper third of the multiple stages in a bid to minimise DC top cover needs to be kept clear for ventilation
case features a perforated drift while promising
metal cover, which the ‘New power reduced distortion and load. What’s more, the C-2a’s Phono 1
company hoped would an extended frequency selector had a fourth option, offering a
recall the appearance of a MOSFETs now response. In fact two 2.5mV MM input sensitivity combined with
classic tube amplifi er. phono inputs are 100ohm loading. This was intended for use
The front panel is fi tted formed the basis provided, with options with the new breed of high-output/low-ish
with one LED power meter of its amps’ selected via a dedicated impedance MC cartridges.
for each channel, the front panel control.
power on/off switch, and Phono 2 is a fi xed MM ADDED VALUE
selectors for two pairs of loudspeakers. input with a standard 47kohm load, but In addition, a pair of sockets on the rear

All the switches are illuminated – power Phono 1 could be configured for MM or of the C-2a gave capacitive loading
being amber and the loudspeaker selectors MC operation. For MM, loads of 47kohm, options for the MM Phono 1 input. With
lighting up green. 68kohm or 100kohm were available, while nothing connected, the load was 220pF
Naturally, a suitable matching preamp the standard MC input offered a 50ohm and plugs were provided to alter this to
was required and this came in the form of 330pF or 470pF. The manual also gave
the C-2a. With vinyl still the audiophile’s the appropriate calculation for the user
wanting to make up plugs for other values.
The rest of the C-2a was equally

well specified. Both Tuner and Auxiliary
inputs were offered, plus two tape loops
with a separate record output control.

High-precision metal film resistors and
polypropylene capacitors were employed
throughout while the amp’s volume control
was a four-gang unit unique to the model.
Two of these gangs were used on the input
to the amplification circuitry and two on a

subsequent gain stage, with the intention
that hum and noise be minimised at lower
volumes [see PM’s Lab Report, p127].
LEFT: The C-2a’s user manual (left) gives good
guidance on connectivity while the brochure
(right) digs deep into the hidden technology

DECEMBER 2020 | www.hifi news.co.uk | 123