Series III Blues Junior: What’s Different?
Back on September 1, 2010, when the Blues Junior Series III was introduced, I went to Guitar Center and bought the first one they’d been shipped. I promptly took it home and had in pieces on my bench. Fender claims a bunch of improvements, specifically:
- Black panel with white letters, reversed so it’s right-side up when the amp is behind you
- Screw-on knobs
- Rattle-reducing retainer for EL84 output tubes
- New “Lightning Bolt” speaker
- “Sparkle” mod
- Dog-bone rubber handle.
Black/reversed panel? Don’t care.
The screw-on knobs are a slight improvement, but the cheesy pots are still soldered to the board. The pots and shafts are protected by the same bushings as found on some old Bronco amps and other low-end designs from the early 1990s.
It’s no better than the old knob on the left, but it makes it worlds easier for Fender and owners to use whatever color knobs they want.
The rattle-reducing retainer?
They stuck a pair of rubber bushings into the half-inch holes at the top of the retainer. I tried this some years back; didn’t find a compelling reason to make it standard. It probably helps a little.
The new rubber handle is more comfortable in your hand and comes up higher, so your knuckles don’t scrape on the Tolex.
Those are mostly cosmetic changes. I don’t give a hoot about cosmetics, just tone.
Sparkle or ice pick?
The “sparkle mod” is the big change. All they did was remove capacitor C10, replacing it with a jumper, and remove capacitor C9 entirely. There’s some history to C10, going all the way back to the original green board Blues Junior. The green board reverb was positioned after the master volume, which turned out to be a bad idea–any hum or noise in the reverb went into the output stage full blast. The input and output were separated by a resistor and a capacitor.
When Fender revised the reverb circuit and switched to the cream board they moved the reverb pickup and insertion points before the master volume. It improved the performance because the reverb changes proportionally with everything else when you change the master volume. Reverb hum and noise get relegated to the noise floor–a big improvement. They used an existing 470K resistor to separate the input and output, but left the resistor and capacitor from the green board in place after the master volume to keep the overall tone the same. The capacitor became C10 on the cream board.
The series III is the same cream board, but Fender realized that the capacitor was slightly limiting both the amount of signal and the frequency range going into the output stage, so they replaced it with a jumper wire. Actually, this mod has been floating around for a while. There’s a mention of it somewhere in the comments on one of these pages and it seems to be popular with some of my European customers.
C9 is a voicing cap. It knocks off a bunch of high frequencies by bleeding them to ground. In the early days of green board mods, I used to make it switchable, between the stock 1500pF and 300pF. The 300pF let many more highs through and gave the amp noticeably more “sizzle.” I never thought that the cream board needed this mod, since it was brighter overall. Fender evidently thought differently, and did away with the cap completely. So if your Series III has too much zing and sizzle, you could always tone it down by adding anywhere from 300 to the original 1500pF.
How does it sound? Sparkly! Kind of Twin-ish, brighter. If you’ve always thought that the cream board Blues Junior was too bright, you’re going to hate the Series III. There’s more snap, more crisp response than the previous cream board. Most people will agree that the amp sounds more Fender-y. Treble settings over 7 or 8 with single-coils can be painful, however. I’d bet, though, that humbucker players who found the BJr muddy will appreciate the brightness.
To sparkle or not to sparkle
But it’s still the cream board at heart. The coupling capacitors are still wimpy and the tone stack is still lame. Fender also went to lower-grade coupling caps in the preamp, although there is probably no audible effect. Of the two capacitor mods, replacing C10 with a jumper adds a small, just-audible roundness and bottom-end warmth to the tone. With the modded Billm tone stack, replacing it isn’t really necessary because the amp adds prodigious amounts of bass and expands the range of mids from none (less than stock) to more than stock. But jumpering C10 doesn’t hurt a thing. I’d do it to any cream board Blues Junior.
Removing or clipping C9 is another matter altogether. It’s the “sparkle” in the sparkle mod. With single coils, I just don’t like the sound of the amp without some amount of high treble roll-off.
The Series III benefits from the same mods as the cream board. Indeed, the enhanced bass from the modified tone stack balances out the amp’s brightness. I’m tempted to add a “taming” cap for C9.
What about that new Lightning Bolt speaker? Overall, I’d say it’s an improvement. The fizzy highs of the old gold label Special Design are gone, but the speaker is plenty bright. The bass is tight, a bit better defined than the gold label. It’s well balanced top to bottom, but the bottom isn’t very deep. I didn’t have an Eminence Red White and Blues on hand to compare, but the Lightning Bolt sounds rather similar. That isn’t a good thing for the Blues Junior. I A/B’d it against the gold label and against my trusty Swamp Thang. The Swamp Thang is the speaker the Series III deserves: full, round bass and moderate highs.
For my part, I’m glad that all of my mods still work for the Series III.
You’ll have to decide for yourself whether you want to jumper C10 on your cream board BJr. If it’s the only mod you do, I don’t think you’ll hear much difference. In conjunction with the basic mods, it adds a bit of useful roundness and fullness to the amp.
The first power supply resistor is now up in the air for ventilation (and not charring the board if it burns), along with the second power supply resistor. Both are supported by little fiberglass tubes or insulation over the leads.
The hum balance resistors on the filament line are now larger, 2- or 3-watt resistors. They no longer fit flush on the board, so they’re angled up in the air, with fiberglass sleeves over the exposed leads. Even though the circuit board now bears a 2010 copyright date, I haven’t found any other changes yet.
The pilot light is still an LED, but now the lens is a faceted red jewel instead of the little lens. The jewel is not interchangeable. It and the bezel are one piece. Although it’s held to the chassis by a nut, there are no commercially available jewels in other colors that fit. Even if you were to change it, you’d have to change the color of the LED too. Red shows up as a dim purple through a blue jewel, for instance.