Photo 1
This month I've decided to forgo answering a question—not that I don't have plenty, and thank you for that, loyal readers. Instead we'll explore a mod to a blackface Fender Vibrolux Reverb and the thinking behind it. It's an easy and completely reversible that yields what I consider to be a more versatile amp.
Not long ago, a customer brought me a Vibrolux combo he'd recently acquired. He wanted to make it one of his regular gigging amps, so he asked me to make sure it was roadworthy. He wanted new caps, tubes, and whatever else was needed. He also wanted to remove and safely stash the original speakers while they were still in working condition. His idea was to thrash a new set of speakers on gigs and not be concerned about reliability or destroying a piece of Fender history.
Replacing speakers is actually a great upgrade for any amp of this era because speakers grow tired over the years, and a fresh set can yield a far greater improvement than most players would believe. In fact, when I install new speakers in an old amp, the owner typically experiences a wow moment. (If you have an older amp, try it—you might have that reaction too.)
Before I dive into repairing or modding an amp, I always ask how the owner expects to use it. For example: Do you like to play dirty, or are you after a big, clean tone with maximum headroom? This feedback gives me an idea of what type of tubes to install and how to tailor the circuit to the player.
It turned out this customer performs a lot of music inspired by Jonny Lang and Kenny Wayne Shepherd. Great—this gave me a reference and prompted me to offer some suggestions. We all know these players were very influenced by the late, great SRV.
Before I dive into repairing or modding an amp, I always ask how the owner expects to use it.
In my brief time working with Stevie before his death, I saw that his massive backline included two Fender Super Reverb combos, each loaded with four Electro-Voice 10s—his favorite speakers for these amps. How he managed to blow speakers with such massive power handling capability with a 40-watt Super is beyond me, but his tech at the time, the legendary René Martinez, always had spares on hand. Anyway, let's see what this knowledge can do for my customer.
First, a Vibrolux Reverb is a bit like a mini Super Reverb. With a dual-6L6 output stage, the amps offer about the same power, but the Vibrolux has two 10s instead of the Super's quad set. But they're voiced differently: While most blackface and silverface Fenders use the same value capacitors in the tone stack—a 250 pF, a 0.1 µF, and a 0.047 µF—the Super Reverb has a 0.022 µF cap in place of the 0.047 µF.
My suggestion was to modify the tone stack in the Vibrolux's first channel. This way, one channel would remain stock, the other would be a bit more like a Super, and he could use an A/B switch to access either channel as desired.
Regarding speakers: Unless you can afford a roadie, I wouldn't advise loading a Super or even a Vibrolux Reverb with EV 10s. These bad boys are heavy! Instead, I suggested swapping in a lighter set of contemporary 10s that sound similar to the EVs. The owner agreed, so let's look at what we did.
Photo 1 shows how I've installed not one but two new caps in the amp's first channel. I like replacing both the .047 and 0.1 µF caps with .022 µF caps. It makes the channel a bit beefier, and that's nice for a guitar with single-coil pickups. It also leans more towards a Marshall tone stack at this point ... but not quite. Of course, Stevie was also a Marshall guy (got to love those 200-watt Majors), so if you really want to go all the way, you can replace the 250 pF treble cap with a 470 pF, but that's not something I wanted from this particular amp.
Photo 2
Now, at this point I'm sure some of you are saying, "Yeah, cool, but there's no reverb on the first channel." Well my friends, I have a bonus for you. Look at Photo 2 and notice the blue wire. That's the audio signal wire from channel 1, which was originally connected to the circled eyelet on the right. Simply remove the wire from this connection at the input of the phase inverter and connect it to the input of the reverb drive circuit, as illustrated on the left of the photo. This routes the channel 1 signal to the reverb and tremolo circuits.
Photo 3
Cool—one more bonus! Finally, for just a little extra push, I like to move the unused 220k resistor and place it in parallel with the other 220k resistor at the input to the phase inverter (see photo).
