Which one did Brian May and Tony Iommi use. And before you wtf me on the second one, Tony Iommy did use one when he started detuning as otherwise, everything he played would sound like mush.
i think brian may used an AC30, and there are Top Boost models that have a treble booster.

and Iommi had Laney put in a treble booster
I believe Brain May's was a custom job and Iommi's was a mod job too (at least as far as I'm aware.)

Both were based on Dallas Rangemasters though (the later Queen tone used SS trannies though.)

BSE make some nice clones of their treble boosters.

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