A stellar 6V6 combo with inspiring, innovative options.
RatingsPros:World-class workmanship. Gorgeous tones. Unique personality. Useful and innovative controls. Cons: Pricey. No reverb. Street: $2,900 (head only) BC Audio Bel Air 40 bcaudio.com | Tones: Ease of Use: Build/Design: Value: |
The latest creation from San Francisco amp designer Bruce Clement is a fresh take on that classic Fender recipe: a 40-watt amp powered by a quartet of 6V6 tubes. Okay, I’m lying. Fender never made such an amp. While the company used dual 6V6s for small combos such as the Princeton, they opted for pairs of tighter, brighter 6L6s in their midsized models. But modern builders such as Victoria, Carr, and Dr. Z have run with the 6V6-driven-medium-wattage concept, producing amps that combine the power of dual 6L6s with the 6V6’s softer, warmer, and quicker-to-distort character. Despite such predecessors, BC’s Bel Air 40 breaks new ground with a distinctive blend of Fender and Marshall attributes and an innovative and inspiring control set.
Point/Counterpoint
The Bel Air 40 resides in a Marshall-style head cabinet. The solid wood cab is flawless, and Clement’s signature “racing stripe” design is eye-catching without being cheesy. But the real beauty lies within. Clement is justifiably renowned for his immaculate point-to-point wiring. Here, the fastidiously routed wires with their sharp 90-degree angles suggest an aerial view of some modernistic metropolis. It’s clean enough to eat from, though doing so may invalidate your warranty. This is masterful work.
The amp’s most newsworthy features are its unconventional controls. In Clement’s words, these “allow you to reach inside the amp, so to speak, and re-wire the power section in multiple ways.” And guess what? It’s true. (Details below.)
Fundamentally Solid
The amp’s core tones are punchy and ultra-present. Thanks in part to a pair of hefty ClassicTone transformers, the fundamental note frequencies feel as grounded as bridge piers. Single notes are clear and powerful. Chords ring harmoniously, with superb string-to-string separation. The frequency response is vast. Bel Air can move serious lows, while the top end shimmers with animation.
Cranked, the amp has the hair-trigger dynamic response of a good plexi. (There’s no master volume control, though there’s a half-power switch that removes two power tubes from the circuit.) Meanwhile, the chiming, articulate highs have more of a Fullerton flavor. The rectifier tube is a GZ34. The treble/mid/bass tone stack has a vintage Marshall personality.
Those are Bel Air’s constants. Beyond that, the amp is something of a chameleon, depending on your settings. The preamp section employs a pair of 6SL7 pentode tubes, in lieu of the usual triodes. These provide crisper response and more clean headroom. But you can switch between pentode and pseudo-triode operation, with a softer, looser sound in the latter setting. It’s a dramatic contrast.
Not the Normal Knobs
There are other unusual options. One toggle alters the amp’s biasing scheme. The fixed-biased setting is relatively loud and tight, while the cathode setting is quieter and “browner.”
There’s also a 3-way bright switch. The off setting is the darkest. The two active settings are both brighter, but with different midrange contours.
The amp’s 3-way negative-feedback loop toggle is fascinating. “No feedback” is the loudest, unruliest option, yet it never gets sloppy—note definition remains excellent. The two feedback-on settings are more reined-in, with relatively taut bass response. This setting interacts with the adjacent cut and presence knobs, affording precise control over the amp’s high-frequency content.
Another cool feature is a “body” control that gradually introduces a larger coupling capacitor, altering the low-end content of your tones. It’s especially useful for trimming lows from heavily overdriven sounds, adding definition for those times when you don’t happen to desire stoner sludge.
A final nifty feature is a tone-circuit bypass switch. These vintage-style tone controls are strictly passive: They only cut frequencies, and can never boost them. But bypassing the tone stack yields dramatic increases in level and frequency range. With a good guitar, the results can be epic.
These are interesting and useful features. In fact, the negative-feedback toggle, bass-regulating body control, and tone stack bypass yield such dramatic results that you wonder why they’re not standard features on more amps.
