There comes a time in an amp’s life when changes happen. We try our hand at the BitMo 3-way voicing/gain mod kit for the inexpensive Valve Junior.
When Epiphone released the 5-watt Valve Junior at Summer NAMM in 2006, it’s doubtful anyone was aware of the industry-wide stir the little $150 tube combo amp was about to create, moving value-conscience guitarists out in droves to get one of their very own.
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Another unforeseen effect following the debut of the adorable, great-sounding-forthe- price Junior was the devoted subculture that sprang up around modifications intended to handle its shortcomings, turning the Valve Junior into the rock n’ roll equivalent of the Nissan 240SX: fun, cheap, and ripe for customization. That the Junior arrived just as the low-wattage, boutique-bedroom amp craze was gaining stride didn’t hurt, either.
One of the first companies to recognize the Valve Junior’s sleeper potential was Mercury Magnetics, offering up mods that received nothing but praise from both the guitar press and Junior owners alike. But because the Mercury Magnetics kit involved replacing both transformers, it didn’t come cheap; amp geeks were paying nearly $300 to mod a $150 amp. This was great for players looking at the Valve Junior as a starting point for experimentation, swapping out tubes and speakers, and now even transformers and caps, to eventually end up with a boutique-sounding amp, voiced exactly as desired, for a car payment south of a grand.
Figure 1
A look at the inside of the Valve Junior. Notice the black (Revision 3) PC board. | |
However, there was a second subset of Valve Junior aficionados who were purchasing the little amp precisely because it was inexpensive and sounded good in stock form – illustrating that not everyone who drinks PBR is being ironic. It also begs the question: why should the less well-heeled be excluded from all of this Valve Junior modding fun? That’s where Bruce Hutcheon comes in, the mastermind behind BitMo’s amp mods, offering up reasonably priced, less intrusive mods that shouldn’t intimidate anyone, from either a price or complexity standpoint.
We met Bruce at the Dallas International Guitar Festival, and even through the cacophony of the show floor, we could tell he was onto something. He offered up a few of his mods for us to try, with the Voicing/Gain being the first we attempted, due to the seemingly easy nature of the mod, and because of some pressing time constraints. The following chronicles our adventure installing the mod; for a general idea of our technical expertise, picture a monkey in a cage with a stick, and a banana just out of reach outside of the cage.
First off, we tracked down a Valve Junior at our local guitar shop, deciding to go with the head version and picking up the Valve Junior 1X12 extension cabinet, too, both readily available for $130 each. The Voicing/Gain mod costs $25, putting the total cost of this rig at $285. The tools suggested by BitMo for the upgrade are: screwdriver, soldering iron, rosin core solder, wire stripper, needlenose pliers, drill and drill bits, dark colored tape and acrylic spray sealer for the included decals, in short, nothing out of the ordinary. The instructions include the same old safety warnings we’ve all heard before, but they bear repeating; rock some goggles or safety glasses when soldering or drilling. Sure, your grandpa never did, and he’s fine, but what about his friend, the old dude with one eye and nine fingers? Yeah, that guy. Don’t be him.
| The little Valve Junior is pretty amazing in its simplicity. To get costs down, Epiphone needed to do their homework on the design side, with the resulting component layout indicating that they did just that, with a surprisingly tidy, efficient looking interior that exuded Feng Shui... | |
The instructions also let you know that as soon as you bust out the soldering iron that the warranty is void, something to keep in mind if you’re the really cautious type. It also includes a few tips to get the most from both the amp and the mod, offering up suggestions on possible tube swaps, such as sub-ing the stock 12AX7 with a NOS 5751, and where to start with the amp settings once the mod is complete. Bruce was also thoughtful enough to include a link to a pdf that covers the basics of soldering if you’re new to this.
To start the actual mod, we needed to remove the chassis from the cabinet, which was straight forward enough, and in its stock form, the little Valve Junior is pretty amazing in its simplicity. To get costs down, Epiphone needed to do their homework on the design side, with the resulting component layout indicating that they did just that, with a surprisingly tidy, efficient looking interior that exuded Feng Shui all over the place.
Bruce provides very well written, thorough instructions for the mod, with one minor oversight, albeit a huge one in our case; he included a very simple diagram on page three. We were pretty much done reading at this point, instead relying on the Mr. Miyagi method of “Picture perfect tree. Now, make like picture,” although a few of the instructions did ultimately stick. The first one was leaving the switch in the middle-off position while soldering, going so far as to suggest clamping it in place. Next was advice on how long to trim the legs on the caps to make everything fit properly, saving potential heartache when read in a timely fashion ( i.e., before the soldering starts).
| Drilling a hole for the gain voicing switch (Revision 3) PC board. | |
In grossly over-simplified terms, the mod consists of a three-position switch, with a couple of caps soldered across one side and to ground on the volume pot, and a resistor soldered across two legs on the other side, with one of those two legs then being run to the R1 resistor on the circuit board and the other to ground. We decided to initially solder everything to the switch, ending up with what looked like a spider from the future.
Once we began soldering the leads from the switch and components to the intended spots on the circuit board was when we encountered our first problem. Since we found ourselves with a misplaced multimeter during the review, we figured what the hell, let’s just eyeball the solder joints and go for it. So once we had everything wired in – before drilling the hole for the switch – we decided to plug in and get some signal, as per Bruce’s instructions. We were immediately greeted with faint, microphonic feedback that increased as we rolled the volume up. Also, as the notes began to decay, they would fart out, with the notes ending abruptly, like an old fuzz tone, except it didn’t sound at all cool, just damned annoying.
