Dear Amp Man,
I am unable to find anything on cascading the half-unused tube in an AA371 Bassman. I have converted the amp to a Marshall tone stack and other suggestions you've made very successfully, but found nothing on tapping into the unused gain stage for the bass side. I've left the normal channel mostly stock and really want more gain on the modded side. The article you wrote on the Supro (“Modding a Supro 6420 Thunderbolt") got me inspired to try this. I've been looking for a layout over a schematic; I'd feel much safer with a layout so I don't damage anything. I'd love a little more gain and to make full use of that tube. Help or a link would be greatly appreciated.
Thanks,
Kevin
Hi Kevin,
It's nice to hear you've successfully incorporated some of my suggestions. Bassman amps have always been a great platform for mods—they're easy to work on and there are quite a few fun things you can do. Because I currently don't have a Bassman to mod and then photograph, I've tried to do the next best thing and draw the modification layout and connections directly on the Fender factory drawing of the physical layout. I'll also give you a list of necessary parts and a step-by-step procedure. Let's go!
This illustration shows the gain stage mod, breaking out the area around tube positions V1 and V2 from a schematic drawing of an AA371 Bassman amp.
This mod is not very extensive, and you'll only need a few parts and a couple of pieces of wire:
- one 3-lug terminal strip (the kind typically manufactured by Keystone)
- two 470k resistors (1/2 watt is sufficient, but I typically use 1 watt for almost everything)
- one 100k resistor
- one 2.7k resistor
- one 0.022 µF 600V capacitor (poly or foil)
- one 0.68 µF 25V or greater capacitor
- two small pieces of shrink tubing or electrical tape
- one ¼" 4-40 screw and nut
- less than a foot of 20- or 22-gauge wire
Before beginning, be sure the filter caps are discharged. If you don't know how to do this, find someone who does. Then:
1. Install the terminal strip in a comfortable location between tube positions V1 and V2. You'll need to drill a small hole in the chassis and mount it using the 4-40 screw and nut. Be sure the screw and nut are very tight. This point will act as a ground connection.
2. Unsolder the wire coming from the bass channel input jacks (red, according to the schematic) that is connected to pin 2 of V1. Connect an additional piece of wire to this and insulate the connection with a piece of shrink tubing or tape. Cut to length and connect the other end to pin 2 of V2 (the input to the unused half of V2).
3. Connect one end of the 100k resistor to pin 1 of V2, but do not solder yet. Connect the other end to the eyelet where the two 100k V1 plate resistors are connected. You may need an additional piece of wire to connect to the resistor, so solder and insulate as necessary.
Warning:
All tube amplifiers contain lethal voltages. The most dangerous voltages are stored in electrolytic capacitors, even after the amp has been unplugged from the wall. Before you touch anything inside the amp chassis, it's imperative that these capacitors are discharged. If you are unsure of this procedure, consult your local amp tech.
4. Connect the 0.022 µF capacitor to pin 1 of V2. You may now solder the connection. Connect the other end of the capacitor to the top terminal strip in the drawing. Do not solder this end yet.
5. Connect one end of the 2.7k resistor and the 0.68 µF capacitor to terminal 3 of V2. Connect the other end of the resistor and capacitor to the center terminal of the terminal strip. You can now solder pin 3 of V2.
6. Connect one end of a 470k resistor to the bottom terminal and the other end to the center terminal of the terminal strip. You may now solder the center terminal.
7. Connect one end of the other 470k resistor to the bottom terminal and the other end to the top terminal. You may now solder the top terminal.
8. Connect another short wire to the bottom terminal of the terminal strip. Cut to length and connect the other end to pin 2 of V1. You may now solder both connections.
And that's it. This modification is based on the typical front end of a Marshall 2204-style head and approximates its gain control set to about 60 percent. The gain can be increased or decreased depending on the relative values of the 470k resistors. If you'd like to make the gain easily variable, you can replace the two 470k resistors with a 1 mA pot. Simply remove the 470k resistors, connect the CW terminal of the pot to the top terminal on the strip, the CCW terminal to the center ground terminal, and the wiper to the bottom terminal. This is now your front-end gain control. If you need more top end, simply connect a small value cap (start with a 100 pF ceramic cap) between the CW and wiper terminal. As with most tube amp modifications like this, feel free to experiment with slightly larger or smaller resistor or capacitor values for your own custom version.
Now break out some humbuckers and a 4x12, and rock on!
[Updated 8/17/21]
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Chase Bliss Clean
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On That’s the Price of Loving Me, “We’re Not Finished Yet” is a love letter to Wareham’s 1968 Gibson ES-335.
The singer-songwriter, 61, has crafted many such moments—most famously during the late ’80s and early ’90s, helping cement the dream-pop genre with cult-favorites Galaxie 500. Take the tenor saxophone, by Ralph Carney, that elevates the back half of “Decomposing Trees” from 1989’s On Fire, or the Mellotron-like atmosphere that bubbles up during “Spook” on This Is Our Music from 1990—both of which, notably, were recorded with journeyman producer Kramer, who’s part of Wareham’s rich sonic universe once again with the songwriter’s new solo album, That’s the Price of Loving Me.
Following This Is Our Music, the final Galaxie 500 album, Wareham and Kramer went their separate ways. The former founded the long-running indie-rock band Luna, formed the duo Dean & Britta with now-wife Britta Phillips, worked on film scores, and released a handful of solo projects. Kramer, meanwhile, grew into a hero of experimental music, playing with and producing everyone from John Zorn to Daniel Johnston. They stayed in touch, even as they drifted apart geographically, and always talked about working together again—but it took the weight of mortality to make it happen.