After making these mods, I installed a new pair of 10" speakers (Photo 3), and the amp was ready for the road.
[Updated 9/1/21]
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Robillard has made more than 40 albums fronting his own band and with Roomful of Blues.
One of today’s most notable DeArmond players is the revered blues and jazz guitar virtuoso Duke Robillard, a deep student of vintage tone who has learned how to recreate many historic guitar sounds. We asked Robillard to share his expertise and experience with DeArmond pickups, which goes back to the mid-1950s, when he and his father built his first guitar for a school science fair. They took the neck from an old, acoustic Kay Kraftsman and cut a Tele-shaped body from two pieces of 3/4" plywood, inspired by the guitar James Burton played on TV’s The Adventures of Ozzie and Harriet. Then, they recycled the Kay’s bridge and tailpiece, and ordered a DeArmond. “A week after that, I was in a band,” Robillard says.
DeArmond originally referred to its pickups as “guitar microphones,” as they were designed to amplify acoustic guitars without altering their organic tone. Of course, once plugged into an amp all bets on that were off, given the breakup characteristics of the small combos that were common at the time. The RH pickups, which James and Szabó, for example, used, are held in place by clamps. The FH and Rhythm Chief models are floating pickups, mounted by what’s often called the “monkey-on-a-stick” method. Essentially, the pickups are held in place by a metal bar that’s screwed to a guitar’s body, and the pickups can slide up and down the bar, like a simian might scale a tree, to find the sweet spot.
DeArmond’s Rhythm Chief 1100.
By the time Robillard founded the swing and jump blues band Roomful of Blues in 1967, he was playing a Gretsch Synchromatic archtop fitted with a DeArmond, in quest of the authentic vintage tones he heard on records from the ’30s, ’40s and early ’50s. “Then I went to a Gibson ES-125, where I ended up finding a way to make a Rhythm Chief 1100 work in the neck position,” he recounts. “Then I added a P-90 for the bridge. I didn’t want to use a guitar with a cutaway because I wanted every setback that the guitar players in 1940 had. That stopped me from going high on the neck all the time, which I think was a discipline that made me a better musician.”
“The cheapest model [the 1000] is really the best sounding one.”
Today, he uses a variety of DeArmond pickups on his guitars, but his favorite is the Rhythm Chief 1100, which has screwdriver-adjustable pole pieces. And he applies the tricks he’s learned over the years, like placing stick-on felt pads under DeArmonds positioned near the bridge, to raise the floating pickup to the correct height. He also notes there is an alternative to attaching the monkey stick behind the bridge. “A lot of jazz players would shorten the bar and have it flattened out, so you could screw it to the side of the neck. That became popular with guitarists who played Strombergs, D’Angelicos, and L-5s, for example.
“The cheapest model [the 1000] is really the best-sounding one,” he continues. “And you need to use a wound G string on an archtop, or it’s going to howl like crazy. It isless of a pickup than a microphone. You can actually talk into it, and I’ve done gigs where something went wrong with the PA and I’ve sung through the pickup.”
Robillard’s latest album, Roll With Me, includes “You Got Money,” played on his DeArmond-outfitted J.W. Murphy archtop.
These days his favorite archtop is a J.W. Murphy with an 1100 with a shortened bar attached to the side of the neck. He puts stick-on felt pads under the treble side to keep the pickup height as he likes, and to preserve the natural sound of the guitar. You can hear Robillard play his DeArmond-outfitted Murphy on “You Got Money,” a track from his new album, Roll with Me, on Bandcamp.
One more recommendation: “Use a small amp because that’s what they sound best with,” he says. “Small tube amps are what these pickups were made for, but if you’ve got a closed-back cabinet they tend to feed back on the low end. Keeping the bass side of the pickup lower helps with that. When you’re setting up the pickup, press down on the last fret and get the treble side high and the base side low, and then just balance it out till you get the right sound.”
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