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AUDIO SIGNAL INPUT CONFIGURATIONS
Standard Input - The standard input for all VAC audio devices is a high-impedance DC coupled connection. Typically, the input impedance for audio devices is greater than 10kΩ; the high impedance ensures that the VAC device does not "load" the output of the audio source. VAC offers both Terminal Block (balanced or unbalanced audio) and RCA (unbalanced audio only) signal connectors.
Loop-Thru Input - A high-impedance (10kΩ) input with a second, or "looping" connector that is passively coupled to the input. A Loop-thru input is useful to loop or daisy-chain several devices (such as distribution amplifiers), or to provide a "fail-safe" signal path, as the passive loop-thru connection does not require power to operate.
DC Coupled - Refers to an input configuration that provides a direct current (DC) connection. In audio products, the DC coupled input ensures that the lowest audio frequency signals are passed without attenuation or distortion.
Balanced Audio - The standard method for connecting professional audio equipment, balanced audio utilizes three wires (two signal conductors and a ground) with the signal on each of the two conductors ideally of equal amplitude and opposite polarity. Balanced audio connections provide superior noise rejection as compared to unbalanced (two-wire) audio.
Unbalanced Audio - The standard method for connecting consumer-grade audio equipment. Unbalance audio requires two wires, a ground and a signal conductor, to transmit the audio signal. While less expensive to implement than balanced audio, unbalanced audio is more susceptible to interference and hum, making it unsuitable for most professional applications, particularly for mic-level or line-level audio signals.
Terminal Block -
VAC uses Phoenix™ two-pin terminal block connectors for unbalanced mono, and three-pin terminal block connectors for balanced mono and stereo audio. Terminal block connectors are compact, reliable, and easy to use (the physical size of VAC's "brick" products precludes the use of XLR of ¼" phono connectors). VAC provides the mating connectors, which incorporate spring-loaded screw terminals for attaching the connector to the customer's wiring.
BNC -
The standard connector for broadcast and professional composite baseband video. BNC connectors are also available on VAC's component video products and select S-video products (those available with separate Y and C cable connections).
RCA -
The standard connector for consumer grade baseband video and audio. VAC offers RCA connectors on composite video, component video, and unbalanced audio DA and switch products.
Mini-DIN -
The four-pin mini-DIN connector is a standard connector for Y/C video (S-video).
XLR -
This three-pin connector is commonly used for professional-grade balanced audio. The XLR connector is physically too large to mount on VAC's "brick" audio products; VAC uses three-pin Terminal Block connectors, which provide similar signal performance in a much smaller package.
GAIN CONFIGURATIONS
Unity Gain - The signal amplitude at each output is identical to the input signal(s). Unity gain is available on distribution amplifiers, and is the only gain configuration available on VAC switches.
Global Variable Gain - The signal amplitude at each output is variable, and all output signal amplitudes are adjusted together with one control. Global Variable Gain is only available on VAC distribution amplifiers.
Individual Variable Gain - The signal amplitude at each output is variable, and is independent of all other outputs. A separate gain control is provided for each output. Individual Variable Gain is only available on VAC distribution amplifiers.
12V AC -
A 12V AC internal power supply is available with most ProSeries products. This option is typically selected when 120V AC commercial power is available. The standard power connector for the 12V AC power supply option is a 2.5mm P5 barrel connector. A 12V AC, 600ma wall transformer is shipped with each unit.
FlexPwr™ - The ProSeries FlexPwr products are designed to operate over a wide range of AC and DC input voltages: 12-32V DC (grounded or ungrounded) or 10-28V AC (ungrounded). These products work well in battery-powered systems, as well as in aircraft operating on 28VDC power systems. A bridge rectifier is used on the internal power supply input so the polarity of the applied voltage does not matter. The power supply input has a filter to minimize the effect of power supply noise on the Brick operation. The power connector is a 2-pin terminal block header (Phoenix Contact #1881448). A 12V AC, 600ma wall transformer is shipped with each unit.
Basic Block™ Power -
All Basic Block products utilize an internal 10-24V AC or DC power supply. A 12V AC wall transformer is included as a standard accessory with every Basic Block. A grounded or ungrounded DC power supply may be used, but ONLY an ungrounded AC supply may be applied to the unit. The standard Basic Block power connector is a 2.5mm P5 style connector; a 2-pin Phoenix Terminal Block connector option is available as a semi-custom part. The wide input power range makes the Basic Block an ideal choice for portable or mobile applications, as well as installations where commercial power is readily available.
Mini Function Block™ Power -
All MFB units utilize an internal DC power supply. The input voltage range is user-selected based on which of two power supply inputs are connected: one input accepts 8-22V DC, and the second accepts 22-36V DC. The units are internally protected against reverse polarity, so applying the voltage backwards (i.e., positive ground) will not damage the device. VAC does NOT ship a wall transformer with the Mini Function Block.
