Blue Series Causing Flickering where A Red On/Off does not

I am posting this more to gain understanding rather than to solve what I think may be an unsolvable problem, but title.

I have some sort of unknown LED fixture in a closet that I was hoping to wire to a blue series in On/Off mode to get scene control in a room, but the fixture flickered the entire time it was on. I received a Red On/Off today and threw it in that location out of curiosity and it works completely fine.

Is there anybody who can explain why this is the case? I think the post I linked may be the answer, but I don’t understand the topic well enough to be sure.


Blue series made a compromise to support non-neutral configurations by implementing leading-edge dimming. Further, on/off mode does not bypass the dimming circuitry- even when configured as on/off you’re still getting a chopped waveform. Red series (I believe) and Zooz Zen27s (I know for certain) use trailing-edge dimming. On/off versions of these devices are truly just what they say (no dimming circuit), so there’s no waveform chopping at all. Some (many?) LEDs don’t do well with leading-edge dimmers, but work fine with trailing edge.

Summary: Inovelli should release a v2 of the Blue that uses trailing edge dimming. It will increase LED compatibility greatly, at the expense of not being able to work without a neutral.

I’m 95% sure I have this all correct- somebody please jump in and point out errors if I have it wrong.

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Ah, ok. That’s what I thought may be happening but I wasn’t 100% sure. Thanks for confirming!

The Red Series dimmer uses a MOSFET w/ Leading Edge dimming.

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Wait, what? I thought the whole point of the Blue 2-1 is that it had a relay for 100% sine wave pass thru when in switch mode.

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@coreystup Per this comment in the link I posted above, it sounds like the relay is just switching the load between the load and the traveler terminal, which I guess means the blue is effectively the same as a red dimmer that’s always in 3-way mode with dimming disabled. I haven’t tested this to verify.

Well thats unfortunate. I purchased these two 2-1’s to use with florescent fixtures in on/off mode after selling two red/black on/offs. I swore I saw 2-1 supported true on/off mode in the manual or somewhere.

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Check out this post… seems like corners were cut, or a hard decision had to be made re: on/off/dimming implementation. Whatever the case may be, it’s a bit disappointing. No true on/off relay separate and isolated from the dimmer, forward-phase dimming… I’m honestly very surprised the other bells and whistles were prioritized over using best-practice for each and every core function.

Edit: this post more directly addresses the on/off relay: