Hafler P505 Installation And Operation Manual

THE

Hafler P505 Professional Power Amp

ha fler

P505

PROFESSIONAL

POWER AMPLIFIER

INSTALLATION AND OPERATION

5910 Crescent Boulevard, Pennsauken, New Jersey 08109

CAUTION:

IF THE SPEAKER FUSES BLOW,

SOME DISTORTED SOUND CAN BE

HEARD. THEREFORE IF AMPLIFIER
MALFUNCTIONS, ALWAYS CHECK
FOR BLOWN FUSES FIRST.

LM135

THE DAVID HAFLER COMPANY

SPECIFICATIONS

Power Rating: 400 watts per channel into 4 ohms at less than 0.04% THD from 20 Hz to

20 kHz with both channels driven.

255 watts per channel into 8 ohms at less than 0.025% THD from 20 Hz to

20 kHz with both channels driven.

800 watts into 8 ohms at less than 0.04% THD from 20 Hz to 20 kHz in

monophonic bridged operation.

IM Distortion (SMPTE): Less than 0.007% from 1 watt to 225 watts, each channel, into 8

ohms.

Typical THD at 255 watts into 8 ohms:

Frequency Response into

Typical Channel Separation at 1
Signal to Noise Ratio: Exceeds 100

Input Impedance: 47,000 ohms, in parallel with 50K ohms input level control.
Input Sensitivity: 2.35 volts for 255 watts into 8 ohms; 0.14 volt

2 volts for 400 watts into 4 ohms; 0.08 volt for

Damping Factor: 200 to 1 kHz into 8 ohms; 60 to 10 kHz into 8 ohms.
Rise Time: 10 kHz, 80 volts p/p square wave, 10% to 90%: 2.5µs.
Slew Rate: 1 kHz, 120 volts p/p square wave, 40
Semiconductor Complement: 27 transistors, 12 power MOSFETs, 33 diodes, 8 zener diodes,

Power Consumption: 240 VA quiescent; 1200 VA @ rated power into 8 ohms, both channels

Size: 7” high plus
Net Weight: 48 lbs.
Shipping Weight: 52 lbs.

1/4”

8

ohms: -3 dB, 2 Hz to 120 kHz at 1

kHz:

dB

Exceeds 90

driven.

feet, 19” wide, 13” deep plus 1” for handles.

dB

1 integrated circuit, 1 diode bridge.

1

kHz: 0.002%

10 kHz: 0.007%

watt.

±0.5 dB, 5 Hz to 40 kHzat255

65

dB

referred to 255 watts into 8 ohms, unweighted.

referred to 1 watt into 8 ohms, A weighting.

V/µS.

watts.

for 1 watt.

1 watt.

WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.
CAUTION: For continued protection, replace the power fuse only with the same type and rating as indicated.

INTRODUCTION

The P505 is a high power two channel audio power amplifier
designed and constructed for professional sound applications. It
can deliver very high power into 4 ohm loads, simultaneously
maintaining a level of performance normally associated only
with ‘state of the art’ amplifiers of lesser power capability.

The rated continuous power output from each channel is 400

watts into 4 ohms. The short term continuous power is in excess

of 500 watts per channel into 2 ohms. This is more than

enough to disable most loudspeakers if improperly applied.

Moreover, the conservative rating method we use, and the
design factors which contribute to its excellent sound and
superior low impedance drive capabilities, necessitate a word of

caution about its peak power potential. Peak power outputs
can be more than double continuous ratings. Each channel is

capable of delivering more than 20 amps into a short circuit!
And, in monophonic applications, the P500 can deliver in
excess of 800 watts continuous power into 8 ohms. Such
reserves of power must be treated with understanding, as the
Hafler Company will not be responsible for misuse, or

consequent loudspeaker damage.

Distinctive features of the P505 reflect the focus of this design

on the specific needs of the professional sound installer. Ease of

installation and setup, through attention to the smallest detail, is

coupled with overrated components, and rugged construction to
deliver ‘workhorse’ dependability. The choice of notably
rugged design binding posts for load connection allows for a

¾”

choice of wiring termination, and they are on

centers to

facilitate the use of dual banana plugs. The mono-stereo
bridging switch is on the back panel, not hidden inside. A
choice of input connectors is provided for. Air filters and
loudspeaker fuses may be replaced quickly without having to
dismount or open the amplifier. The Hafler ‘total design’
approach minimizes your time and cost of installation and
equipment service, and provides a high level of protection to
associated equipment and operating personnel.

The P505 incorporates a number of protective devices.

-

Separate power supply fuses for B + and B

on each channel,
individual thermal sensors on each heat sink, a relay to
disengage the output if excessive DC offset is detected, a delay
to avoid turn-on transients, and accessible output fuses on the
back panel to protect the load are in addition to the AC line fuse,
which must be located inside to conform to safety codes.
Connections and variable controls are located on the back panel,
secure from accidental manipulation. The front panel bears only

the power switch with its combination pilot lamp and over

temperature indicator.

