Component video switching

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:39 am

Component switching thru A/V receiver

February 12 2003

I am planning on buying a new receiver since mine currently does not do component switching. I am looking at the Sony STR-DA4ES which does component switching with 50mhz bandwith. Is this good enough for hd switching. Is there going to be a loss in video or anything? Thanks.

Marty

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:41 am

I consider the minimal acceptable bandwidth to be flat to 100 MHz, -3 dB at 200 MHz. If you buy a switch, such as the AA 1154, which is flat to 30 MHz, -3 dB at 60 MHz:
1. you will probably see no difference if your monitor can only display 1280 pixels horizontally.
2. there will be a difference that is very hard to see if your CRT can display 1920 pixels horizontal.
3. some pixels will get changed if your display is digital (plasma, DLP, etc.) but it will be very hard to see.

Ken - KQ6QV

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:41 am

The analog signal on the component cables never exceeds 38MHz, right?

a

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:42 am

The frequency response of audio does not exceed 20Khz yet your preamp and amp should go out to 100-200Khz to properly pass a 20Khz signal. The same is true of video and the 37Mhz of 1080 really should have 100-200mhz bandwidth. The real trick at this time is having a display that would resolve this potential issue so in reality you could get away with something much lower at this time but... What if you get a new display in a few years that can resolve this? Then you need new cables and switching. Properly operating equipment and cables are investment in the future.

Richard F. Fisher

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:43 am

I guess I should run my component cables directly to the TV. Based on my Yamaha specs "Monitor Out - DC to 30 MZ, -3DB" WHy do they offer this type of feature if it does not support the signal?

Matt

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:44 am

I guess I should run my component cables directly to the TV.

Try it both ways. You're the best judge of what works for and is visible to you.

Why do they offer this type of feature if it does not support the signal?

Was probably designed for DVD's lower bandwidth requirement. Also see the first response. It might not be visible.

a

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:47 am

Note to all: Pay attention to whether a frequency spec is a "flat to" spec or a "-3 dB" spec. One is usually twice the other for the same circuit.

Ken - KQ6QV

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 11:48 am

I consider the minimal acceptable bandwidth to be flat to 100 MHz, -3 dB at 200 MHz.

This is correct.

Just like in audio you need the 3rd or 4th harmonic to pass the original frequency with out roll off. For audio this is 20k x 2 =40k (2nd) and 40k x 2 = 80k (3rd) and 80k x 2 = 160khz hence 100-200khz bandpass for audio.

For HD video we have 37m x 2 = 74m (2nd) and 74m x 2 = 148m (3rd) and 143m x 2 = 296Mhz hence the 200-240Mhz as tested and suggested by the ISF for broadcast.

If you have a capable display this is what you would want. As you pointed out most of us don't have that so less bandwidth will be acceptable. For most consumers I have been recommending at least 100Mhz @ -3db.

Richard Fisher

HDTV Forum · Post by **HDTV Forum** » Fri Jun 25, 2004 12:11 pm

The Outlaw 950 was recently reviewed by WSR, issue 76, September 2003, page 84.

We have had discussions concerning bandwidth requirements of component video for over a year. This reviewer has a Phillips 55PP9352 HDTV. He used the Outlaw for component switching rather than direct connections and this is what he found...

"I found that some of the razor sharp images I am accustomed to while feeding the display direct from the (Dish) 6000 were slightly degraded."

The video switching is rated at 45Mhz.

Richard Fisher