This 1968 Epiphone Al Caiola Standard came stocked with P-90s and a 5-switch Tone Expressor system.
Photo courtesy of Guitar Point (guitarpoint.de)
Hello and welcome back to Mod Garage. Not long ago, I came home late from a band rehearsal, still overly excited about the new songs we played. I got myself a coffee (I know, it's a crazy procedure to calm down) and turned on the TV. I ended up with an old Bonanza episode from the ’60s, the mother of all Western TV series. Hearing the theme after a long time instantly reminded me of the great Al Caiola, who is the prolific session guitarist who plays on the song. With him in mind, I looked up the ’60s Epiphone “Al Caiola” model and decided I want to talk about the Epiphone/Gibson Tone Expressor system that was used in this guitar.
The Epiphone Al Caiola model was built in the Gibson Kalamazoo factory and was similar to an Epiphone Sheraton, with a longer 25 1/2" scale. It was built from late 1963 until 1969 and was available with different pickups like Gibson mini-humbuckers and P-90s. The guitar would be renamed the Al Caiola Custom to make way for the Al Caiola Standard that was introduced in 1966, but both models had the Tone Expressor system.
The guitar has a Telecaster-like wiring configuration: two pickups, master volume and master tone, 2-way pickup-selector switch. Since the circuit only has a 2-way switch instead of a 3-way switch, you can’t play both the neck and bridge pickup at the same time. (Maybe Al Caiola didn’t like a middle-position sound; who knows?) There are also five additional mini-slider switches labeled 1—5 which make up the Tone Expressor system.
“With the individual slider switches of the Tone Expressor system, you can combine all five switching positions in any way you like, so you have countless possible combinations.”
Having a look under the hood reveals the Gibson Varitone system used on the ES models. My first thought was this was new wine in old bottles, but after having a deeper look, there are differences between the standard Gibson Varitone and the Tone Expressor system. The Gibson Varitone uses a 1.5 H inductor, while the Tone Expressor system has a 15 H inductor on board. The Varitone is a rotary switch, so you can only dial in one of the switching positions, no combinations. With the individual slider switches of the Tone Expressor system, you can combine all five switching positions in any way you like, so you have countless possible combinations. Electronically, the Tone Expressor is a switchable band-rejection filter; mids are attenuated and the result is a crisp, more twangy tone.
In this first of two parts about this very special circuit, I want to describe the switching positions of the Tone Expressor system. First, here are the individual parts:
• 500k audio master volume and master tone pot with a 0.02 μF tone cap. This configuration will work with mini-humbuckers as well as P-90 pickups.
• 2-way pickup-selector slider switch. Having the possibility to engage both pickups together (no matter if in parallel or in series) would enhance this wiring noticeably.
• 15 H inductor (choke). The inductor in this circuit creates a series of notch filters together with the caps of the individual switches, so the circuit doesn’t remove all signal above a certain frequency, but only a certain amount above and below that frequency. There is a lot of debate about using an inductor or not, and if so, what type.
Personally, I think adding an inductor is not the best choice. The design may have worked at the time, but today, most of us are looking for different sounds. While the Varitone has its fans, it was never very popular because it can suck tone, and a lot of people say that it doesn’t have a major effect anyway.
If you want to use an inductor and find a matching one, these have center-tapped primaries and secondaries. Use the entire primary or the entire secondary, and ignore center taps for the Varitone wiring. I had the chance to measure several original inductors (labeled TF-90-1C), and they all showed something between 12 H and 17 H; keeping their tolerances in mind, you can use any inductor in this ballpark.
• 10 M resistors. There is a 10 M resistor connected to the circuit in series to each of the five caps. These “pull-down” resistors prevent loud popping noises when using one of the switches—standard when switching capacitance like on the Varitone system.
• 100k resistor. Together with the caps on the switches, the single 100k series resistor creates a frequency selective voltage divider, which is essential to create a proper frequency notch. The value is well-chosen so there is no need to replace it.
On the Varitone rotary switch, position No. 1 is the bypass mode. The Al Caiola, with its slider switches, naturally doesn’t need an extra switch for this. When no switch is engaged, the Tone Expressor system is in bypass mode. In general, we can say that the bigger the cap, the thinner the tone, and vice versa. Or in other words: The bigger the cap, the more the humbucker tone is tidied up towards a more twangy and single-coil-like tone.
An up-close look at the controls for the Tone Expressor system.