PRODUCT DIMENSIONS
Dimensions - The VAC ProSeries, LS Series, Basic Block, and Breakout product lines are solid epoxy encapsulation packages with several standard sizes. All of the products (except the LS Series) have 6-32 brass inserts molded into the epoxy for easy, mechanically secure mounting. The following table shows the size of the epoxy packages dimensions (not including connectors) for VAC's "brick" products. Dimensions for Legacy Series devices are included in the product listings.
| Unit |
Dimensions |
Metric |
| Basic Block |
2.2" x 2.2" x 0.65" |
56mm x 56 mm x 17mm |
| Breakouts |
2.2" x 2.2" x 0.65" |
56mm x 56 mm x 17mm |
| LS Series |
1.8" x 3.0" x 0.60" |
46mm x 76mm x 15mm |
| 1 Layer ProSeries |
2.2" x 4.4" x 0.65" |
56mm x 112mm x 17mm |
| 2 Layer ProSeries |
2.2" x 4.4" x 1.4" |
56mm x 112mm x 36mm |
| 3 Layer ProSeries |
2.2" x 4.4" x 2.15" |
56mm x 112mm x 55mm |
| 4 Layer ProSeries |
2.2" x 4.4" x 2.9" |
56mm x 112mm x 74mm |
PRODUCT FAMILIES
ProSeries™ - VAC's more versatile family of distribution and switching products. Compact, epoxy-encapsulated audio and video distribution amplifiers and switches, designed to the demanding needs of broadcast engineers and AV professionals. Rugged enough for military applications, competitively priced, ProSeries products meet the challenging requirements of today's video professionals.
COMBO™ - ProSeries™ combination audio + video Distribution Amplifiers and switches. COMBO products deliver all the reliability and performance of VAC's ProSeries audio and video switches and DAs in a single, cost-effective package. Available for both composite and Y/C video with balanced mono, balanced stereo, or unbalanced stereo audio.
Basic Block™ - Cost-effective, compact (2.2" x 2.2" x 0.65"), line driver and two-output DA solutions. Like all VAC "brick" products, Basic Block devices are epoxy-encapsulated, and designed for exceptional reliability, even in extreme conditions. All Basic Block products operate from 10-24V AC or DC power.
Mini Function Block™ (MFB™) - Low-cost, miniature (2.0" x 1.5" x 0.5") four-output DAs and four-input switches with solder-tab connections. MFBs are ideal for applications where space is at a premium. Terminal Block connectors are now available for the MFB product line, allowing easy and quick connection and disconnection.
LS Series™ - The LS Series of composite video DAs was developed to support customers who design the old VAC Legacy DAs into products and require a replacement product with the same form-fit-function. The Legacy products were discontinued because the old internal dip electrical parts were discontinued by the manufacturers. The new LS Series uses new SMD parts and utilizes the new potting process developed for the ProSeries DAs. The user needs to compare the old and new specifications to insure the differences between the Legacy products and LS Series products will not affect their application.
Legacy - VAC's original "brick" products. While many of these older products are no longer in production, several of our "best sellers" are still available while supplies last. VAC is phasing out the Legacy products as critical components are becoming obsolete.
Breakout - Small (2.2" x 2.2" x 0.65") passive connector adaptors. Breakouts provide simple and reliable conversion between connector types.
SWITCHING
Switch Control Options:
- Local Control - VAC "brick" products use small two, three, or four position DIP switches for local control. The DIP switches are molded into the products' epoxy packaging, and allow easy control for diagnostics and installation, as well as user control when space is critical.
- Local/Remote Control - The standard configuration for VAC's "brick" switches, allows local control via a DIP switch molded into the product package, as well as remote control and monitoring via two six-pin mini-DIN connections. Mating connectors are included with all Local/Remote Control switches. Remote control signaling can be dry contact (switch closure), or computer control via TTL or CMOS level commands.
Power Fail Bypass - VAC's exclusive Power Fail Bypass use a passive relay to connect Input 1 to the switch output whenever the switch loses power. This feature acts as a failsafe mechanism, ensuring that the highest priority video signal is always available at the switch output.
Vertical Interval Switch - VAC's Vertical Interval Switches are composite video switches that are designed to switch during the vertical blanking signal of the Input 1 video signal. When used in a genlocked video system, the vertical interval switch enables switching between sources without video picture roll at the monitor.
Automatic Switch - VAC's Automatic Video Switch (AVS) is a two-input device designed to switch between a primary and alternate input depending on the presence or absence of video signal on the primary input. Also known as auto-sensing switches, AVS are used to automatically switch to a backup signal when the primary signal is lost, or as a "priority override" switch, automatically switching to the priority channel whenever a signal is present. VAC offers AVS products for both composite and Y/C video formats.
Non-Selected Input Termination - The terminating impedance of the switch inputs that are not currently connected to the output. For video switches, non-selected inputs are all terminated to 75 Ω. For audio switches, the standard non-selected input termination is an open circuit; however, audio switch non-selected input terminations of 600 Ω and 10 kΩ are also available.
VIDEO SIGNAL FORMATS & TERMS
Composite Video - Analog baseband video, where the signal is a combination, or composite, or the luminance (brightness) and chrominance (color) picture elements. NTSC and PAL are video signal standards that utilize composite video.
