{"product_id":"marshall-jmp-1992-super-bass-2-channel-100w-amp-head-1974-rev-102644755","title":"Marshall JMP 1992 Super Bass 2-Channel 100w Amp Head - 1974","description":"\u003cp\u003e\u003cb\u003e\u003cstrong\u003eMarshall \u003c\/strong\u003e\u003c\/b\u003e\u003c\/p\u003e\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e\u003cp\u003eJMP 1992 Super Bass 100W – 1974 – Japanese Export Specification\u003c\/p\u003e\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e\u003cp\u003eA superb \u003cb\u003e\u003cstrong\u003e1974 Marshall JMP 1992 Super Bass 100-watt head\u003c\/strong\u003e\u003c\/b\u003e, built for the Japanese market and representing a particularly interesting variation of Marshall's legendary early-'70s Super Bass.\u003c\/p\u003e\u003cp\u003eThe 1992 Super Bass is one of the great vintage Marshall circuits. Originally developed as the bass counterpart to the 1959 Super Lead, it quickly became a favourite among guitarists looking for a bigger, warmer and more rounded response than the brighter, more aggressive Super Lead.\u003c\/p\u003e\u003cp\u003eWith its \u003cb\u003e\u003cstrong\u003e100-watt all-valve output stage, four-input layout and non-master-volume circuit\u003c\/strong\u003e\u003c\/b\u003e, the Super Bass delivers enormous headroom, exceptional dynamics and a wonderfully rich, full-bodied sound.\u003c\/p\u003e\u003cp\u003eThis example dates from \u003cb\u003e\u003cstrong\u003e1974\u003c\/strong\u003e\u003c\/b\u003e, placing it firmly within the highly regarded metal-panel JMP period, and carries serial number \u003cb\u003e\u003cstrong\u003e6488F\u003c\/strong\u003e\u003c\/b\u003e.  The circuit is very original with red shellac present on most solder joints and the amp comes with a period Rose-Morris\/Marshall sticker on the front(see pictures).\u003c\/p\u003e\u003cp\u003eJapanese Export Specification\u003c\/p\u003e\u003cp\u003eThis particular amplifier was originally manufactured for the \u003cb\u003e\u003cstrong\u003eJapanese market\u003c\/strong\u003e\u003c\/b\u003e and features several differences from the more familiar UK and European models.\u003c\/p\u003e\u003cp\u003eMost notably, it has a \u003cb\u003e\u003cstrong\u003ehardwired mains cable\u003c\/strong\u003e\u003c\/b\u003e rather than a detachable IEC connection, and there is \u003cb\u003e\u003cstrong\u003eno external voltage selector on the rear panel\u003c\/strong\u003e\u003c\/b\u003e.\u003c\/p\u003e\u003cp\u003eThese are features associated with certain export-market Marshall amplifiers of the period and form part of what makes this example particularly interesting.\u003c\/p\u003e\u003cp\u003e\u003cb\u003e\u003cstrong\u003eFor customers in North America, our amplifier engineer can configure the amplifier for 110V operation before shipping.\u003c\/strong\u003e\u003c\/b\u003e This work will be carried out professionally, ensuring the amplifier is correctly configured for its destination.\u003c\/p\u003e\u003cp\u003ePlease contact us before purchasing if you require a different mains voltage configuration.\u003c\/p\u003e\u003cp\u003eClassic Super Bass Tone\u003c\/p\u003e\u003cp\u003eAlthough originally designed as a bass amplifier, the \u003cb\u003e\u003cstrong\u003e1992 Super Bass has long been one of the most desirable vintage Marshall circuits for guitar\u003c\/strong\u003e\u003c\/b\u003e.\u003c\/p\u003e\u003cp\u003eCompared with the equivalent 1959 Super Lead, the Super Bass generally offers a warmer, fuller response, with a thicker bottom end and a slightly smoother, less aggressive top end.\u003c\/p\u003e\u003cp\u003eThere's enormous clean headroom available, but when pushed, the amplifier develops a wonderfully rich, harmonically complex overdrive with incredible depth and authority.\u003c\/p\u003e\u003cp\u003eThe two channels can also be jumpered, allowing the brighter and darker inputs to be blended for additional tonal flexibility.\u003c\/p\u003e\u003cp\u003eWhether paired with a vintage Greenback-loaded 4×12 or a more powerful G12H cabinet, the Super Bass delivers that unmistakable early-'70s Marshall sound — huge, open and exceptionally responsive to the guitar.\u003c\/p\u003e\u003cp\u003eRecently Professionally Serviced\u003c\/p\u003e\u003cp\u003eThe amplifier has recently undergone a \u003cb\u003e\u003cstrong\u003ecomprehensive professional service by Dave Wittering\u003c\/strong\u003e\u003c\/b\u003e, former Marshall senior service engineer.