We tried resoldering all of the connections; the problems remained. We tried swapping out the Valve Junior’s 12AX7 for a known good one; the flatulence and feedback continued. We made sure the power tube was seated properly; still it persisted. I can still hear it. At this point we were officially stymied, so off to our favorite local shop it went. The verdict? A bad volume pot. If you didn’t see that one coming, don’t worry – we didn’t either. But it does raise a good point: you may want to live with the amp for a while before doing any mods to give any like problems a chance to pop-up. It’s a lot easier to swap the amp out for a new one at your local guitar store than solder in a new pot. We would like to give big ups to Ronny Boles and Bill Nix at Somewhere in Iowa Guitars for being kind enough to track down the problem for us.
Once that was out of the way, we decided to drill the hole for the switch in the chassis and finish things up. Bruce offers up advice for placement, suggesting placing it between the volume knob and input jack. Figuring he knows what’s best, we did as instructed and wrapped things up, placing the chassis back in the box. He also included a nice water transfer decal, to indicate whether the switch is in the “Low,” “Mo’,” or “Whoa!” positions.
“So, how does the mod sound?” I can hear you asking. Amazing, I’m happy to reply. Remember the earlier part about calling in some help to chase down the feedback? Ronny and Bill have been in the vintage guitar business almost since its inception, and, between the two of them, have plenty of sweet old amps floating around. What they don’t own currently, they did at one time. The BitMo mod made their collective jaws drop. We plugged it a 4X12 cabinet, and it sounded incredible. The Valve Junior was plenty impressive before the mod, but the three-way Voicing/Gain mod turned it into something you could easily rock at gigs.
| Finally, the switch is installed and working! | |
In position one, or “Low,” the mod is supposed to give the Junior more of a blackface tone, adding a bright cap to the circuit and offering up the most headroom of the three positions. We botched this position because we used instructions from June, when Epi was still shipping the green PC board (revision twos), but the amp we purchased in August had a black, or revision three, PC board. Speaking with Bruce indicated that this would work, but would sacrifice some clean headroom, due to Epiphone moving things around from one board revision to the next, and Bruce’s need to counter – moving the spots where his components are placed in a kind of cross-continental, electronic game of chess. After we heard what this thing is capable of in “Whoa!” mode, I’m fine with losing a little headroom in the “Low” position. Keep in mind that Bruce ships current kits with updated instructions.
Position two, or “Mo’” mode, imparts more of a British flavor to the Valve Junior, increasing the gain and bottom end. This was a nice setting with the Junior’s volume knob between nine and 12 o’clock, offering up a convincing Faces-era Ronnie Wood-esque medium grind. This would be great for fat rhythms, and less sustainy, stringier sounding leads.
The capper here is the aptly named “Whoa!” position. All of the bases can be covered here – clean-ish, grind, and distorted, all while retaining the amp’s new-found, British-flavored thickness. Park the amp’s volume control at three o’clock and you’re golden. The guitar’s volume knob becomes your amp’s channel- switching control, and when the hot-rodded Junior is running balls-out, it sounds incredible with creamy, singing sustain, inspiring me to indulge in longwinded jams. I’m sure my neighbors hate this thing, but who cares, I pay taxes too. It was so nice to be able to get that familiar fat tone without breaking either the eardrums or the wallet.
Bruce has managed to take a very good thing – the stock Epiphone Valve Junior – and with a relatively simple mod, make it a thousand times better, taking it from good to great. This amp and mod combo would be great for most any live club situation when a cranked-sounding tube amp is needed. It’s almost a must for home recording, although I can’t guarantee it won’t wake up the young ‘uns. We’d like to thank Epiphone for unleashing the Valve Junior upon an unsuspecting public. The combos go for $150, and the heads and the cabinets go for $130 each. They are available wherever fine instruments are sold. For more information, visit
epiphone.com.
The BitMo kits are available from
thetubestore.com, or you can order one from Bruce via his eBay store.
Decisions, Decisions…
BitMo offers several reasonably priced kits to add additional tonal flexibility to the stock Valve Junior, priced from between $25 and $70.
The kits are available through either eBay or thetubestore.com.
BitMo Brat –
This mod kit adds a tone control with a pull-switch which adds gain and a British top boost overdrive.
BitMo Tweaky –
Starts off with the Spanky mod, adding no additional knobs, switches, wires, drilling or decals – nothing but tone. Includes instructions for differently voiced mods: Swanky (blackface), Yankee (tweed), Cranky (British high-gain) and Skanky – over the top!
BitMo Trio –
This mod combines BitMo’s two most popular kits: The Duo Tone/Fat Boost control mod and the 3-way Voicing/Gain switch, providing a total of six unique voicings and gain settings.
BitMo Voicing/Gain –
The 3-way Voicing/Gain mod on its own.
BitMo Duo Tone Control –
The Duo Tone mod sold separately.
BitMo Studio 10-uator –
This kit adds an attenuator to either the back of your Valve Junior, or as a stand-alone kit housed in a plastic case. | |
Bitmo: Hear it for yourself!
To make these clips we used a stock, Eminence-loaded Valve Junior 1X12 extension cabinet, and a Duncan P-90 equipped Hamer Special Korina Jr., which ended up being a match made in heaven.
The clips start off with the un-modded rig being put through its paces, then played with the same guitar and same settings after the mod. For the amount of time and money put into these mods, we were amazed.
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