Celestion Greenback G12M (1966–1980s; reissue 1980s–present)
If you've ever heard a Marshall stack on a classic rock record, you've heard this speaker. The G12M — nicknamed "the greenback" for its distinctive green plastic magnet cover — is arguably Celestion's most legendary guitar speaker. It entered the company's log book on 6 May 1966, though Marshall was already loading them into 4×12 cabinets by late 1965, and at least one surviving example is dated March of that year. The T1221 code refers to the 15-ohm version; T1220 is the 8-ohm variant, and T2168 is the same speaker without the plastic cover.
The G12M was Celestion's first guitar loudspeaker to use a ceramic magnet structure, which offered nearly the same magnetic flux as the earlier Alnico designs in a smaller, more compact package. The ceramic magnet speakers first appeared around late 1964 to early 1965 and tend to sound slightly more aggressive than their Alnico predecessors. The original early T1221s had no doping at all on their cones; over the years, Celestion added more edge doping and increased power handling. The speaker went through many changes during its production run, but the essential character — warm, "woody" mids that compress nicely when pushed hard — remained the thing guitarists chased.
Sonically, the Greenback is darker and thicker than Celestion's Alnico Blue, with a prominent midrange that gives overdriven guitar tones their characteristic body and growl. It's a tighter-sounding speaker than the G12H, with a warm, "juicy" midrange and a little more character to the tone. Angus Young has been a Greenback devotee since AC/DC's early days, and the speaker was an important ingredient in Van Halen's "brown sound." People often describe the tone as "woody," and the speaker compresses nicely when pushed hard enough.
After a few years out of production in the 1980s, Celestion reissued the G12M in the late 1980s, and it has remained in production ever since — though production has since moved from England to China. The Heritage line, which recreates the late-1960s pre-Rola period speakers, was recently discontinued; the EVH G12M is apparently the same speaker under a different label and remains in production as of January 2025.
Known Specs
- Size: 12" (305mm nominal diameter)
- Power handling: 25W RMS
- Impedance: 8Ω or 16Ω (T1221 is 15Ω)
- Frequency range: 75Hz–5kHz
- Resonance: 75Hz
- Sensitivity: 97–98dB (1W/1m)
- Voice coil: 1.75" (44.5mm), round copper
- Magnet: 35oz ceramic
- Chassis: Pressed steel
- Cut-out diameter: 11.1" (283mm)
Original 1960s and 1970s examples are highly collectible — a single working vintage Greenback can fetch $300–$600 or more depending on condition and provenance. New reissues sell for considerably less. The speaker remains a staple for classic rock and blues guitarists, and can be heard on countless albums.
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