"This is one of the best amps I've ever played" – new video investigates the Fender Twin Reverb Kurt Cobain used on Nirvana's Bleach

We love finding out more about the gear behind iconic albums, and some players might be surprised to hear the tube amp in the signal chain for Kurt Cobain's often metallic and sludgy tones on Nirvana's debut Bleach were courtesy of a Fender Twin Reverb owned by producer Jack Endino.

It's still with Endino, now at Soundhouse Studio in Seattle, and Nirvana fan Aaron Rash took a trip out to see and try it for himself.   

Endino's assistant engineer saw Rash's video on recreating the tone to About A Girl from Bleach and reached out to the YouTuber to correct a photo detail in the video; Cobain actually used a Silverface Twin on the song, not a Blackface-era '67 as suggested. He then invited Rash to come and play the amp and meet Endino.

Rash brought his Univox High Flyer guitar with him; a model Endino hadn't seen since Cobain had one for Bleach. The producer then dialled in the controls for Rash to play About A Girl with a DS-1 for the overdriven parts. And there's the sound (accounting for the mic'd cab we hear on the record). With some pointers from Endino on chord voicings, no less! 

"It definitely freaked me out because the moment I played that chord through that amp, I totally got goosebumps," admits Rash. "That was it – that was that sound."

It's not a stock Fender Twin Reverb; Endino modded the amp himself. The producer noted the similarity to the schematic of the Fender Bassman and changed out the phase inverter circuit before the power amp section to make it more like the one in a 100-watt Bassman. But Endino's main mod was increasing some of the coupling caps in size between preamp and the power amp to get a little more low-end. 

The amp has some unusual vents at the size that were there when Endino purchased it in 1983 – and could have come that way from the studio. 

Check out more of Aaron Rash's Nirvana videos at his YouTube channel.