Filter
Top Products
14
1. Your Cable TV or Satellite receiver box might require a Cable TV ground isolator.
2. Use balanced input lines with your Parasound A 31. (See Balanced and Unbalanced
Lines in this section).
3. When rack mounting, always use the insulated “shoulder” washers. These break the
ground loops caused by metal-to-metal contact between the rack, the components, and their
rack-mount bolts. Extra washers are available from rack manufacturer Middle Atlantic
Products, www.middleatlantic.com.
Bare Speaker Wire Ends
If you plan to use connections with bare wire ends, use a wire stripper to remove just
enough insulation to expose a 1⁄2" (13 mm) length of bare wire. You can insert the stripped
wire into the hole that goes sideways through the terminal’s metal post. Before inserting the
wire, twist its bare strands to prevent any of the strands from making contact across the two
speaker terminals. If you have a soldering iron, you can “tin” (apply a small amount of molten
solder) to each stripped bare wire to prevent it from unraveling, fraying and oxidizing.
Parasound A 31 Design Overview
Circuit Designed by John Curl
Parasound design consultant John Curl has been a legend among audiophiles and
electronic engineers for decades. He pioneered measurements to correlate musical accuracy
with the materials used in parts, worked with world-class touring companies, has designed
highly coveted audio classics, including the original Mark Levinson JC-2, Denneson JC-80,
Vendetta Phono Preamplifier, and CTC Blowtorch preamplifiers; master recorders for Wilson
Audio and Mobile Fidelity; and the mixing consoles used in live concerts by The Grateful
Dead and the Montreux Jazz Festival in Switzerland.
As our featured amplifier designer since 1990, he has created many products that have
earned Parasound worldwide acclaim. John is particularly proud of what he and Parasound
have accomplished together: “The circuits I design for Parasound are extremely sophisticated
and are typical of products that are far more expensive. I can’t think of any other audio
products that offer nearly as much bang for the buck.”
Parts Selection
Every part within the A 31 is carefully chosen for its accuracy and reliability. Metal film
resistors with 1% tolerance are selected for their precision and because their values don’t
drift as they heat up during operation. Polypropylene and mica capacitors are used
extensively for their superior linearity and low dielectric absorption. Semiconductors are
selected for superior performance in their specific roles in the circuit. Gold has the best
conductivity of any metal, so we use high quality gold-plated input connectors and speaker
terminals. The double-sided circuit boards are FR4 glass epoxy for long-term durability. The
chassis is made of heavy gauge steel to safely house the internal circuitry. This attention to
detail when selecting parts makes the difference between a very good amplifier and an
outstanding amplifier.
The Power Supply
The heart of the power supply is a 1.5 kVA toroid power transformer, chosen for its
efficiency, low hum field, and high power rating. Encapsulating this massive power
transformer in an epoxy-filled steel canister assures ultra-quiet performance.
The A 31 power transformer employs multiple independent secondary windings so that
each amplifier channel has its own power supply, assuring more than ample DC voltage at all