Product Review (July 2003) - Key Digital Systems
Flash 4 KD-SW4x1 4-Channel Video Switcher

Video switching, either in a display or in an external unit, is a reality with today's complex home theater systems. Multiple video sources often pose a common problem that can only be solved by adding a video switcher into the system. The risk of degrading the video signal becomes an unfortunate issue that must be addressed. Quality video switching does not come cheaply and after spending thousands on a high-definition display, few users are willing to cut corners if it means compromising picture quality. Key Digital Systems, known for their cost effective video products has introduced the Flash4, a high-bandwidth 4-to-1 video switcher that works with both component (YPrPb) and RGB video signals. The Flash4 is only 4 inches deep, but is designed to fit nicely into a standard 19" rack (ears included). The front panel is simple with a power light and four blue lights indicating the active input channel. An input selector button sequentially switches through the four video inputs connected to the unit.

The inside of the Flash4 is a clean multi-layer printed circuit board. Surface mount technology helps reduce parasitic capacitance and inductance. This is particularly important with high-bandwidth video signals. The split-plane circuit board design separates the digital interface electronics from the video switching to keep high frequency noise out of the video signals. Overall, we were impressed with the internal build quality of the Flash4 product. Video bandwidth rolls off -3dB at 140MHz, which ensures HDTV signals will not be degraded. All common SDTV and HDTV scan rates are supported with the Flash4.

Each of the four channels has six RCA connections to accommodate either component (YPrPb), RGB or RGB/HV video signals. When component video or RGB video with sync-on-green is connected, three of the six inputs are used for video. The remaining three inputs can be used for two channel analog audio and a PCM digital signal. If RGB video with separate HV signals are connected then only a PCM digital audio signal can also be switched. Each of the three video component inputs (YPrPb or RGB) as well as the PCM digital input is properly terminated with 75 ohms to prevent reflections. The two inputs used for left and right analog audio or the horizontal and vertical drive signals in the case of RGB video have high input impedance. There's also a standard 9-pin RS232 serial interface that can be used to select any input on the Flash4 when combined with an external controller. Power is supplied by an external AC adapter that works with any voltage between 100-240VAC for universal support.

The IR remote included with the Flash4 video switcher is a standard sized unit. The remote has a lot of buttons, but the majority of them are not used. The first four numbers on the remote are used to select the input to the display. The Channel Up/Down buttons can also be used to select the inputs.

Our setup included a reference InFocus ScreenPlay 7200 high definition projector and a 100" Stewart FireHawk filmscreen mounted on a Luxus Deluxe frame. We fed analog video to the projector from several sources. Two set-top boxes were connected to the Flash4 switcher along with our JVC HM-DH30000U D-VHS high-definition VCR and HTPC. HDNet's Bikini Destinations on D-VHS produces an excellent reference picture with low noise and rich colors. Skin tones and fine detail remained accurate with or without the Flash4 in the video chain. We saw similar results with both set-top boxes and the HTPC. The transparency of the video switcher is very important and the Key Digital Flash4 appeared to deliver both functionality and performance whether video was 720p or 1080i. We saw no video degradation when using the Flash4.

The Key Digital System's Flash4 video switcher proved to be a quality product that introduced no noticeable video degradation in our setup. The unit offers flexibility by supporting both component and RGB video systems. The ability to also switch PCM digital and two channel analog audio when used with component video sources makes this product even more attractive.
- Kevin Nakano

