The Tone City TC-T37 Mad Stone Classic Germanium Diode is a Tone City fuzz pedal, currently around $79.80. Close alternatives include the Electro-Harmonix Percolator and the Sola Sound Tone Bender MK1. It pairs well with the Marshall Studio JTM ST20C MkII 20W 1x12 Combo and the Marshall JTM45 45W Tube Guitar Amp Head.
Tone City TC-T37 Mad Stone Classic Germanium Diode
Tone City · pedal
The Tone City Mad Stone is a budget distortion pedal built around germanium diode clipping. Germanium diodes clip at a lower threshold than silicon, so the voicing is softer, warmer and more compressed than a typical silicon distortion, with a rounded top end and a smooth, vintage-flavoured breakup rather than a sharp, cutting edge. It sits in a compact mini enclosure at an accessible price and is aimed at players wanting classic, warm distortion character without a boutique outlay.
What stands out
“Germanium diodes clip at a lower threshold than silicon, so the voicing is softer, warmer and more compressed than a typical silicon distortion, with a rounded top end and a smooth, vintage-flavoured breakup , cutting edg…”
— from the listing
“Players who want vintage germanium-style distortion at low cost find the Mad Stone a practical option”
— from the community notes
“Germanium clipping gives it a warmer, softer and more compressed voice than silicon-based distortions, with a rounded top end and vintage-flavoured breakup”
— from the reviews
“The Tone City Mad Stone is a budget distortion pedal built around germanium diode clipping”
— from the listing
“That makes it flattering on bright rigs and forgiving at high gain, but it is , aggressive modern distortion, and the budget build and mini enclosure keep control spacing tight”
— from the reviews
Trade-offs
“cutting edge”
— from the listing
- distortion
- germanium
- top end
- vintage
- breakup
- clipping
- compressed
- diode
Good for
- Busking
- Live
Price updated Oct 24, 2026
Genres the Tone City TC-T37 Mad Stone Classic Germanium Diode is commonly used in
- Alternative
cited
Inferred from shared tonal signals, not a stated genre tag. - Punk
cited
Inferred from shared tonal signals, not a stated genre tag. - Rock
cited
Inferred from shared tonal signals, not a stated genre tag. - Classic Rock
cited
Inferred from shared tonal signals, not a stated genre tag. - Hard Rock
cited
Inferred from shared tonal signals, not a stated genre tag. - Blues
cited
Inferred from shared tonal signals, not a stated genre tag.
Amps that pair well with the Tone City TC-T37 Mad Stone Classic Germanium Diode
Marshall Studio JTM ST20C MkII 20W 1x12 Combo
Marshall
22% matchMarshall Studio JTM ST20C MkII 20W 1x12 Combo takes that edge of breakup character and pushes it toward low gain
Comes later in the signal chain
Marshall JTM45 45W Tube Guitar Amp Head
amplifier
22% matchfills a frequency gapFills in a frequency range the other side doesn't cover, instead of piling more onto what's already there. (bright → warm)
Marshall JTM45 45W Tube Guitar Amp Head's warm balances out the bright tone
Comes later in the signal chain
Ampeg V-4
Ampeg
tonal matchComes later in the signal chain
Ampeg V-4 pushes a edge of breakup tone toward mid-forward
Ampeg BA 108
Ampeg
tonal matchComes later in the signal chain
Ampeg BA 108 takes that edge of breakup character and pushes it toward mid-forward
Ceriatone HRM 50
Ceriatone
tonal matchComes later in the signal chain
Stack Ceriatone HRM 50 on top and a edge of breakup tone tightens toward mid-forward
Ceriatone Overtone Special HRM Bluesmaster 50
Ceriatone
tonal matchComes later in the signal chain
Feed a edge of breakup signal into Ceriatone Overtone Special HRM Bluesmaster 50 and it comes out closer to mid-forward
Park P45H
Park
tonal matchComes later in the signal chain
Park P45H leans warm right where the bright tone needs it
Gallien-Krueger Fusion 210
Gallien Krueger
tonal matchComes later in the signal chain
Gallien-Krueger Fusion 210 pushes a edge of breakup tone toward mid-forward
Pedals that stack with the Tone City TC-T37 Mad Stone Classic Germanium Diode
Spaceman Explorer 6-Stage Phaser
Spaceman
20% matchsits in the right chain slotPlaced for where it does its job cleanly in the chain, not for a tonal interaction with the anchor.
