Fender 1958 "tweed" Harvard Guitar Amplifier

Last Update 07-08-2012

I promised myself that I wouldn't buy any more gear until I got my house built... and then this gem appears at a price I couldn't refuse.

A "tweed" Fender amp had on my want list ever since I tried out a narrow panel tweed Champ. Now I understood the hype behind these things. The Champ, as great as it sounded, was pretty much a one trick pony and for the $$$ they were asking I passed on it. I decided a bigger amp would suit my needs better, something with two 6V6 power tubes. That selection was deliberate because my collection consisted of amps with 6L6s and EL34s. The 6V6 has a unique sound from the other two and I like variety in my arsenal. But it is very rare to find tweed amps above 10 watts selling for less than $3000 The house was a higher priority so I wasn't actively looking for one.

I forget what I was searching for on the net but this tweed amp crossed my path. Just when I decide to stay out of music stores, I find another piece of gear to buy. Time to get off the net so I can save $$$ for a house. Tweed amps are hard enough to come by, but a Harvard amp is the rarest of the bunch. They were introduced in 1955 (narrow panel era) and made for only six years, and this model had the lowest production count. And here was a war-hardened relic with stories to tell - and a price far below the market value. It was exactly what I was looking for - a classic tweed low-wattage model with a big variety of tones. It went straight to my amp tech for a thorough inspection and other than a recap, new handle, and new power tubes it was good as is. My tech has seen MANY amplifiers pass his shop, but this is the first Harvard he has seen.

I knew there was a reason this amp was cheap. This 1958 5F10 Harvard puts out 10 watts into a 10" speaker but the speaker is not original. Neither is the output transformer original. The tweed covering it is hardly mint. But hey - it sounds great! Controls offered are sophisticated volume and tone - that's it. There are three instrument inputs, each having a different input impedance. Back then it was common to have one amp shared between a guitar player or harp player or singer, and this was perfect for all three in a bedroom band. For a guitar player these three inputs are like three different amps using an A/B pedal.

I was going to re-tweed the amp, but my internet friends strongly urged me against it. It will drop the value enough that I will never get back the money I put into it. And they LOVED the look of that road-worn amp. I have to admit they were right, and I grew to like it better as is.

I did ask my tech to replace the original two prong power cord with a grounded three prong cord. The original grounding system was unsafe and presented a hazard if the plug was inserted backwards (back in the 1950s polarized grounded AC plugs did not exist). And there was a capacitor between neutral and chassis that established a pseudo ground - besides being unsafe, that cap was before the power switch and always soaking power even with the switch off! It was little surprise that many tweed amps arrived at the repair shop with these caps blown - and it was a messy cleanup job when they blew.

The tech recommended a Heybour output transformer, as they are designed to sound like the originals in the tweed amps. Mercury output transformers used to be popular, but players were unhappy with the sound and were paying this tech to REMOVE the Mercury output transformer from their amp for something better.

Don't let the 10 watt rating fool you - this beast is loud. Fender designed these amps for clean undistorted headroom for the country players of the day. They never intended the volume to be cranked to 12 (that's one higher than you, Spinal Tap!) but decades later players discovered a lovely crunch hidden in these innocent little boxes. Indeed, the 15 watt 5E3 tweed Deluxe is highly sought after for the same reason.

If you're tempted to try to play a Harvard (or any amplifier less than 50 watt) through a 4x12 or 4x10 cabinet... DON'T. Four speakers increases the current demand out of the amplifier and it will burn out the $$$ output transformer. of this 10W amp. I wouldn't risk it with a 2x12 or 2x10 cabinet either.

Loud isn't the only thing that tweeds do well. This Harvard responds very well to playing dynamics. Stroke the strings lightly and you get that clean Fender sound, while hard playing will push it into that lovely overdrive. The tonal colors in between are unbelievable. Complimenting the sound is the 5Y3 rectifier tube which imparts a compression effect on hard sharp transients because the rectifier tube cannot instantaneously respond to current demands.

The Harvard has this uncanny knack to make any guitar sound good. I have a good Les Paul, Tele, and Strat with no dispute that they sound good, but the amp made my POS Epiphone Genesis sound good!

A trait unique to tweed amps with dual 6V6s is the cathodyne (aka "split load") phase inverter. This circuit contributes some distortion of its own and I have yet to hear of a modeller that models the phase inverter distortion. A cathodyne PI differs from the more common long tailed pair PI in that the latter is much cleaner thereby delivers maximum power to the power output stage, and amplifier technology had been steadily advancing power output from 1940 to 1960. Back in the 1950s the lesser cathodyne PI was used in lower wattage amps because it required fewer parts which kept the cost of the amp reasonable. The Harvard was considered a practice amp and Leo Fender wanted to keep it in a certain price range, whereas the big performer tweed Bassman and Twin used 6L6s with the LTP PI. The onset of distortion from the cathodyne PI is gradual (also responding to touch), and it distorts before the 6V6s do. So the low wattage tweeds have a grind that is unique to them.

