I play an Epiphone Thunderbird IV and i was thinking to change the passive pickups to active pickups can anyone recommend a good active pick up for this kind of bass
Epiphone SG G 400
Marshall JH-1
Peavy Vyper
Marshall MG 10
Epiphone Thunderbird IV
Hartke A100
I know Bartolini and EMG both make passive drop-in replacements, but I can't think of any actives.

The problem is that the T birds pickups are an unusual size and shape, and there's only a handful of options for direct replacements. Anything else would require modification to your bass.
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There are the Basslines: http://www.seymourduncan.com/products/basslines/cutting-edge-1/ssb45_passive_p/ Those SSB-4's get a lot of love.

I've heard lousy things about the EMGs, and the Barts are a love/hate deal.

You might be able to snag some pups from an Epi Tbird Pro... those are active. Also, the Gibson Tbird Pups are made for high output, even though they are passive.... you may luck out on finding a pair of those (but they'd be expensive)

Then there's always Fralin T-bird pickups... but it's almost $300 for a set... so... yeah...
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trade out the electronics for an active system. the pickups for passive can and often are used with active systems.
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