\u003c\/p\u003e\u003cp\u003eThe work was completed in \u003cb\u003e\u003cstrong\u003eSeptember 2026\u003c\/strong\u003e\u003c\/b\u003e and included:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eReplacement of the bias circuit smoothing capacitors\u003c\/li\u003e\n\u003cli\u003eReplacement of the polarity decoupling capacitor\u003c\/li\u003e\n\u003cli\u003eInstallation of a dedicated chassis earth\u003c\/li\u003e\n\u003cli\u003eNew matched quartet of \u003cb\u003e\u003cstrong\u003eOEM Marshall EL34B output valves\u003c\/strong\u003e\u003c\/b\u003e\n\u003c\/li\u003e\n\u003cli\u003eThree new \u003cb\u003e\u003cstrong\u003eOEM Marshall preamp and phase inverter valves\u003c\/strong\u003e\u003c\/b\u003e\n\u003c\/li\u003e\n\u003cli\u003eReplacement OEM Bulgin HT fuse cap\u003c\/li\u003e\n\u003cli\u003eElectrical safety inspection\u003c\/li\u003e\n\u003cli\u003eFull operational testing\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eThe amplifier has therefore benefited from a fresh complement of Marshall valves alongside important electrical maintenance, ensuring it is ready to be enjoyed as intended.\u003c\/p\u003e\u003cp\u003eSpecification\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eModel:\u003c\/strong\u003e\u003c\/b\u003e Marshall JMP 1992 Super Bass\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eYear:\u003c\/strong\u003e\u003c\/b\u003e 1974\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eSerial Number:\u003c\/strong\u003e\u003c\/b\u003e 6488F\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003ePower:\u003c\/strong\u003e\u003c\/b\u003e 100 watts\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eCircuit:\u003c\/strong\u003e\u003c\/b\u003e Non-Master Volume Super Bass\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eConfiguration:\u003c\/strong\u003e\u003c\/b\u003e Four-input, two-channel head\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003ePower Valves:\u003c\/strong\u003e\u003c\/b\u003e 4× new OEM Marshall EL34B\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003ePreamp Valves:\u003c\/strong\u003e\u003c\/b\u003e 3× new OEM Marshall ECC83\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eMarket:\u003c\/strong\u003e\u003c\/b\u003e Japanese export specification\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eMains Connection:\u003c\/strong\u003e\u003c\/b\u003e Original-style hardwired mains cable\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eVoltage Selector:\u003c\/strong\u003e\u003c\/b\u003e No external rear-panel selector\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eVoltage Conversion:\u003c\/strong\u003e\u003c\/b\u003e 110V configuration available before shipping\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003e\u003cstrong\u003eProfessionally Serviced:\u003c\/strong\u003e\u003c\/b\u003e September 2026\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003e\u003cstrong\u003eDedicated Chassis Earth Fitted\u003c\/strong\u003e\u003c\/b\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cb\u003e\u003cstrong\u003eFully checked and tested\u003c\/strong\u003e\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eThe \u003cb\u003e\u003cstrong\u003e1974 JMP Super Bass is a fantastic example of Marshall's golden era\u003c\/strong\u003e\u003c\/b\u003e, offering a slightly different flavour to the more familiar Super Lead while retaining all the power, dynamics and unmistakable character of a proper 100-watt vintage Marshall.\u003c\/p\u003e\u003cp\u003eThe Japanese export specification adds another interesting element to this particular amplifier, while the recent comprehensive service and fresh set of OEM Marshall valves make it a very appealing example for players looking for authentic early-'70s Marshall tone.\u003c\/p\u003e\u003cp\u003eWhether you're after enormous clean headroom, thick vintage crunch or simply the sound of a great 100-watt Marshall being pushed hard, the \u003cb\u003e\u003cstrong\u003e1992 Super Bass is an exceptional amplifier\u003c\/strong\u003e\u003c\/b\u003e.\u003c\/p\u003e\u003cp\u003e\u003cb\u003e\u003cstrong\u003eWorldwide shipping available.\u003c\/strong\u003e\u003c\/b\u003e The amplifier will be carefully prepared and securely packed using purpose-made Overdrive Guitars packaging, with the valves protected for transit and shipment fully tracked and insured.\u003c\/p\u003e\u003cp\u003e\u003cb\u003e\u003cstrong\u003eFor international customers, we can arrange for the amplifier to be configured for 110V operation by our engineer before dispatch.\u003c\/strong\u003e\u003c\/b\u003e\u003c\/p\u003e\u003cp\u003eCollection and demonstration are also available from our West London showroom.\u003c\/p\u003e","brand":"Marshall","offers":[{"title":"Default Title","offer_id":53807385903440,"sku":"rev-102644755","price":2499.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0944\/0919\/5856\/files\/16389f28-8a70-4cb1-a9cd-8dd8c1381acc.jpg?v=1792054965","url":"https:\/\/overdriveguitars.com\/products\/marshall-jmp-1992-super-bass-2-channel-100w-amp-head-1974-rev-102644755","provider":"Overdrive Guitars","version":"1.0","type":"link"}