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

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Page 1

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

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 ........

ECO-2501 (08/03/04)

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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: 650 589-1355

web: www.wohler.com

e-mail: [email protected]

ECO-2325 (04/28/04)

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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

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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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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

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

-10

-20

-30

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.

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.

(This page intensionally left blank)

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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

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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

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

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)

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

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

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

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)

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

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

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

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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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 2: Operation

Figure-2a: Front Panel Features

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

Front Panel Features

(Continued)

Phase Indication LEDs

These three LEDs indicate the instantaneous and average phase (polarity) conditions between the two signals in the channel pair (or downmix) assigned to the left and right speaker channels. The two smaller LEDs labeled FAST show instantaneous phase relationships in the signal. The larger LED labeled AVG will indicate the average phase condition. Indication is as follows:

• The left FAST LED glows (or blinks) GREEN for in-phase signals.

• The right FAST LED glows (or blinks) AMBER for out-of-phase signals.

• The lar ge AVG LED indicates the average phase condition by glowing GREEN for in-phase signals, or RED for

out-of-phase signals.

In general, observing the AVG LED alone is sufficient for proper phase monitoring. While it is normal for stereo signals to contain some intermittant instantaneous out-of-phase and in-phase conditions (FAST LEDs), a steady RED glow of the AVG LED indicates an out-of-phase alarm condition.

AES/SDI Digital Source Select Switch

This two position toggle switch allows the operator to choose between the two digital input sources; SDI or AES. When this toggle switch is set to AES, the unit will monitor the AES signals as input on the AES IN BNC connectors (IN 1 and IN

2) on the rear panel (Item C, page 12). When this toggle switch is set to SDI, the unit will monitor the SDI signals as input on the SDI IN BNC connector on the rear panel (Item G, page 12).

Section 2: Operation

Balance Control

This control changes the volume balance between the left and right speaker channels. Note that this control attenuates the signal from the source, so that the left and right bass frequencies (summed together and reproduced in the woofer channel) will respond to balance adjustments in tandem with the left and right speaker channels. See page 16 for more information concerning the balance control characteristics.

SDI Status LED

This bi-color (GREEN/RED) LED, labeled SDI, glows GREEN as long as a valid SDI digital datastream is being received. It glows RED if TSR errors are present in the signal. If there is no SDI signal present the LED will be unlit. This LED functions whether or not the SDI digital signal is selected for monitoring through the unit.

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 2: Operation

Figure-2a: Front Panel Features

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

Section 2: Operation

Rear Panel Features

Please refer to Figure-2b on the facing page to familiarize yourself with the rear panel features of the AMP2-VSDA/AV and AMP2- VSDA/AM unit. The following sections describe these features and are referenced, by letter, to Figur e-2b.

Power Connector

Attach a standard IEC-320 power cord between this connector and mains power (100 - 250VAC, 50/60 Hz). The front panel Power LED (Item 4, page 8) will glow GREEN to indicate operating voltages are present.

AES Balanced XLR Input Connectors (AES IN 1 and AES IN 2)

These two 3-pin female XLR input connectors (AES IN 1 and AES IN 2) are meant to receive standard AES signals and are configured for balanced, 110 Ω connections. Note that the unit will monitor these inputs only when the Analog/Digital Source Select Switch (Item 8, page 8) is set to DIGITAL, and the AES/SDI Digital Source Select Switch (Item 10, page 10) is set to AES. For XLR pinout information see the diagram under Selected Analog Output Connectors (Item J, page 14).

Note: Do not input signals simultaneously to the XLR and BNC (Item C) AES input connectors of the same channel (i.e. XLR connector AES IN 1 and BNC connector AES IN 1).

AES Unbalanced BNC Input Connectors (AES IN 1 and AES IN 2)

These two female BNC input connectors (AES IN 1 and AES IN 2) are meant to receive standard AES signals and are configured for unbalanced, 75 Ω connections. Note that the unit will monitor these inputs only when the Analog/Digital Source Select Switch (Item 8, page 8) is set to DIGITAL and the AES/SDI Digital Source Select Switch (Item 10, page 10) is set to AES.

Note: Do not input signals simultaneously to the BNC and XLR (Item B) AES input connectors of the same channel (i.e. BNC connector AES IN 1 and XLR connector AES IN 1).

