The Bandmaster Reverb head was built from 1968 to 1980 and has enough grille-room to install a pair of 8" speakers—a popular mod.
Fender introduced their piggyback amps in the blonde era, in 1960. Before that, during the tweed era, there were only combo amps. The piggybacks were designed to be loud, clean, and have lots of punchy bass from closed cabinets with 12" or 15" speakers. Most have solid-state rectifiers with no sag, and either two or four 6L6GC power tubes producing typically between 50 and 85 watts. They have massive power and output transformers, keeping things firm at high volumes and compatible for use with bass guitars. An exception to all the above is the smaller Tremolux amp, which we'll come back to.
A higher speaker impedance reduces the clean headroom, which is sometimes useful.
An advantage of using separate speaker cabinets is the flexibility to vary tone and volume by pairing amps to the cabinets they were designed for or to any other cabinet, as long as you stay within the safe impedance range: between -50 percent and +100 percent of the amp's rating. There is a huge difference in tone and volume playing a 4-ohm Bandmaster through a small and light cabinet with a modest, vintage-style 10" speaker at 8 ohms versus a closed-back 4x12 at 8 ohms with loud Celestion speakers. Or you may use a bass guitar with a single 15" bass-style cabinet. I encourage you to experiment and learn how to pick the right pairing for the right job. A rule of thumb is to match the amp and cabinet impedance, for the most possible wattage and volume. A higher speaker impedance reduces the clean headroom, which is sometimes useful.
Now, let's discuss the black-panel Tremolux—the only small piggyback amp. It has a normal channel, a vibrato channel, a GZ34 tube rectifier, two 6L6GCs, and lighter transformers, and was originally designed for a 2x10 closed-speaker cabinet. This amp produces a modest 35 watts and breaks up much earlier than its bigger brothers. It is sought by Fender players looking for natural tube distortion.
The Tremolux—a tiny, low-powered titan of the Fender head family—is sought by players desiring more tube-driven breakup.
Moving up the scale, the black-panel Bassman and Bandmaster amps may look similar, but their innards are not. Both are dual-channel amps powered by 6L6GC tubes and diode rectifiers, built for driving 2x12 speaker cabinets. The main differences are that the Bandmaster has tremolo and a smaller, 40-watt-output 125A6A transformer (same as the Vibrolux Reverb). The AB763-circuit Bandmaster's two channels—"Vibrato" and "Normal"—have similar preamp circuits and sound alike. The main difference is that the Bandmaster has tremolo. The circuit design and tone stacks relate very much to the Deluxe, Vibrolux, Super, and Pro combos, with typical sparkling, clean, and scooped black-panel sound.
The black-panel Bassman AB165 is different than other black-panel amps. At low volumes, black-panel Fenders sound clean, but when turned up, the Bassman distorts more because of an extra preamp-tube stage. Its tone is also slightly bigger and firmer than the Bandmaster, because of its larger output transformer. The Bassman's "Bass" channel is voiced for bass guitar, with a deep switch, while the normal channel is voiced for guitar, but without vibrato. I find the black-panel and silver-panel 50-watt Bassman to be a great bass amp, with articulate and strong lower mids that fit well in a band context.
Both the Bandmaster and Bassman continued in the silver-panel era, but with changes. The Bassman's power was first increased to 100 watts with four 6L6GC power tubes. A 70-watt version became available in the late '70s. In 1968, the Bandmaster Reverb was introduced, with a 5U4GB rectifier tube and a smaller 125A6A output transformer (same as the Vibrolux Reverb), both resulting in more sag and reduced clean headroom. The cabinet height grew a few inches to fit the reverb tank. The 4-ohm Bandmaster Reverb is one great, versatile tone platform with reverb, vibrato, and rich EQ possibilities, useful with all kinds of guitars, pedals, and speaker cabinets. If you own a silver-panel Bandmaster Reverb, you might consider getting an amp tech to revert the bias circuit back to black-panel specs, for better bias control.
Finally, the most powerful black-panel piggyback amps are the Showman and Dual Showman, with four 6L6GCs producing 85 watts. They came with single or dual 15" JBL speakers and large output transformers wanting 8- or 4-ohm loads, respectively. Be aware that some Dual Showman amps actually have a 4-ohm output transformer, and sometimes the faceplate says only "Showman." It's also worth echoing that Fender added reverb to the silver-panel version, to create the Dual Showman Reverb. And now, you know the basics of Fender's piggyback gems.
Leo Fender's study in perfection: a 1957 Stratocaster, leaning on a 1955 Bandmaster. To hear the definitive voice of this model-year Strat, listen to Buddy Guy's debut solo album, 1968's A Man and the Blues.
Fender's use of parts already in inventory gave this guitar its Bakelite-style pickup covers and dials. Note the slight fractures in the pickup covers, due to the material's brittle nature.
The instrument began to see substantial alterations a year earlier. The body wood, which had been ash, was changed to alder starting after the middle of 1956, due to its better consistency for finishing. The neck profile, which was originally round and clubby, evolved into a distinct V shape. Also by mid-'56, the original round guide for the high E and B strings was changed to a rectangular design known as a butterfly clip. And the control knobs and pickup covers, which were a brittle Bakelite-type material, began receiving more durable plastic, although some production models still sported Bakelite-style dials in early '57.
