Wohler AMP2-VSDA/AM, AMP2-VSDA/AV User Manual

AMP2-VSDA/AM and

AMP2-VSDA/AV

2U Digital Audio Speaker Monitor

With SDI Input and Output on BNC, Two AES Inputs on

BNC and XLR, Two AES Outputs From SDI on BNC, Four

Analog Inputs on XLR, Two Selected Analog Stereo Outputs

on XLR, Two Mechanical VU (AV) or PPM (AM) Level Meters,

Summable Channel Assignment, and Phase Indication

Document P/N 821576 Rev-B

User Manual

CONTENTS

Title and Contents .......................................................................

Introduction .........................................................................................

Section 1: Features, Specs, and Installation ....................

Description and Features ......................................................................

Applications and Specifications ............................................................

Installation ...........................................................................................

Section 2: Operation .................................................................

Front Panel Features ............................................................................

Rear Panel Features ..............................................................................

Audio Amplifier and Speaker Configuration .........................................

Section 3: Technical Information .........................................

General Technical Observations ............................................................

SDI to AES Converter PCB (919096) ....................................................

AES to Analog Converter PCB (919050) ...............................................

AES Digital Gain Calibration Fine Adjustment (919050) ........................

1
2
3
4
5
6
7
8
12
16
17
18
19
20

21

AES Error Jumper Location (919050 PCB) ............................................

PPM Meter Specifications and Level Threshold Settings ........................

VU Meter Specifications and Level Threshold Adjustment......................

AMP2-VSDA/AV and AMP2-VSDA/AM Interconnect Block Diagram ........

22

23

23

24

ECO-2501 (08/03/04)

AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Introduction

Congratulations on your selection of a Wohler Technologies AMP2-VSDA/AV or AMP2-VSDA/AM audio monitor unit. We are
confident it represents the best performance and value available, and we guarantee your satisfaction with it.

If you have questions or comments you may contact us at:

Wohler Technologies, Inc.

713 Grandview Drive

South San Francisco, CA 94080

Introduction

650 589-5676 Fax: [phone]

web: www.wohler.com

e-mail: [e-mail]

All rights reserved. Copyright held by Wohler Technologies.

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© 2004 Wohler Technologies Inc. ALL rights reserved

ECO-2325 (04/28/04)

AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Section 1

General Features

and Specifications

Description

Features

Applications

Specifications

Installation

Sect. 1: General Features and Specifications

© 2004 Wohler Technologies Inc. ALL rights reserved

3

AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Section 1: Features, Specs, and Installation

AMP2-VSD A/AV and

AMP2-VSDA/AM

Po wered Audio Monitors

AMP2-VSDA/AM Series Front Panel

Description

The AMP2-VSDA/AV and AMP2-VSDA/AM are exceptionally high quality stereo audio monitoring systems in compact, two
rackspace cabinets. All AMP2 Series units contain three audiophile-quality drivers and three power amplifiers; two amplifiers
(and two speakers) that reproduce midrange and high frequency information in stereo, and a third amp/driver combination (and
speaker) that handles summed Low Frequency (LF) information below the 500 Hz crossover point. The AMP2 Series unique
audio design has two important advantages. First, it provides optimally focused sound in an Ultra Near Field tm (1 to 3 feet)
environment. This allows higher SPL for the operator while reducing overall ambient sound and adjacent bay crosstalk. Second,
electronic rather than acoustic cancellation of bass frequencies provides positive audible detection of reversed polarity (“out of
phase”) audio feeds. A unique LED display also visually shows “phase” (polarity) relationships of the signals selected for
monitoring.

The AMP2-VSDA/AV model features mechanical meters with VU ballistics characteristics and the AMP2-VSDA/AM model
features these meters with PPM ballistic characteristics. A toggle switch on the front panel allows selection between SDI or AES
input sources. Two banks of four buttons on the front panel are used to independently assign from one to to four (summed)
channels to each of the two (left and right) speaker channels. AES signal status is indicated by two bi-color (RED/GREEN) LEDs,
while SDI signal status is indicated by one bi-color (RED/GREEN) LED.

The rear panel features an SDI input and loop-through on BNC connectors, two AES inputs on unbalanced BNC connectors, two
alternate AES inputs on balanced XLR connectors, two AES outputs (converted from the SDI input) on BNC connectors, four
Analog outputs (of the selected digital source) on balanced Phoenix connectors, a stereo analog output of the two channels
assigned to the left and right speakers on two balanced XLR connectors, and four analog inputs on XLR connectors with a switch
on the front panel for selecting between the selected digital (AES or SDI) and the Analog inputs.

Wohler Technologies proprietary three-LED stereo phase indication feature allows visual monitoring of phase relationships of the
sources selected for monitoring through the speakers.

