Updated 6-18-2004
Quarter-A

Marantz introduced  the PM-94 and PM-84 integrated amplifiers that featured its patented Quarter-A circuitry in the late 1980s.  These amplifiers operated in Class A mode up to one-quarter of their rated output before switching to Class AB.  Class A circuitry was the domain of many high-end amplifiers having relatively low power, usually less than 50 watts. 

The Marantz PM-94 and PM-84 integrated amplifiers were the finest that the company had ever built, up to that time.  They featured a level of design sophistication and striking good looks that reflected the legendary Marantz quality the company had long been known for. 

Marantz started work on the Quarter-A series of amplifiers in the mid-1980s.  The PM-94, PM-84 and PM-74 were introduced to the American market in 1988.  The top-of-line, the PM-94, received rave reviews from all the audio magazines that tested it, including Stereophile.  Interestingly, Stereo Review chose to test the PM-74, as it was more in keeping with its mid-fi readership, but the article did mention the PM-94 and PM-84.  Although operating in Quarter-A mode and similar in exterior appearance, inside each amplifier was distinctly different, as you will find out at this website.

Design Influences

Marantz drew upon several of its legendary components when doing the control layout for the PM-94 and PM-84 integrated amps.  Both the 7T Pre-amplifier and the 1200B Integrated Amplifier can be seen to have influenced the design of the new PM series integrated amplifiers Marantz planned to market in the late 1980s.

 
Marantz 7T Preamplifier

Marantz 1200B Integrated Amplifier

Interestingly, the control layout on the PM-94 and PM-84 were a mirror image of the control layout on the 7T preamp and 1200B integrated amp.  On the '94 and '84, the left and right channel bass and treble controls are on left of the front panel, with selection and volume control knobs on the right; it is just the reverse on the 7T preamp. On the 1200B, there were no knobs for bass and treble, but sliding controls in the center of the panel. 

Clearly, with the PM-94 and '84, Marantz wanted to revive the classic Marantz look, coupled with sonic performance the rivaled any other integrated amplifier on the market.  In this, Marantz certainly succeeded.  Check the rest of the website and learn more about what in all probablility is the finest integrated amplifer Marantz ever built.

Anthony Young
Webmaster

Note: The Quarter-A Reference Site is non-commercial and for information purposes only.