Review System

Projector: InFocus ScreenPlay 7200 High-Definition DLP™ Projector (ISF calibrated)
Stewart Filmscreen Luxus Deluxe FireHawk ScreenWall
Scaler: Focus Enhancements CenterStage CS-2 Scaler
Preamplifier/Processor: Parasound AVC-2500U THX-Ultra DTS/DD Preamp/Processor
Amplification: Parasound HCA-2205AT THX-Ultra Five Channel Amplifier
Bass Management: Miller & Kreisel BMC Mini 5.1 Bass Management Controller
Front Speakers: Miller & Kreisel S-150THX (L+R) and S-150AC (Center) Speakers
Rear Speakers: Miller & Kreisel SS-250 Tripole® Surround Speakers
Subwoofer: Two Miller & Kreisel MX-350THX MkII THX-Ultra Push-pull Subwoofers
Room Treatments: Echo Buster panels and Bass Buster towers
Set-top Box #1: Samsung SIR-T165 Terrestrial HDTV Receiver with DVI
Set-top Box #2: RCA DTC100 HDTV/DSS Satellite Receiver
D-VHS VCR: JVC HM-DH30000U D-VHS High-Definition D-Theater VCR

HTPC: Sony Vaio PCV-RZ22G Multimedia PC with MIT MDP-100 High Definition Receiver card
A/V Cables: Ultralink Platinum and Advanced Performance Series Cables
DVI Cable: Monster Cable M Series M500DVI DVI-D Cable
Power Conditioning: Panamax MAX® 5500 ACRegenerator
Video Generator: Sencore VP300 SDTV/HDTV Video Pattern Generator
Color Analyzer: ColorFacts Display Analysis System with Eye-One Pro Colorphotometer

Review - At a Glance

Key Digitial Systems - Flash4 KDSW4X1 Video Switcher


  • Switching for up to 4 Component Video and Audio or 4 RGB/HV plus digital PCM Audio.
  • Any SDTV and HDTV formats accepted 480i, 576i, 480p, 576p,1080i/540p & 720p.
  • VGA support up to 1920x1080p @ 60Hz
  • Front panel manual control button.
  • All video inputs and outputs have female RCA cable connectors.
  • Infra Red Remote.


  • Manual control button on front panel.
  • S-Video, Composite, Component and RGBHV switching.
  • RS 232 port provides direct access control to systems such as Crestron, AMX, Panja, Dataton.
  • Rack mountable - 1U.
  • Crystal clear image.
  • Cost effective.

    Technical Specifications:
    Inputs:   4 Input groups: Each Input Group consists of Component Video (YPrPb) and Audio inputs: analog L,R plus digital PCM or R,G,B,H,V plus digital PCM. Each Input Group consists of 6 discrete jacks
    Video: Three RCA jacks Component Video (YPrPb) or R,G,B,H,V (H&V could be send through L&R Audio connectors)
    1 V p-p @ 75 Ohm terminated Composite
    Sync on "Y"

    2 RCA jacks
    High Impedance Line type inputs Left and
    Right inputs (also used for H&V in RGBHV mode)

    1 RCA jack
    Standard Digital PCM

    Scanning Rates :

    All known video types accepted: 50 Hz or 60 Hz
    refresh:480i, 576i, 480p, 576p, 1080i/540p,
    720p; Supports VGA switching resolutions up to 1366x768/72. Input and Outputs - same scanning format


    3 db at 140 MHz, liner phase pass band

    Video Gain :

    Unity X2 gain for YPrPb and R, G and B

    Switching Control :

    Via manual switch on front panel. Via Infra Red Remote. Pressing 1 digit (1 to 4) on the remote performs matrix switch operation. (Default setting)

    RS232 Control :

    The RS232 control will perform identical function to the IR remote control

    Display :

    Front display contains a rows of 4 LED's each correspond to each input


    17" x 4" x 1.75"


    6 lbs. (boxed 8 lbs)

    Enclosure type:


    Rack mountable:

    Included Brackets, (1U high)

    Input Power:

    100 to 240V AC, 0.9A

    Source: Manufacture supplied
    Model Number: KD-SW4x1
    MSRP: $599
    Warranty: 2 years parts and labor

    Company Information
    Key Digital Systems, Inc.
    314 West 231 Street, Suite 504
    Riverdale, New York 10463, USA
    Phone: 718-796-7178
    Fax: 718-796-6664

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