Lectrosonics PA8 User manual

PA8
8 CHANNEL POWER AMPLIFIER
LECTROSONICS, INC.
Rio Rancho, NM
OPERATING INSTRUCTIONS
and trouble-shooting guide
(and I-PA8 EuroVersion)

2
INTRODUCTION
The PA8 8 Channel Power Amplifier is a unigue single rack-space solution for zoned,
distributed loudspeaker systems with eight separate power amplifiers, each with an
output power capability of 10W (4 Ohms) or 6W (8 Ohms.) The PA8 is passively
cooled, and features full short-circuit and thermal overload protection. The amplifier
outputs are muted at turn-on and turn-off, to eliminate transients.
Precautions: 1. Spill no liquids on the equipment and do not drop any objects through
openings in the equipment. 2. Do not place the equipment near heat sources such as
radiators, heating ducts, or amplifiers and do not expose it to direct sunlight, excessive
dust, moisture, rain, mechanical vibrations, or shock.
TABLE OF CONTENTS
INTRODUCTION ................................................................................................... 2
GENERAL TECHNICAL DESCRIPTION .............................................................. 3
INSTALLATION ..................................................................................................... 4
FRONT PANEL DESCRIPTION............................................................................ 5
REAR PANEL DESCRIPTION .............................................................................. 5
OPERATING INSTRUCTIONS .............................................................................. 5
TROUBLESHOOTING........................................................................................... 6
SPECIFICATIONS ................................................................................................ 6
SERVICE AND REPAIR ........................................................................................ 7
RETURNING UNITS FOR REPAIR ...................................................................... 7
WARRANTY ..........................................................................................Back cover

3
8 Channel Power Amplifier
Rio Rancho, NM – USA
GENERAL TECHNICAL DESCRIPTION
The PA8 uses a straightforward, low parts count design for long term reliability. The heart of the power supply is a low
radiation toroidal transformer. The toroidal transformer generates less heat than a comparable non-toroidal type, and
emits considerably less 60Hz energy. This is particularly important when the PA8 is used in close proximity to micro-
phone preamplifiers.
The input to the PA8 is fully balanced and RF filtered. The level control feeds a monolithic power amplifier. The
amplifier has a voltage gain of 26dB (x20). Each power amplifier is internally power limited to protect itself from short
circuits, excessively low impedances, or highly reactive loads. Thermal limiting is also integrated into the power
amplifier, with an intelligent shutdown mode that minimizes thermal shock to the device under extreme operation. Any
two channels may be used in the bridged mode for higher power (20W/8 Ohms or 12W/16 Ohms).
The block diagram of the PA8 is shown below.
PA8 Power Amplifier
Block Diagram
Power
Supply
Channel 1 of 8
Power
Amp
Channel
Level
Speaker
Out
+10V
-10V
+12V
-12V
Balanced In
Figure 1 - PA8 Block Diagram

4
INSTALLATION
Installing the PA8 properly is simple, and only requires attention to a few issues. The PA8 should be used in a
grounded metal rack. One open rack space should be provided above and below the PA8 for proper ventilation. Shown
below are the connections for both non-bridged and bridged operation.
Input
DRIVING DEVICE
PA8
GND
Output
GND
Input Output
DRIVING DEVICE
PA8
GND
GND
In 1 Out 2
DRIVING DEVICE
PA8
Out 1In 2
GND
GND
In 1 Out 2
DRIVING DEVICE
PA8
Out 1In 2
GND
GND
BRIDGED OUTPUT
Two adjacent channels of a PA8 may be connected as
shown in Figure 4 to allow bridging operation. In the
bridged mode, the minimum speaker load is 8 Ohms, and
maximum power output is 20W into 8 Ohms. Note that
since the Channel Level controls of both bridged chan-
nels will be active, they should be set to the same level.
The loudspeaker is connected to the “+” output terminals
of each channel, while the “-” outputs are left uncon-
nected.
When driving the PA8 with an unbalanced source, the (-)
terminal is connected to the ground of the driving signal,
as well as the ground terminal of the PA8 input. Figure 3
shows this configuration.
Figure 5 shows bridging operation using an unbalanced
source.
Figure 2 - Balanced Input / Non-Bridged Output
Figure 3 - Unbalanced In / Non-Bridged Out
Figure 4 - Balanced In / Bridged Out
Figure 5 - Unbalanced In / Bridged Out
NON-BRIDGED OUTPUT
The standard PA8 configuration would have a balanced
output device (like the MM8 Matrix Mixer) driving each
channel of the PA8. The speaker is connected in the non-
bridged mode. Maximum output power is 10W into 4
Ohms, or 6W into 8 Ohms. Figure 2 shows this configu-
ration.