AES Output (From SDI Input) Connectors (1 and 2)

These two "AES OUT-FROM SDI" BNC connectors output an AES digital signal as converted from the SDI IN input connector (Item F) and function regardless of any monitor selection settings. The left AES OUT-FROM-SDI connector (next to AES IN 1) outputs a signal converted from SDI sub-group 1 (channels 1/2) and the right AES OUT-FROM-SDI connector (next to AES IN 2) outputs a signal converted from SDI sub-group 2 (channels 3/4).

AES Input Termination DIP Switch

This 4-position DIP switch module is used to set the termination characteristics for the AES inputs. In the event that either of the two AES input channels is fed to downstream equipment, the associated DIP switch section (section 1 = AES IN 1 and section 3 = AES IN 2) must be placed in the UP (Unterminated) position. If there is no downstream equipment connected, then the associated DIP switch section must be placed in the DOWN (Terminated ) position. See below for a diagram of termination settings. Note: Sections 2 and 4 of the DIP module are not used.

AES Input 1 Termination (919050)

Term. 1 Term. 2Term. 1 Term. 2Term. 1 Term. 2Term. 1

Unterminated

SDI Output Connector

Term. 2

2344

IN 1

Note: Positions S2 and S4 of DIP switch are not used.

IN 1

Terminated

AES Input 2 Termination (919050)

IN 2

Unterminated

1 234

IN 2

Terminated

The SDI OUT loop-through connector outputs a reclocked (regenerated) copy of the signal entering the SDI IN input connector (Item G). This female BNC connector is configured for an unbalanced, 75 Ω connection.

SDI Input Connector

The SDI IN input connector is meant to receive a standard SDI signal. This female BNC connector is configured for an unbalanced, 75 Ω connection. The unit monitors sub-group 1 (channels 1/2) and sub-group 2 (channels 3/4) of SDI Group ID #1. Note that the unit will monitor the SDI input only when the Analog/Digital Source Select Switch (Item 8, page 8) is set to DIGITAL, and the AES/SDI Digital Source Select Switch (Item 10, page 10) is set to SDI.

(Continued)

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 2: Operation

Figure-2b: Rear Panel Features

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

Rear Panel Features

(Continued)

AES Input Level Gain Calibration DIP Switc h

Input Level Gain Calibration, the analog level which corresponds to a given digital input value, is settable via this DIP switch. The factory setting is +4 dB (analog) = -20 dBFS (digital). See the silk-screened chart on the rear panel or the diagram below for Level Gain Calibration settings.

Converted Analog Out Connectors (1-4)

These four Phoenix connectors output analog signals converted from the selected digital inputs (but not the Analog inputs). These ouputs are not affected by the position of the Analog/Digital Source Select Switch (Item 8, page 8). These 3-pin male Phoenix connectors are configured for a balanced low impedance connection. Phoenix connector pin-out information is silk-screened just above these connectors on the rear panel (see Figure-2b).

Section 2: Operation

Selected Analog Output Connectors

These two 3-pin male XLR connectors are analog outputs of the selected source(s) as assigned to the left and right speakers. The left connector outputs the left channel (Channel A) and the right outputs the right channel (Channel B). Both connectors are configured for low impedance connections and the output signals are not affected by the volume/ balance controls or headphone mute. For XLR pinout information see the diagram below.

Pin-2

High (+)

Pin-3

Low (-)

Female XLR Pinout Male XLR Pinout

Analog Input Connectors (CH. 1 - CH. 4)

These four 3-pin female XLR connectors accept standard analog audio signals and are configured for balanced 70K Ω connections. For XLR connector pin-out information, see the diagram under Item J. Note that the Analog inputs are monitored only when the Analog/Digital Sour ce Select Switch (Item 8, page 8) is set to ANALOG.

Pin-1

Gnd

(Shield)

Pin-1 Pin-2

Gnd

(Shield)

Pin-3

Low (-)

High (+)

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

Section 2: Operation

Figure-2b: Rear Panel Features

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 2: Operation

Audio Amplifier and Speaker Configuration

General Description

All models in the AMP Series contain high performance transducers (speakers) driven by three power amplifiers; two amplifier/ driver combinations handle midrange and high frequency information in the left and right (stereo) speaker channels, while the third amplifier channel 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.

