Panasonic EH69 matching IRE with a Japanese VHS source

[jwillis84]

This may be a question too clever to be true.

If I used a Japanese NTSC-J recorder to playback an NTSC-M tape into a Panasonic EH69 world recorder would the IRE and lack of "setup" be correct?

As far as I've read "setup" is only optionally added at the Ouput stage of a source in the United States and Canada.

Professional equipment will sometimes have a switch to "turn it off" to leave setup at IRE 0.

Japanese NTSC-J does not have any setup by default and should thus not apply it on its output.. other than a voltage step-down for the power supply. It seems to me the IRE of the Input to the Panasonic EH69 would then be correct.

Black levels should be correct and it would be about as good as you could get... asuming the VHS source still plays properly.

This is mostly a theorectical exercise.. except I stumbled upon an old NTSC-J recorder and was thinking of trying it.

Its also not very practical for everyone to find a Japan market VHS source.. but its a curious idea for VHS to DVD conversion.

[JVRaines]

The theory is that if both devices have the same definition of "black," then you're okay. But you will still find that, in the real world, black level is all over the place on recorded tapes.

[jjeff]

An EH-59(and other international Panasonics) will make a proper spec DVD if you can provide it with a 0 IRE source. The problem is almost all our SD(composite and S-video) devices output +7.5 IRE, resulting in a washed out recording. OTH the output of a EH-59 will also not boost the SD IRE to +7.5 so if you watch your washed out DVD on a EH-59 via composite or S-video it will actually look OK because our displays are expecting a +7.5 source, it won't be boosted by the output but will be hot on the DVD, resulting in a proper looking DVD. Of course if you play that DVD on a standard N. American DVD player it will look washed out, it will also look washed out watching via HDMI or component directly from the EH-59 as HDMI and component are 0 IRE even in N. America, it will be looking for a 0 IRE DVD(or HDD) but it will probably be recorded +7.5 hot and again look washed out.
Not sure if I answered your question but the key is to supply the EH-59 with a 0 IRE source, something that's not easy to find in N. America. I can't remember if I've tried but theoretically playing a DVD on a EH-59 and then recording it on another EH-59 should result in a proper spec DVD, I personally never play DVDs on my recorders so it's a moot point to me, I much prefer a good quality DVD player, all of which I've found to output +7.5 IRE and no way to darken it

[jwillis84]

The theory is that if both devices have the same definition of "black," then you're okay. But you will still find that, in the real world, black level is all over the place on recorded tapes.

Thanks.. that was what I was thinking.. with the caveat you mentioned.

[jwillis84]

An EH-59(and other international Panasonics) will make a proper spec DVD if you can provide it with a 0 IRE source. The problem is almost all our SD(composite and S-video) devices output +7.5 IRE, resulting in a washed out recording. OTH the output of a EH-59 will also not boost the SD IRE to +7.5 so if you watch your washed out DVD on a EH-59 via composite or S-video it will actually look OK because our displays are expecting a +7.5 source, it won't be boosted by the output but will be hot on the DVD, resulting in a proper looking DVD. Of course if you play that DVD on a standard N. American DVD player it will look washed out, it will also look washed out watching via HDMI or component directly from the EH-59 as HDMI and component are 0 IRE even in N. America, it will be looking for a 0 IRE DVD(or HDD) but it will probably be recorded +7.5 hot and again look washed out.
Not sure if I answered your question but the key is to supply the EH-59 with a 0 IRE source, something that's not easy to find in N. America. I can't remember if I've tried but theoretically playing a DVD on a EH-59 and then recording it on another EH-59 should result in a proper spec DVD, I personally never play DVDs on my recorders so it's a moot point to me, I much prefer a good quality DVD player, all of which I've found to output +7.5 IRE and no way to darken it

I agree with what your saying jjeff.. with the exception that "cooking" the video that way will probably result in a "constrast" loss due to the white levels being punched up through the IRE ceiling. Kind of like taking your sunglasses off and getting glare.

I'm still working on my little project, but after some thought.. decided I needed to be able to "see" the problem on an instrument.

I got a waveform monitor.

I happen to already have a couple SignVideo proc-amps and a TBC-3000 which has a bar signal pattern generator built into it.

I had always thought the SignVideo proc-amp was calibrated and the bar LEDs would be easy to interpret.

Not so!

[edit]

Well after rearranging the gear and trying again fresh.. the IRE +7.5 on the waveform monitor is IRE +7.5 on the bar graph of the SignVideo proc-amp.. I guess it just needed time to warm up. I didn't think about thermal stability of the equipment.