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Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo , this item is no longer available, below are some similar products you may be interested in.

Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo

35-watt 1-channel All Tube 1x15" Guitar Combo Amplifier - Blue Rhino Hide Tolex
Item ID: Thunderbolt
Sorry, the Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo is no longer available. We've left this page up for reference only.
Check out the great alternatives on this page or call toll-free (800) 222-4700 to speak with a Sweetwater Sales Engineer about similar products.
Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo
Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo
Supro S6420 Thunderbolt 35-watt 1x15" Tube Combo

Plug in, Crank it Up, and Rock!

This article was Written By

Our Product Research Team

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Just in time for its 50th anniversary, Supro has reissued the S6420 Thunderbolt tube guitar amplifier. 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 this Thunderbolt reissue, you'll be treated to a huge, raw, overdriven, rock 'n' roll tone cascading from a custom designed 15" Supro TB15 speaker. Simplistic, sporting only a tone and volume control, the Supro S6420 Thunderbolt tube guitar amplifier's cathode-biased 6L6 output section produces 35 watts of pure rock 'n' roll power. Call your Sweetwater Sales Engineer and get plugged in!

The Supro S6420 Thunderbolt Combo Guitar Amplifier at a Glance:
  • Supro - a brief history
  • The Supro Thunderbolt - a historic mistake, a modern miracle
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 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 they 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!

The Supro S6420 Thunderbolt 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
Deliver some pure rock 'n' roll tone with the Supro S6420 Thunderbolt tube guitar amplifier!

Warranty Info

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Offer applies only to single-receipt qualifying purchases. Select manufacturers may require that only the manufacturer’s products qualify towards the minimum purchase amount needed to be eligible for promotional financing. Otherwise, an invoice that meets the minimum purchase amount and contains at least one qualifying manufacturer product is eligible for promotional financing. No interest will be charged on promo purchase balance, and equal monthly payments are required on promo purchase until it is paid in full. The payments equal the amount financed divided by the number of months in the promo period, rounded up to the next whole dollar. These payments may be higher than the payments that would be required if this purchase was a non-promo purchase. During the last month(s) of the promo period the required monthly payment may be reduced due to the prior months’ rounding. Regular account terms apply to non-promo purchases. New Accounts as of 07/31/2025: Purchase APR is 34.99%. Penalty APR is 39.99%. Min Interest Charge is $2. Existing cardholders: See your credit card agreement terms. Subject to credit approval.

Offer applies only to single-receipt qualifying purchases. No interest will be charged on the promo balance if you pay it off, in full, within the promo period. If you do not, interest will be charged on the promo balance from the purchase date. The required minimum monthly payments may or may not pay off the promo balance before the end of the promo period, depending on purchase amount, promo length and payment allocation. Regular account terms apply to non-promo purchases and, after promo period ends, to the promo balance. New Accounts as of 07/31/2025: Purchase APR is 34.99%. Penalty APR is 39.99%. Min Interest Charge is $2. Existing cardholders: See your credit card agreement terms. Subject to credit approval.

The estimated required monthly payment shown which excludes taxes and delivery equals the amount financed divided by the number of months in the promo period, rounded up to the next cent. During the last month(s) of the promo period the required monthly payment may be reduced due to this rounding. These payments apply only with the financing offer shown. If you make these payments by the due date each month, you should pay off this amount financed within the promo period, if it is the only balance you are paying off. If you have other balances on your account, this payment will be added to any other minimum monthly payments.

Applies only to select items from this manufacturer. Ask your Sweetwater Sales Engineer for more details.