Initially designed within the '40s, rotational speaker cabinets creatively utilize the Doppler effect by terminating a woofer into a pivoting drum and a tweeter into a rotating horn. The results are much more consonant than commonplace tremolo or vibrato effects, creating sounds extending from wealthy and gleaming to delicate, marvellous and twirling. These novel speakers were rapidly received by jazz organists, cemented by blues and shake legends such as Buddy Guy, Jimi Hendrix, Pink Floyd and The Beatles, and afterwards, the effect was reenacted by guitar pedal producers.