5
8 Channel Power Amplifier
Rio Rancho, NM –USA
FRONT PANEL DESCRIPTION
POWER SWITCH - Turns AC power on and off.
POWER LED - Indicates the presence of AC power to the PA8.
CHANNEL LEVEL 1-8 - Controls the volume level of each channel.
REAR PANEL DESCRIPTION
LINE INPUTS 1-8 - Accepts balanced or unbalanced signal. Fully balanced differential input, RF filtered.
SPEAKER OUTPUTS 1-8 - Drive minimum 4 Ohm loads non-bridged, and minimum 8 Ohm loads bridged.
AC POWER RECEPTACLE - Accepts standard detachable 120VAC power cord.
AC POWER FUSE - Accepts a 3A, 250V (1.5A, 250V when wired for 230VAC operation) Slo-Blo fuse.
LECTROSONICS, INC.
RIO RANCHO, NM U.S.A. POWER AMPLIFIER
POWER
OUTPUT LEVEL OUTPUT LEVEL
CH 8CH 7CH 6CH 5CH 4CH 3CH 2CH 1
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
1
2
345
6
7
8
0
CAUTION WARNING
LINE IN
1
2
3
4
LECTROSONICS, INC.
5
6
7
8
SPEAKER OUT LINE IN
MADE IN U.S.A.
TO REDUCE THE RISK OF FIRE
OR ELECTRIC SHOCK, DO NOT
EXPOSE THIS EQUIPMENT TO
RAIN OR MOISTURE.
TO REDUCE THE RISK OF FIRE,
REPLACE ONLY WITH SAME TYPE
3A, 250V "SLO-BLO" FUSE
120V AC
300 WATTS
SPEAKER OUT
PA8
POWER
AMPLIFIER
CH 5
CH 6CH 7CH 8 CH 1CH 2CH 3
CH 4
F
U
S
E
F
U
S
E
F
U
S
E
Figure 6 - PA8 Front Panel
Figure 7 - PA8 Rear Panel
OPERATING INSTRUCTIONS
Refer to the Installation section of this manual for proper connection of the PA8 to other equipment and speakers.
Remember that the PA8 expects a loudspeaker load without a matching transformer at the speaker. Adjust the
Channel Level controls until a comfortable sound level is reached.

6
TROUBLESHOOTING
SYMPTOM POSSIBLE CAUSE
No sound from system 1) Channel Level control not turned up
2) Channel input incorrectly wired
3) Power switched off
4) Fuse may be blown
SPECIFICATIONS
Line Input
Type: Electronically balanced and RF filtered
Impedance: 20k Ohms, Balanced or Unbalanced
Input Level for Rated Output: -2dBu (615mVRMS) at maximum level
+15dBu (4.36VRMS) at mid level
Output Power: 10 Watts into 4 Ohms, 6 Watts into 8 Ohms
20 Watts into 8 Ohms with bridged mono
configuration
Output impedance: 4 Ohms minimum
Maximum System Gain
Line Input to Speaker Out: 20dB (x10)
Signal-to-Noise Ratio: 88dB relative to 10W at 4 Ohms
System THD: Less than 0.1%, 20Hz to 20kHz (10W into 4 Ohms)
System IMD: Less than 0.1%, 60Hz/7kHz (10W into 4 Ohms)
Slew Rate: 12V/uS
Power Consumption: 200 Watts max at 120VAC
Euro Version*: 200 Watts max at 230VAC
Weight: 8 lbs, 9 ozs
Dimensions: 19" wide x 1.3/4" high x 8 1/4" deep
*Euro version, I-PA8 is CE marked and runs on 220VAC.
Specifications subject to change without ntice
This product meets the CE Compliance Standards - EN55022 and
EN50082-1:1998. A copy of the Declaration of Conformity may be
requested from your dealer or by contacting the factory directly:
Lectrosonics, Inc.
Marketing Department
581 Laser Rd. NE, Rio Rancho, NM 87124 USA
tel: [phone] fax: [phone] e-mail: [email protected]

