Have any of you installed these preamps into you Alembic? The luthier says he is installing the 5k preamp into an Alembic "Clone". This leads me to think most "Real Alembic" owners would not want to alter their bass. To each is own.

I have an East dual filter preamp in my Hamer 12-string bass.  The filters helped tame the overwhelming high end those basses tend to have.  I would not think, nor would I want, to replace an Alembic preamp with one of these; or any of the other filter preamps out there for that matter.  Alembic sound like Alembic because of the electronics more than anything.

I agree. That's why I would be skeptical about modding my Alembic series 1 with th a t preamp.

I plead guilty, for a lighter sentence. . 🥴🫣🙄.
I had an Europa 5 with standard electronics and later wanted a series alembic but the ones i liked were out of my reach financially at the time so when I bumped into John East at Manchester (UK) bass day i discovered he was producing filter based electronics and persuaded him to make me a set of electronics to put in my bass. which he did. It had low pass and high pass filters for each pickup, master volume and pan. All knobs were stacked so the q was on top of the filters and vol and pan on another.
It sounded good and the low pass filter range started at 80hz. However I found that the filters lacked punch and was experiencing noise. So i returned the original alembic electronics and sold the bass last year. The electronics I transferred to my only non alembic bass.
And now have a series bass. 🥳

I explored the idea of installing a custom set of John East filters/electronics in a Hyak bass I had a while back. It just so happened a fellow Club Member had a new-old-stock set of Hyak electronics that were the perfect match for it, so I scrapped the idea. (those NOS parts did finally make it into that bass too, and I hear it's doing well) 

No idea how the East filters would have sounded, but almost anything would have been better than what I had, which was just passive treble-cut pots and volume controls. I ran everything wide open and straight through to a tube preamp. Sounded pretty good. Always knew it could be better.