Musician Magazine’s Interview with Kye

October, 1998 - “Used tube amps can be more than just a bargain – they can out-perform some new amps that cost three times as much,” says Kye Kennedy, a vintage amp repair guru who services and restores amplifiers belonging to many of Nashville’s best-known session players. “The most important way they can out-perform is in durability. A hand-wired, i.e., vintage, amp’s weakest link is its components [tubes, capacitors, etc.]. Conversely, a modern PC-board modular design’s weakest link is the PC board itself. Other ‘modern’ weak links are ribbon cable, undersized resistors, and design flaws.”

Many players believe that the “warmth” and “feel” of tube sound have yet to be successfully duplicated – although recent developments in physical modeling technology have brought digital approximations much closer to authenticity – and you’ll still find that many studio players and road pros continue to opt for tube-based amps even though they generate lots of heat, which can bake the innards of lesser-quality components.

Since the inception of the tube guitar amplifiers, heat was not a huge issue because the internal wiring was hand-soldered (often referred to as “point to point”). Point-to-point wiring requires fairly intensive and expensive labor, but the end result is a very solid and durable connection between all internal components such as tubes and filter caps.

In the mid to late Seventies, many tube amp manufacturers (including Marshall) switched to “printed circuit board” (PCB) construction, which are commonly found in computers. From a manufacturing standpoint, there are many advantages to PCB design, including increased precision during assembly, elimination of human error, and significantly shorter wire traces (for higher fidelity sound). But let’s face it, the main reason PCB design is featured in the vast majority of modern amp designs is that it’s much cheaper. In other words, it’s a corner-cutting measure. This may be fine in computers, but, over time, the heat of tubes can literally fry many PC boards.

Before we give all PCB amps a bad rap, it’s important to notes that there are different grades of printed and circuit boards. High-quality brands, such as Rivera and Mesa/Boogie, use very reliable “military grade” boards to provide pro sound, amazing features, and reliability at a reasonable price. Many discriminating buyers look to new, hand-wired “boutique” amps, made by manufacturers such as Matchless or Victoria, for the benefits of their no-compromise construction, but if you can’t come up with the cash needed to procure a boutique rig, an upgrade may be in order.

According to Kennedy, manufacturers shouldn’t be blamed for modern amp construction. “Tube theory has not been taught in schools since the Sixties, leaving qualified designers to fend for themselves,” he says.

“Some have never looked in a receiving tube manual to see what parameters tubes require to work reliably. Additionally, corporations can’t survive if they have to pay soldering technicians to “hand assemble” amps. There simply wouldn’t be enough profit to maintain a board of executives, much less a factory.”

Amp manufacturers in the Sixties and early Seventies weren’t faced with the same cost constraints, which explains why select models remain excellent bargains today. “With a few repairs and preventative maintenance, used amps can be a rewarding purchase for the working musician,” says Kennedy. The key to transforming a dusty pawnshop piece into a tour-quality took is to always assume that the amp in question is going to need a thorough restoration, regardless of how cool it might look if left unadulterated.

According to Kennedy, the transformer is typically going to be fine because these are durable components that typically don’t break down.

Tubes, filter caps, and speakers are another story. Kennedy advises to plan on at least replacing the following components: all tubes, electrolytic caps, the plate load resistor, screen resistor, control grid resistor, and filter resistors, because even if an amp were to sit in a closet untouched for thirty years, these components will deteriorate over time. “The screen and control grid resistors are particularly important because in most popular amps, they are mounted on the tube sockets, where they get cooked by the rising heat from the tubes like hot dogs over a fire,” explains Kennedy. He also recommends that for safety reasons, a three-prong electrical cord may also need to be installed on some older models.

When it comes to speakers, let your ears be the judge. Many players like the sound of an original Jensen (assuming it’s not blown_, but installing a new Celestion “Vintage 30,” for example, can reinforce the low-end while eliminating the piercing high end associated with many old speakers. No matter what you are looking to upgrade, plan on paying from $50 an hours (or more, depending on your geographical location) for qualified techs (unless, that is, you have a working knowledge of electronics and are handy with a soldering iron).

Keep in mind that since most techs charge an hour minimum per job, it makes more economic sense to bite the bullet up front and globally restore the amp versus replacing the tubes now and changing filter caps a few months down the road. Basically, replacing everything at once eliminates time and money wasted on trouble-shooting problem components.

If you’re interested in the collectability of an old amp more than its actual performance potential, Kennedy says you shouldn’t restore it. By the same token, don’t expect the amp to be a reliable tool for recording and gigs. “On a collectible amp, you have to make a decision as to whether you are going to play it at the club every weekend,” he says. “Replacing all those parts may affect it’s snob appeal, but, let’s be realistic: Would you take a ’69 Impala on the road if it had the original tires, belts, and hoses? Old parts should be replaced before they ruin a gig, because they will blow during your big showcase for the record company.”

A good example is how repair techs can modify an amp to accept Russian and Chinese tubes; vacuum tubes haven’t been made in the U.S. for decades and “new old-stock” tubes are expensive, hard to find, and have often deteriorated over the years. Whether you choose to take this route is up to you, but a tube amp without working tubes is no more valuable than a glorified doorstop.

Finding the right amp

In terms of models to look for, vintage Vox, Marshall, and “tweed” or “black-face” Fender models are going to command high dollars. By contrast, many “silver-face” (post-CBS buyout) Fender models are identical in construction or can be wired to “black-face” specs. The best part is that they can be had for less than $500, sometimes less than $400 (once again, depending on where you live). Throw in a couple hundred dollars for restoration, and you have an amp that costs about the same as many lower cost PCB amps, but one that features the same tone and quality of new “boutique” amps (which can cost several thousand dollars).

Every player and repair tech has his or her own opinion on what old tube amp is most suitable for an upgrade: Kennedy prefers silver-face Dual Showman Reverbs and Pro Reverbs, while Richard Koerner, a respected amp technician (and owner of Time Electronics in Union, New Jersey), suggests a variety of models for those seeking a sound a bit outside the norm. “I highly recommend the [silver-face] Fender Vibrosonic Reverb,” Koerner said, “It’s essentially a Twin Reverb, but with a 15” JBL speaker. This gives it a distinctive low end and great clean tone – which, interestingly also made it popular fore Rhodes piano. If you find one and it needs a new speaker, the JBL model E130 is still available today.”

According to Koerner, those seeking a groovy alternative to the Fender Super Reverb should seek out an Ampeg VT40 If you’re one who believes that there’s no substitute for a Marshall, but can’t afford a “Plexi,” Koerner recommends grabbing models made between ’70 and ’72. These models are easy to “hot rod,” and, believe it or not, also make great bass amps. He also suggests that anyone looking to copy the sound of classic Pink Floyd or the Who should scour pawn shops for ’70 to ’72 Hiwatts. Compared to Marshalls, they feature a cleaner sound, with a broader fidelity range. Finally, Koerner notes that the Fender Single Showman is a sleeper with its single 15” JBL. And bassists who want gobs of tube power but can’t afford the big Ampeg SVT, should seek out a 400 watt Fender 400PS.

According to Kennedy, if you’re looking for modern features like channel switching, line outs, and effects loops, check out the Paul Rivera-designed Fenders from the early Eighties. The Concert and Super Champ are both excellent amps that can be had for peanuts, though Kennedy suggests installing a beefier choke transformer. “These amps [and some other brands] are hand-wired,” Kennedy said. “This makes them easy to rebuild over, and over again, much like an old Ford truck.”