75 Ohm Terminators why?

[old_tv_nut]

The monitor input is designed to take 1V pp - If you are running without terminations, it is getting 2V pp. Apparently it has enough headroom to tolerate this and not clip whites or peak chroma carrier on full amplitude yellow and cyan, but you shouldn't count on that.

[vol.2]

Originally Posted by old_tv_nut

The monitor input is designed to take 1V pp - If you are running without terminations, it is getting 2V pp. Apparently it has enough headroom to tolerate this and not clip whites or peak chroma carrier on full amplitude yellow and cyan, but you shouldn't count on that.

Okay. Thanks for that. So there is a good reason to run with the terminators in place; mainly to not overly tax the input components.

Yes, it doesn't seem to be an issue without the terminators. I was able to properly calibrate the monitor and tracks beautifully and all colors are about as close to perfect as I have ever seen.

I ordered some more terminators (others are being used elsewhere) and I'll install those and recalibrate when I get them

[ppppenguin]

If you don't terminate, the signal will be reflected from the monitor input back towards the source. If the source has a good, accurate 75 ohm impedance it will absorb that reflection and no harm is done. Otherwise part or all of the signal will be reflected back towards the monitor. Depending on cable length this can cause frequency response errors or possibly ghost images.

In practice, it's often not a problem if a monitor is left unterminated. The frequency response errors and ghost images will often be negligible.Most monitors will tolerate excess video amplitude. There's no question of stressing or harming a monitor with 2Vp-p of video. But just because you can often get away without terminating doesn't make it right.

The fun starts when somebody puts a 50 ohm termination in the box of 75 ohm ones. This can be malicious, by accident or because you're in an environment where both 50 and 75 ohm equipment is being used.

[vol.2]

Originally Posted by ppppenguin

If you don't terminate, the signal will be reflected from the monitor input back towards the source. If the source has a good, accurate 75 ohm impedance it will absorb that reflection and no harm is done. Otherwise part or all of the signal will be reflected back towards the monitor. Depending on cable length this can cause frequency response errors or possibly ghost images.

In practice, it's often not a problem if a monitor is left unterminated. The frequency response errors and ghost images will often be negligible. Most monitors will tolerate excess video amplitude. There's no question of stressing or harming a monitor with 2Vp-p of video. But just because you can often get away without terminating doesn't make it right.

The fun starts when somebody puts a 50 ohm termination in the box of 75 ohm ones. This can be malicious, by accident or because you're in an environment where both 50 and 75 ohm equipment is being used.

Okay. Thanks for that explanation. That makes a lot more sense now. Yes, the sources I'm using are all 75 ohm so that seems okay. I have the terminators coming in the mail already, so I will "make it proper" when they arrive, but it was just kind of driving me crazy that I was doing it without understanding why.