When

When I get the wherewithal, I would definitely like to do crap like recording a part, then sending it through FOUR FENDER TWIN REVERB AMPS to get a tremolo effect that is "tense and swampy".

"The vibrato sound is fucking incredible, and it took a long time. I put down the rhythm track on an Epiphone Casino through a Fender Twin Reverb without vibrato. Then we played the track back through four old Twins, one on each side. We had to keep all the amps vibratoing in time to the track and each other, so we had to keep stopping and starting the track, recording it in 10-second bursts. This sounds incredibly egotistical, but I wanted an intro that was almost as potent as 'Layla' -- when that song plays in a club or a pub, everyone knows what it is instantly. 'How Soon Is Now' is certainly one of the most identifiable songs I've done, and it's the track most people talk to me about."

"The tremolo effect came from laying down a regular rhythm part (with a capo at the 2nd fret) on a Les Paul, then sending that out in to the live room to four Fender Twins. John was controlling the tremolo on two of them and I was controlling the other two, and whenever they went out of sync we just had to stop the track and start all over again. It took an eternity."

(source)