july 2011

AMP brand amplifiers seem to have a cult-like status and a small, but loyal following.

Hey Zach,
I have an AMP BH-220 head and XB-15 speaker cabinet. I bought the rig in the ’80s and I’m the original owner, but I don’t know much about it and can’t seem to find anything significant searching online. A local music store found some initial information for me in your Blue Book of Guitar Amplifiers, but nothing about the value. I’m considering selling this rig, but have no idea what it’s worth. Can you help? Thanks!
—Neil Springer, Macomb, MI

Hi Neil,
You’re right—there isn’t much hard information out there about this amp. However, based on my research AMP brand amplifiers seem to have a cult-like status and a small, but loyal following. With the exception of a few original owner’s manuals and spec sheets, most of the history I found regarding AMP was on web forums.

According to California records, AMP (Amplified Music Products) was founded in 1981 in Chatsworth, California, with Russ Allee listed as president. Before AMP, Allee earned his reputation while working for the Acoustic Control Corporation, where he designed the Acoustic 360 and 370 series of bass amplifiers. After forming AMP, he had another former Acoustic Control Corporation employee, Steve Rabe, design the preamp for the AMP 420 bass heads.

Rabe left AMP around 1984 to start his own company, SWR Engineering, where he continued to develop and produce bass amplifiers. Allee stayed on with AMP until the company folded in 1988. Gibson reportedly bought AMP soon after, and began offering the “new” GB-440 bass amp that was nearly identical to the AMP Model 420. (While this is unverified, the story goes Allee either designed Gibson’s GB-440 or Gibson simply used Allee’s model 420 and called it the GB-440.)

Allee went on to work with David Nordschow of Eden Electronics to develop the Eden World Tour Series of bass amps. It’s no surprise that the AMP 420, SWR SM-400, Eden WT-800, and Gibson GB-440 are very similar in design and appearance—but most users agree that each amp sounds different, and each possesses varying pros and cons.

Your amp, the BH-220, is a variant of AMP’s original BH-420, but has less power and fewer features. Specifications include a 240- watt output at 4 Ω (150 watts at 8 Ω), solid-state preamp and power sections, a Volume control, a Tonal Balance control, an Enhance switch, two inputs, a power-amp input jack, two speaker outputs, a headphone jack, an effects loop, a 5-band EQ section, a balanced direct pre-EQ XLR jack, and a post-EQ line out. Your amp originally retailed for $599 and the BH-420 retailed for $799.

The XB-15 has a unique design that features a speaker cabinet and protective carrying case. While the speaker cabinet sits inside the case for travel, the cab rests on top of the case when in use—and the case actually becomes part of the speaker cabinet. This allows for “clean open E 40 Hz fundamental notes unmasked by overtones.” Specifications include a 250-watt power rating and an AMP 15B-8 15" speaker with a 5 pound, 5 ounce magnet. The original retail price for the XB-15 was $699.

Most contributors in the online discussion forums agree that the AMPs are great sounding amplifiers, and are often given more accolades than their SWR and Eden counterparts. Construction and performance appear to be high quality, and I was hard-pressed to find a bad review. Based on this, these amps should be quite collectible and demand a premium in value, right?

Yes, the AMP bass amps are rare, but I often have to remind people that rarity should not be confused with desirability. A rare item seldom translates into more value or worth. AMP was unable to create any notoriety while in business (even though their products appear to be topnotch quality), meaning collectors did not take notice—most AMPs are or were used by players. Used values on AMP items generally appear to be between $200 and $300, regardless of model. And I would estimate the value of your rig to be between $450 and $600.

Even though AMP has a cult-like status and quality build, there just aren’t enough people interested in them, or enough amps in the market to create the demand that would drive up the value. I don’t set the values—I simply report on them from what I see in the market. For anyone who is looking for a great bass rig, consider this a steal. I absolutely consider this rig a treasure and one that few people know about. Unfortunately for the seller, he’ll probably feel like he’s getting cheated. But consider this: If no one out there is willing to pay what you feel an item is worth, is it really worth that much?

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In terms of ease of use and versatility, the Super-Matic may be the most elegant and practical stab at a self-tuning system yet.


In a recent Rig Rundown on premierguitar.com, Black Crowes and North Mississippi All Stars guitarist Luther Dickinson called tuning a “microsecond to microsecond battle.” For many pitch-obsessive players, that isn’t far from the truth. And if you’re a tuning freak who switches between tunings and guitars in performance? Well, that can add up to a lot of variables—and stress—pretty quickly.

The dream of a self-tuning system has probably been around as long as the electric guitar itself. And the Fret-King Super-Matic reviewed here is not the first guitar to attempt the feat. But in terms of ease of use and versatility, the Super-Matic may be the most elegant and practical stab at a self-tuning system yet.