The Verdict
TheBel Air 40 is a magnificent instrument. Its build quality is phenomenal. The core tones are lovely. An array of unconventional controls provides remarkable tonal flexibility, not to mention a fascinating lesson in amp topology. Yeah, there’s an elephantine price tag in the room. But the amp’s multiple design innovations, unusually labor-intensive build, top-shelf parts, beautiful tones, and flawless construction more than justify the cost.
Watch the Review Demo:
An all-tube guitar amplifier with a unique set of front-panel controls that let the player reach inside the amp.
San Francisco, CA (October 11, 2018) -- Boutique guitar amp builder BC Audio (bcaudio.com) revealed the Bel Air 40, a meticulously hand crafted all-tube guitar amplifier with a unique set of front-panel controls that let the player reach inside the amp, so to speak, and re-wire the power section. The Bel Air 40 features four 6V6GT Power Tubes, two octal 6SL7GT preamp tubes and a GZ34 tube rectifier, and is built with true point-to-point construction – no turret, eyelet or printed circuit board. Power ranges from 40 watts to under 5, depending on how the Power Tube Configuration switches are set.
“We're used to seeing lots of knobs and switches on guitar amps. Normally, those controls operate almost exclusively in the preamp section, while the power section just sits there amplifying what comes its way. This amp turns that approach on its head,” says Bruce Clement, BC Audio founder, award-winning guitarist and tube amp master builder. “The Bel Air 40 gives the player control over what's really going on in that mysterious part of the amp that you can't normally touch, the part that is the key to great tone – the power section.”
Power Tube Configuration Switches:
- "Quad/Pair" switches between two or four 6V6s. This serves as a half-power switch, with the Quad setting providing more girth and punch.
- "Pentode/Triode" reduces power by about half in Triode mode, and also noticeably changes the tone and feel of the amp, with Pentode mode being tight and clean, while Triode mode feels smooth and loose.
- "Fixed Bias/Cathode Bias" changes the dynamics of the power section, cathode bias mode being slightly lower-powered, more compressed and a little bit browner.
More Power Section Control:
- "Presence" brings out the chime and sparkle, while "Cut" tames the highs generated by overdriving the power tubes.
- The 3-way “NFB” (Negative Feedback) switch alters the damping and open-loop gain of the power section, with the Zero NFB setting being the most raw and touch-sensitive.
Preamp Section:
- The Bel Air 40 is a non-Master Volume design. It uses 6SL7GT octal preamp tubes for their rich, thick sound and power-tube-like breakup. Controls include Volume, a 3-way Bright switch, Body (for tightening up the low end), and a three-band EQ that can by bypassed for the purest exploration of the power section's overtones.
Pricing: $2900 (pro-net), direct from bcaudio.com. Matching 2x12 speaker cabinets are available from $850.
For more information:
BC Audio
A reinvented plexi with octal preamp tubes and true point-to-point wiring.
The Plexiglas panels on the front of those early 100-watt heads earned them the nickname “plexi,” although the official model names were 1959 and Super Lead. (Marshall also made 50-watt plexis.) While guitarists no longer need to summon such volume onstage thanks to modern sound reinforcement, for many, the 100-watt plexi remains the definitive hard rock machine. And to this day, the model tends to be the starting point for designers hoping to craft the ultimate high-wattage beast.
Mutant Marshall
The Super Lead is also a jumping-off point for San Francisco-based builder Bruce Clement of BC Audio, but the guy jumps pretty darn far. While the basic topology of Clement’s 100-watt JMX 100 clearly descends from the Super Lead, by no stretch of the imagination is this amp a clone. The circuit includes many refinements and departures, but two are especially significant. Unlike vintage Marshalls, the JMX 100 is entirely point-to-point wired, with absolutely no circuit board, turret board, or terminal strip. Also, the amp eschews the usual 9-pin preamp tubes in favor of octal (8-pin) SSL7GT tubes, which are larger and longer than the 12AX7/ECC83 models found in most amps. As on the original 1959, the power section employs a quartet of EL34s, though the earliest 1959s used KT66 tubes.
