Need more headroom or gain? Spin the bottles.
[Originally published: 9/2/2019]
You might guess from the title of this column that I love Fender amps. And you’d be right. From a musical and engineering perspective, I think vintage Fender blackface amps are the best ever made. With bright, American-style speakers, they deliver pure and natural tone. Their channels, with volume and EQ, are intuitive for any guitar, bass, or keyboard player. It’s impossible to not find a decent tone in less than 10 seconds. From a technical perspective, their handmade tube-based circuits are simple, and they were built with high-quality components. And today, there are easily available parts and schematics, and an abundance of other online technical information, which makes it possible for many techs and players—including you—to service these amps.
Classic Fender blackface amps have been an inspiration for an entire industry. They’ve appeared on countless stages and an incredible amount of great albums by legendary performers. Why? Mostly tone and clean headroom. So, for this debut column, let’s discuss what we can do to make those two factors work best for you via tubes.
Reverb and tremolo were the main functional innovations in Fender’s blackface line. The king of blackface amps, the Twin Reverb, produced 85 watts from four 6L6 tubes and had enormous power and output transformers, a non-sagging diode rectifier, and two powerful 12" speakers. The 4x10 dual-6L6 40-watt Super Reverb has half that power, a softer tube rectifier, and smaller transformers. Still, the massive array of four 10" speakers is screamingly loud and sometimes difficult to handle for its weight (65 pounds), size, and volume. A 4x10 is more directional and scooped in the low mids than a 2x12. So a guitar plugged into a Super Reverb can end up competing with the bass. Experience is required to tame these amps. Once you know how to handle them, you will be rewarded with an overwhelming and physical sonic experience.
In the blackface world, the 1x12, double-6V6 22-watt Deluxe Reverb’s advantage is that it’s small and light, at 42 pounds. It breaks up earlier than its bigger relatives due to the less powerful 6V6s, small transformers, and a small speaker cabinet. Additionally, the original Oxford 12K6-5 speaker farts out early and is very weak, although it also delivers a true signature vintage Fender sound. And who doesn’t want their amp to break up easily these days? I have kept the Oxfords in my Deluxe amps. Before the internet, few people knew they could replace the 6V6s with 6L6s and replace the Oxford to double the Deluxe’s volume.
The V6 12AT7 phase inverter tube can be replaced with a 12AX7 to reduce headroom in large 6L6 amps.
Via my website, fenderguru.com, I often get questions about how to achieve different tones in blackface amps run at lower volumes. The answer often lies in the tubes. So let me share some simple tube tricks that will help you develop an understanding of how tubes function—and how they can be used to affect changes—in the typical two-channel AB763 circuit in the Twin, Super Reverb, Vibroverb, Pro, Vibrolux, and Deluxe amps of the original blackface era.
The tubes in these circuits are typically identified as V1 through V10, looking at the back of the amp from right to left. Here are some tricks:
- The V1 12AX7 tube in an amp’s normal channel can be removed for more preamp gain and reduced headroom in the vibrato channel. It can also be replaced by weaker tubes, like 12AY7s or 5751s, for less volume/gain. I always pull out this V1 since I use the vibrato channel and want solid preamp gain, which the single V2 delivers.
- The V3 12AT7 reverb driver for the vibrato channel can be replaced with a 12AU7 for less reverb and improved reverb knob control.
- If you’re only using the normal channel, think about removing the V2 through V5 tubes for the vibrato channel. That will give you more gain and headroom in the normal channel. (FYI, the 12AX7 in the V5 position is the tremolo tube.)
- The V6 12AT7 phase inverter tube can be replaced with a 12AX7 to reduce headroom in large 6L6 amps.
- Several alternatives to 6L6 power tubes exist. I mostly use 6L6GCs. In a Twin Reverb, you can pull either the V7 and V10 or V8 and V9 tubes for half power and earlier breakup. Ideally, but not totally necessary, you should disengage one speaker to match the impedance change.
- In a blackface Deluxe, the GZ34 in the V9 slot is the rectifier tube. If I want reduced headroom and more sag, I use a 5U4GB.
And there you have it: You’re on your way to becoming a Fender guru, too!
This 1994 Vibro-King hangs with another versatile tone machine—a Fender Strat. The combination can yield enough clean or gnarly sounds that some players might want to leave their overdrive pedals at home.
This bruising 60-watt powerhouse is ready for anything, with three speakers, five reverb and tremolo controls, and a fat boost.
