Tone library / Nirvana / Heart shaped box

Heart shaped box amp settings — Univox U.30B

The Nirvana guitar tone for “Heart shaped box”, dialed in for a Univox U.30B with a Lero Telocastor. Studio version, In Utero (1993) — Steve Albini recording

Original rig

Fender Jaguar (or mystery partscaster per Aaron Rash research) into EHX Big Muff Pi into Mesa Boogie Studio Preamp with Crown power amp. EHX Polychorus on the solo.

Raw, scooped wall-of-fuzz on chorus; cleaner verse with volume rolled back. Aggressive yet melodic grunge saturation.

Amp settings — Univox U.30B

Knob	Setting (0–10)
Gain	6
Bass	7
Mid	4
Treble	6
Master	5

Don’t have a Univox U.30B? See this song on other amps → Match your own rig →

Guitar

PICKUPbridge TONE6 VOLUME6

Signal chain

01Big Muff Pi (or any high-sustain fuzz)

RECOMMENDED — not currently owned. Essential for the chorus fuzz wall. Engage for chorus, bypass for verse.

Volume 7 · Tone 5 · Sustain 7

Why these settings

The Univox U.30B is a vintage solid-state practice amp with limited gain and no presence/reverb controls — it cannot produce Big Muff-level saturation alone. Set amp near-clean (gain 6, mid scooped to 4) and let the recommended fuzz pedal handle all dirt. Your Telocastor's bridge single-coil will be brighter than Cobain's Jaguar humbucking circuit, so tone knob rolled to 6 tames the ice-pick.

PRO TIPThe verse-to-chorus dynamic IS the tone — keep verse volume at 6 on the guitar, then stomp the fuzz and dig in harder for the chorus. Cobain's strumming precision on this track is deceptively tight despite the sloppy image.

Get this tone on your amp

These settings are for a Univox U.30B. ToneAdapt matches any song to whatever amp, guitar and pedals you own — first match is free.

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Song, artist and gear names are used to identify the tone being matched; ToneAdapt is not affiliated with or endorsed by the artists or manufacturers mentioned. Settings are AI-generated starting points — trust your ears.