Speaker Configuration

All AMP2 (2U) products are configured with two speaker channels (left and right) to reproduce midrange and high-range audio frequencies (in stereo) and one woofer speaker channel to reproduce the summed (combined) low-range audio frequencies from the left and right speaker input channels.

See below for a simplified diagram of the AMP2 audio amplifier/speaker configuration.

Balance Control Characteristics

The balance control attenuates the signal from the source, so that the left and right bass frequencies (summed together and reproduced in the woofer channel) will also respond to the balance control.

Example:

If an audio signal of a voice speaking English is fed to the left (A) input and a voice speaking Spanish is fed to the right (B) input, then the left speaker channel will reproduce the midrange and high-range frequencies of the English speaking voice, the right speaker channel will reproduce the midrange and high-range frequencies of the Spanish speaking voice, and the woofer speaker channel will reproduce the summed (combined) low-range frequencies of both voices.

If the balance control is rotated to the left (English), then the Spanish speaking voice in the right speaker channel will diminish in volume and the Spanish speaking voice in the woofer speaker channel will also diminish.

The converse is true if the balance control is panned to the right.

Note that if the balance control is rotated completely to the left, the volume in both the left speaker channel and woofer speaker channel will increase slightly to maintain overall output level. See the simplified diagram below for placement of the balance control in the audio amplifier circuit.

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

Section 3

T echnical Information

General Technical Observations SDI to AES Converter Module PCB (919096) AES to Analog Converter Module PCB (919050) AES Digital Gain Fine Adjustment (919050) AES Error Jumper Locations (919050) PPM Level Meter Specifications and Level Threshold Settings VU Level Meter Specifications and Level Threshold Adjustment AMP2-VSDA/AM Series Interconnect Block Diagram

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 3: Technical Information

General Technical Observations

General Mechanical Observations

Elimination of cabinet and component sympathetic vibrations (resonances) requires considerable attention to mechanical details. Because of this, and the physical constraints of the speaker’s acoustic enclosures, even minor changes to any of the mechanical details of the unit can seriously impair its acoustic performance. This especially applies to the speaker baffles. If mechanical work on the unit is necessary, be sure to make adequate notes to permit accurate reassembly.

Unfortunately, the unusual and wholly proprietary method of magnetic shielding is usually degraded slightly by any disassembly of the unit, except removal of the rear panel. Almost any maintenance or repair will require removal of the cover. If an immediately adjacent video monitor shows magnetic interference after reassembly of the unit, it must be returned to the factory to restore the shielding completely.

General Audio Circuitry Observations

Since a single-sided power supply is used, all amplifier sections are “biased” with a 1/2 supply reference, so all opamp signal terminals on the main board should have a DC level of +12V, +/-0.7V. Signal inputs to the main audio board from any of the input select circuits are via the balanced input stage, in lieu of the XLR analog inputs on the basic unit. Signal feed points for level meters and the phase indicator are immediately after the input stage, and before the volume control section.

The signal pick-off for the headphones is after the volume and balance controls. Speaker muting is controlled by circuitry that senses connection of headphones to the jack.

The power amps are attached to an aluminum heatsink plate (which is also connected to the circuit common for these devices). The heatsink plate forms an operational module separate from the chassis, which allows access to the solder side of the circuit board while power is applied to the circuitry. To avoid thermal shutdown of the power amp(s), they should NOT be operated without their tabs being fastened to the heatsink plate.

Variations in the frequency response of different production runs of drivers has sometimes required minor adjustments in the equalization/crossover components in individual runs of units. Some of these components may have values slightly different than those indicated in the schematic, which are the nominal ones. If any of the drivers (speakers) are replaced, it may be helpful to change some of these components to achieve maximum flatness of response.

The operating threshold of the woofer limiter is critical to both satisfactory reproduction of musical transients and preventing damage to, or destruction of, the speaker itself. The side speaker output limiter circuits are similarly important, though not as critically adjusted.

The woofer power amps are arranged in a bridge configuration; care must be taken to avoid letting EITHER speaker terminal contact the chassis (common) OR THE GROUNDED LEAD OF ANY TEST EQUIPMENT so as not to short out the power amps. The side speaker outputs are single-ended, so these precautions are not necessary for them.

