The circuit is nothing complicated. All you need is one of the many Magick Eye tubes existent out there, with many different beam patterns, that might need a slightly different pin-out connection, but all of them work in a main common way – it taps in the path of the signal level of roughly 10 to 25 Volts (depends on the type of tube used), and a high DC voltage of something between 200 to 250 (B+).

I used a Russian EM80/6BR5 I scored off Ebay. The EM80 tube has a “U” shaped fluorescent target and two rods connected to the anode, producing two angled shadows on the edge triggered by the control voltage (input signal).

The schematic I used is the one below, posted by Michael on the 18watt site.

I tapped the control voltage (signal) off one of the plates of the EL 84 tubes, and got the high voltage of about 250v off one of the filter caps.

Check this video out of how cool this can be!

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And all this without even replacing the tubes that the amp is shipped with (Sovteks). I suggest replacing the tubes, to a JJ (former Tesla) set. From there things get serious. But at least now for the sake of seeing how much a simple mod like the JP1 can boost your Epiphone Valve Junior tone character.

Snip It!

That’s all it comes down to – snipping a jumper. Technically eliminating the C3 (22uF) electrolytic cathode capacitor from the circuit on the second half of the pre-amp tube (12AX7). Simple as that! The amp will start singing – but not in falsetto.
All the tool you need is a simple wire cutter (preferably a flat one). No soldering iron, no soldering skillz, NOTHING! You can do it! If you can clip your nails, you can snip the JP1 labelled jumper on your Epiphone Valve Junior.

Follow the steps in the video and report back with comments on your impressions. Good luck!

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I was particularly stunned on how dark this guitar amp sounds! In the video I have a Fender Telecaster (Mexican) that sounds crystal clear through my Gabriel V18 or V33 guitar amps. Bright, beautiful upper mids, etc. The overdrive was nevertheless EL-84-ish but without any definition or character or identity. i guess that’s what should be expected from a $150.00 (shipped) head, right?

The speaker cabinet has an AlNiCo Blue Celestion speaker , and has an open back. But even with this speaker the amp is simply too dark.

But the amp has potential. And we’ll discover that as we will start modding it. Stay tuned!

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I don’t know how many times it happened that I spent so much time on trying to guess how to open a unit just to be able to get to the heart of the problem and fix it. Yes, even pulling the chassis out of an Epiphone Valve Junior can be intimidating for the first comer.

Tools Needed

Really there is not much science to it. I used a chisel to extract the plastic chassis screw caps, masking tape to protect the tolex and cabinet metallic corners, a phillips screwdriver for the chassis screws, a flat wide screwdriver to pry the rear panel out and a piece of wood to protect the rear controls while I was doing this. But it really comes down to whatever tools can do the job after all.

The steps

Just as seen in the video tutorial, the steps are very simple to remove the chassis from the Epiphone Valve Junior head. I suspect that similar steps can be taken in the case of the Epiphone Valve Junior guitar combo amp.

1. Remove the plastic screw caps: Use masking tape to protect the tolex or metallic corners, and with a chisel (or a similar tool) gently go under the screw cap edge and pry it up until it can be grabbed with your fingers and popped out. Use common sense to work with the chisel, you don’t want to cut your tolex, or worst, your fingers. The plastic caps will come out very easy. Then, partially remove the screws since we don’t want the chassis to dangle and slip out as we or turn the head around.
2. Remove rear panel screws: That’s pretty much it to it.
3. Pull out the rear panel: This was the trickiest part since the rear panel was stuck and I wasn’t able to remove it by hand, so I needed to use the flat screw driver to pry it open (one side first, then the other one). To protect the control from scratching, I used a piece of wood. Once the sides were partly out it was very easy to open and remove the panel.
4. Pull the chassis: Place the head face down and remove all the chassis mounting screws completely. Then gently grab the chassis by the transformers and pull it out slowly.

That’s it! Next, we’ll start talking about identifying the board version of your Epiphone Valve Junior.

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So, what will you do, if you are a serious guitar player but have no cash to spend on one (two or three) of the big name tube guitar amp?

Epiphone launched the Valve series and with it, an intriguing model called
Epiphone Valve Junior Head, a single ended amp, class A, all tube (!), head version (recently reviewed in the Vintage Guitar Magazine). A simple one-knobbed, robust 5 Watt amp, that can deliver some serious tone into say a matching Epiphone Valve Junior 1×12 Extension Cab via three impedance output jacks (4, 8 and 16 ohms) on the rear. All this with a 12AX7 tube in the preamp section and a EL84 for the power amp.

Nothing special up to now you might say!

But listen to this! The
Epiphone Valve Junior Head Tube Guitar Amplifier, costs USD 149.99, the Epiphone Valve Junior 1×12 Extension Cab costs USD 159.99, or you can get the Epiphone Valve Junior Half Stack for only USD 249.99!!! If that’s not enough, here is also the elegant Epiphone Valve Junior Combo Amp for USD 199.99 !!!
All are shipping free from Musicians Friend!

Something must be wrong, they must have miss-priced it, or there was a typo of some sort. No, it is true. You can arm yourself with tube overdriven guitar tone for a quarter of what other big name boutique guitar tube amps are out there!

And as if this didn’t convince you to put your hand on it, hear this: You can actually mod the amp, – of course if you own a soldering iron and if you can change a spare wheel on your car – to a killer tone machine with a minimal expense by simply replacing the Output Transformer, and changing the tube brands, and a couple of components here and there. More details in actually how to do this found on the www.sewatt.com forum – an absolute place to discuss specific mods on this amp!

There will be a video tutorial on how to do this VERY SOON!

Now, make yourself a favor. Stop playing on your crappy solid-state (or hybrid tube) guitar amp and get your hands on the one (or more) of the two models!

Epiphone Valve Junior Head Tube Guitar Amplifier

Epiphone Valve Junior 1×12 Extension Cab

Epiphone Valve Junior Half Stack

Epiphone Valve Junior Combo Amp

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