One element inside your amp that has a definite wear-out time whether you use the amp or not is the filter capacitors. If you keep an amplifier long enough, the filter capacitors will fail – it’s a question of when, not if. But there are capacitors available that will never wear out.
Immortality Mod #4: Replace electrolytic capacitors with plastic film types
Warning! These mods are located in the highest voltages in the amplifier. If you want to do this yourself, you must be absolutely certain before you start that you already know how to do it safely. If you have any doubts at all, take it to a tech who can do it safely. And always unplug your amp for at least several minutes before opening it!
Gather a list of the capacitance values and maximum voltages in your amplifier, then track down suitable film replacements. A suitable replacement for an electrolytic cap:
- has a capacitance as high or higher than the replaced capacitor – or can be combined to make enough capacitance.
- has a voltage rating as high or higher than the replaced capacitor.
- is a metal can “motor run cap,” a “DC link cap” or a “Medium power film capacitor.” Do not use “motor start capacitors,” as they will not be durable.
For our example, we’ll look at replacing the caps in a Fender Super Reverb AB763 (see table). You can find the schematic online at ampwares.com/ffg/schem/twin_reverb_ab763_schem.gif
Fender made their first filter cap from two 70”F/350V caps in series to equal a 35”F/700V capacitor. The use of two caps and the higher voltages was probably to get higher reliability. But film caps are tougher than electros. The B+ voltage is normally 460V here, so we need a bit more voltage than that. Taking a clue from the rating of the other filter caps we’ll shoot for 525 VDC. That’s plenty for a normal 460V, plus maybe a 10 percent surge to 506V.
The next three caps are the replacements for the phase inverter and preamp B+ filters. In the catalog I consulted, there are two parts that work: one is 20”F/450-630V and the other is a larger 25”F/450-630V. Oddly, the 25”F part is cheaper than the exact replacement size of 20”F, so I picked that one. 
The bias filter capacitor may be the most important filter cap in your amp. If this one shorts, you will buy at least new tubes, and possibly a new power transformer. I found a 10”F film cap that is also physically small. We can make a bigger capacitance at the same voltage by hooking capacitors in parallel. The particular cap I found was 10”F/250V for $2.23, so I specified five of them to be hooked up in parallel. This is equal to a 50”F/250V capacitor and costs $11.15. I could have used a 50”F/370VAC metal can capacitor, but this is quite large physically, and there is little ripple current stress, so I chose the smaller, plastic-cased 10”F units in parallel.
I listed prices because it is possible to spend a lot more on film capacitors if you don’t shop carefully. Our tab for film caps for the whole amplifier is nearly $60. To compare, Mouser Electronics sells a 20”F/500V film cap for $12.47 and Antique Electronics Supply sells a 20”F/500V electro cap for $6.35. The film capacitors are moderately more expensive for equal ratings. However, the amp tech’s time to put all new capacitors in will likely be $50-$100. Spending a little more for parts once means you’ll never have to replace them again just because they wear out.
WHERE TO FIND CAPS Mouser Electronics DC link caps and medium power film mouser.com Digi-Key Electronics DC link caps and medium power film digikey.com Johnstone Supply HVAC motor-run capacitors johnstonesupply.com |
R.G. Keen
Cheif Engineer
Visual Sound
www.visualsound.net
Gibson originally launched the EB-6 model with the intention of serving consumers looking for a “tic-tac” bass sound.
The Gibson EB-6 was announced in 1959 and came into the world in 1960, not with a dual-horn body but with that of an elegant ES-335. They looked stately, with a thin, semi-hollow body, f-holes, and a sunburst finish. Our pick for this Vintage Vault column is one such first-year model, in about as original condition as you’re able to find today. “Why?” you may be asking. Well, read on....
When the EB-6 was introduced, the Bass VI was still a glimmer in Leo Fender’s eye. The real competition were the Danelectro 6-string basses that seemed to have popped up out of nowhere and were suddenly being used on lots of hit records by the likes of Elvis, Patsy Cline, and other household names. Danos like the UB-2 (introduced in ’56), the Longhorn 4623 (’58), and the Shorthorn 3612 (’58) were the earliest attempts any company made at a 6-string bass in this style: not quite a standard electric bass, not quite a guitar, nor, for that matter, quite like a baritone guitar.
