Hi and welcome to my listing for this "Marshall" mod kit for the original hum prone V.1 (version 1) Epiphone Valve Junior 5W Class A Combo, (green circuit board and 8 digit serial numbers starting 0105 to 1105, produced early 2005 to November 2005 ).
(8 digit serial numbers 1205 to 0707 (December 2005 to July 2007) are V.2 amplifiers which need my V.2 kit).
(14 digit serial numbers and a black circuit board are the latest V.3 spec which need my V.3 kit).
1. Drop HT voltage to a safer level so increasing valve/tube life.
2. Fit extra HT filtering to further reduce hum.
3. Fit HT fuseholder and fuse to protect mains transformer should a fault occur on the HT rail.
4. Re-bias pre-amp tube to give a Marshall "crunch" sound.
5. Reconfigure input to 1meg high impedance (makes your guitar "come alive").
6. Change interstage resistive network to further clean up sound.
7. Fit Standby switch (increases valve/tube life).
8. Fit Pentode/Triode switch (Pentode = normal, Triode = low power)
9. Fit output impedance selector switch (gives the option of using 4 or 8 ohm speakers).
10. Fit Line-out jack with built in ground lift.11. Mallory 150M coupling capacitors to give a smoother sound.
12. Convert heater (filament) supply to DC as later models
Instructions and pictures are kept in a folder. The folder is stored on a download site. You will receive a download link via email which will be sent to you at
the same time as you receive confirmation from eBay that the kit has been shipped.
I will use your PayPal registered email address unless you inform me of an alternative preferred email address. If you don't receive the link, please check your spam filter/junk folder, or contact me directly (email@example.com).
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Your amp can feature some or all of my latest prototyped and fully tested mods
Some of them in more detail:
HT voltage: the stock amp has a much too high HT voltage. This results in the EL84 output valve being worked too hard. Designed working voltage is 250V. Maximum voltage is 300V. I've measured anything up to 348V (on a V.1) and 330V on a V.2 My mod reduces this to around 300V. What's more, the absolute maximum anode (plate) dissipation for an EL84 is 12watts. I have measured and calculated anything from 12.5 to 14.7watts. These are dangerous levels which can result in a burnt out valve, or shortened valve life at the very least. My mod reduces anode dissipation to around 10.7watts. You can now use your NOS Mullard safe in the knowledge that you won't destroy it!
Standby Switch - absolutely essential in my opinion. All valve amps (especially those with silicon rectifiers) should have a standby switch. It allows the valves to become fully warmed up before applying the HT (high tension) (high voltage) to the valves. Eliminates cathode stripping and other damage. With proper use of the Standby Switch (wait at least 30 seconds before switching on, and switch to standby before switching off the mains power switch) your valves should last at least twice as long!
HT Fuse: let's take a look at the protection for the Valve Junior. The mains lead itself is protected by a 5amp fuse. The mains input to the amp (mains transformer primary winding) is protected by a T1AL 250V time delay (slo blo) fuse. The heater (filament) supply is protected by a T4AL 250V fuse. Both legs of the auxiliary output are protected by T1.6AL 250V fuses. That leaves the HT winding (with no protection)! Imagine if the output valve is damaged by vibration and shorts out. Or, what if a power supply capacitor blows or shorts - voila! there goes your expensive mains transformer! For the sake of a few quid it ain't worth the risk!
Output impedance selector switch - handy if you want to use an external speaker cabinet, or if you want to change the internal speaker to an 8 ohm model. The output transformer has two output taps available (4 & 8 ohms), this switch simply switches either to the output jack.
Pentode/Triode Mode selector switch. A rather elegant way of reducing the output power from 5watts (pentode) to 2watts (triode). This is in response to people asking me for a quieter amp when in clip, as 5watts class A valve is still very loud! I looked at all the usual well-worn options including, power soak, L-pad attenuator, master volume etc, but none of these gave me what I consider the really sought after true output valve distortion at a lower volume. Research into old valve data sheets from the fifties brought me to the conclusion that this was how the old-uns did it, and is a well tested and thoroughly documented way of using the EL84 output valve.
Line-Out Jack. Again, never wanting to follow the crowd, I looked at what others were doing and decided there was a better way of doing it. Rather than take the line-out signal from the pre-amp output, I decided to take the signal after the output transformer, thus giving it the true output valve distortion sound. Now there is no need to mic up at a gig, simply run a lead from the line-out jack to the mixer desk, or into a more powerful amp. You will get a truly awesome valve sound, simply, with no worries over microphone feedback.
Here's an email I received from Pete, who'd already fitted the Mercury Magnetics transformers and choke before buying one of my mod kits:
"Dear Nigel, Many, many thanks for the info and advice. The specs I looked at when I was considering the Mercury Magnetics mods looked well researched and tested. Considering the price, I can tell you that it's not worth the gains in sound quality. Your mods, however are worth more than the cost in terms of the sound quality outcomes and technical advice that comes with the components. Very best regards, Pete"
Here's a few comments received from other satisfied customers, (for my modded amps):
I have to say I'm very impressed with the amp - it's a really good match for my Jazzmaster. Whatever you're doing, you're doing it right! I never thought you could get those wonderful, open, valvey sounds at this kind of volume. It makes you wonder why Epiphone make them like this in the first place!
Mark (refering to a basic modded V.2 combo)
I have been trying out the EVJ out against a £1000 + TopHat Club Royale - 20w boutique valve amp, and this was just with the EVJ at about ten to max, and a health warning to my neighbour...
I couldn't figure it out, they were so close at those volumes, but to cut hours down to minutes, the outcome was this: when I put the EVJ 8 ohm out into the TopHat speaker I got the best (subjective of course) result. Whereas the TopHat benefited over the EVJ with the 12" speaker, I actually preferred the clarity and openness of the EVJ, which was revealed even more with it being released from the "constraints" of the 8" speaker, playing through the TopHat's 12". Somehow with the EVJ the notes "meant more" with "more space around them".
