> video is 75ohm, audio is 110ohm... keep this in mind when modding
Video is indeed 75 ohm impedance (not "resistance"!). But analog audio runs in "bridged" mode, with source impedance 600 ohms or less (sometimes as low as 100 ohms) and load impedance 10K. This is not an "impedance mismatch", it's supposed to be that way.
A VGA KVM switch should (if it's designed well) present a 75 ohm impedance (since this impedance is used in the VGA connections as well as in component video).
Digital audio over coax to an RCA connector (SPDIF, now called IEC 958) is 75 ohms and can use the same RG59 cables as component video. If you have an XLR jack for digital audio you are then dealing with 110 ohms (AES/EBU
A cheap passive switch as some are recommending here is almost certainly NOT 75 ohms.
Using Y-adapters to combine signals of almost any sort is an absolutely TERRIBLE idea. The impedances will be all wrong. Even for analog audio, let alone video.
Here's an idea: Any VGA KVM switch is also switching the H and V sync lines... and it shouldn't alter those signals any more than it should alter the R G and B signals. So it ought to be possible to run digital audio through one of those (the impedance will even be correct), or analog audio through both of them (the impedance won't matter). I'm going to try it.
Now that we've thrown 'em off the trail, use the form below to get in touch with the people at Engadget. Please fill in all of the required fields because they're required.
ok i now know there is no auido from HD15 so can all the video be put to one RCA say yellow
> video is 75ohm, audio is 110ohm... keep this in mind when modding
Video is indeed 75 ohm impedance (not "resistance"!). But analog audio runs in "bridged" mode, with source impedance 600 ohms or less (sometimes as low as 100 ohms) and load impedance 10K. This is not an "impedance mismatch", it's supposed to be that way.
A VGA KVM switch should (if it's designed well) present a 75 ohm impedance (since this impedance is used in the VGA connections as well as in component video).
Digital audio over coax to an RCA connector (SPDIF, now called IEC 958) is 75 ohms and can use the same RG59 cables as component video. If you have an XLR jack for digital audio you are then dealing with 110 ohms (AES/EBU
A cheap passive switch as some are recommending here is almost certainly NOT 75 ohms.
Using Y-adapters to combine signals of almost any sort is an absolutely TERRIBLE idea. The impedances will be all wrong. Even for analog audio, let alone video.
Here's an idea: Any VGA KVM switch is also switching the H and V sync lines... and it shouldn't alter those signals any more than it should alter the R G and B signals. So it ought to be possible to run digital audio through one of those (the impedance will even be correct), or analog audio through both of them (the impedance won't matter). I'm going to try it.