The only change this vintage EB-6 features is a replacement set of Kluson tuners.
Photo by Ken Lapworth
Gibson, Fender, and others during this era would in fact call these basses “baritone guitars,” to add to our confusion today. But these vintage “baritones” were all tuned one octave below a standard guitar, with scale lengths around 30", while most modern baritones are tuned B-to-B or A-to-A and have scale lengths between 26" and 30".)
At the time, those Danelectros were instrumental to what was called the “tic-tac” bass sound of Nashville records produced by Chet Atkins, or the “click-bass” tones made out west by producer Lee Hazlewood. Gibson wanted something for this market, and the EB-6 was born.
“When the EB-6 was introduced, the Bass VI was still a glimmer in Leo Fender’s eye.”
The 30.5" scale 1960 EB-6 has a single humbucking pickup, a volume knob, a tone knob, and a small, push-button “Tone Selector Switch” that engages a treble circuit for an instant tic-tac sound. (Without engaging that switch, you get a bass-heavy tone so deep that cowboy chords will sound like a muddy mess.)
The EB-6, for better or for worse, did not unseat the Danelectros, and a November 1959 price list from Gibson hints at why: The EB-6 retailed for $340, compared to Dano price tags that ranged from $85 to $150. Only a few dozen EB-6 basses were shipped in 1960, and only 67 total are known to have been built before Gibson changed the shape to the SG style in 1962.
Most players who come across an EB-6 today think it was a response to the Fender Bass VI, but the former actually beat the latter to the market by a full year.
Photo by Ken Lapworth
It’s sad that so few were built. Sure, it was a high-end model made to achieve the novelty tic-tac sound of cheaper instruments, but in its full-voiced glory, the EB-6 has a huge potential of tones. It would sound great in our contemporary guitar era where more players are exploring baritone ranges, and where so many people got back into the Bass VI after seeing the Beatles play one in the 2021 documentary, Get Back.
It’s sadder, still, how many original-era EB-6s have been parted out in the decades since. Remember earlier when I wrote that our Vintage Vaultpick was about as original as you could find? That’s because the model’s single humbucker is a PAF, its Kluson tuners are double-line, and its knobs are identical to those on Les Paul ’Bursts. So as people repaired broken ’Bursts, converted other LPs to ’Bursts, or otherwise sought to give other Gibsons a “Golden Era” sound and look ... they often stripped these forgotten EB-6 basses for parts.
This original EB-6 is up for sale now from Reverb seller Emerald City Guitars for a $16,950 asking price at the time of writing. The only thing that isn’t original about it is a replacement set of Kluson tuners, not because its originals were stolen but just to help preserve them. (They will be included in the case.)
With so few surviving 335-style EB-6 basses, Reverb doesn’t have a ton of sales data to compare prices to. Ten years ago, a lucky buyer found a nearly original 1960 EB-6 for about $7,000. But Emerald City’s $16,950 asking price is closer to more recent examples and asking prices.
Sources: Prices on Gibson Instruments, November 1, 1959, Tony Bacon’s “Danelectro’s UB-2 and the Early Days of 6-String Basses” Reverb News article, Gruhn’s Guide to Vintage Guitars, Tom Wheeler’s American Guitars: An Illustrated History, Reverb listings and Price Guide sales data.
Originally released in the 1980s, the Victory has long been a cult favorite among guitarists for its distinctive double cutaway design and excellent upper-fret access. These new models feature flexible electronics, enhanced body contours, improved weight and balance, and an Explorer headstock shape.
A Cult Classic Made Modern
The new Victory features refined body contours, improved weight and balance, and an updated headstock shape based on the popular Gibson Explorer.
Effortless Playing
With a fast-playing SlimTaper neck profile and ebony fretboard with a compound radius, the Victory delivers low action without fret buzz everywhere on the fretboard.
Flexible Electronics
The two 80s Tribute humbucker pickups are wired to push/pull master volume and tone controls for coil splitting and inner/outer coil selection when the coils are split.
For more information, please visit gibson.com.
Gibson Victory Figured Top Electric Guitar - Iguana Burst