In keeping with the most historic Fenders, the company logo on this instrument is in spaghetti-style script.
The 1957 Fender Stratocaster pictured this month—serial number 19129—displays the features common to that banner-year model, including a one-piece V-profile maple neck with the spaghetti-style logo on the headstock, single-line Kluson Deluxe tuners (between 1954 and 1957, the tuning machine covers had no "Kluson Deluxe" stamp), a comfort-contoured alder body in a standard two-tone sunburst finish, a single-ply 8-screw white pickguard, and a 3-position pickup selector switch. This particular guitar still has the Bakelite-style pickup covers and knobs, because the Fender company never wasted parts, using what they already had in inventory while transitioning to new appointments.
The dash in front of this guitar's serial number stamp is part of its 1957/'58 lineage.
One master volume located closest to the player's hand controls all the pickups, while separate tone controls are assigned to the neck and middle pickups. The bridge pickup has no tone control, giving that position its full-take-off sound. The neck plate is stamped with a dash (only seen in 1957 and very early '58) in front of the five-digit serial number. The February 1957 list price for a Stratocaster with a vibrato arm was $274.50. The current value is $30,000.
The worn maple neck, scraping on the upper horn, and the condition of the case indicates that this guitar was once a hard-played and well-traveled workhorse.
Behind our Strat is a 1955 Fender Bandmaster amplifier. It has the characteristics shared by most narrow-panel amps made by the company between 1955 and 1960. These include two channels, with each channel having two inputs labeled "mic." and "inst.," two volume controls with the same labeling, treble, bass, and presence dials, and standby and on/off switches, along with a ground switch. The 26-watt amp has two 6L6G power tubes, one 12AY7, and two 12AX7 preamp tubes, along with a 5U4G rectifier. The 21 1/4" x 22 1/2" x 10 1/2" cabinet has three Jensen P10R speakers. The top one has its blue bell-shaped cover removed to allow it to fit in front of the tubes and chassis. The original price for a 1955 Bandmaster was $289.50. The current value for the amp is $8,000.
Sources for this article include The Fender Stratocaster by A.R. Duchossoir, The Stratocaster Chronicles: Celebrating 50 Years of the Fender Strat by Tom Wheeler, The Fender Stratocaster: The Life and Times of the World's Greatest Guitar and Its Players by Dave Hunter, and Fender Amps: The First Fifty Years by John Teagle and John Sprung.
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| I’ve got some problems with my current rackmount setup. Here are the specs: Marshall JMP-1 preamp (from Britain, I use a converter so it will work in the states), MosValve MV-962 Power Amp (solid state), Digitech 256XL Effects Processor (soon to be replaced with TC Electronic G-Major), Juice Goose Power Conditioner (1800 watts), Korg Pro Tuner and a Dunlop Crybaby. I run my Les Paul to wah to preamp – the rack is controlled by a Behringer MIDI foot controller. It runs through a Marshall 1960 lead 300-watt 4x12 cab This amp sounds unbelievable except for the extreme noise problems. When I add gain in the preamp, I have to switch to a clean channel whenever there is a break in the song to keep the noise from being audible. The causes may be using a volt converter for the British JMP-1 – which also requires the use of a three to two prong adapter – or the MosValve Power Amp, which only has a two-prong power cord (nonremovable). I think the combination of sacrificing the ground wire on the preamp and the power amp may be the cause, but it’s all that can work. I have heard the G-Major effects unit has a noise gate that will at least partially solve this problem, but for the money I’ve invested in my setup I would like a total solution so I can enjoy it to the fullest. Any ideas? - Andy |
Andy,
While too many ground connections can cause what’s known as “ground loops,” there is always the necessity for one good ground connection in a system. That said, it looks like you’ve already called out what I believe to be the source of your problem: the lack of a good common ground connection. This is a big mistake that cannot only be the source of your noise, but also a major safety concern.
Without a ground connection for the JMP- 1, your guitar cable shield is not at ground potential, which also means your guitar is not at ground potential, which means there is no noise reduction possible from the internal guitar shielding. But the problem continues in the other direction as well. Because of the lack of ground connection through the AC line cord, the chassis of the JMP-1 is not shielded, which can lead not only to the unit being susceptible to picking up external noise and hum, but emitting hum and digital clock noise as well. There are all sorts of digital noise suppression circuits inside the JMP-1 that are completely useless without an earth connection (ground).
You also run the risk, should the AC hot leg inside any piece of gear come in contact with its case, of placing yourself at a 120V potential. Grab a grounded microphone, or worse yet, another other guitar player that happens to be holding his guitar strings, and you’ll both “see the light!” In reality, it’s no laughing matter and could get you killed.
Luckily, I believe there is a solution. According to the schematic of the JMP-1, it uses a dual primary transformer, and there are internal jumpers on the PC board that can be configured for 120V or 240V. Take your unit to a qualified tech and have him convert it to 120V operation and install the correct fuse. Once that’s done you can use the standard IEC cable, complete with ground connection, and your rig should only make the sounds you expect it to.
Now you can do your part to help stamp out noise pollution.