November 1984: Genocide's "Toxic Metal" demo
Genocide's only demo with drummer Phil Hines, a hardcore punk drummer from the band Dissonance. Hines works the torturously slow groove which starts the song and contrasts that with a d-beat to pick up the pace while not playing all that fast. It's a stark contrast how the d-beat was the fast, aggressive beat of hardcore punk at the beginning of the decade, and a slow, groovy contrast to blast beats by the end of the decade. The fastest part of the song is the Slayer riff at 1:30, then some Slayer-style solos - the drummer loses power on the kick drum when trying to play faster during the second solo.
Phil Hines died on Christmas in 2006 and a memorial remembered him as a hardcore punk drummer. RIP
Summer 1985: Repulsion meets Death
Scott Carlson (and later Matt Olivo) join Death for a few months, and Kam Lee introduces them to the blast beat. Scott is Death's first bassist. He records five rehearsal tapes with the band between May and August, with Olivo joining for the last. Kam Lee leaves the band, Carlson and Olivo return to Michigan to reinvigorate Repulsion, and they all make history as being the first of many lineups to leave Death.
October 1985 Genocide's "Violent Death" demo
Carlson and Olivo return to Michigan and death metal legend takes hold. Not only do they find a drummer who is twice as fast as their old one, but they learn of the guy when they read about his arrest for grave robbing in the newspaper. He allegedly stole the head of a woman named Helga, who was the prosecutor's grandmother, but got off easy because he was underage. That's the story behind the Repulsion song "Helga Lost Her Head" - that's the stuff of death metal legend indeed.
More unbelievably, they found a drummer twice as fast as the last guy. Dave Grave lays a d-beat under the slow intro riff, now sped up, and plays faster during the other parts. A fast d-beat underlays the first solo, and he gets into some real blast beats during the second solo. The contrast of fast and slow is very strong here, with the fast sections being a rapid kick-snare beat. Matt Olivo's soloing is more controlled, more resembling scale runs than the cat-in-a-blender Slayer squealing. The drummer's ability allows for the Slayer riff to speed up before that solo, which provides a lot of contrast that Phil Hines could not. Still, the riffing and blasting have not yet met.
January 1986 Genocide's "The Stench of Burning Death" demo
Repulsion gets nastier and thrashier and continues to increase their speed. This time, the slow intro is gone - the song starts straight into the fast break out of it, and the drums play a nearly constant blast beat all the way through, The primitive rhythmic contrasts are replaced with a moment where the drums cut out, and the rest is straight blasting. The one remaining guitar solo is skillfully fast, the scale runs more controlled, yet the overall speed increase keeping it just as chaotic. The morbid, multi-paced death metal turns into relentless ripping death-thrash and begins grinding along with a sick drummer.
June 1986 Repulsion's "Slaughter of the Innocent" demo (better known as the "Horrified" LP)
The slow intro returns with the d-beat, the fast drumming gets faster, the production gets dirtier and nastier. The bass track is distorted and doubled, which gives it a gut-churning feeling like no other. While the thrashy crunch of the previous demo was nice, this is simply dirty and disgusting music that needs this sound. The guitar solo is faster and more chaotic than ever, it leads straight into a break, which rips right back in and ends the song.
This is where grindcore gets the grind. These are unmistakable blast beats, a monster of a drummer pounding the kick and snare as rapidly as possible, the guitars roaring in a dirty blur, and another layer of guitar-like distortion added to the bass. This laid the foundation of grindcore - first released on LP by members of Carcass, acknowledged by Napalm Death, loved by Impetigo - this is as close as one band ever got to inventing a genre.
Another band who pioneered this extreme style was Napalm Death. Here are two versions of the same song from a few months apart.
December 1985: Napalm Death's "Hatred Surge" demo
Moderately-paced crust punk with moderately-paced drumming. The band clearly had an aggressive edge here, but they hadn't yet pushed the boundaries of their style.
March 1986 - Napalm Death's "From Enslavement to Obliteration" demo
While the same song by name, this song is a completely different beast. 42 seconds in, that blast beat makes this a completely different type of music. It goes from frustrated to furious. Napalm Death have named Repulsion as an influence, and this seems to be around the point in time they heard them. In contrast to Repulsion - this makes a heavy use of speed and dynamic contrasts like the earlier Repulsion demos did, and they pick their spot for the blast beat very well. It seems Repulsion influenced Napalm Death, then Napalm Death influenced Replusion in turn, all observed in a series of four demos in six months.
This is one brief insight into the history of grindcore, but a significant insight into how death metal and grindcore evolved in their early years.