The Fender “High-Powered” Twin

Photo: VG Archive. Amp courtesy Dave Rogers.

1958-’59 Fender Twin

Preamp tubes: one 12AY7, two 12AX7
Output tubes: four 5881 (6L6 equivalents), fixed bias
Rectifier: GZ34 (5AR4) tube
Controls: Volume, Volume, Treble, Bass, Middle, Presence
Output: 80 watts RMS +/-
Speaker: two 12” Jensen P12N

Many tweed-o-philes get more excited about the small and mid-sized amps that they can crank up in bijou clubs to attain that seminal tone without turning patrons out the door, but the high-powered Twin undoubtedly represents the zenith of Fender amps of the 1950s.

The Twin is such a legendary amp format that it has become almost a generic, like Kleenex or Band-Aid. We’ve lived with its later incarnations as underappreciated house amp or dusty rec-room beer holders for so long that its upholstered predecessor appears almost alien to us – but the model under the microscope this month really is the first Fender Twin, for all intents and purposes. Sure, the Twin debuted as a wide-panel tweed combo of 1952, and the low-powered, narrow-panel 5E8-A Twin of 1956-’57 is more emulated by the copyists. But at around 25 and 40 watts respectively, these early renditions are mere poor relations to the big boy that this format would grow up to be, in terms of wattage, at least. In 1958, however, the 5F8 (soon 5F8-A) Twin unleashed a whopping 80 watts of output power on the unsuspecting guitar world, and forever established what “a Twin” should be; muy grande power in a relatively compact 2×12″ grab-and-go combo package.

Or should that be “herniate and go”? Less so in the case of the tweed-era Twins, perhaps, than in that of the gut-busting blackface and silverface Twin Reverbs, but with all the weighty iron they packed, these were still heavier than anything else to come down the pike up to that point. That said, you’re looking at something just a few ticks away from a Marshall JTM100 stack, but roaring through a mere two Jensen P12N speakers. That’s a lot of firepower in a 26″ x 20″ x 101/2″ pine box. Let’s crawl inside and look around…

The birth of the 5F8-A Twin is often pegged to the addition of another two 5881 output tubes to the pair in the 5E8-A that preceded it, but it’s a very, very different amp in a few other crucial ways. To wit, it’s actually a lot closer to being a 5F6-A Bassman with four 5881s and two 12s – which, yeah, many people think is just a low-powered Twin with four 10s instead of two 12s. Have we lost you yet? Good. To clarify; in addition to the obvious doubling of power, the 5F8-A circuit employed a long-tailed-pair phase inverter, the only other Fender at that time other than the Bassman to be given this eloquent PI. This change helped to minimize distortion at the inverter stage, meaning more of the full, unadulterated tonal goodness was translated to the 5881s and their bigger output transformer. This constitutes just a few wiring changes and half a dozen or so new resistors, and it still uses just the one tube that the 5E8-A’s driver/splitter network required, but it takes an amp up to the big leagues, and makes the Twin’s evolution complete. From the paraphase PI and cathode-biased output stage of the original 5C8 Twin (capable of generating only 25 watts from two 6L6/5881s), to the fixed-bias output stage and cathodyne inverter of the 5E8-A, to the 5F8-A’s fully evolved circuit, that’s a pretty big leap in just six years, and it shows how Fender was romping along and really pushing the envelope. Rock and roll and electric country were getting into full swing as commercial genres, popular guitar-based music was finding its way to bigger and bigger stages, and players were demanding more volume to help them cut through (much is made of Jim Marshall’s move to 100-watters in the mid ’60s for the very same reasons, but it was happening here first, folks!).

Our 5F8-A also gained a Middle control, a sturdy GZ34 (5AR4) rectifier, and firmer power filtering (20uF electrolytic capacitors in place of the 16uF caps), the latter two of which would particularly contribute to its more robust performance. This is a good place to point out that the Twin’s pair of Jensen P12N speakers really weren’t up to the task if you cranked the amp up full-whack. It’s amazing that so many of these speakers (well, some at least) even survive to this day. Their ratings changed over the years, but P12Ns of the era were nominally rated at around 30 watts RMS (the reissues claim 50 watts). Why put only 60 watts worth of speaker in an 80-watt amp? For one thing, that was one of the most robust speakers available in the day, for decent money at least. But for another, Leo Fender really wasn’t intending that these amps be wound up to the max for a full-on crunchfest. He was designing for headroom, and 80 watts meant that you could retain better headroom than anything else on the market with the Twin up to about 6 or 7 on the dial and putting out 60 clean watts, give or take. Push it past that point though and, woah boy, this fella’ really roars!

For all its impressive muscularity, the 5F8-A simply isn’t going to be every player’s favorite flavor of tweed Twin. For one, as we alluded to at the top of this piece, many guitarist’s goal with the tweed vibe is to get to the sweet spot quickly and easily, without rupturing too many eardrums in the process. Eric Clapton and Keith Richards can get away with the full 80-watt glory, certainly, but most corner stages down at the Rusty Nut aren’t going to let you fire one up on a Saturday night. For the rest of us, a Super, Pro, low-powered Twin, or even a little Deluxe will do the job beautifully… But if you ever land on a big stage where you can do justice to a 5F8-A Twin, hang on tight and enjoy the ride.

Dave Hunter is an American musician and journalist who has worked in both Britain and the U.S. The Guitar Amp Handbook and other titles.

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