“[Kramer has] been saying for years, ‘It’s crazy we haven’t made a record together,’” says Wareham over Zoom, his shimmering silver hair flanked in the frame by a wall-hung cherry red Gibson SG and a poster of Rainer Werner Fassbinder’s 1975 drama Faustrecht der Freiheit. “He was living in Florida, and I was living elsewhere and doing other things. But I did lose a couple of friends over the pandemic, and it did occur to me, you can’t just say, ‘I’ll get to it’ forever. Not to be morbid, but we’re not gonna be here forever. We’re not getting any younger, are we?”
Dean Wareham's Gear
Wareham was a member of the early indie dream-pop trio Galaxie 500. After their split, he formed indie rock stalwarts Luna as well as Dean & Britta, with wife and Luna bandmate Britta Phillips.
Photo by Laura Moreau
Guitars
Amps
- Lazy J 20
- Mesa/Boogie California Tweed
Effects
- EAE Hypersleep reverb
- EAE Sending analog delay
- Dr Scientist Frazz Dazzler fuzz
- Danelectro Back Talk
- Joe Parker Raydeen overdrive
Strings, Picks, and Accessories
- Curtis Mangan nickel wounds (.010–.046)
- Dunlop Nylon .88 mm picks
- Truetone 1 Spot Pro CS12
In 2020, Dean & Britta recorded a covers album, Quarantine Tapes—the perfect opportunity, amid the agony of lockdown, to finally get Kramer involved. The producer mixed their hazy version of the Seekers’ “The Carnival Is Over,” which planted the seeds for a bigger collaboration on That’s the Price of Loving Me. At first, though, Wareham didn’t have any songs, so he gave himself a hard deadline by booking some time at L.A. studio Lucy’s Meat Market.
“What is it in a song that makes people cry? What is it that moves you? It’s something unexpected.”
“I don’t write songs every day—sometimes I don’t write songs for a whole year or something,” he says with a laugh. “The only thing that gets me to do it is booking studio time. Then I have to write some songs because it’ll be embarrassing if I show up with nothing.”
The space itself—decked out with a jaw-dropping amount of vintage guitars and amplifiers and keyboards—helped animate his sleepy-eyed and gently psychedelic songs. “I thought I had a few nice instruments,” Wareham says, “but I showed up, like, ‘Oh, your Les Paul’s from 1955? I think I’ll play this one. Your Martin is from the ’40s?’” Speed and spontaneity were essential: They worked six full days, with Kramer guiding him to capture every performance without overthinking it.
Wareham’s latest was produced by Kramer, a former member of Shockabilly, Bongwater, and the Butthole Surfers who owns the legendary underground label Shimmy-Disc. He produced all three Galaxie 500 LPs.
“[That’s] how I worked with Kramer back in the day too,” he recalls. “Maybe it kinda spoiled me—he was always like, ‘Yep, that’s it. Next!’ I got lazy about going back and redoing things. We’d make the decision and move on: keep that drum track and bass track. Maybe Britta [bass, backing vocals] would change a few things. Sometimes you’re with people who think every single thing should be replaced and made perfect, and you don’t actually have to do that. When it came time for me to overdub a guitar solo or something, Kramer would just allow me two takes generally: ‘Do it again a little differently. That’s it. That’s good.’”
“I thought I had a few nice instruments, but I showed up, like, ‘Oh, your Les Paul’s from 1955? I think I’ll play this one.’”
The material itself allowed for such malleability, with ringing chord progressions and gentle melodies often influenced by the musicians who happened to be gathered around him that day. “You Were the Ones I Had to Betray” has the baroque-pop sweetness of late-’60s Beatles, partly due to the sawing cellos of L.A. session player Gabe Noel, who also added some boomy bass harmonica to the climax. “It’s an instrument you’d mostly associate with the Beach Boys, I guess,” Wareham says. “It kinda sounds like a saxophone or something.”
Wareham, his 335, and Mesa/Boogie California Tweed at a recent Luna show, with bassist Britta Phillips in the background.
Photo by Mario Heller
It’s easy to get wrapped up in the warm hug of these arrangements, but it’s also worth highlighting Wareham’s lyrics—whether it’s the clever but subtle acrostic poetry of “The Mystery Guest” (“I’d never done that before, and it’s not that hard to do actually. Sometimes it’s just to give yourself a strange assignment to get yourself thinking in a different way”) or the hilarity of “We’re Not Finished Yet,” which scans as carnal but is actually a love letter to his semi-recently acquired 1968 Gibson ES-335.
“Sometimes it’s just to give yourself a strange assignment to get yourself thinking in a different way.”
“I read this poem about a guy polishing an antique wooden cabinet or something,” Wareham explains. “I thought, ‘That’s funny—it’s vaguely sexual, how he’s like rubbing this thing.’ I thought it would be funny if I wrote a song not about a piece of furniture but about the guitar—the experience of buying this. The lyrics in there: ‘I waxed you; I rubbed you; I reamed you.’ It all sounds like a dirty song, but it’s like, ‘No, I had to get the peg holes reamed!’ It works kind of as a love song, but that’s what it’s really about.”
Which brings us back to that idea of the unexpected. The most beautiful touches on Loving Me, crafted with his ol’ producer pal, are the ones that appear out of nowhere—like the blossoming guitar overdubs of “New World Julie” and “Dear Pretty Baby.” Kramer, he says, liked to “run two or three guitar tracks at once, where it becomes a symphony of guitars.”
These surprises, indeed, are the moments that stick with you.
YouTube It
Luna’s four-song performance on KEXP showcases Dean Wareham’s sparse, low-key indie rock vibe as well as his simple and sweet guitar embellishments.