A major factor in the P505’s superiority is the choice of
power MOSFET devices as the output interface between the
signal and the load. These transistors exhibit intrinsic
self-regulating characteristics that serve to protect both the
amplifier and the associated equipment against damage due to
overheating or inadequate current limiting. The benefits over

-

conventional circuitry are obvious

the prorectlve circuitry
which is a chief cause of extraneous signals in traditional
designs is eliminated, and you have greater reliability from a
simpler design.

The P505 retains the time-proven design parameters that have
established the Hafler reputation for exceptional amplifier
performance: complementary push-pull circuitry, direct
coupling beyond the initial input, all silicon discrete devices,
minimal use of feedback, conservative specification of all
components, and a carefully distilled circuit topology. You can
expect the manufactured product to consistently deliver the
same high standards of power output, low distortion and low
noise normally associated with laboratory prototypes.

Thank you for purchasing this Hafler amplifier. Our
Technical Services Department is available to answer any
questions at [phone]. We are here to see that your
experience with Hafler products is satisfactory and profitable in
every way.

P505 POWER AS A FUNCTION OF IMPEDANCE

POWER PER CHANNEL

BOTH CHANNELS DRIVEN

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Adequate ventilation is a primary consideration when

filters

installing any high power amplifier, because of its appreciable
heat output. Cool air is drawn in through the foam filters on the
sides, and the warm exhaust is to the rear. Make sure this flow is
not impeded, and do not allow the system to work in a closed

-

box. The filters must be kept clean

just slip them out, wash
them, and squeeze dry. Replacements are available from the
Hafler Company, but if you choose to obtain them locally, make
sure you use ‘open cell’ foam for air conditioner filters.
Amplifiers supplied for overseas use with line voltages above

-

200 VAC use a different fan than those intended for 100

120
VAC. If conversion to the other line voltage range is indicated.
be sure the correct fan is obtained from the factory. See “AC
Line Connections for Overseas Use.”

CONNECTIONS

The front panel is designed for mounting in a standard EIA

19” wide rack, using four

#l10-32

screws and countersink
washers. It is sufficiently rigid to support the P505 safely. The
panel is slightly under the 7” height to allow clearance between
adjacent units. The feet may be unscrewed from the bottom to
facilitate such installation.

A power transformer of this size will radiate a noticeable hum
field, even though Hafler transformers are specially engineered
to reduce this effect. If the amplifier is likely to be installed
close to equipment which may be sensitive to such a field, such
as microphone amplifiers or other high gain audio stages, be
sure you have adequate separation.

AC Line

A 3-wire grounded power cord is provided on the

P50.5.

It
must be connected to a properly grounded (earthed) AC
receptacle for your safety. Never break off the ground pin on the
plug to avoid obtaining the proper adapter for 2-wire
receptacles. Do not use cords which are frayed, or whose plug is
damaged. Do not disconnect by pulling on the cord. Grasp the
plug itself.

High power output puts heavy demands on the supply wiring.
Each P505 requires 15 amperes (at 120 VAC) for proper
operation. A separate 20 ampere line is recommended. If
extension cables must be used, keep them short, and use #14
gauge or heavier 3-wire cord.

Input

The amplifier is supplied with standard 2-circuit (tip-sleeve
or T-S) ‘phone’ jacks for normal unbalanced input connections.
These use single conductor shielded cable (shield connected to

the sleeve), or you may choose two wire shielded cable. With
two wire cables, and an unbalanced input, the signal, or ‘hot’

(black) lead connects to the plug tip and the ground (white or
red) lead connects to the sleeve. Hum is usually minimized in
two wire cable by connecting the shield to the ground wire at
one end only.

¼’ PHONE PLUG

I

SLEEVE

INSULATING

SHIELD

GROUND LUG

PLUG BODY

\

MAY BE CONNECTED

(see TEXT)

SHIELDED CABLE

TO

If very long input signal cables are required, a balanced input

is usually advisable, using two wire shielded cable, and adding

the Hafler BL500 option, which eliminates the need for

hum-sensitive external input transformers. Then the 2-circuit
(T-S) phone jacks may be replaced by 3-circuit (tip-ring-sleeve
or T-R-S) jacks, wired with the ‘low’ (white or red) lead to the
ring, and the shield to the sleeve. Or, 3-pin ‘Cannon XLR’

connectors may be installed via the chassis knockout provided.

The XLR connectors are often preferred for either balan

ced or
unbalanced lines because of a locking provision. Because there
are two wiring standards, you want to make sure all your

equipment is consistent. The IEC International standard
connects the shield to pin # 1 and the signal (‘high’ - black wire)

-

to pin #2. On a balanced line, the return (‘low’

white or red
wire) would go to pin #3. The defacto American standard,
which is not as widely used, interchanges the connections to the
#2 and #3 pins.

Some applications may require the use of an input
transformer, to convert balanced lines to unbalanced
connections ahead of the power amplifier. Such transformers
are very sensitive to magnetic fields, such as those generated b

y
the power transformer. You may have to install them a fair
distance from the P505 to avoid hum pickup.

Output

The red and black binding posts were chosen for heavy duty
construction to handle the high currents which may be involved.
They are spaced for dual banana plugs, or you can connect bare
wire ends through the vertical holes in the shafts, which are
visible when the cap is unscrewed. To be certain that no wire
strands are unsecured, a tinned end, or a spade lug soldered to
the wire is recommended.

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