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CRT Primer

Updated: January 2008


Analog Devices (Composite/S-Video/Component/RGBHV)


Composite/S-Video/Component to RGBHV conversion

A typical analog non-HD signal, such as a video or S-Video signal or a 480i component signal will need some sort of signal processor to upscale the signal so it won’t look grainy on your CRT projector. This processor is typically called a line doubler or a scaler. Depending on the model of projector and your tube size in the projector, your ideal resolution will vary (see projector resolution ‘sweet spot’).

Most line doublers or scalers will have more than one input so that all or most of your analog video signals can be switched within the signal processor.  The output of a scaler or line doubler will typically have a BNC output or an SVGA connector that has the RGBHV signal on its pins.

Many A/V receivers will have video, S-Video and component switching right in the receiver. This is handy, as your video sources will switch at the same time as your audio signals without having to push extra buttons. Note however that a low to midrange A/V receiver typically will not convert a video signal to S-Video and vice versa, so if you’re running S-Video signals into the receiver, you’ll need to connect the S-Video output of the receiver to the scaler. If you’re also running composite video signals into the receiver, you’ll need to then also connect the composite video output of the receiver to the scaler.


Keep in mind as well that a lot of the lower end A/V receivers can actually degrade the video signals passing through them, so if you suspect a poor quality video signal is due to the video switching circuits in a receiver, simply bypass the video switching portion of the receiver, and connect your video source directly to the doubler/scaler. A well designed video switching section of a receiver will have no visible affect on the signal.

Now let’s add some confusion to the mix.

Many of the older line doublers and scalers will NOT accept a component signal with a higher resolution than 480i. Therefore, a progressive DVD player component signal (480p) or an HD signal (1080i, 720p) will not be processed correctly by an older scaler/doubler. If you try to connect higher than a 480i signal to a scaler that cannot accept such a signal, you might get no image at all, or you’ll get two images side by side.

How to get around this: If you want to retain a scaler as part of your video system, you’ll have no choice but to get a late model scaler that will accept a component signal higher than 480i. Most of the post 2006 scaler models will accept and process a component signal up to 720p. Examples of these will be the late model Lumagen and DVDO scalers, the Faroudja DVP 5000, Crystalio, and many other scaler makes and models. Check the specifications of the scaler you’re looking to upgrade to to ensure that the component input can be higher than a 480i signal. The bad news is that late model scalers are more expensive than earlier ones, the upside is that they are available on the used market at this point, and chances are the signal processing in a later model scaler will be visibly better than an older unit, so you’re upgrading your picture quality of all of your sources at the same time.

There are a number of other methods to convert a component signal to RGBHV. One method is to use a TRANSCODER which is usually just a signal converter. You input a component signal, you get an RGBHV signal at the output. Many transcoders will not scale the signal, it’s merely a format converter. There are a number of brands out there, and range in price from about $75 for a no name brand, to $600 or more for a broadcast quality rack-mount unit.

Most of these transcoders only have one input and one output, so you’ll need to do source switching externally, either via your A/V receiver or an external component switcher.

I carry various types of transcoders, including models from Audio Authority (see here). We also feature the RTC2200 Component to RGB, TC1600 RGB to Component Converter, Box1020, and Box1040 products sold by our third party vendors.

Another method to convert a component source to RGBHV is to use a card that fits into your projector or video switcher that accepts a component input. One such card is the Sony made IFB 12 card, originally designed for 480p signals only, but with some minor modifications, can also be used to convert a 1080i component HD signal. This card is somewhat hard to find, but is available on the used market for cheap. The card will only fit Sony projectors and Sony switchers. The ISS2200 component input card for NEC projectors and switchers is also available from one of our third party vendors.

Finally, some of the Moome HDMI input cards for CRT projectors and switchers feature a component input in addition to an HDMI input.  Perfect if you only have 2 sources such as HD satellite/cable (component) and Blu-ray or HD-DVD (HDMI). So external component switching will be needed if you have more than one source with component outputs.


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