So, to sum it up, the amp for me is your "H" modded EVJ into a 12" speaker cab - of course it was a fraction "edgier" than the TopHat, but definitely with more "life" - and a lot cheaper! Obviously the extra 15w is going to tell at volume, but for reasonable to loud; it's a pretty damn good outcome!
Class A all the way!
H (refering to a modded V.2 combo fitted with Hammond 125DSE for a deeper, cleaner Fender sound)
thanks very much for the amp. What a great sound!
At low volume with a tube screamer in front (with keely type mods) it sounds fantastic and doesn't annoy my wife (much!)Wound up it's lovely and dynamic with a really full and controlable sound.
The 8ohm output allows me to run it through an extention cab which is even better. What do you think about upgrading the speaker? A 10 inch doesn't look like it will fit.
Mike (refering to a fully loaded V.2 combo)
Hi Nigel - finally today the parcel arrived and to cut the long story short - all I do since 5 pm is play guitar through Briggs Valve Jr and my various amps boxes etc ...
It sounds fabulous - BLUESY & SWEET - with volume between
10 am - 2pm but the speaker has it's limits above that.
I'm sure that even the brilliance and overall body will improve with fine new valves yet this is already fabulous by any standards.
When I plug it into Fender Deluxe Reverb - it is Paradise for sure, and if I add some reverb and tremelo it's like a drug for women in an old fashioned dancing hall :-)
The baby adores my Keeley moded Blues Drive for those screaming bluesy overdrives, yet I can play most of the stuff just by playing volume; I also like it with my tube compressor (if needed) and it loves also my very transparent ZenDrive : sounds like a $10'000 Dumble ...
In short, this baby is BETTER than my Cornford Harlequin, and with even finer valves and maybe new speaker will be as boutque as it gets, so I am definitely selling most of my amps and various pedals: THD Univalve, Gibson GA-15Rv, Fender Cyber Champ, Fame class A 6L6 hand made in Russia and most pedals ... all on sale :-)
Finally, as you knew anyway, after few hours of playing the amp sounds even better so the question is now:
When will I sleep :-)
In summary - great job - thanks - I can strongly recommend your work to anybody as the mdifications make this a boutique league amp for 1/10th of the price.
Davor :- )
(from Switzerland) (refering to a fully loaded V.1 combo fitted with Hammond 125CSE for a more VOX type saturated tone)
A quick word about Version 1 and Version 2 combos.
Original Valve Juniors (Version 1) suffer from hum, buzzing noises, dull tone and low gain. I have tried and tested many of the mods available on the internet and after much trial and error have come up with a reliable, absolutely fabulous sounding amplifier. In listening tests, everyone who’s compared my modified version to the original has been astounded by the difference. The original was a good starting point but really needs these mods to make it useable and bring it alive. Greatly reduced is the hum and noise, increasing the signal-to-noise ratio, so you can now really use it in the studio. It’s now a touch brighter and cleaner at low volume, and when you wind up the volume control it’s just jaw-dropping. You won’t believe your ears. Much louder than its rated output of 5watts would suggest! It’s the amp that many people have dreamed about owning. A high quality, compact, all-valve, low-power, single-ended pure class A amp, suitable for studio, practise, pub gigs, or miked up at larger venues. Your sound engineer will love it! And the best bit?...........the price! I’ve priced up the components to build a similar spec amp from scratch and come up in the region of £250, and that doesn’t include labour and tooling costs! This modified Epiphone Valve Junior is the guitarist’s bargain of the century. If a boutique amp maker was to design and build a small class A amp these days using modern components on a large scale at the lowest possible price, then I’m sure this would come close to the finished article.
Gibson/Epiphone soon realised the problems with the ac heater (filament) supply and circuit board design, (no doubt after receiving many complaints about the hum and noise). So from serial numbers starting 1205 (mmyy) (December 2005) they altered the board design to use psuedo star earthing, and converted the valve heater supply to dc. The ht power supply was given an extra stage of filtering. They also changed the input jack and improved the internal wiring to the jack and volume pot. These models I've called Version 2.
The basic amplifier section was left unchanged.
So, it still suffers from poor definition, dull tone, lifeless sound, and low gain.
My mods to Version 2 combos and head amps resolve these issues.
Modding kits for V.2 Combos and Head amps also available. See my other listings.
In the following 2 videos I have compared an unmodified original Version 1 combo with my modified Hot Fender Version 1 combo
The original Valve Junior combos introduced in 2005 I've called Version 1.
Video 1 Video 2
A word about the videos; the guitars were plugged straight in to the amps. No effects at all. The sound was recorded straight into the camera’s microphone. It has an automatic recording level which reduces high volumes so as not to overload the recording device. In other words it acts like a compressor. So, loud sounds come out more or less the same as quieter sounds. No sound processing was carried out during the editing.
It really must be heard “in the flesh” to appreciate just how good this amp is.
The first thing to remember is that valve amps run at and can store very high voltages that can be LETHAL! Follow my guidance procedures for checking if the filter caps have discharged before proceeding.
Secondly, great care is needed as the pcb (printed circuit board) can be easily damaged by excessive heat or rough handling - especially whilst trying to remove and refit resistors. Also, too little heat can often result in dry joints, resulting in intermittent operation.
Thirdly, there are many mods on the internet. Some of which are useful, some of which can be improved upon, and some a complete waste of time. Which do you go for and which work best?
I have now personally modded over 50 amps with no problems whatsoever reported. All my mods are thoroughly researched and developed and tested before making available.
Please be aware that any work that is undertaken without the manufacturer's permission will invalidate their warranty.