Furman IT1210 User Manual

FURMAN SOUND, INC.
1997 S. McDOWELL BLVD.

PETALUMA, CA 94954 U.S.A.

PHONE: [phone]

FAX: [phone]

Web: www.furmansound.com

E-Mail: [e-mail]

Introduction

Thank you for your purchase of a Furman IT-1210 10 Amp Balanced Power Isolation Transformer,
and congratulations on your choice. This specially wound and shielded toroidal isolation transformer
is designed specifically to reduce hum pickup by sensitive equipment when ultra-low-noise is a must.

Features

• Provides precisely balanced AC power for ultra-low-noise installations

• Typically gives a 16 dB improvement in background noise floor in system-wide installations

• Toroidal transformer with center-tapped secondary is the most efficient, compact design, with

least magnetic field leakage

• Soft Start circuit prevents turn-on transients and high inrush currents

• Faraday shield reduces electrostatic coupling between primary and secondary

• Extreme Voltage Shutdown circuit protects against dangerously high or low input voltages

• Microprocessor-control led "smart" AC voltmeter monitors line voltage, flashes alerts for

marginal and extreme conditions

• Provides basic power conditioning functions (spike suppression, RFI filtering)

• Ground fault interrupter (GFCI) protection

Description

Designed for the most critical, ultra-low-noise installations, the IT- 1210 can supply 10 amps of
balanced AC power to a home theatre system, recording studio, video or film production facility,
broadcast station, etc. Its purpose is to drastically reduce hum and buzz caused both by ground
currents from power supply filtering and by radiation from supply cables into sensitive signal
sources like guitar pickups, tape heads, and microphones. Its effect is startling! It not only
dramatically reduces the noise floor but also noticeably improves dynamic range and sonic clarity.

The IT- 121 O's heart is a specially wound and shielded toroidal isolation transformer with a
center-tapped secondary. It is housed in a 2-unit (3.5" high) rack mount chassis. The back panel
provides 12 balanced outlets, widely spaced with plenty of clearance for "wall warts"; the front
panel provides two more. An IT-1210 can be installed in minutes without need for an electrician. It
provides clean and completely safe power-there is no need to "lift grounds" or compromise the
integrity of safety ground wires to achieve hum, reduction.

Special features include an accurate, self-checking AC voltmeter that not only measures normal
voltages, but also flashes eye-catching special pattern alerts for off-scale but not extreme
conditions (80-90 or 130-140 volts); an Extreme Voltage Shutdown circuit to cause a protective
shutdown if the unit is exposed to dangerous voltages (like accidental connection to 220V)1- and a
special "Soft Start" circuit to prevent the large inrush surge currents and spikes that would
otherwise occur at turn-on and turn-off with such a large transformer.

Background

In much the same way that balanced audio lines can reduce the pickup of hum and other types of
electromagnetic interference (EMI), the use of balanced AC power lines in sensitive audio, video, or
computer installations can make an enormous difference in system noise. But power distribution in
North America, unfortunately, is not balanced. The distribution standards currently in use were
derived from practices established over a century ago, when electric power use was limited to
lighting and motors-long before any EMI-sensitive applications existed. The emphasis then was on
convenience (from the power utilities' standpoint) and safety, but not noise cancellation. The result
was a three-wire distribution scheme in which 120V branch circuits have a hot wire and a neutral
wire, with the neutral tied to a third wire connected for safety to an earth ground. The third wire does
not carry any current unless there is a short circuit. This unbalanced scheme causes hum in audio
circuits for two main reasons: First, the current flowing in the hot wire induces hum in any other
nearby wires, which may carry vulnerable low-level audio signals. Second, because the impedance
of chassis and cable shielding to ground is not zero, ground current flowing, from power supply
capacitors and from EMI pickup causes a voltage drop at 60 Hz and its harmonics which is added to
the audio signals.

With a center-tapped isolation transformer, the AC power feeding a studio can be balanced at its
source. The current carrying wires then are no longer "hot' (120V) and "neutral" (OV), but two equal
and opposite lines of 60V each (referenced to the safety ground connected to the center tap), whose
difference is 120V. This type of power, when run around a room, does not induce hum into nearby
audio wiring, because the two power conductors induce equal and opposite voltages that cancel
each other out. Similarly, ground currents are all but eliminated by the same common-mode
cancellation effect. No longer is it necessary to adopt cumbersome and expensive star-ground
systems or use massive bus bars or heavy ground rods. All such systems are doomed to yield only
mediocre results because of the impossibility of reducing the ground impedance to zero. The
common-mode rejection of a truly balanced AC supply is far simpler, cheaper, and more effective.

Balanced power is a technology whose time has come. Balanced, or "technical" power, is now
recognized by the US National Electrical Code (Article 530) for critical, low noise applications.

Installation -

The power source to which the IT-1 210 is connected must be adequate for use at 10 amps, and a
dedicated 15 amp circuit is recommended. Consult a qualified electrician if in doubt. The IT-1210 is
designed for mounting in a standard 19-inch equipment rack. Because of its weight, the best position
for it is the bottom slot of the rack. Its toroidal transformer minimizes magnetic leakage, but
nevertheless, due to its high capacity, it will radiate an appreciable magnetic field. Therefore, we
recommend that it not be positioned adjacent to sensitive, low level signal processors, especially mic
preamps, mixers, tape recorders, etc. Power amps may be more suitable "rack neighbors."

The maximum benefit is derived from balanced power when ALL equipment in an installation is
powered with it. Therefore, try to position the IT-1210 in a central location so its power can be easily
distributed everywhere it's needed. If the total power consumption of all equipment exceeds 10 amps
at 120 volts, delete high level or mechanical devices first (such as power amps, motors). If possible,
physically isolate any such equipment that has to be powered with conventional power through a
different circuit, and route their AC cords away from all other cabling.

The balanced power produced by the IT-1210 is restricted to use with electronic equipment only.
Balanced power may not be used for lighting equipment, and access must be limited to use by
qualified personnel only.

If you are installing the IT- 1210 in a rack that has rear as well as front mounting rails, you may
wish to order adjustable rear rack ears from Furman. They allow the IT-1210 to be securely attached
both in front and in back. Order model RRM-2.

Operation

Circuit Breaker/Switch: The IT-1210 has just one control: the large blue switch on the front panel

that is both a precision magnetic circuit breaker and an on-off switch. This breaker will trip (snap to
the "off" position) if the current drawn through the IT-1210 exceeds 10 amps. If this occurs, reduce
the load by unplugging some equipment, then flip the switch back to the "on" position.

Soft Start/Outlets On/Off Indicator: When power is first applied to the IT-1210, the Soft Start
feature is activated, indicated by a steady yellow color. Soft Start limits the inrush current to the
IT-1210's transformer, which would otherwise be excessive. The result is that the IT-1210's output
voltage does not reach its full level until several seconds have elapsed. When it has reached its
maximum level, the LED color turns to green, indicating that all outlets are fully powered.

Should the power at the IT-1210's outlets go off for any reason-either because the power switch is

in the "off" position or because an Extreme Voltage Shutdown has occurred, the LED will light up red.

Extreme Voltage Shutdown: This LED status indicator is normally off. It monitors a hazard
particularly common in the entertainment industry: wiring faults-for example, accidental connection to
220V. The IT-1210 senses voltages that are so high or low that operation would be impossible
(under 80V or over 140V) and shuts the power down before damage can occur. Upon initially
applying power to the IT-1210, this indicator will be lit if the input is receiving less than 80 volts or