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

Section 3: Technical Information

SDI to AES Converter Module PCB (919096)

The 919096 (Serial Digital to AES Converter) module allows selected Wohler Technologies audio monitoring systems to be connected directly to a serial digital video signal containing embedded audio. T wo levels of component signals (eg., D1, D5, a nd Digi Betacam type) are currently supported; synchronous audio at 48 KHz with either 20-bit data packets or audio and extended data packets. The 919096 module demultiplexes (extracts) the audio data from the video data, reformatting it to the AES standard. A companion digital-to-analog converter module (919050) is used to convert the AES signal to Analog audio.

In the AMP Digital Series units, channels 1 and 2 (first subgroup) and channels 3 and 4 (second subgroup) from SDI Group ID #1 are demuxed before being input to the AES to analog conversion module (919050). Access to SDI Group ID #2, #3, and #4 is optional and should be specified at time of order.

919096 Specifications

Input characteristics:

Receiver type:

Sensitivity performance:

SDI input level:

Input formats:

Audio sampling rate:

SDI output type:

SDI output:

SDI output level:

AES from SDI output:

AES data bits:

Error Indication:

75 Ohm (BNC), AC coupled, 15 dB minimum return loss, 10-270 MHz Auto equalizing with clock regeneration T olerates cable loss of at least 30 dB @ 135 MHz 400 - 1000 mV Component, either 525 or 625 lines w/ 48 KHz audio 48 KHz Fully regenerated copy of SDI input signal (equalized and regenerated,

scrambled NRZI) 15 dB minimum return loss, risetime 0.75-1.5 ns (20-80%) 800 mV +/-10% 75 Ω BNC 20 Bi-color LED (red/green)

Off = no signal Green = signal present Red = Error

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 3: Technical Information

AES to Analog Converter Module PCB (919050)

Description

The 919050 Digi-2 (Dual Input AES to Analog Converter) module allows selected Wohler Technologies products to receive input signals in the AES or SPDIF digital audio data formats. Sampling rate and format selection are sensed and set automatically.

Two front panel mounted bi-color (RED/GREEN) LEDs provide visual indication of input signal status. The LEDs light GREEN when receiving a valid, error-free data stream, but turn RED when errors are detected. See Item 5, page 8 for more information about error detection and indication.

There are two AES inputs, which are configured with unbalanced 75 Ω BNC connectors and balanced 110 Ω XLR connectors. This module also features a four-channel balanced analog line-level output, which can be configured with unbalanced 75 Ω BNC connectors or balanced 110 Ω Phoenix or XLR connectors.

919050 Specifications

Input formats:

Digital-to-Analog Conversion:

Sampling rate:

Termination:

Analog out (of digital source), S/N: THD (full output):

Max output of analog out:

Nominal output level for "Full Code" digital source:

D to A gain calibration, (dB = dBFS):

Standard input connectors: Optional input connectors:

Standard output connectors: Optional output connectors:

Error Indication:

AES/EBU or SPDIF 24-bit low jitter 31 kHz to 48 kHz Removable (DIP switch selectable)

Greater than 96 dB Less than 0.008%

+24 dBv (0 dBv = 0.775 vRMS)

+24 dBv

+8 = -20, +4 = -20, +6 = -9, 0 = -18 (DIP switch selectable) BNC: 75 Ω, unbalanced

Phoenix or XLR: 110 Ω, balanced BNC: 75 Ω, unbalanced

Phoenix or XLR: 110 Ω, balanced Two Bi-Color LEDs (on front panel):

Green = OK Red = Error, no lock to signal, or no signal.

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

Section 3: Technical Information

AES Digital Gain Calibration Fine Adjustment (919050)

The digital gain calibration is set at the factory for +4 dB (Analog) = -20 dBFS (Digital). Three other values (+8 = -20, +6 = -9, and 0 = -18) may also be user selected via a DIP switch on the rear panel (Item H, page 14). However, if a fine adjustment of the calibration is desired, perform the following procedure:

1) Remove the top cover. Save screws for later reassembly.

2) You must remove the 919083 PCB to access the trim pots (P1-P4) on the 919050 PCB (see Figure-3a below for trim pot

locations).

3) Connect a digital (AES) source of known digital amplitude and set the unit’s controls to monitor that source. For convenience

sake, it would be best to use your facility’s digital reference level, but any nearby level may be used with appropriate scaling of output level required.

