Jellyfish Audio Repair & Upgrade Kit B for Marshall Plexi / JTM45 JTM50 JCM50 guitar amplifiers

Description

This listing is for a kit including two high gain 12AX7 valves to refurbish and improve a JTM45 or JTM/JMP 50 amplifier. The kits offered here provide the key components you can change to breathe new life into your amplifier and keep it rocking through the 21st Century! Marshall Plexi amps have lots of gain up at the front end preamplifier stages and it is in this area that things start to go wrong and have most effect in an amplifier of this age. Original 1960's amplifiers were made using cheap Carbon composition resistors. These kits focus on changing just a few key parts for more modern, higher specification components that can reduce the hiss and noise your amplifier produces and improve the reliability of the amplifier and protect it from high voltage faults that can destroy valves and take the amp out right in the middle of your live guitar solo! In particular,carbon composition anode resistors are notorious for changing value with time,breaking down internally and becoming unstable and microphonic. Many vintage amplifiers that make sputtering, hissing and crackling noises do this because anode resistors in the preamp stages have gone unstable, so these are key components to change. Changing the preamp valves sometimes makes a huge difference to the brightness and clarity of your sound, so our kits include the option to change two of the front end ECC83/12AX7 valves to bring back the focus and punch these stages bring to your performance. Each of our kits comes with details about which components fit,where and some safety and fitting instructions to help you. Kit A: Contains the key preamp stage resistors and capacitors,along with output stage coupling capacitors to improve hiss/crackle noise and reliability of your amplifier. Kit B: Contains the same parts as Kit A plus two bias smoothing capacitors and two 12AX7B high gain low noise ECC83 replacement valves,manufactured by the same company that supply Marshall (see our other listing to purchase Kit B).