Photo courtesy of Guitar Point (guitarpoint.de)
Here is what each switching position does:
• Switch No. 1 with 1000 pF cap corresponds to position two of the Varitone rotary switch and has a very subtle effect. It’s an unmistakably PAF-style humbucker tone, but with the bass frequencies tidied up a little. This setting can help cut through a mix and will prevent a boomy, woolly tone when playing full-tilt.
• Switch No. 2 with 3000 pF cap corresponds to position three of the Varitone rotary switch and is my favorite setting. Still a PAF-style humbucker tone, but tighter and with more transparency. This tone never gets too boomy and rides on the edge of the P-90 territory.
• Switch No. 3 with 0.01 μF cap corresponds to position four of the Varitone rotary switch. This reminds me of a typical P-90 tone with a tight bass and clarity in the high frequencies—very cool for some break-up blues playing.
• Switch No. 4 with 0.03 μF cap corresponds to position five of the Varitone rotary switch and is a very twangy and single-coil like setting that sounds like a Stratocaster—very useful and versatile.
• Switch No. 5 with 0.22 μF cap corresponds to position six of the Varitone rotary switch and is the most twangy setting. It reminds me a lot of a good Telecaster, especially with the bridge pickup.
Next month, we will look into different ways to set up and mod this circuit, so stay tuned!
Until then ... keep on modding!
This Japan-made Guyatone brings back memories of hitchin’ rides around the U.S.
So, as I’m prone to do, I started digging around hitchhiking culture and stories. Surprisingly, there are organized groups that embrace the hitching life, but the practice remains on the fringe in the U.S. Back in the 1950s, writer Jack Kerouac wrote the novel On the Road, which celebrated hitchhiking and exposed readers to the thrill of maverick travel. Heck, even Mike Dugan (the guitarist in all my videos) hitched his way to California in the 1960s. But seeing that fellow on the side of the road also sparked another image in my brain: Yep, it always comes back to guitars.
Let me present to you a guitar that’s ready to go hitching: the Guyatone LG-180T, hailing from 1966. The “thumbs-up” headstock and the big “thumb” on the upper bout always made me think of thumbing a ride, and I bought and sold this guitar so long ago that I had forgotten about it, until I saw that hitchhiking dude. Guyatone was an interesting Japanese company because they were primarily an electronics company, and most of their guitars had their wooden parts produced by other factories. In the case of the LG-180T, the bodies were made by Yamaha in Hamamatsu, Japan. At that time, Yamaha was arguably making the finest Japanese guitars, and the wood on this Guyatone model is outstanding. We don’t often see Guyatone-branded guitars here in the U.S., but a lot of players recognize the early ’60s label Kent—a brand name used by an American importer for Guyatone guitars.
With a bit of imagination, the LG-180T’s “thumbs up” headstock seems to be looking for a roadside ride.
Kent guitars were extremely popular from the early ’60s until around 1966. The U.S. importer B&J fed the American need for electric guitars with several nice Kent models, but when the Guyatone contract ended, so did most of the Kent guitars. After that, Guyatone primarily sold guitars in Japan, so this example is a rare model in the U.S.
“Unless you are a master at guitar setups, this would be a difficult player.”
This headstock is either the ugliest or the coolest of the Guyatone designs. I can’t decide which. I will say, no other Japanese guitar company ever put out anything like this. You have to give the Guyatone designers a thumbs up for trying to stand out in the crowd! Guyatone decided to forgo an adjustable truss rod in this model, opting instead for a light alloy non-adjustable core to reinforce the neck. Speaking of the neck, this instrument features the most odd-feeling neck. It’s very thin but has a deep shoulder (if that makes any sense). Totally strange!
Another strange feature is the bridge, which offers very little adjustment because of the three large saddles, which sort of rock back and forth with the tremolo. It’s a shame because these pickups sound great! They’re very crisp and have plenty of zing, but unless you are a master at guitar set-ups, this would be a difficult player.
This could be why the LG-180T only appeared in the 1966 and 1967 catalogs. After that, it disappeared along with all the other Yamaha-made Guyatone electrics. By 1969, Guyatone had gone bankrupt for the first time, and thus ended guitar production for a few decades. At least we were blessed with some wacky guitar designs we can marvel at while remembering the days when you could play in the back end of an explosive 1973 AMC Gremlin while your mom raced around town. Two thumbs up for surviving our childhoods! PG