4) Using an accurate DMM (preferably one having direct reading in dBv/dBu), measure the level on the Converted Analog Output phoenix connectors (Item I, page 14). Be sure to make measurement of the FULL balanced output, NOT just between one of the outputs and ground!

5) Locate trim pots P1, P2 , P3, and P4 (see Figure-3a below). Adjust P4 (channel 1) through P1 (channel 4) for the desired analog level corresponding to the digital signal amplitude being supplied to the unit. For example, if your “house” Analog/Digital correspondence is for a -18 dBfs digital level to correspond to an Analog level of +0dBu, it would be easiest to set the digital source to -18 dBfs, set the gain calibration DIP switch for -18dBFS = 0dBu and then set P1 through P4 for 0dBu outputs on the phoenix Analog Output connectors. But, if a digital source of -20dBfs is applied, even though the facility references are for -18dBfs, then the analog output levels should be adjusted for a -2.0 dBu analog output level on the phoenix connectors.

Note: If the meter being used to measure the analog outputs is not so accurate at those relatively low signal levels, you may wish to increase the digital signal amplitude by some convenient factor like 10 or even 20 dB. (But of course you may not increase above digital full scale.)

Figure-3a:

AES/EBU to Analog Module PCB (919050) Digital Gain Calibration Trim Pot Locations

P4 - Adjusts Channel 1

P3 - Adjusts Channel 2

P2 - Adjusts Channel 3

P1 - Adjusts Channel 4

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

AES Error Jumper Locations (919050)

Section 3: Technical Information

To disable indication of faulty AES data (and leave only indication of faulty reception), place jumpers on both H14 and H18. See Item 5, page 8 for more information.

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AMP2-VSDA/AV and AMP2-VSDA/AM User Manual P/N 821576 Rev-B Section 3: Technical Information

-6 dB PPM

+8 dB PPM

0 dB PPM

+4 dB PPM

Level Gain Calibration DIP Switch Settings

AMP2-AMPPM Meter Driver PCB (919028)

PPM Level Meter Specifications and Level Threshold Settings

The two (one per meter) Level Threshold DIP switches in the AM (PPM) unit are only accessible by removal of the top cover . Each DIP switch is physically located on the inside front panel above the level meter to which it is dedicated. Each meter can be independently set with a possibility of four settings; -6, 0, +4, or +8 dBv . Factory setting is +4 dBv . See the diagram below for DIP switch settings.

AMP2-AMPPM Meter Driver PCB

Level Threshold DIP Switch Settings

PPM Level Meter Specifications

Level Meter Type:

Level Meter Scale:

Level Meter Threshold:

Level Meter Dynamics:

Mechanical Specify BBC (1 to 7)

and 2 (specified when ordered)

-6, 0, +4, or +8 dBv: DIP switch selectable (internal)

PPM

or EBU type 1

VU Level Meter Specifications and Level Threshold Adjustment

Level Gain Calibration adjustment for the AV (VU) unit is done by adjusting two trim pots (P1 and P2) on the level meter driver PCB (919036V). The units top cover must be removed to access this PCB, which is mounted in the center of the chassis bottom. P1 adjusts the left meter; P2 adjusts the right meter . Clockwise rotation of either meter will increase the level of the associated meter . Adjustment range for each meter is 0 to +8 dBv .

Turn pots clockwise to

IC2IC1

increase the display level threshold (sensitivity) in the associated meter

179036 rev B Top Side

Level Meter Type:

Level Meter Scale:

Level Meter Threshold:

Level Meter Dynamics:

Left Meter

Right Meter

VU Level Meter Specifications

Mechanical Standard VU 0 to +8 dBv (factory set to +4 dBv),

trim pot adjustable (internal) VU (full ANSI)

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

Section 3: Technical Information

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

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

NOTE:

PCB layout and schematic support documentation is available upon request.

Wohler Technologies, Inc.

713 Grandview Drive

South San Francisco, CA 94080

650 589-5676 Fax: 650 589-1355

web: www.wohler.com

e-mail: [email protected]

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

Wohler T echnologies, Inc.

713 Grandview Drive

South San Francisco, CA 94080

650 589-5676 Fax: 650 589-1355

web: www.wohler.com

e-mail: support@wohler .com