From the Mind of a restless Innovator
Trev Wilkinson, the brains behind the Super-Matic, has been tinkering with electric guitar design for decades, and his hardware innovations are among the more lasting developments of the last 30 years. His Wilkinson roller nut, which caught the guitar playing public’s eye as a feature on Fender’s Strat Plus in 1987, remains widely used and influential. And his locking tuners and bridges are go-to parts for guitarists improving and modifying their stock instruments. Wilkinson probably could rest on his laurels at this point. But as his ongoing work with the Fret-King and Vintage brands attests, Wilkinson sees room for innovations— big and small—in even the most iconic electric guitar designs.

On the surface, there’s little hint of what this guitar can do. The heart of the self-tuning system is the Wilkinson ATD HT440 bridge, which is conventional enough looking at first glance, but upon closer examination reveals itself to be a little engineering marvel. Just aft of each fully adjustable saddle there’s a capstan that anchors the string. Each capstan is attached to an individual motor and gearbox. The motor and gear box assembly interface via a microprocessor with a hex pickup just forward of the bridge and a tuning selector for accessing presets.

The interface between player and the tuning selector is itself quite unobtrusive. There’s a very small (and at first easy-to-miss) button mounted on the treble side of the pickup, and on the bass side, a small oval LCD readout that relays simple data about preset selection, whether a note is sharp or flat (when the built-in chromatic tuner is in use), and system status alerts for broken strings, battery life, and partial tuning. The entire system runs on a 9-volt battery, which Fret-King says will last for up to 250 tunings.

The guitar itself is a handsome, modern twist on a Strat profile. The two-piece alder body has a reassuring heft—particularly with all the onboard electronics— but could benefit from a few smoother body contours at the body edges, which will occasionally give you a jab in the ribs. The 25 1/2" scale neck with rosewood fretboard and medium-jumbo frets is basically a comfy slim C shape, if a little bit flattish for my tastes.

The guitar’s standard electronics include Wilkinson WHHBZ33 offset pole piece “Zebra” humbuckers and a Wilkinson WHSM single-coil in the middle position. They’re wired via a 5-position selector switch and Wilkinson ’s Vari-coil system which enables variable splitting using the aft-most tone control, which is arguably a less clumsy and tonally varied approach than push-pull pot coil tapping.

Tuning on the Fly
The Wilkinson ATD HT440 bridge isn’t totally intuitive if you’re new to the technology, but it’s a very streamlined system with a minimum of controls that’s easy to get a feel for—especially if you treat yourself to a video tutorial from Wilkinson himself on the Fret-King web site (fretking.com). Once you grow accustomed to using the master function button (which doubles as an on/off switch and preset selector) and learn the symbols and preset numbers displayed on the LCD, the ATD HT440 works almost as naturally as a pedal tuner.

Factory presets include standard EADGBE, Drop D, Open G, Open E, DADGAD and GDFCDG. And setting up the Super-Matic for any one of them is a simple process of holding the function button down until the number 1 appears, clicking the button repeatedly until you find the number that corresponds to the desired preset, and strumming once. You’ll hear a quick burst of activity from the miniature motors in the bridge as they turn the capstans, and if you have the guitar’s volume up, the odd sound of the strings changing pitch in unison. Occasionally it will take a second slow strum for the system to read, process, and retune each note, but it rarely takes a third strum if you’re patient and deliberate.

One of the coolest aspects of the Super-Matic is the ability to store your own tunings, which is also a straightforward, if slightly more complex process called Strum ’N’ Store. You have to find and dial in the tuning yourself using the onboard chromatic tuner. But once you have the tuning in place, you hold the button for 10 seconds to unlock the ATD HT440 system, scroll to the preset number you want to use and strum the strings. Once a green light on the LCD confirms that the tuning is stored, you depress the button for another 10 seconds to re-lock the system.

There are limitations to Strum ’N’ Store. There’s a two-step pitch range limit in both flat and sharp directions for each string. So players who favor low tunings that drop the 6th string to C, for instance, won’t be able to use the preset function. The capstans can also only handle a maximum string thickness of .011 on the 1st string and .052 on the 6th, which covers most players, but leave some heavy-string fans and slide players who like fatter wire out of the mix.

No matter what the tuning, the Super- Matic has the tone-shaping potential to get the most out of it. The combination of the Vari-coil system and the 5-position switch puts a lot of sonic flavors at your fingertips. Running the Super-Matic straight into a Vox TB35C2 Bruno and a Fender Vibroverb, DADGAD and open G tunings growled aggressively and brimmed with harmonics, especially through the hot bridge humbucker. Rolling off the Vari-coil control and splitting the bridge humbucker gave the DADGAD setting a quieter, but crystalline quality that highlighted harmonic detail, while open G chords kicked with snappy Keith Richards sass.

