Visual Cortex pre-encoder expander

Save two for me if I don’t respond immediately, it’s a busy time :slight_smile:

The LUMA output on this will be very nice to have on hand.

@luix In reference to the RGB knobs, will it be possible to have a straight pass through of the RGB channels, I guess I should say, if the knobs are set all the way counter clockwise (or all the way clockwise) will it allow for an uneffected clean pass through of the RGB without the attenuverter effecting the signal?

I am sure this is possible, but, was just hoping for some insight on how this has been designed for this module. Thanks!

It works exactly like that.

The luma is unaffected by the RGB knobs and goes out directly.

The RGB goes to a bit higher than 1v when the knobs are fully clockwise, and -1v when it goes counterclockwise.

On the middle (12’ clock) the gain is 0 and the channel will not pass thru. Hope that makes sense.


UPDATE! The pcbs are been fabbed now in china :slight_smile:

Tomorrow I’ll record a vid on the module and publish the costs and form to reserve a module. I’m planning on doing a 30 built run, and 30 pcb set, with some spares :slight_smile:


Here is a vid I recorded to try to clear what I think is important.

TBH the only thing I dont like about this module is that potentiometers are too tight (close) so I sacrified some ergonomics in favor of having luma outs plus as-much-as-possible skiff friendly module.


It looks awesome! Ready to order :money_with_wings:

I am really happy this has the Luma output and will likely not be fussing with the knobs to much. So sounds perfect to me. Thanks!

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Nice video and great work @luix!

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@luix How do I order one diy panel and pcb. Thanks :alien: :mushroom:
Please DM me for payment

IDGI why it needs 5x lm6172 ? Don’t they 2 channel on each chip

You have to buffer each input (3), each output (4), so you’re looking at 7 opamps minimum, or 4 LM6172’s. I guess you also need some for the luma mixer, too?

@joem is correct, the signals need gain in this case so they need to be amplified as well. I breadboarded a single channel similar circuit few years back and it would have used 6 LM6172’s (my memory’s hazy - no input buffer, inverting amp and inverting output buffer I think).

More updates on this, PCB from factory came and I built it.

I’m noticing some bleed noise on channels when doing the “hard edge” test that Lars always recommend to detect bleed, otherwise the board is good to go. I wrote to Lars and Phil to see if anything can be done to remove/reduce this.

This means maybe two more weeks of delays so you all start ordering yours. I don’t want to ship you a board that has some noise (even if is small) and I’ll end up refunding paying stuff so just want to be super honest and clear with what you will be getting… I will record a clip explain this hard edge test, and showing the bleed so you all know a little bit more on how you should test your video equipment/modules.


What’s a little noise on a hard edge! :slight_smile: Standing by, @luix


I feel a little stupid here, so please excuse the noob question!

Can anyone explain, simply, why I might want to do this with my Visual Cortex? I’ve read through the thread here, but I can’t get a grasp on what this upgrade might be used for, in practical terms?

this gives your visual cortex LZX standard 1/8 outputs of whatever is coming out at the composite/svid/component outs

this could be used for feedback, further processing connecting to another system lots of fun stuff!

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So we’re not placing orders yet right? Don’t want to miss this when it’s time!

Im waiting for final PCBS with ground plane to reduce bleed noise, they have been manufactured and their are on their way to me so should be receiving them next week probably.


One use case would be if you have another module with its own set of video outputs and you want to feed it a signal that’s mixing both of the Visual Cortex’s compositing channels together. Some LZX modules have RGB 1v outs (Color Chords, Marble Index, Mapper, Memory Palace), just as the Visual Cortex has two sets of RGB ins in its compositing section.

However, the only way you could get full RGB (or the functional equivalent, at least) out of a Visual Cortex without any sort of expansion attached is via the component outputs. BUT, in order to put this back into another part of the LZX system, it would need to be decoded again via another Visual Cortex input decoder section or a TBC module, as it is now a valid video signal instead of the LZX 1v standard. This expansion panel serves as a much less cluttered way to continue processing a fully patched Visual Cortex, or to take advantage of final output via another module (such as the DVI/HDMI output of the Memory Palace).

Did that help? :exploding_head:


Thanks Tylerm, that’s very clear explanation.
I guess I’ll join the queue for this awesome upgrade!

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