The Fender Tremolux

The Fender Tremolux
circa 1960 Fender 5G9 Tremolux
Preamp tubes: one 12AY7, two 12AX7 for tremolo and PI
Output tubes: two 6V6GT, fixed bias
Rectifier: 5U4GB tube
Controls: Independent Volumes for each channel, shared Tone, Speed, Depth
Output: 18 watts RMS
Speaker: Jensen P12Q

Most amp nuts are utterly fascinated by Fender’s rapid evolution from archaic to modern through the course of the 1950s. Within that arc, the transitional moments are often among the most interesting, and the amp models that represent these provide curious little gems of discovery. The final version of the tweed Tremolux, fascinating in and of itself, is also worthy of study for the many transitional elements of Fender circuitry that it displays. In a nutshell, this is the small-to-medium-sized amp getting (for the first time) the big-amp treatment, and represents a very real bridge to the ubiquitous Deluxe Reverb of the mid ’60s.

The late-’50s Tremolux is an unsung tweed amp that has nevertheless been appreciated by the players who had the good fortune to encounter one in good condition. Our example here would be noteworthy for its vintage alone; with an original Jensen P12Q dating from the second week of 1960, pots from early ’60, and a tube chart stamped “JE,” denoting May 1960, it’s certainly from among the last batches of tweed amps made shortly before Fender gave over to blond and tan Tolex (aside from retaining a tweed-covered Champ for some years). Given this, it’s surprising to see that the tube chart also carries the 5E9-A model designation, that of the penultimate rendition of the tweed Tremolux, when all aspects of this amplifier’s circuitry and appointments denote it as the final evolution of the tweed Termolux, the 5G9 (which also makes us wonder if Fender applied 5G9 tube charts to any Tremoluxes, if not to this late an example). The clues that lead to the 5G9 are precisely the same big-amp elements Fender was applying to a sub-20-watt amp for the first time here, so let’s proceed by checking off those ingredients.

The tweed Tremolux, in all its forms, is often referred to as “a 5E3 Deluxe with tremolo added,” and for earlier incarnations – any real 5E9-A, or the 5E9 before it, for example – that was true enough. For such an innovative company, Fender was slow to bring tremolo to the table, and when its first tremolo-equipped amp came out in ’55, it really just added an extra tube and a tremolo circuit to the Deluxe – voila, the Tremolux. As such, a look inside the 5E9-A displays 5E3-related elements such as a split-phase (cathodyne) inverter, cathode-biased 6V6s, a 5Y3 rectifier, those three 16uF filter caps on the left of the eyelet board, and more. The early Tremolux’s bias-modulating tremolo sounded great, but presented a potential instability in the bias circuit. By way of improving the robustness of the model, Fender introduced a number of major changes to the 5G9 of 1957, essentially making it a big amp in a mid-sized package.

Here’s where the 5G9 Tremolux reveals itself as a sleeper, and a major footnote in amp history as well. We generally think of all Fender 6V6 amps prior to the Tolex years as having split-phase inverters and cathode-biased output stages, but the 5G9 Tremolux graduated beyond these and several other small-amp elements, to take on circuitry that only the tweed Bassman and high-powered Twin were blessed with at the time. Hell, even the Pro, Super, Bandmaster, and low-powered Twin of the late ’50s retained the split-phase inverter, but this Tremolux was long-tailed-pair all the way. Serious big-amp stuff. On top of that, it was Fender’s first 6V6-based amp to be given fixed bias in the output stage. Between them, these two upgrades enabled the Tremolux to retain the deep, lush bias-modulating tremolo circuit, without risks to output-tube stability. 

More? Sure, there’s plenty. The 5G9’s rectifier tube was boosted from 5Y3 to 5U4GB, and it was also given a choke in the filtering stage, another first for a push-pull 6V6-loaded Fender (if we discount the short-lived 5E4-A Super with 6V6s). A look at the circuit board also reveals a surprise. Where did the big filter caps go? Even the amps in that quartet of medium-large tweed models – the Pro, Super, Bandmaster, and low-powered Twin – had their big 16uF caps on the board. But the 5G9 Tremolux? Ahhhh, this privileged fellow has had his big electrolytics moved to the underside of the chassis and hidden beneath a “cap can” to allow room for the tremolo circuitry and upgraded filtering to co-exist in the same amp. This is something seen only on the Bassman and high-powered Twin at this time, but it’s a treatment the Deluxe and Deluxe Reverb would receive in the Tolex amps of the ’60s.

In addition to the circuit changes, the Tremolux had a bigger cab than other 6V6 amps from ’56 onward, the same cab as the 1×15″ Pro combo, in fact, although this 18-watter retained its 12″ speaker. This and the above upgrades help to make the Tremolux more than just a big amp in a medium amp’s guise on paper; the 5E9 sounds bigger, too. Our general impression is that this 1960 Tremolux, with its fixed bias, choke, and long-tailed pair PI, really sounds somewhat like a Bassman in a lower-output/1×12″ package. At low to medium volumes it has the relative tightness, liveliness, and fidelity to punch out the twang, and when it starts to break up at noon or beyond (give or take depending on the guitar you pair it with) it has a bold, well-defined growl, without quite the brown, compressed implosion of a cranked 5E3 Deluxe. The groovy part is that it offers all of this at pub and club volumes, with a rich, throbbing tremolo besides. Add it all up, and it might just be plenty of players’ vision of the ultimate medium-sized Fender tweed amp… even if they don’t know it. In the Tolex years, the Tremolux graduated to 6L6s after a brief, quirky segue via 6BQ5 (EL84) output tubes, but you could argue that as a smaller member of the large amp line, the model never quite achieved the tonal splendors it had offered as a larger member of the small amp line.

Dave Hunter is an American musician and journalist who has worked in both Britain and the U.S. He’s a former editor of The Guitar Magazine (UK).

This article originally appeared in VG’s December 2009 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.

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