Grunge guitarists played loud, with Kurt Cobain's early guitar sound coming from an unusual set-up of four 800 watt PA system power amplifiers. Guitar feedback effects, in which a highly amplified electric guitar is held in front of its speaker, were used to create high-pitched, sustained sounds that are not possible with regular guitar technique. Grunge guitarists were influenced by the raw, primitive sound of punk, and they favored "... energy and lack of finesse over technique and precision"; key guitar influences included the Sex Pistols, The Dead Boys, Celtic Frost, Voivod, Neil Young ("Rust Never Sleeps", side two), The Replacements, Hüsker Dü, Black Flag and The Melvins. Grunge guitarists often downtuned their instruments for a lower, heavier sound. Soundgarden's guitarist, Kim Thayil, did not use a regular guitar amplifier; instead, he used a bass combo amp equipped with a 15-inch speaker as he played low riffs, and the bass amp gave him a deeper tone.