Sunday, October 17, 2010

The Supro Thunderbolt

Imagine a Fender Pro Jr. with a 15" Jensen speaker.  But for the power tubes, that would describe the Supro Thunderbolt.

The Valco Cmpany in Chicago made Supro amplifiers. The Supro Thunderbolt model was introduced in late 1964 as a bass guitar amp. This amplifier was a very simple design having only a volume and tone control and a single 15-inch Jensen speaker.

The tube compliment included 2 RCA 6L6CG power tubes, 2 - 12AX7 preamp tubes with one possibly being used as a phase inverter and 1 5U4 rectifier tube.

The amplifier chasis was housed in the bottom of an open backed cabinet with the two control knobs mounted on the amplifiers faceplate.

For those not familiar with the Valco Company, a merger of the National Guitar Company and the Dobro Guitar Company formed it in 1942 by three company principals, Victor Smith, Al Frost and Louis Dopyera.

The company started manufacturing Hawaiian guitars and amplifiers under its own name and as a subcontractor for Oahu, Harmony, Airline, Kay, National, and Gretsch. Supro was their house brand name.

By the late 1960’s The Valco Company had become roughly the third-largest amplifier manufacturer in the United States. In 1964 Valco introduced the Thunderbolt Bass Amplifier (model S6420.

The Thunderbolt came covered in Supros traditional blue ‘rhino hide’ tolex with horizontally striped grey grill cloth. In 1967, black tolex replaced the blue rhino hide to keep more in line with Fender.

The amp was marketed as a bass amplifier, but guitarists noticed its great sound. My good friend Doug Abbott played his bass through a borrowed Thunderbolt one at a gig we did around 1967. As a bass amp, the Thunderbolt was not at all impressive. It distorted like crazy when turned up.

The amp just did not have enough power for those low frequency bass notes. Bass players of the day complained.

Not only did the speaker and tubes distort, the baffle board that held the massive speaker fluttered.

Valco/Supro attempted a quick fix by adding a wooden brace across the speaker hole and another brace on the baffle board’s backside. Next Valco also eliminated the rectifier tube in favor of a solid-state rectifier. These improved the amp’s performance as a bass amplifier somewhat.

But bass players were not at all satisfied with this Supro amp.

However, as a guitar amp, the Thunderbolt was a something else. That raw tube distortion combined with the heavy bottom of the Jensen 15 sounded huge.

Guitarists had earlier noticed the Thunderbolt. Jimi Hendrix used one early on with the Isley Brothers and Jimmy Page used one on early Led Zeppelin recordings.

Airline was Montgomery Wards brand name for musical instruments. Valco created a similar amplifier for them known as model 62-9020A, which is the same circuit as the famed Supro Thunderbolt.

Outside the amplifier was different in appearance, sporting dark brown grill cloth with a fancy logo. On the inside was the same Thunderbolt amplifier.

By 1967, Valco merged with Kay. However, this was end of the line for Valco. The merged company went out of business in 1968.

This is an older Zinky amp
But now the Supro brand name has been revived.

In the mid 2000’s former Fender amp designer, Bruce Zinky left that organization and started his own company.

His first hit was a small practice amp called The Smokey, which still is available with a plastic housing or housed in and empty cardboard cigarette pack with a tiny speaker poking out of the center.

Zinky went on to produce high quality boutique amplifiers under his name. Recently Zinky acquired the rights to the Supro name and is now producing high quality updated replicas of former Supro amplifiers

All of the new amps are made in the USA by Absara Audio. The project designer is David Koltai, with circuits curated by Bruce Zinky. 

The new amps were just exhibited at the Summer NAMM and feature not just an updated version of the original S6420 Thunderbolt, but a hotrod version that is designated the S6420+ Thunderbolt(+).

The other new Supro amp include the 1624T Dual­Tone with twin 12” Supro speakers rated at 24 watts, the 1690T Coronado with twin 10” Supro speakers and a pair of 6L6 power tubes pumpling out 35 watts and the S6450R Thunderstorm, which comes with twin parallel channels, a 3 way tone stack, twin 6L6 power tubes and 3 way rectifier switching options; 35 watt, 45 watts and 60 watts.



Robert said...

Hi, just found your blog today and I'm enjoying it. Last week I came into an absolutely perfect Supro Thunderbolt. It looks as though it's been in storage for a long time. I hate to do this but I'm not sure how to proceed. I'd like to sell this item to someone who will appreciate it. That's all I'll say for now in case this sort of comment is not allowed. I'll monitor the blog for info requests.

Anonymous said...

Shoot me an email I would love to hear more about the supro that you found.


Anonymous said...

Hi - I've got a sweet small supro - it has like maybe 1 10-inch speaker in it and i love it. I'd love to get my hands on a bigger version. !!! They grind so great.

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