...you know my opinion about the driver and junction box position for a totally passive design...
...i prefer drivers and junction boxes...on the extreme zone for a better air circulation not only for cob heatsinks ...for drivers ventilation too... ...the drivers can go on a vertical heatsink too... with the fins oriented on vertical for better passive ventilation design...
...but i know you make temp test too... ...then for my pov go ok with your amb temps... my dudes are with high ambs temps... but i suposse with high amb temps...all passive ways are not good solution too... need fans or maybe a/c system....or liquid way.... ...but on passive way we can help the air circulation with a design with drivers or junction boxes not near or over to heatsink/s for better air circulation... just my pov bro...
...off course temp tests give you better pov.... if go ok for your needs...why not?...
...i respect all ways... inclusive the magic yellow tape....from supra... ...
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...i hope you dont look this post on criticism way... its just my pov...
...A big salute to BROS... take care and stay safe... love for all
Saludos