Internal Beauty
I’m embarrassed to admit it, but the first time I peered inside a BC Audio amp, I was so spellbound that it took me a moment to realize the entire thing was wired point-to-point without turret board. (See interior view photo.) The immaculate rectilinear layout resembles a roadmap of some idealized future metropolis. Wire runs are kept to a bare minimum. This is simply magnificent work.
(Like some other point-to-point builders, Clement insists that eliminating extraneous wire contributes to the quality and immediacy of an amp’s sound. I’m no electrical engineer, so I remain agnostic on this claim. After all, most of our beloved vintage amps were created with conventional turret board. On the other hand, many of my favorite amps of recent years have also been point-to-point.) The parts are top-shelf, including the ClassicTone transformers.
The exterior is equally lovely. The head cabinet is solid pine wrapped in black tolex with eye-catching red racing stripes. (BC Audio also sells cabinets with matching stripes, though I reviewed the JMX 100 through an old THD cabinet. The miked speaker in the demo clip is a 65-watt Celestion Creamback.)
Playing for Peanuts
Clement says he inherited an affection for octal tubes from his dad, a WWII pilot and passionate electronics hobbyist. “Octal preamp tubes were used in the early days of audio before ‘miniatures’ like the 12AX7 were developed in the 1950s,” he says. “My dad told me that when they first came out, people called them ‘peanut tubes.’” According to Clement, overdriven octal preamp tubes produce a sound closer to power-amp distortion relative to those “peanuts.”
The amp’s sound bears out that claim. Clean tones have more sparkle and snap than equivalent vintage Marshall tones. At times you’d swear you’re hearing a large format Fender. Note fundamentals are rock solid. Transients are crisp and definitive, transmitting every nuance of pick and finger. This is one articulate amp!
Ratings
Pros:
Superb build. Point-to-point wiring. Quality components. Authoritative and articulate distortion from octal preamp tubes.
Cons:
Expensive, if justifiably so.
Tones:
Ease of Use:
Build/Design:
Value:
Street:
$3,000
BC Audio JMX 100
bcaudio.com
Gain of the Gods
There’s no shortage of fine distortion when you advance the gain, but it doesn’t have the ratty/fuzzy quality you encounter with many modern high-gain heads. At hot settings, notes and chords have a clear, clanging sonority that really does sound more like hard-working power tubes than overburdened preamp tubes. Maximum-gain sounds aren’t as filthy as you may be accustomed to hearing from Marshall-derived amps, but that clarity and headroom yield godlike saturation when you connect a great-sounding fuzz pedal. The octal preamp tubes are also uncommonly responsive to your guitar’s controls. Even at high-gain settings, you can roll back your guitar’s volume pot for chiseled-in-rock clean tones.
Plexi fans know that the real fun starts when you jumper the clean and bright channels together. That’s true here, though you don’t need a jumper cable. Above the gain controls for each channel is a 3-way toggle that lets you drive either or both channels. There’s only a single input jack, so you need this switch to change channels, unless you connect a footswitch to the rear-panel jack. The normal channel is far darker than the bright one, which means you can obtain a vast palette of tones solely by setting the toggle to “both” and varying the balance. Meanwhile, the 4-band tone controls have subtle, surgical ranges, more suited to fine-tuning tones than dramatically altering them. I suspect that many players will “set and forget” the tone controls and perform much of their tone shaping simply by adjusting the bright/normal blend.
It should go without saying that this amp can get absurdly loud. But unlike vintage plexis, the JMX 100 has a fine-sounding post-phase-invertor master volume circuit. In fact, I recorded the demo clips with the master volume only halfway up.
The Verdict
No one can deny that the JMX 100 boasts superb workmanship and a huge array of rich, articulate, and harmonically pleasing colors. Whether it’s the right high-gain head for you may hinge on whether your favorite tones rely on fizzy preamp-tube distortion, or whether you prefer authoritative power-amp distortion with sufficient headroom to slather on upstream fuzz and distortion pedals as needed. The $3K price is formidable, but bear in mind that this is an extremely labor-intensive build, and that every bit of that labor was executed by hand with supreme skill. The JMX 100 is a masterful piece of work.