Run Spaceman Explorer 6-Stage Phaser after Tone City TC-T37 Mad Stone Classic Germanium Diode in the signal chain, clear of Tone City TC-T37 Mad Stone Classic Germanium Diode's own gain stage
Comes later in the signal chain
Greer Southland
Greer
20% matchGreer Southland takes that edge of breakup character and pushes it toward clean boost
Comes earlier in the signal chain
Cusack Music Screamer
Cusack Music
20% matchCusack Music Screamer pushes a edge of breakup tone toward mid-forward
Comes earlier in the signal chain
Xotic SP Compressor
Xotic
15% matchshapes the dynamic responseShapes how the tone responds to picking dynamics rather than its frequency or gain.
Xotic SP Compressor's own smooth character is the real reason this is worth trying
Comes earlier in the signal chain
T-Rex Junior Roomate
T Rex
13% matchsits in the right chain slotPlaced for where it does its job cleanly in the chain, not for a tonal interaction with the anchor.
Run T-Rex Junior Roomate after Tone City TC-T37 Mad Stone Classic Germanium Diode in the signal chain, clear of Tone City TC-T37 Mad Stone Classic Germanium Diode's own gain stage — goes in the amp's FX loop (or last, into a clean amp)
Comes later in the signal chain
Alexander Pedals Now We Are Ghosts Reverb
Alexander Pedals
13% matchsits in the right chain slotPlaced for where it does its job cleanly in the chain, not for a tonal interaction with the anchor.
Alexander Pedals Now We Are Ghosts Reverb's ambient voice goes after Tone City TC-T37 Mad Stone Classic Germanium Diode in the signal chain — it's not there to compete with Tone City TC-T37 Mad Stone Classic Germanium Diode's own germanium character — goes in the amp's FX loop (or last, into a clean amp)
Comes later in the signal chain
Dunlop Echoplex Preamp
Dunlop
tonal matchComes later in the signal chain
Dunlop Echoplex Preamp's smooth balances out the bright tone
MXR CAE Wah
MXR
tonal matchComes earlier in the signal chain
MXR CAE Wah belongs in front of Tone City TC-T37 Mad Stone Classic Germanium Diode, since a wah tracks picking dynamics best on the raw signal
Cheaper alternatives
Boutique & premium upgrades
EarthQuaker Devices Hoof Hybrid Fuzz
EarthQuaker Devices
56% similarityShared character: warm, bright, smooth
Walrus Audio Eons Five-State Fuzz
Walrus Audio
55% similarityShared character: distortion, vintage charm
EarthQuaker Devices Fuzz Master General
EarthQuaker Devices
48% similaritySimilar voicing: germanium, bright
Benson Amps Germanium Fuzz
Benson Amps
47% similarityShared character: warm, smooth, distortion
Benson Amps STÖRKN Fuzz
Benson Amps
47% similaritySimilar voicing: germanium, fuzzy
Catalinbread Karma Suture GE
Catalinbread
45% similarityShared character: warm, smooth, distortion
Similar character
Electro-Harmonix Percolator
Electro-Harmonix
48% similarityShared character: smooth, aggressive playing
Sola Sound Tone Bender MK1
pedal
44% similarityShared character: vintage charm, high gain settings
JHS Pedals JHS 1966 Italy Tone Bender
JHS Pedals
44% similarityShared character: smooth, aggressive playing
Questions people ask
What are good alternatives to the Tone City TC-T37 Mad Stone Classic Germanium Diode?+
The closest matches in character are the Electro-Harmonix Percolator, the Sola Sound Tone Bender MK1, the JHS Pedals JHS 1966 Italy Tone Bender. Budget picks: Electro-Harmonix Flatiron Fuzz. Boutique upgrades: EarthQuaker Devices Hoof Hybrid Fuzz, Walrus Audio Eons Five-State Fuzz, EarthQuaker Devices Fuzz Master General.
What pairs well with the Tone City TC-T37 Mad Stone Classic Germanium Diode?+
Strong matches from rig and tone-complementarity evidence: Marshall Studio JTM ST20C MkII 20W 1x12 Combo, Marshall JTM45 45W Tube Guitar Amp Head, Ampeg V-4 — Marshall Studio JTM ST20C MkII 20W 1x12 Combo takes that edge of breakup character and pushes it toward low gain.
How much does the Tone City TC-T37 Mad Stone Classic Germanium Diode cost?+
Around $79.80 (live listing price, updated Oct 24, 2026).