It's just trem right? I'd say the thing that makes it sound different is layered guitar tracks played so the dip isn't so obvious. Sort of like the dips overlap with overpeaks. So you're hearing a subtler effect but still can hear the odd change in volume that's a bit more dramatic.
The main guitar? Amp tremolo. In an interview, he said that the trem kept going out of sync with the song, so they had to record the rhythm guitar in short segments and edit the in-sync bits together.
Wikiwikiwiki:
"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 vibrating in time to the track and each other, so we had to keep stopping and starting the track, recording it in 10-second bursts... We did it in three passes through a harmonizer, set to some weird interval, like a sixth. There was a different harmonization for each pass. For the line in harmonics, I retuned the guitar so that I could play it all at the 12th fret with natural harmonics. It's doubled several times."
This is an extract from "The Smiths: The Songs That Saved Your Life" by Simon Goddard. Highly recommended for all Smiths fans, especially anyone who plays an instrument.
"The compelling effect in question was achieved without the aid of samplers or digital simulators, but manually on traditional analogue equipment. The first step involved taking a basic rhythm guitar part, which had been recorded as a 'dry' DI (direct-input) take without any effects. Porter was already in the habit of taping a safety DI guitar track for every Smiths recording in case needed to alter or manipulate the sound at a later point in the mixing process. The song's texture was further enhanced by Porter's employment of noise gates and the same dry guitar track fed through a quarter note delay signal. 'I had all these combinations which were pretty much all the same guitar but through various faders', says Porter, 'each with slightly different sounds on. It was a combination of all these things'.
THis dry guitar pattern was next relayed to four Fender Twin Reverb amplifiers, each with its own vibrato tremolo switch. As Marr's plain rhythm was played back through the speakers, Porter and Marr controlled the vibrato on one pair of amplifiers apiece to create the swampy, shuddering texture required. Whenever their tremolo slipped out of sync, the recording was stopped, the tape spun back and recommenced, sometimes recording in bursts of only ten seconds at a time."
I don't think they were freely available in the 80s. And they'd be primitive digital and sound like shit if they were. Also were they really that big before "The Queen Is Dead?".
I thought it was a tremolo but it just sounds loads more complex, which it clearly is :s Bloody hell, I can't begin to imagine how you'd go about developing a sound like that and in such a complicated manner. It sounds fucking amazing.
Here's a nice old video of them playing it live (with excellent sound quality):
[youtube][/youtube]
So the sound can be replicated with pedals. dunno how though? just a trem i guess, with a delay pedal to loop it. v clever, he is/was an amazing guitarist!