The Harvard stands alone in this one feature - a 6AT6 preamp tube. No other Fender amp used this tube. While the 12AX7 is a dual triode tube, the 6AT6 is a cute little single triode tube. Leo had designed the Vibrolux, but felt that another model between that and the Princeton was needed. So he simply removed the tremolo circuit of the 5F11 Vibrolux create the 5F10 Harvard. But there was an unused triode stage with the removal of the tremolo so the Harvard was designed with the single triode 6AT6 to eliminate redundancy. The Harvard is closely related to the Deluxe with four significant differences 1) plate voltages 2) 12" speaker (Deluxe), 3) bias scheme (fixed versus cathode), and 4) the Harvard lacks the tone recovery stage of the Deluxe. Had Leo used the redundant triode as the tone recovery stage, the 10w Harvard would had been too close to the 15w Deluxe.

There was a 6G10 Harvard made during its last years 1960/61 which is closest to the Princeton with its single 6V6 power tube. Speculation is that Fender was about to discontinue the Harvard as it was never a big seller. Leo never wasted anything, so he repackaged the Harvard in a Princeton cabinet to use up the supply of Harvard badges without building new cabinets. Leo was really frugal but practical.

Omissions aside, the Harvard has this crisp snarl that I had not heard from any amp. The clean sound has this crisp high transient edge that is pleasant on the ears and really gives different guitars their voice. Gradually increasing the volume drove the amp into overdrive, all the way to the bark of a Marshall (which was in fact derived from a tweed Bassman) - and it still had that high end edge. By varying touch or lowering the volume, you can control the overdrive remotely. And the relative loudness between these extremes is very even. This is a cool feature. Variations of the tone control was interesting - this is not your simple cut in high frequencies, there is something more sophisticated going on here. I learned that with the tone control at midway, that is the "default" tone setting - turning the control either direction brings in a different treble boost via different value capacitors. Playing my tele, strat, and les paul yielded wonderful results (I will include sound samples later). My brother's vintage Hamer Standard sounded GREAT through the Harvard - and I sold that guitar to him years ago because I couldn't get the sound I wanted out of it! Yet further proof that the amp is as vital as the guitar. Tweed amps have a pleasant articulation with picking strings, and the Harvard is no exception.

With my arsenal of assorted speaker cabinets and speakers, I plan on doing some experimenting. My tech tells me of a customer who got a lovely sound with a tweed driving Celestion G12 alnicos. The speaker was a non-original 1960s Fender ceramic speaker; the original period correct Jensen alnico speaker was missing, so I acquired a Weber 20w alnico speaker with a safe power margin so it doesn't blow at full bore. I really like the Weber so I left it in.

My tech also suggested varying the phase inverter tube - the original is GE 5751 and a 12AX7 will crunch it up some more.

When recording guitar, many players claim that the small amps sound better. I've done some impromptu video recordings of the Harvard and there is some truth to that method.

I located some NOS tubes at a hamfest and took home some 6AT6s and 6AV6s. Later I found piles of RCA, Sylvania, GE, etc 6AT6/6AV6 tubes from a seller on the 'bay. The 6AV6 has higher gain than the AT, but my experiments showed that if you push the input too hard it made the amp "brown out" unpleasantly (instead of a voltage brownout, it caused a current brownout). There is a 6AU6 tube but it is NOT interchangeable (6AU6 is NOT a triode it is a pentode and is not pin compatible). The experiment with the 6AV6 did yield more overdrive but at the expense of that edgy snarl. Both me and my brother preferred the original 6AT6. But the 6AV6 may have a useful purpose in the future.

Unbeknownst to me, this Harvard was predestined by a prior acquisition - a Fender Reverb reissue tweed. These two in addition to my Telecaster make an excellent combination, audible and visual. This was not at all planned, but nonetheless interesting that they "fell into place". The Harvard and Reverb are an interesting study of contrast of new vs fossle - a fifty year difference in age. I mean, LOOK at the wear on that tweed... Fender "relics" can't touch this thing!

Harvards are very hard to come by because owners simply do not give them up. Collectors have told of owning many tweed amps, then trimming out the collection to a select few which always included the Harvard. And there is another group of collectors who have never had the pleasure of owning or playing through a Harvard. The most famous proponent of the Harvard was Steve Cropper who used it to great effect on Booker T songs and many soul songs of the 1960s. The late Jerry Garcia was known to keep a Harvard in his dressing room as a warmup amp, but it is unknown if it appeared on a Grateful Dead track. There's another student who learned his licks playing through a Harvard, later to become famous - Randy Rhoads! Fender revived the Harvard in the 1990s but in name only - it bears zero resemblance to the sound, features, or looks of the tweed amp.

contact info

Home