The Verdict
The Fret-King Super-Matic does a truly impressive number of things for a single guitar, which should be little surprise given the creative record of its creator. None of the Super-Matic’s features reek of gimmickry, though. The ATD HT440 system is smooth and intuitive once you take a few minutes to acquaint yourself with its rhythms and commands. And the Vari-coil electronics and triple-pickup array give you a million ways to highlight the harmonic advantages of each tuning. A lot of guitars claim to be a guitar for every performance situation. Such an animal may never really exist, but the innovative, high-quality, super-playable, and ultra-versatile Fret-King Super-Matic comes pretty close.

Buy if...
hauling multiple guitars for alternate tunings to gigs wears you out.
Skip if...
you have little trust in guitar innovations past the development of the Telecaster.

Street $1599 - Fret-King - fret-king.com

Canadian luthier Michael Dunn has spent most of his life experimenting with interior resonators.

Decades ago, while working as a classical flamenco guitar maker in Spain, Michael Dunn ran across a steel-string guitar with a D-shaped soundhole and an interior sound box and reflector. “I thought this was a whole new world,” says Dunn. He took measurements of a similar guitar he found in London, and from there, the experiments began. The Canadian luthier has spent most of his life experimenting with interior resonators. “I’ve taken that technology and modified it, reshaped it, and re-jigged it in every imaginable way,” says Dunn.

The original interior sound box idea came from Mario Maccaferri in the 1930s. Maccaferri placed a smaller sound chamber into the main body of his guitars. Based on Maccaferri’s patented design, Dunn’s interior sound boxes are typically mandolin-sized boxes attached to the underside of the soundhole. These chambers have their own ports that redirect sound waves into a reflector. This acoustic technology allows the instrument to project more at higher frequencies, according to Dunn.

As a Django Reinhardt fan, Dunn builds a lot of Selmer-style guitars. Nearly half of the guitars he makes have his interior resonator boxes. However, he additionally builds archtops, Weissenborn-inspired lap slide guitars, harp guitars, OM guitars, and other types of instruments. Dunn is still thinking outside the box and implementing innovative designs. He is currently working on a cello that a musician can wear while playing. “They give me all the crazy stuff to build,” says Dunn with a laugh.

Dunn has made well over 500 instruments in the last 45 years. “I try to make the guitar as responsive and balanced as I can,” he says. “By responsive, I mean the sound of the guitar is what the musician is going to do with it—not what I did to it. I think a good guitar should be able to sound a half dozen different ways in the hands of a half dozen good players.”

The Cubist
Inspired by Cubist artist Juan Gris, this guitar looks off-centered and as if it’s constructed from various parts of other guitars. It features fanned frets and a soundboard made of Sitka spruce and cedar. The back comprises panels of rosewood, ironwood, ebony, bloodwood, blackwood, satinwood, purpleheart, and sumac. Instead of the traditional soundhole, there is a rear “sound slot,” which is formed by one panel being more elevated than another.

Mystery Pacific
This Gypsy guitar features a D-shaped soundhole and a 25 3/16" scale length. It also sports Dunn’s internal sound chamber, which enhances the guitar’s upper frequencies. The front wall of the interior sound box is located on the straight side of the “D,” and the sound box has a hole that directs sound into the parabolic reflector.

The Bugatti
Dating back to the early 1900s, French Bugatti automobiles were exotic, handbuilt touring machines. Dunn’s Bugatti guitar is made of ebony and satinwood with a yellow cedar soundboard inspired by Bugatti cars that were painted black and yellow. This guitar’s body is 19" long with a 14" lower bout. Two panels on the back represent the sides of the car’s hood, and the horseshoe-shaped soundhole is modeled after the car’s grille.

The OM
This orchestra-model guitar is the most recent addition to Dunn’s line. It looks like a traditional OM guitar, but features an internal sound box and refl ector. Knowing that the market for Gypsy and Selmer-style guitars is more limited than that for OM guitars, Dunn hopes to increase awareness of his interior resonators with his new OM design.

Hawaiian Guitar
The square-neck Hawaiian lap-slide guitar has a 25 3/16" scale length and a thin body that’s hollow up to its neck block. This particular guitar is made of wenge wood. Dunn’s Weissenborn-inspired instruments typically range from $3000 to $3500.

Pricing and Availability
Pricing is determined on a per-instrument basis due to custom specifications of each guitar. The base price of Dunn’s non-resonator custom guitars is around $4000. The models with interior resonators, such as the Mystery Pacific, Ultrafox, and OM guitars, typically fall between $5000 and $6000. The Bugatti model runs about $15,000, and the Cubist guitar costs roughly $10,000. Dunn builds around 15 guitars a year. Some of his Gypsy-jazz models are available immediately. Otherwise, the availability ranges from six months to a year.