Reissue of the JCM 900 4100 100W head.
Marks that can be entered for this maker: Serial number (plate), Transformer code, Speaker code, Born-on / QA sticker, Panel features (no code).
The introduction year is not documented, so the model narrows nothing.
Sold-listing reading: fair $656, good $794, excellent $819 USD · 8 sold listings · as of 2026-10-15. clean, solid row: eight Model 4100 heads and nothing else in the filtered block, band 656-1145 USD and 8 lots (sample_flag solid). This is the cheapest 100W Marshall head measured in the run - below the JCM 800 2203 (1691-4213) and far below the Plexi 1959 (3003-16287) - and within the row the year barely matters (1990-1999, 1993, 1995, 1996 and a 2000-serviced unit all land inside the same 500-USD corridor). Excluded nothing from the filtered block; the fallback block is where the traps are (Model 4500 50W, Model 2100 MKIII, SN20H Studio, 4102 combo, 1936/1960A cabinets, a JCM900 pedal and an amp cover). Alignment verified: PRICE DROP markers at the same three positions (4/7/8) in both arrays. Reverb exposes the price and condition but not the exact sale date, so asof = measurement date; no Fair/Poor sale observed; fair = lowest sold price in sample Condition tiers normalised to monotonic order (the source sample had a condition tier below the lower one).
Evidence: Blue Book of Guitar Values — marshall · reverb.com