Ashly P70-800 Руководство пользователя - Страница 3

Просмотреть онлайн или скачать pdf Руководство пользователя для Усилитель Ashly P70-800. Ashly P70-800 6 страниц. 70 volt power amplifiers

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DESIGN THEORY

Ashly P70 series amplifiers use a direct-coupled output stage with totally

discrete high-voltage, wide bandwidth electronics. A modulated power supply

improves output device efficiency, allowing more power with less heat dissipation.

The input section is a complimentary Darlington differential amplifier stage for

high common-mode rejection, low noise and low distortion. All voltage gain stages

in the amplifier operate class A for low distortion. The complimentary MOSFET

output stage has almost infinite current gain, therefore the output driver stages are

nearly lossless. All circuitry within the feedback loop is discrete which allows the

amplifier to recover instantly and cleanly without any spikes or glitches from a

clipped condition. This overall design approach inherently assures low noise, low

distortion, and excellent transient and overload response. Inputs are bridging and

active balanced, and all input connections can operate as balanced or unbalanced.

Turn-on delay relays are not needed because of the symmetry of the totally discrete

complementary electronics.

The P70 amplifiers incorporate output VI limiting to protect against exces-

sive current at the speaker terminals. If current becomes too high, the amplifier

instantaneously reduces output voltage to a safe level. This protects against low

impedance loads, a short across the outputs, as well as DC. Additionally, an internal

fuse follows the output signal of each channel. Under normal operating conditions

however, the VI limiter handles any fault condition at the output. A blown fuse will

only occur in the rare event of amplifier failure. All electronic components are

mounted to rugged glass-epoxy circuit boards. Large computer-grade electrolytic

capacitors assure long service.

The P70 series amplifiers are packaged in a rugged 16-gauge steel chassis. The

power transformer is located at the front center of the chassis to minimize front panel

torsion. Each channel's electronics and heat sink are identical yet completely

independent and modular, each with a single plug-in connector for ease of servicing.

Large custom black-anodized extruded aluminum heat sinks with fan cooling

provide plenty of thermal headroom.

Ashly P70 Owners Manual

1. INPUTS

4" tip-ring-sleeve (TRS) phone jacks, balanced XLR jacks, and balanced screw-

terminal inputs. The three types of connectors are internally wired in parallel and may

be used with balanced or unbalanced connections. The inputs are configured for pin

2 hot, meaning that a positive voltage applied to pin 2 will result in a positive output

voltage across the speaker terminals. Pin 2 of the XLR jack is equivalent to the tip of

the 1/4" TRS jack as shown in figure 1. An optional plug-in input transformer is

available on all P70 amplifiers.

reduce ground-loop and environment-induced hum and noise. If an unbalanced input

connection is used, then the (-) connection (XLR pin 3) should be connected to input

ground ( XLR pin 1). If the 1/4" input jack is used unbalanced, the use of a mono (tip-

sleeve) plug will automatically tie the (-) connection to input ground. The CHASSIS

GROUND terminal is internally connected to the chassis, the AC earth ground, and the

p ower amplifier's signal ground. The INPUT GROUND terminal is tied to the XLR

pin 1 and the 1/4" jack sleeve.

Ashly P70 Owners Manual

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Figure 1: P70-400 Rear Panel With Standard Input

The standard input panel of the P70 series amps is equipped with balanced 1/

It is recommended that balanced input connections be used when possible to

Figure 2: Input Connectors

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