In this stage photo of Jimi Hendrix during his days as a sideman you can clearly see a non-descript 1x15 cabinet with no logo or visible controls to his left, partially off camera. It is certainly the Supro Thunderbolt bass amplifier he reputedly used during his time with Little Richard and the Isely Brothers. The thunderbolt has a very distinct look from the front, like a speaker cabinet without a head on top (the amp is loaded on the bottom of the cab with all 2 controls accessible from the rear, not a great design, but since it only sounds really good for guitar with volume and tone at 10 it probably didn't matter to JH). In the January 2003 issue of Vintage Guitar, Christopher Tackett closed his article on the vintage Thunderbolt with the following statement, "Jimi Hendrix owned a S6420 Thunderbolt, and Jimmy Page used Supro amps for recording much of the early Led Zeppelin material. Whether or not he used a Thunderbolt is unclear, but his playing on “Heartbreaker” sure sounds like one."

In the book Secrets from the Masters, Jimmy Page discusses his use of the Supro Thunderbolt. On page 176 he states, "I was using the Supro amp for the first album and still do. The “Stairway To Heaven” solo was done when I pulled out the Telecaster, which I hadn’t used for a long time, plugged it into the Supro, and away it went again."

The mentioned model was Supro 1690T modified with a small 12 inch speaker.

In this video Jessica is talking about her Benson amps and her relationship with them. One of the amps she's used on tour is a 60's Supro Thunderbolt. There is a picture of the amp in the video and in the accompanying article on Premiere Guitar: https://www.premierguitar.com/articles/30945-rig-rundown-deep-sea-divers-jessica-dobson

In this photo of Lloyd's rig from a solo tour you can't miss the Supro 1x15" combo amplifier next to one of his distinctively painted 62RI Stratocasters. Additionally, a Guitar Player Magazine interview in 1993 stated "Lloyd tends a stable of vintage Fender amps, including a '50 Deluxe, a '52 Pro, a '55 Tremolux, and a '56 Princeton. He also uses a '59 Ampeg Jet, a Vibraverb reissue, and a '65 Supro." That would be the 1x15" pictured here which, if it is genuinely a 65, can only be the notorious Thunderbolt Bass Amplifier. The amplifier is explicitly confirmed, however, by the following sources:

Guitar Player, December 2009, "'Scuse me while I hit this guy: Why Jimi Hendrix punched Television's Richard Lloyd – and why he didn’t mind" by Charles M. Young (published online on May 13, 2024)

The four of us—me, Richard, drummer Billy Ficca and bassist Keith Hartel—were riding in a Honda compact SUV. Even with the clubs furnishing the “backline” (bass amp and most of the drum kit), the car was dangerously overloaded, with two Stratocasters, two Precision basses, an ancient Supro Thunderbolt amplifier, Billy’s snare and cymbals and kick-drum pedal, all our bags, souvenirs that Richard bought in every truck stop, half-consumed bottles of prescription and nonprescription medicine that Richard bought in every drug store, half-consumed bottles of herbal elixirs that Richard bought in every New Age emporium, and a boggling array of books on occult weirdness, brain science and the sexual habits of tribal peoples around the world.

[...]

The Jamie Neverts Story is a great album. All the guitars were recorded through Richard’s Supro Thunderbolt, which is turned up to 10 for a taste of distortion, though most of the tones are pretty clean. You can hear the lyricism that sometimes gets buried in the guitar wash on Jimi’s own albums. There are minimal overdubs, just Jimi’s slashing style married with Richard’s slashing style.

Facebook, Supro, September 21, 2017

Richard Lloyd from legendary NYC band Television (band), with his trusty Supro Thunderbolt!

Premier Guitar, "Richard Lloyd: The Alchemist" by Tzvi Gluckin (December 25, 2018)

**Do you get your gain from letting the amp break up naturally?

Yeah. I mean, I am using some pedals live and I have been for a number of years. Lately, I’ve been using a Supro reissue. For a while I was using a Thunderbolt, and now I’m using a Black Magick. They break up pretty good, pretty early. You can pretty much get your tone out of the amp. I had about eight of them at one time. I sold a bunch off in the ’90s, but I kept my ’65 Thunderbolt. I’ve kept a number of others. They’re numbered; I don’t know the names of them. I am a big fan of Supro.

That’s what you’re using on those first two Television records?

On the third one [1992’s Television]. For instance, the solo on “Call Mr. Lee”—that’s through my Supro ’65 Thunderbolt, straight in, turned all the way up.

In this 2016 Guitar World article James is quoted saying: "I like to use a lot of low-wattage, old tube amps when I record. My obsession with that actually started with the Silvertones from the mid-late Sixites. On stage, I’ve been using a [Fender] Princeton and Custom Supro Thunderbolt. Guitar wise, I have a Gibson 330 I record a lot with, and my stage guitar is a 135. I also have a Nineties SG I use as a second guitar. I also use a lot of different things for pedals. Lately, I’ve been using the JHS Colour box and Xotic EP Booster to get the amps where I need them to be."

In a performance featured in a video by SuproUSA, Chris McQueen uses a Supro Thunderbolt amplifier alongside a Heritage 335 guitar.

No. We recorded the record ourselves, so it left us a lot of time to experiment with tones. Once we recorded the bed track, when I was doing the guitars, I set up a whole lot of amps in a room. I had my ’73 Marshall Super Bass, a HiWatt Half Stack DR104 and a Fender Super Reverb from the early 70s. I also had a Supro Thunderbolt from, I think, 1966 and a bunch of other little amps: Silvertones, Fender Champs and stuff.

Doug Fieger mentioned in an interview with Vintage Guitar® magazine that he was inspired by Hendrix and Page to acquire a Supro Thunderbolt amplifier. He noted that Page also used a Rickenbacker Transonic during his time with the Yardbirds, which led Fieger to add one to his collection as well.

On this video from the single Dull Days you can see lots of his gear including the Supro on many takes