Features

• 104 dB SPL at two feet

• Only two rack spaces high

• Excellent high frequency response for positive detection of
background whine and noise

• Audible and visual indication of phase/polarity problems

• Thorough magnetic shielding for placement next to video
monitors

• Choice of either VU

• SDI input and loop-through on unbalanced BNC connectors

• Two AES/EBU inputs on unbalanced BNC connectors

• Two alternate AES/EBU inputs on balanced XLR connectors

• Four analog inputs on balanced XLR connectors

• Two AES outputs (converted from SDI input) on unbalanced BNC connectors

or PPM high quality mechanical level meters

• Four analog outputs (from selected digital source) on balanced
Phoenix connectors

• Stereo analog output of the channels monitored by the left and
right speakers on two balanced XLR connectors

• Independantly assign and sum together two, three, or four
channels of the selected source to left and right speakers via
two banks of four button switches on the front panel

• Select AES or SDI input source via a front panel toggle switch

• Select analog or selected digital input source via a front panel
toggle switch

• One SDI signal status/error indication LED

• Two AES signal status/error indication LEDs

• Headphone output

• Power indication LED

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© 2004 Wohler Technologies Inc. ALL rights reserved

AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 1: Features, Specs, and Installation

Applications

The AMP2-VSDA/AV and AMP2-VSDA/AM are ideally suited for use in VTR bays, mobile production vehicles, teleconferencing

installations, multimedia systems, satellite links and cable TV facilities, and on-air radio studios. Designed and manufactured in the U.S.,
both models are backed by a strong warranty and a satisfaction guaranteed return policy.

General Specifications

Input Connectors:
Analog Input Impedance:

Digital Input Impedance:
Peak Acoustic Out (@ 2 ft.):
Power Output,

RMS Each Side (4
RMS Bass (4

ΩΩ

Ω):

ΩΩ

ΩΩ

Ω):

ΩΩ

Frequency Response,
Sixth Octave:

Input Level for Maximum
Output (Volume Full On):

Hum and Noise (analog):
Distortion, Electrical:

Distortion, Acoustic:

Input Overload:
Converted Analog Out S/N:
Converted Analog Out THD:

SDI: BNC, AES: BNC/XLR, Analog: XLR
XLR: 70K Ω, bal.

BNC: 75 Ω, unbal., XLR: 110 Ω, bal.

104 dB SPL

14 W transient / 10 W continuous
35 W transient / 25 W continuous

80 Hz - 16 kHz ± 5 dB)
(-10 dB @ 40 Hz, 20 kHZ)

0 dBv balanced / -10 dB unbalanced
Better than -68 dB below full output
Less than 0.15% at any level below

input threshold
6% or less at worst case frequencies

above 120 Hz, including cabinet
resonance; typically less than 1.5%

+26 dBv balanced
>90 dB
<0.008%

Magnetic Shielding:

<0.8 Gauss any adjacent surface

Power Consumption
(Average Maximum):

AC Mains Input:

45 W
100-240VAC, 50-60 Hz Universal

NOTE: See page 19 for SDI specifications and page 20 for AES specifications.

Physical Specifications

Weight:

Dimensions (HxWxD):

18 lbs. (8.2 kg)

3.5 x 19 x 12 inches
(89 x 483 x 305 mm)

Audio Response Curve

+10

0

d

-10

B

-20

-30

5k

Hz

2k1k50020010050 20k20

Typical 1/6 Octave Audio Response Curve

Units are designed to meet, at time of manufacture, all currently applicable product safety and EMC requirements, such as those of
CE. 0 dbV ref. 0.775V RMS. Features and specifications subject to improvement without notice.

© 2004 Wohler Technologies Inc. ALL rights reserved

10k

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Section 1: Features, Specs, and Installation

Installation

Mounting

The unit should be mounted where convenient for operating persons, ideally at approximately ear/eye level for best high frequency
response and visual observation of the level meters. Its superior magnetic shielding eliminates concerns about locating it adjacent
to most types of CRT monitors, including even high-resolution color monitors.

Heat Dissipation

Heat dissipated by the speaker amps is conducted directly to the left side of the chassis; no special considerations for cooling are
necessary as long as the ambient temperature inside the rack area does not exceed approximately 60°C (140°F).

Sympathetic Vibration

Sympathetic vibration from other equipment (cables, etc.,) in the rack may be serious enough to interfere with the unit’s sound
quality out in the listening area. The use of thin card stock and/or felt or foam weather-stripping type materials between adjacent
vibrating surfaces, or tying up loose cables, etc., may be required to stop vibrations external to the unit.

Mechanical Bracing

Even though the unit is fairly heavy, the chassis is securely attached to the front panel at eight points along its surface, not just at
the four corners of the chassis ears. This feature will reduce or eliminate rear bracing requirements in many mobile/portable
applications. The weight of internal components is distributed fairly evenly around the unit.

Audio Connections

Connection of the audio feeds is straightforward. Please refer to the system interconnect block diagram on page 24 for clarification of the
general signal paths into and out of the unit.