I'd like to pay respect to the Fender Vibro-King. I still remember how I first admired it, brand new in guitar magazines, in 1994. It was the raw, wild, and blonde Viking cousin of the classic vintage Fender amps. I immediately wanted one and got my first in 2004. So, let me share my view on this flagship from Fender's Custom Shop.
The most recent model, the 20th Anniversary Edition, was discontinued in 2014. Other than a change from EL84 to 6V6 tubes in the reverb section for improved durability, the amp circuit was fairly consistent during its years in production. There were various color schemes: blonde, black, light brown, dark brown, naked maple, and hand-tooled Tolex. And for its 3×10 array, Fender used various speakers, starting with blue-framed Eminence alnicos, then Jensen P10Rs and Celestions in custom models.
With dual 6L6GC power tubes and a class AB push/pull configuration, its big-iron transformers produce a whopping 60 watts at 2 ohms. The large power transformer contributes significantly to an overall weight of about 70 pounds. With the right or wrong speakers, this amp can weigh as much as 88 pounds. But contrary to older, less robust vintage Fenders, the Vibro-King's massive, solid cabinet can carry heavy speakers and deliver tons of punchy bass response. A set of Weber 10A150s or Eminence Swamp Thangs has never been more fun. Fender did offer a matching 2×12 extension cabinet for those who wanted a full Vibro-King stack, but I find it loud enough with the three-speaker complement.
Sonically, the Vibro-King falls between tweed and black-panel-era Fenders, whether sparkling clean or wildly cranked, and even at low volume. The amp's distortion is attributable to the design of the preamp section and the lack of a negative feedback loop in the power section. You can dial in a wide span of tones using volume, EQ, and the fat boost—more than a typical vintage Fender amp.
Players seem to either love or hate the Vibro-King. I suspect the haters haven't experimented enough with speakers and EQ settings. The Vibro-King also has an unusual control panel, with a dedicated reverb section, with dwell, mix, and tone dials, and the usual tremolo depth and intensity, plus volume, treble, bass, and mid knobs, and a slider for that fat boost.
If the amp is set in its sweet spot, the footswitchable fat boost will allow you to flip between a clean tone for rhythm or a cranked-up lead tone for solos.
I've kept the light Eminence alnico speakers in my own 1994 Vibro-King. I love the loose low end and strong upper mids. I've found some of the best modern Jimmie Vaughan tones with my amp, but it can also easily do Keith Richards. The quick, snappy response and touch sensitivity allows trebly nuances from your fingertips, strings, and fretboard. If you're into more generic tones or the familiar black-panel Fender sound, Jensen P10Rs or C10Qs will do that for you, too.
Some advice to those who are not into reverb or tremolo: Steer away from this amp! As mentioned, five out of nine faceplate controls are dedicated to reverb and tremolo. If you're into that, the Vibro-King is a delight. The reverb section has the same controls as the classic vintage Fender standalone reverb unit and offers a huge selection of tones. However, the EL84 Vibro-King is known for occasional issues with the reverb circuit, causing overwhelming waves of reverb and burnt tubes. But you can get lucky. I had an EL84 reverb tube in mine for over 15 years.
If the amp is set in its sweet spot, the footswitchable fat boost will allow you to flip between a clean tone for rhythm or a cranked-up lead tone for solos. For some players, this eliminates the need for a boost pedal. It's also worth noting that the tone controls are quite sensitive and differently biased than black-panel and silver-panel Fenders. Expect to spend some time finding good settings.
Here are two tone strategies to try:
- Low volume and high/maximum EQ settings with the fat boost on, which creates a tweed/blonde tone with little clean headroom and lots of preamp gain at low volumes.
- High volume and low EQ settings with the fat boost off, to craft a clean, scooped, black-panel tone, with little or no preamp gain and lots of headroom.
If you haven't played a Vibro-King, you're missing an exciting experience. It's not the amp for everyone, but for some it's the Fender amp they've always looked for. Skeptical? Watch the YouTube clip below of Gary Clark Jr. onstage with the Rolling Stones and John Mayer. As difficult as it can be to cut through when four guitarists are playing together, Clark tears it up with a humbucker-loaded ES-335 through a Vibro-King. Until the next time, may the tone be with you.
The Rolling Stones, Gary Clark Jr. & John Mayer_Going Down Live
To get an earful of Gary Clark Jr.'s Vibro-King tone, check out the Rolling Stones and their additional guest, John Mayer, stomping through the Don Nix-penned blues-rock classic, "Going Down," in 2012.
Fender subtly updates a classic, delivering value, dynamics, and versatility.
