Supro S6420+ Thunderbolt Plus 60/45/35-watt 1x15" Tube Combo

60/45/35-watt 1-channel All-tube 1x15" Guitar Combo Amplifier with Rectifier Switch Option - Blue Rhino Hide Tolex
5/5 2 Write review Item ID: ThunderboltPls
Supro S6420+ Thunderbolt Plus 60/45/35-watt 1x15
Supro S6420+ Thunderbolt Plus 60/45/35-watt 1x15
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Supro S6420+ Thunderbolt Plus 60/45/35-watt 1x15" Tube Combo
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A Modern Take On a Holy Grail Tone

A hot-rodded version of the reissued Thunderbolt, the Supro S6420+ Thunderbolt Plus tube guitar amplifier features a 3-way rectifier switch option for more headroom and versatility. Like the Fender Bassman, the Thunderbolt was originally intended to be a bass amplifier. While far from a stellar bass amp, the Thunderbolt quickly became a holy grail tone device for electric guitar players. Indeed, the first time you crank up the Thunderbolt Plus, you'll be treated to a huge, raw, overdriven, rock 'n' roll tone cascading from a custom designed 15" Supro TB15 speaker. Make no mistake - the Supro S6420+ Thunderbolt Plus tube guitar amplifier produces pure rock 'n' roll power. Call your Sweetwater Sales Engineer to learn more!

The Supro S6420+ Thunderbolt Plus Combo Guitar Amplifier at a Glance:
  • Supro - a brief history
  • The Supro Thunderbolt - a historic mistake, a modern miracle
  • 3-way rectifier switch option adds modern headroom and versatility
Supro - a brief history

Supro's roots can be traced back to the 1930s, when the National Resophonic and Dobro guitar companies merged to form a manufacturing entity called Valco. Valco manufactured Spanish acoustic guitars, metal-faced resonator guitars, and electric lap steel guitars under a variety of brand names including Airline, Oahu, and National. They also designed amplifiers for several other companies such as Gretsch, Harmony, and Kay. It was during this time that Valco also began producing guitars and amplifiers under the Supro name. Extremely popular amongst Southside Chicago blues musicians in the 1960s, Supro amplifiers proved equally popular with the British musicians who were influenced by them. By the late 1960s, notable guitarists ranging from Jimi Hendrix to Albert Lee to Jimmy Page were seen playing Supro amplifiers. Original Supro amps often sell for premium prices on the used market because of their legendary unique tone.

The Supro Thunderbolt - a historic mistake, a modern miracle

Once upon a time, a certain manufacturer created one of the worst-sounding bass amps ever produced. It was underpowered, distorted like crazy, and the speaker's baffle board couldn't handle low frequencies, so it fluttered around in a disruptive fashion. The manufacturer continuously tried to market the amp to bass players, but they all turned up their noses. All seemed lost. Then, one day, an adventurous lad plugged an electric guitar into the amp, turned it all the way up, and experienced the most amazing, raw tube distortion they had ever heard. It sounded positively huge! Before you knew it, guitarists from all over the land wanted to experience this epic, raw, overdriven, tooth-rattling sound for themselves. A promising young guitarist named Jimi was even spotted playing through one while he was on tour with Little Richard and the Isley Brothers. The rest, as they say, is history!

3-way rectifier switch option adds modern headroom and versatility

Although the Supro Thunderbolt's tone is clearly awe-inspiring, its simplistic design does give rise to limitations that could hinder its usefulness as a gigging amp. A jack-of-all-trades it is not, which is why Supro designed the S6420+. The S6420+ includes a 3-way rectifier switch that adds modern headroom and gigging versatility to the Thunderbolt. With the S6420+, you're given the choice of a 35-watt (cathode-biased) or 45-watt (grid-biased) 5U4 tube rectifier mode, as well as a high power 60-watt (grid-biased) solid state rectifier setting. Because of the S6420+, your Thunderbolt doesn't have to be a one trick pony.

The Supro S6420+ Thunderbolt Plus Combo Guitar Amplifier Features:
  • 35-watt cathode-biased 6L6 output section delivers plenty of tone and volume
  • 1 x 15" custom designed Supro TB15 speaker delivers classic vintage sound
  • Tone and volume knobs makes dialing in your tone simple
  • 3-way rectifier switch option adds headroom and tonal versatility
The Supro S6420+ Thunderbolt Plus tube guitar amplifier could easily become your favorite amp!

Additional Media

Guitar Amp Buying Guide

Tech Specs

Type Tube
Number of Channels 1
Total Power 35W/45W/60W
Speaker Size 1 x 15"
EQ 1-band
Preamp Tubes 2 x 12AX7EH
Power Tubes 2 x 5881/6L6WGC, 1 x 5U4GB (Rectifier)
Inputs 2 x TS
Height 19"
Width 23.625"
Depth 10.5"
Weight 45 lbs.
Manufacturer Part Number S6420+

Customer Reviews

Based on 2 reviews
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Supro thunderbolt

This supro amp rocks! It is simple yet very responsive. The tone and volume controls have a huge effect on the overal sound, no need for trebile, mid and bass, you have tone controls on your guitar; use them! The rectifier switch for me is the sweetest feature! You can change the amp color like no other. Want Texas blues, got it. Want clean fender tone, got it. Want some warm crunch, got it. The 35W class A setting is just awsome period! This is full old school, and I love it. A spring reverb would be nice but pedals work real nice with this amp. Bass response with the 15 inch speaker is very nice. Can be very loud too.
Music background: Old school

Simple Perfection!

So, I got my 2015 LP Deluxe (from Sweetwater, 'natch!) and put it through my blond Fender Super Sonic Twin (that was originally bought by Steven Segall!) and it sounded great, but... I don't know about you, but too many knobs don't mean better tone. The Fender has again knob on the CLEAN channel! Dumb. I stumbled across some demos reviews on the Thunderbolt, liked what I saw and heard and bought one from my Sweetwater Sales Dude, Dan VanAmoroengen. There are just 2 knobs: Volume and tone and that's all you need. Well, it also has the 35/45/60 watt rectifier switch, but that doesn't count-It also doesn't seem to do much either... When I got the amp the recto knob was off and lying in the bottom. I'm going to contact Supro and ask if mine is defective or what.) Set the tone knob where you like it, volume, ditto and you're good to go.I played a party at a Knights of Columbus hall last night. Nothing was mic'd except the bass drum and the Supro had plenty of balls to fill the place and then some.If you're looking for channel switching and all that crap, look elsewhere. Everybody seems to want a channel switcher, but I've seen that most players use distortion pedals anyway, so why bother with extra channels? i want an amp that sound really good clean and also sounds great with pedals. I use a "Greenie" distortion from which is perfect for this amp. Wasn't so good with the Fender...One thing to consider is that Supro somehow got away without putting the power tube or rectifier tube in protective cages and the 3 of them hang down below the top back pane so DO NOT stash anything in the bottom of the amp. (I thought that the "CE" rules made amp makers put the bottles in cages, not to protect the tubes, but so Joe Dipshit guitar player wouldn't get burned???)If this was stolen, would I buy another? You betcha!!!!Anybody in the Boston Area want to buy a nice Fender Super Sonic 100W Twin???!!! ;-)
Music background: Pro in the 60's-70's. Now just an old fart who still rawks! (Or at least thinks he does!)
See also: Combo Amps, Supro, Supro Guitar Combo Amps