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© 2004   Wohler Technologies  Inc.   ALL rights reserved

14

AMP2A-VTR

 and 

AMP2A-VTR2

  User Manual  P/N 

821580

  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 "A" (left) input and  a voice speaking Spanish is fed to the
"B" (right) 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 

panned to the left

, then the Spanish speaking voice in the right speaker channel will diminish in

volume, the Spanish speaking voice in the woofer speaker channel will also diminish, and the English speaking voice in
both the right speaker channel and woofer speaker channel will increase slightly (to maintain overall output level). The
converse is true if the balance control is panned to the right.

See the 

AMP2 (2U) Audio Amplifier and Speaker Block Diagram

 above for placement of the balance control in the

audio amplifier circuit.

Summary of Contents for AMP2A-VTR

Page 1: ...ion and Features Applications and Specifications Installation Section 2 Operation Front Panel Features Rear Panel Features AudioAmplifierandSpeakerConfiguration Section 3 Technical Information General Technical Observations Level Meter Rear Panel 6 Position DIP Switch Settings Level Meter Internal 10 Position DIP Switch Settings Level Meter DIP Switch Locations Level Meter Alternative Scales Level...

Page 2: ...eing walked on or pinched particularly at plugs convenience receptacles and the point where they exit from the apparatus 11 Only use attachments accessories specified by the manufacturer 12 Use only with the cart stand tripod bracket or table specified by the manufacturer or sold with the apparatus When a cart is used use caution when moving the cart apparatus combination to avoid injury from tip ...

Page 3: ...nc ALL rights reserved 3 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B Sect 1 General Features and Specifications General Features and Specifications Description Features Applications Specifications Installation Section 1 ...

Page 4: ...s 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...

Page 5: ...umption AverageMaximum ACMainsInput Phoenix Terminal Block 3 pin male 90KΩ balanced 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 l...

Page 6: ... 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 C...

Page 7: ...04 Wohler Technologies Inc ALL rights reserved 7 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B Operation Front Panel Features Rear Panel Features Audio Amplifier and Speaker Configuration Section 2 ...

Page 8: ...headphone Clock wise rotation of this control increases the loudness of the monitored audio in both speaker channels Headphone Jack This jack accepts a standard 1 4 phone type stereo plug When you plug in headphones the speakers will mute 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...

Page 9: ... 2004 Wohler Technologies Inc ALL rights reserved 9 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B Section 2 Operation Figure 2a Front Panel Features AMP2A VTR2 FrontPanel AMP2A VTR FrontPanel ...

Page 10: ...age phase condition by glowing GREEN for in phase signals or RED for out of phase signals In general it is sufficient to regard the AVG LED as adequate 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 almost always indicates an out of phase alarm condition Bal...

Page 11: ... 2004 Wohler Technologies Inc ALL rights reserved 11 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B AMP2A VTR2 FrontPanel AMP2A VTR FrontPanel Figure 2a Front Panel Features Section 2 Operation ...

Page 12: ...e 3 pin male Phoenix connectors INPUTS CHANNEL 1 4 GROUP 1 2 accept standard analog audio signals and are configured for balanced 90K Ω connections The two banks groups of input connectors are interleaved and either group of four inputs GROUP 1 or GROUP 2 may be selected for monitoring using the 2 position Group Select Switch on the front panel Item 10 page 10 Channel input numbers are silk screen...

Page 13: ... 2004 Wohler Technologies Inc ALL rights reserved 13 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B Section 2 Operation Figure 2b Rear Panel Features AMP2A VTR2 RearPanel AMP2A VTR RearPanel ...

Page 14: ... 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 A left input and a voice speaking Spanish is fed to the B right input then the left speaker channel will repro...

Page 15: ...on General Technical Observations Level Meter Rear Panel 6 Position DIP Switch Settings Level Meter Internal 10 Position DIP Switch Settings Level Meter DIP Switch Locations Level Meter Alternative Scales Level Meter Phase Correlation Feature AMP2A VTR Interconnect Block Diagram AMP2A VTR2 Interconnect Block Diagram Section 3 ...

Page 16: ...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 f...

Page 17: ...evel displayed on the LED bargraphs Factory setting is 4 dB See DIP switch diagram below for settings Bargraph Display Mode DIP switch sections 4 and 5 determine how peak levels are displayed for the associated meters on the front panel There are four possible settings VU Only VU PPM Floating Segment PPM Only and PPM PPM Floating Segment The VU Only selection has a VU floating segment when a Peak ...

Page 18: ...s 2 dB Return Fall Time is 2 8 seconds 24 dB Integration Rise Time is 5 ms 2 dB Return Fall Time is 1 5 seconds 20 dB Integration Rise Time is a single sample Return Fall Time is 1 5 seconds 20 dB IEC268 10 Type 1 IEC268 10 Type 2 DIN 4506 Single Sample Level Meter Internal 10 Position DIP Switch Settings This 10 position DIP switch is accessed by removing the top cover of the AMP unit and is loca...

Page 19: ...MP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B Internal Level Meter 10 Position DIP Switch Module see page 18 Rear Panel Level Meter 6 Position DIP Switch Module see page 17 Level Meter DIP Switch Locations 919174 PCB Section 3 Technical Information ...

Page 20: ...lation region is always OFF to serve as a marker The Phase Correlation display is visible ONLY so long as the VU audio level is above this blank segment tenth from the bottom Level Meter Phase Correlation Feature 15 50 30 40 35 26 22 18 4 6 10 12 2 2 0 15 8 6 12 1 5 0 correlation 1 5 0 Section 3 Technical Information Level Meter Alternative Scales The standard scale used on the AMP2A VTR and AMP2A...

Page 21: ... 2004 Wohler Technologies Inc ALL rights reserved 21 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B AMP2A VTR Interconnect Block Diagram Section 3 Technical Information ...

Page 22: ... 2004 Wohler Technologies Inc ALL rights reserved 22 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B AMP2A VTR2 Interconnect Block Diagram Section 3 Technical Information ...

Page 23: ... 2004 Wohler Technologies Inc ALL rights reserved 23 AMP2A VTR and AMP2A VTR2 User Manual P N 821580 REV B NOTE PCB layout and schematic support documentation is available upon request NOTES ...

Page 24: ...V B Wohler Technologies Inc 31055 Huntwood Avenue Hayward CA 94544 1 888 596 4537 Fax 510 870 0811 web www wohler com e mail support wohler com Wohler Technologies Inc 31055 Huntwood Avenue Hayward CA 94544 Phone 510 870 0810 Fax 510 870 0811 US Toll Free 1 888 596 4537 www wohler com support wohler com ...

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