Sparkly tones. Dynamic response. Great value.
Low-end loses some focus at high volumes.
$899
Fender '68 Custom Princeton Reverb
fender.com
The Princeton was never the amp for everybody, but it came pretty close. If you’re working with a loud drummer and like your tone clean as can be, it won’t take long to reach the limits of 12 watts and a ten-inch speaker. On the other hand, it’s not uncommon to hear guitarists say: “If your band’s too loud for a Princeton, then your band is too loud.” The dictum is truer than ever in an age of better and more powerful P.A. systems.
Fender stopped making the original Princeton Reverb in the late ’70s, though the company has used the Princeton name for other models over the years, some of which bore little resemblance to the original. A few years ago, Fender added a Princeton Reverb to its line of ’65 Reissues, and recently introduced the ’68 Custom Princeton Reverb featuring circuit tweaks that, while less vintage-correct, are friendlier to pedals and deliver more modern and immediate response.
Silverface Beauty
Despite the amp’s name, Fender is up-front about the fact that this is not a strict reissue. While the amp captures the general vibe of vintage units, it’s wired for less headroom and less negative feedback (for a more dynamic response).
Fans of Fender design minutiae will love the vintage-accurate silver-and-turquoise front panel and grille cloth, aluminum trim, and chrome hardware. In fact, the only obvious differences between the Custom ’68 and a vintage Princeton Reverb are on the rear panel, where there is now a standard cord socket, a metal cage protects the power tubes, and in a nod to 21st century safety compliance, there’s no ground switch.
The amp has two inputs (the second is padded by –6 dB). Six knobs control volume, treble, bass, reverb, and the tremolo’s speed and intensity. A blue jewel power light replaces the original red one. The rear panel is similarly streamlined: there’s a fuse, an on/off switch, two speaker outputs (one for the built-in speaker, another for an extension), a 1/4-inch TRS jack for the included vintage-style two-button footswitch (for controlling reverb and tremolo), and RCA in and out jacks for the amp’s spring reverb tank.
The tube array is vintage-correct: two 6V6 power tubes, three 12AX7s, a 12AT7 reverb driver, and a 5AR4 tube rectifier. The transformer is a Schumacher, and the speaker is a Celestion Ten 30.
Sparkly Tones
It took all of one note from a Gibson ES-335 with stock ’57 Classic pickups to know I was going to like this amp. Even at living room volume, the Princeton possesses the sparkly and slightly spongy response you hope for from a good Fender amp. The nice, fat jazz sound from the neck pickup had me reaching for my Real Book. The output remained clean until the volume knob reached 4 or 5. This setting was loud and clean enough for most jazz gigs. Above that, the Princeton gets surprisingly loud and begins to break up in a most musical way.
What really knocked me out was how sensitively the amp responded to varying types of pick attack and guitar volume knob settings.
But what really knocked me out was how sensitively the amp responded to varying types of pick attack and guitar volume knob settings. With the amp’s volume around 6, I could go from playing clean chord comps with my thumb to a more saturated sound when digging in with a pick. The amp’s inherent compression narrowed the volume differences between those extremes, which makes the ’68 Princeton ideal for conveying dynamics without blowing away your bandmates in louder passage.
I also tried the Princeton with a Squier Classic Vibe Telecaster Custom and loved what I heard. Played clean, the tones are quintessentially Fender, ranging from nice, jazzy warmth with the neck pickup and the guitar’s tone control rolled back, to biting bridge-pickup twang with the controls wide-open. Just for fun, I tried a Jim Campilongo-inspired move and turned the Princeton’s volume, bass, and treble knobs up all the way, controlling the volume only with the guitar. Played this way, the amp had amazing range, though it became hard to control the bass response at louder volumes. When pushed with a TS-9-style pedal, the amp provided excellent overdriven sounds.
You’d expect this amp to have sweet-sounding reverb, and it does. But as nice as the reverb sounds, complete saturation occurs with the knob at about 5 or 6, which Fender chalks up to the reduction in negative feedback. The amp’s vibrato is gorgeous, deep, and as authentic-sounding as the reverb.
The Verdict
The Custom ’68 Princeton Reverb is a great amp. It’s not a down-to-the-letter vintage replica, but for some players it may prove more versatile than an original. Yes, some gigging players need a little more volume than the Princeton can deliver. But anyone seeking that classic sparkly Fender tone at a less-than-boutique price needs to check out the ’68.
Review Demo - Fender '68 Custom Princeton Reverb
[Updated 12/6/21]