On Mutt Lange's Def Leppard:
First, guesses by producers and musicians, that can also be used as methods:
EQing: Scoop out the mids. Compress the stew out of it. Add a bunch of 10k and 16k. Or boosting from 12 to 16k. Or HPF, a mid scoop and Aphex, with a few cents up and down on a Harmonizer with 15 to 30ms delay each side for a bit more width possibly dont hard pan those returns.
Effects: A harmonizer like the Eventide. Eventide H3000 set on the "FAT AS CAN BE" program with some reverb or delay. Or a stereo harmonizer just a little off unison on each side. Manley mic pres and C12s.
One of the methods used is with a Dolby A machine, and its called the vocal mod or even "the John Lennon mod." The method involves encoding the background vocals with Dolby but not encoding the playback, thus giving the vocals extra high end and sizzle.
"The Dolby A" was a 70's noise reduction machine. The amount of compression on each band is inversely proportional to the volume of the band, which means that quieter sounds get brighter while louder sounds remain almost unchanged. This adds brightness and air without generating any new harmonic content or distortion.
The bands are as follows:
Band 1 has a low pass filter around 80Hz.
Band 2 is the results of the input signal minus band 1 and 3, essentially a band pass filter from 80Hz to 3kHz.
Band 3 has a high pass filter around 3kHz.
Band 4 has a high pass filter around 9kHz.
The machine was also abused as an enhancer:
The most common Dolby A mod was disabling the two lower bands so that only the high-frequency portion of the signal was compressed, giving even more air to vocals. This is the vocal mod we mentioned.
There are other Dolby-licenced technologies besides the Dolby A, such as the Dolby S noise reduction type (derived from the Dolby SR), which involves combining both fixed and sliding bands, anti-saturation, spectral skewing and modulation control. S type provides 24dB noise reduction at high frequencies and 10dB at low frequencies. Modern high-end cassette decks generally contain Dolby S-type that can make cassette tapes sound "nearly as good as CDs."
Multi-tracking vocals: 10 or 12 takes of backing vocals. On some songs on Def Leppard, there could be 100 vocals tracked together. When you layer 24+ tracks of vocals sung in the way he has them you may get an effective mid scoop in the eq without adding any eq, but the singer has to be pretty accurate hitting pitch and timing because if you tune and do trimming correction all you will get is a flanging effect. Addition of whisper tracks. Because the tracks sound like theres just one singer, though, it might have been just one, along with one background singer, Mutt. You don't hear multiple timbers. Using other voices besides the singers. Then building one huge voice out of them. For a high voice (like Avrils, who Mutt also worked with, there was a man singing the "Complicated" chorus, then they heavily EQed his take to just add one specific frequency range to Avril's take, and same with other singers, so the end result is it sounds like just her singing. Mutt may also have backing vocalists drop consonants and sing only vowels sometimes so the BVs don't rub with the primary tracks.
According to one forum, for Def Leppard the whole group and Mutt would stand around a mic and do the parts. Mutt and bassist Rick Savage sing high. Mutt has a pure tenor voice, and very precise singing ability.
Now according to Mike Shipley, engineer with Mutt on the albums: the "Pour some sugar" BVs were done like this: layer 3 people singing in unison on 20 tracks, bounce them to one track. Do another 20 tracks and bounce them to one track. EQing heavily on the bounces. Then repeat the process. Rebounce the vocals a few times, taking out the offensive frequencies very heavily on a narrow bandwidth first the honky frequency build up, then the shrill middle frequency, the same way so the sounds ends up kind of "concave" sounding with a lot of smooth high end.
"Mutt would make everyone everyone overemphasize the diction of the words," according to Shipley, which gets the sound of those BVs, along with how tight the tracking up is. A lot of the distinct sound is because of Mutt's voice. "We would no use reverb on any of the BVs," but Shipley used multi tap delays to thicken and widen the sound as much as he could, and even more EQ in the mix. "That kind of vocal sound kinda sounds best done on analog because of what the multiple bounces do to the sound. ... Doing it digitally needs boxes like the 'Hedd' to get the right kind of saturation."
Also, Shipley said they would use a lot of tumbling flanged delays. No mic pre's other than what were in the SSL 4K were used on either album. Compression with a Teletronix LA-2.
Sometimes, they layered up different guitars for different tonal qualities. Les Pauls for low end, teles/strats for high end. String by string technique for certain parts (such as the Hysteria pre chorus) to avoid any arpeggiation. Sometimes, they tuned open strings to a chord for similar reason.
Pyromania: According to Shipley, after trying dozens of amps, "I’m pretty sure we ended up with just a little Marshall combo amp after we’d tried everything," through condenser mics, to get the "commercial distortion" sound. A custom 100 watt head with an old cabinet.
Hysteria: According to Shipley, all the guitars are though a Rockman guitar headphone amplifier (made famous by another band, Boston). Not amps. "There might have been a couple passes of clean guitar through a small amp, but most all of it was recorded through a Rockman. That meant an awful lot of EQ’ing and processing. All the clean sounds, all the jangly parts, and all the distorted guitars were Rockman. It would get a bit irritating, because we’d try everything and just keep going until we found something that worked. Because we did it for so long, it never was that satisfying; we’d just look at each other after weeks of working on it and just go, 'I guess this is the best we could do,' and that was it."
But he elsewhere said, "We had a specific sound in mind for Hysteria and at that time because we were living in a world of electronics, we had to utilize those tools because we couldn't get the tones right. On Pyromania for example, the previous record the group did, we had like 200 amps in the studio but because they weren't a straight power chord band, you had to get the distortion and tones right first. So it was a lot of work and lot of layering was involved. But going back to your question, when it comes to mic'ing techniques, it is different for every player. Back in those days it was more condensers than dynamics being used but we'd experiment endlessly with microphones and went to such amazing lengths to get the tones we were after."
Shipley: "All the other songs on the record, the song's drums were all samples from the Fairlight CMI (computer musical instrument) sampler. There are no real drums. The cymbals are played, but the bass drum, snare, and toms are all machine. We had all kinds of drums in there, and I sampled them into the Fairlight and detuned them. We'd sample them in at half-speed, thinking that we'd get a better sound, because that's when Fairlight was at 8 bits – you had to get around that part of it. We sampled [Ludwig] Black Beauty snares, other snares, and all kinds of bass drums. We ended up with something that Mutt liked that we could detune a little bit. When we were sampling in the sounds, we used [Neumann] KM 84s and we used [Shure SM]58s. There were so many mics. The toms were primarily Simmons toms back then, which were electronic. We experimented, EQ'd, and mangled the sound up a little bit to come up with the drum sound. It was pretty unnatural, but that was kind of the point."