The Epiphone Valve Junior

We will modify your own Valve Junior or supply ready modified amps to order.

• About our modifications
• Modification Options
• Mastertone Manual

The Epiphone Valve Junior is an nice valve amplifier. 5 Watts, Class A Sovtek and/or Electro Harmonix 12AX7 and EL84 valves Single-Ended 8” Eminence Special Design Speaker (version 3 combo) 4, 8 and 16ohm speaker outlets (head & version 3combo)
So, why modify it?   It’s a pretty good little amp and great value for money but, out of the box, it doesn’t sound as good as it could because it’s made to a price and doesn’t always use the best quality components. By changing component quality and values the sound can be opened up and a wider range of tones can be achieved. Adding new components provides an even wider range of sounds.

• 5 watts is just TOO LOUD for most people to be able to crank it up and get the true valve distortion sound that they are looking for - even a bluesy crunch will not be achieved until the amp is pretty loud.
  In a medium size room, which is where most people have to practice, a 1 watt valve amp can be so loud that you would have to shout really loud to be heard (about 100 decibels) - and around 1/10th of a watt is what is often referred to as “bedroom level” for late night noodling.

By adding a Master Volume control and Power-Scaling™
(see http://www.londonpower.com/pscaling.htm) you can achieve any level and combination of pre-amp and output stage distortion down to less than 1/10th watt.

About our modifications

The internet is full of modification ideas for Valve Junior amplifiers but many of the modifications contradict each other and don’t always work well together when combined into one amp. I have chosen what I believe to be a successful combination of changes and additions which allow the amp to reach it’s full potential and provide a wide range of tones from clean to insane distortion and all at volumes down to ‘bedroom level’.

*Please note that I am licensed to install Power Scaling™ and use genuine London Power components for the Power Scaling™ circuit.

Modification Options

We offer a range of mods to your own Valve Junior as well as ready modified amplifiers.
There are 3 versions of the Valve Junior (see the FAQ's "How do I know which version I have?")

All versions

1. Master Volume
2. Power Scaling™ 5 watts down to 0.1 watt of pure valve tone
   (see the Power Scaling page and FAQ's)
3. Gain Switch (low gain/high gain)
4. Standby Switch
5. HT Fuse
6. Line Out jack
7. 60% of the components are changed for better quality and/or different values
8. 15 components are added (not including Power Scaling)
9. HT Voltages are corrected
10. Bigger power supply smoothing capacitors are fitted to reduce hum
11. Volume and Master Volume controls are full size CTS and Alpha pots
12. Standby switch is a full size high voltage switch rather than a small micro switch.

Version 1

1. Heater converted to DC
2. Modifying the input jack
3. Ground improvement mod

Version 1 and 2

1. Output Impedance selector (combo)