Y/C Video - Also known as S-video, this is a mid-level analog baseband video format that uses separate channels for luminance (Y) and chrominance (C). Y/C Video offers higher signal quality than composite, but requires two transmission paths versus a signal path for composite.
S-Video - Also known as Y/C video, this is a mid-level analog baseband video format that uses separate channels for luminance (Y) and chrominance (C). S-video offers higher signal quality than composite, but requires two transmission paths versus a signal path for composite.
Component Video - A high-quality video signal format that utilizes multiple video channels to transmit elements of the video signal on separate channels. Component video offers the advantage of high quality video, as chrominance cross-talk is eliminated, and more bandwidth is available for each signal element. The primary disadvantage of Component video is the requirement for multiple signal channels.
RGB - A high-quality component video signal format, that transmits red, green, and blue on separate video channels. The horizontal and vertical synch information is combined onto the green channel.
RGBS - A high-quality component video signal format, that transmits red, green, blue and synchronization on separate video channels. The synchronization channel is combination of horizontal and vertical synch information.
SDI - Serial Digital Interface, the broadcast standard digital format for baseband digital video signal transmission. Unlike analog signal formats, SDI signals can be regenerated, so that very little, if any, signal quality is lost in transmission.
NTSC - The informal term for the analog broadcast (television) video signal standard for the United States; defined by the National Television Standards Committee, or NTSC, from which the term is taken. The standard, more correctly defined as RS-170, was later adopted by other countries such as Japan, Canada, and Korea.
PAL - The abbreviation for Phase Alternating Line, PAL is the broadcast (television) video signal standard for Europe and most of the world, excluding the Americas and some Asian countries. Because PAL uses a different frame rate than NTSC, the two systems are not compatible, and specialized equipment (or software) is required to convert between the two standards.
Baseband - A video or audio signal that is not modulated. Unlike with modulated signals (typically radio frequency, or "RF"), a transmission line can carry only one baseband signal. All VAC distribution and switching products are designed for baseband signals.
Genlock - Short for generator locking, refers to synchronizing two or more baseband video signals so that the timing for both signals is identical. In a genlocked system, the operator can use a vertical interval switch (VIS) to switch between sources without "rolling" the resultant video signal. Genlocking is also used in video editing systems to combine computer graphics with standard video, and to combine video from multiple sources that may not have been genlocked originally.
ProSeries VIDEO SIGNAL INPUT Configurations
Standard Input - The standard input impedance for all VAC video products is 75Ω (for Y/C video products, 75Ω per channel) DC-coupled connection. VAC standard video products are available with BNC, RCA or mini-DIN (Y/C video only) connectors.
Loop-Thru Input - A high-impedance (10kΩ) input with a second, or "looping" connector that is passively coupled to the input. A Loop-thru input is useful to loop or daisy-chain several devices (such as distribution amplifiers), or to provide a "fail-safe" signal path, as the passive loop-thru connection does not require power to operate. The loop-thru connection must be terminated, either via a connected device, or with a 75Ω terminator.
Differential Input - A 75Ω DC-coupled input that incorporates differential circuitry to place a high impedance path between the input and output signal grounds. Unlike the standard and loop-thru inputs that look at the input signal with respect to ground, this input looks at the signal difference between the input signal and input ground shield. While a differential input does not provide complete ground isolation (VAC's VL-2 and VL-2A provide complete ground isolation using opto-isolator circuitry), it is a compact, reliable and cost-effective solution for most types of ground-loop induced noise.
Loop-Thru Differential Input - As the name implies, combines both a Loop-thru and a different input, and provides the benefits of both features.
DC Coupled - Refers to an input configuration that provides a direct current (DC) connection. In video products, the DC coupled input ensures a proper DC reference for the video signal.
LS Series VIDEO SIGNAL INPUT Configurations
Standard Input - The standard input impedance for all LS Series VAC video products is 75Ω DC-coupled connection. VAC LS Series products are available with BNC connectors.
Loop-Thru Input - A high-impedance (>5KΩ) input with a second, or "looping" connector that is passively coupled to the input. A Loop-thru input is useful to loop or daisy-chain several devices (such as distribution amplifiers), or to provide a "fail-safe" signal path, as the passive loop-thru connection does not require power to operate. The loop-thru connection must be terminated, either via a connected device, or with a 75Ω terminator.
Differential Input - A 75Ω DC-coupled input that incorporates differential circuitry to place a high impedance path between the input and output signal grounds. Unlike the standard and loop-thru inputs that look at the input signal with respect to ground, this input looks at the signal difference between the input signal and input ground shield. While a differential input does not provide complete ground isolation, it is a compact, reliable and cost-effective solution for most types of ground-loop induced noise.
Loop-Thru Differential Input - As the name implies, combines both a Loop-thru and a different input, and provides the benefits of both features.
DC Coupled - Refers to an input configuration that provides a direct current (DC) connection. In video products, the DC coupled input ensures a proper DC reference for the video signal.
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