7
8 Channel Power Amplifier
Rio Rancho, NM –USA
SERVICE AND REPAIR
If your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the equipment
needs repair. Make sure you have followed the setup procedure and operating instructions. Check out the intercon-
necting cords and then go through the TROUBLE SHOOTING section in the manual
We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop
attempt anything other than the simplest repair. If the repair is more complicated than a broken wire or loose connec-
tion, send the unit to the factory for repair and service. Don’t attempt to adjust any controls inside the units. Once set
at the factory, the various controls and trimmers do not drift with age or vibration and never require readjustment.
There are no adjustments inside that will make a malfunctioning unit start working.
LECTROSONICS service department is equipped and staffed to quickly repair your equipment. In-warranty repairs
are made at no charge in accordance with the terms of the warranty. Out of warranty repairs are charged at a modest
flat rate plus parts and shipping. Since it takes almost as much time and effort to determine what is wrong as it does
to make the repair, there is a charge for an exact quotation. We will be happy to quote approximate charges by phone
for out of warranty repairs.
RETURNING UNITS FOR REPAIR
You will save yourself time and trouble if you will follow the steps below:
A. DO NOT return equipment to the factory for repair without first contacting us by letter or by phone. We need to
know the nature of the problem, the model number and the serial number of the equipment. We also need a phone
number where you can be reached 8 am to 4 pm (Mountain Standard Time).
B. After receiving your request, we will issue you a return authorization number (R.A.). This number will help speed
your repair through our receiving and repair departments. The return authorization number must be clearly shown on
the outside of the shipping container.
C. Pack the equipment carefully and ship to us, shipping costs prepaid. If necessary, we can provide you with the
proper packing materials. UPS is usually the best way to ship the units. Heavy units should be “double-boxed”for
safe transport.
D. We also strongly recommend that you insure the equipment, since we cannot be responsible for loss of or damage
to equipment that you ship. Of course, we insure the equipment when we ship it back to you.
Mailing address: Shipping address: Telephones:
Lectrosonics, Inc. Lectrosonics, Inc. Regular: [phone]
PO Box 15900 581 Laser Rd. Toll Free [phone]
Rio Rancho, NM 87174 Rio Rancho, NM 87124 FAX: [phone]
USA USA
World Wide Web: http://www.lectrosonics.com Email: [e-mail]

LIMITED ONE YEAR WARRANTY
The equipment is warranted for one year from date of purchase against defects in
materials or workmanship provided it was purchased from an authorized dealer. This
warranty does not cover equipment which has been abused or damaged by careless
handling or shipping. This warranty does not apply to used or demonstrator equipment.
Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any
defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot
correct the defect in your equipment, it will be replaced at no charge with a similar new
item. Lectrosonics, Inc. will pay for the cost of returning your equipment to you.
This warranty applies only to items returned to Lectrosonics, Inc. or an authorized
dealer, shipping costs prepaid, within one year from the date of purchase.
This Limited Warranty is governed by the laws of the State of New Mexico. It states the
entire liablility of Lectrosonics Inc. and the entire remedy of the purchaser for any
breach of warranty as outlined above. NEITHER LECTROSONICS, INC. NOR
ANYONE INVOLVED IN THE PRODUCTION OR DELIVERY OF THE EQUIPMENT
SHALL BE LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, CONSEQUENTIAL,
OR INCIDENTAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THIS EQUIPMENT EVEN IF LECTROSONICS, INC. HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL THE LIABILITY OF
LECTROSONICS, INC. EXCEED THE PURCHASE PRICE OF ANY DEFECTIVE
EQUIPMENT.
This warranty gives you specific legal rights. You may have additional legal rights which
vary from state to state.
LECTROSONICS, INC.
581 LASER ROAD
RIO RANCHO, NM 87124 USA
November 1, 2001
LIMITED ONE YEAR WARRANTY