AES/EBU inputs are via female BNC or 3-pin female XLR connectors. Digital BNC inputs are configured for 75 Ω unbalanced
connections; digital XLR inputs are configured for 110 Ω balanced connections. Analog inputs are via four 3-pin female XLR
connectors. Analog inputs are configured for 70K Ω balanced connections. Care should be exercised to avoid mismatched cable types
and other similar causes of undesired reflections in RF signal systems. If severe enough, such reflections can result in corruption of the
digital datastream.

AC Power

The unit's AC mains connection is via a standard IEC inlet, with safety ground connected directly to the unit's chassis. The
universal AC input (100-240VAC, 50/60Hz) switching power supply is a self-resetting sealed type, with automatic over-voltage
and over-current shutdown. There is no user-replaceable fuse in either the primary or secondary circuit.

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© 2004 Wohler Technologies Inc. ALL rights reserved

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Section 2

Operation

Front Panel Features

Rear Panel Features

Audio Amplifier and Speaker Configuration

© 2004 Wohler Technologies Inc. ALL rights reserved

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B

Section 2: Operation

Front Panel Features

Please refer to Figure-2a on the facing page to familiarize yourself with the front panel features of the AMP2-VSDA/AV and
AMP2-VSDA/AM units. The following sections describe these features and are referenced, by number, to Figure-2a.

Speakers

1

The monitor features two mid-range speakers (left and right) and one woofer speaker. T wo amplifier/driver combinations
handle midrange and high frequency information in the left and right (stereo) speaker channels, while the third channel
reproduces and sums the left and right channel information below the 500 Hz crossover point in the woofer (bass) speaker(s).
Note that the woofer channel is NOT a dedicated LFE (subwoofer) or Center channel. See page 16 for more information
concerning the AMP2 Series audio amplifier/speaker configuration.

Audio Level Meters - Mechanical

2

Audio levels for the left and right sources selected for monitoring are respectively displayed in the left and right mechanical
level meters. The AMP2-VSDA/AV model uses meters exhibiting VU ballistic characteristics. The AMP2-VSDA/AM
model uses meters exhibiting PPM ballistic characteristics. See page 23 for Threshold Level adjustment and settings for
the VU and PPM type of meter .

Speaker Assign Channel Buttons (Left and Right)

3

Use the left bank of four buttons to assign one to four of the four available channels for monitoring from the left speaker
channel. Use the right bank of four buttons to assign one to four of the four available channels for monitoring from the
right speaker channel. Channel buttons toggle On/Off and will light up BLUE to indicate they are selected.

Operation for channel selection for each bank of four buttons is as follows:

Single Channel Select: Press and release a single channel button to select that channel (and deselect any previous

1)

selection). Pressing and releasing the selected channel button again will deselect it.

Multi-Channel Select (Summing): Press and hold down a desired channel button, then press other channel buttons to

2)

add (sum) additional channels (or press any again to deselect). Release all buttons to accept the selection set. When
multiple channels are selected, pressing and holding an already selected channel button will allow further modification to
the selection set. Releasing all buttons accepts the new selection set. Pressing and immediately releasing an already
selected channel button will select only it and deselect all other channel selections. Note that if channels assigned to
either the left or right level meters are multi-channel (summed), then the respective level meter will indicate summed audio
levels.

If the user presses a previously selected (lighted) channel button, but then decides not to make any changes to the selection
set, the user should keep the button depressed for at least 1.5 seconds before releasing it. This will preserve the current
selection set as though the button was never pushed.

Power LED

4

This LED glows GREEN to indicate the unit is connected to mains power and an operation voltage is present.

AES Status LEDs (AES 1 and AES 2)

5

These two bi-color GREEN/RED LEDs (AES1 and AES2) indicate the input presence and status of the two AES input
signals. Either LED glows GREEN as long as a valid AES/EBU digital datastream for the associated input channel is
being received. Either LED glows RED to indicate errors in signal reception or data errors (if the data has been tagged
as inappropriate for conversion to analog by having the validity bit set). These LEDs function whether or not the AES
digital signals are selected for monitoring through the unit.

Note: If you wish to disable data error indication (and leave only indication of signal reception errors) you can place
jumpers on H14 and H18 of the 919050 AES-to-Analog conversion PCB. See page 22 for component locations.

Headphone Jack

6

Select the headphone audio sources as you would for the internal speakers. When you plug in headphones, the speakers will
mute. This jack accepts a standard 1/4” phone type stereo plug.

Volume Control

7

This controls the loudness of the audio reproduced by the internal speakers or connected headphone. Clock-wise rotation
of this control increases the loudness of the monitored audio.

Analog/Digital Source Select Switch

8

This two position toggle switch allows the operator to choose between two primary input sources; ANALOG or DIGITAL.
When this toggle switch is set to ANALOG, the unit will monitor the signals as input on the rear panel ANALOG IN
XLR connectors (Item K, page 14). When this toggle switch is set to DIGITAL, the unit will monitor the digital
source (AES or SDI) as selected by the AES/SDI Digital Source Select Switch (Item 10, page 10).

(Continued)

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© 2004 Wohler Technologies Inc. ALL rights reserved