Parasound Halo JC 5, Руководство пользователя

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Class A-A/B Operation
Pure class A operation provides the purest sound. However, an amplifier operating entirely in class A
would be enormous, highly inefficient, and generate far too much heat. Class A/B combines the main
advantage of Class A with the efficiency of Class B operation. It is a compromise that reduces the heat
generated in pure class A operation and the higher-order odd harmonic distortions created in class B. In class
AB, the driver and output stages are always partially turned on, which provides a nominal amount of pure
class A operation. At higher power levels, when the musical waveform swings from positive to negative and
vice versa, each bank of transistors is allowed to rest momentarily. This resting, or quiescent time, makes it
possible to deliver high amounts of power without overheating. It also makes possible the use of passive
cooling and avoid fans, whose noise can be heard over the music. The JC 5 input and driver stages employ
pure Class A while its output stage operates with higher level of pure Class A power than many amplifiers
selling for twice or three times its price. The result is less fatiguing, more natural sound.
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 JC 5 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 JC 5 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 JC 5 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 JC 5 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 JC 5 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.