Owner's Manual

15
Total Protection - DC Servos
Even a miniscule amount of Direct Current (DC) will burn out speakers without any warning. Every power
amplifier must have some way to insure that DC from its power supply never reaches its + or - speaker
terminals. Most amplifiers simply use adjustable trim controls to reduce their DC offset or capacitors to block
DC. Unfortunately, trim controls can allow DC offset to increase over time, and even the most expensive
capacitors in the audio signal path will “veil” sonic clarity and attenuate bass response.
Parasound power amplifiers incorporate ingenious and fast-acting DC servo circuits, completely
eliminating the need for coupling and blocking capacitors. The A 23+ is direct (DC) coupled from its input
jacks to its speaker terminals. This advanced circuitry never needs adjustment or maintenance. It operates
outside the audio signal path to keep the DC offset at the output of the A 23+ at a constant 0.00 Vdc. The
results are startling clarity, freedom from listening fatigue, and formidable bass response.
Total Protection - Relays
Each channel of the A 23+ has a high-quality protection relay with gold-plated contacts for long-term
reliability. These relays function to protect either the amplifier, the speakers, or both. When the A 23+ is first
powered on, these relays remain open for approximately three seconds as the positive and negative power
supplies stabilize and reach equilibrium with no DC offset at the speaker terminals. This prevents annoying
popping or other transient noises. Relay protection also prevents damage to your speakers in case of a
catastrophic amplifier failure. Any amplifier that doesn’t use relay protection for its speaker outputs
compromises the safety of the amplifier and your speakers.
Total Protection - Current Overload
Specialized current-sensing transistors are connected to the output stages of the A 23+ to constantly
monitor the current flow through the output transistors. If the current drawn by this stage exceeds a
predetermined safe level due to a load impedance below 1 ohm or a short circuit at the speaker terminals, the
output relay will open immediately to prevent the output transistors or other parts from failing.
Total Protection - Fuses
In addition to the main fuse on the rear panel each channel of the amplifier has four internal fuses for the
positive and negative DC voltage rails of input stage and two for the output stage These fuses provide backup
protection in case the over-current protection does not work in time, or if an internal part fails. In the event of a
part failure, these fuses halt operation to minimize damage to additional parts.