Supro S6420 Thunderbolt Amplifier 1965

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This Supro S6420 Thunderbolt came to us with a changed speaker, so we dropped in a Jensen C15N from 1966 to round out what was otherwise one of the nicest Thunderbolts I've found.  For some reason, every one we've had prior has been beat up, changed, and somewhat mistreated.

The amp has been responsibly serviced, with some internal caps updated and a grounded power cable added.  

It sounds tremendous and it breaks up as expected with full range response from the 15" speaker.  Higher volume bursts with an open low E vibrate the grill against the internal cross supports in the baffle.  I experimented with a shim (a small piece of cardboard) between the grille and the baffle, which mitigated the noise.  I removed it after testing.  I suppose all Thunderbolts do this as the baffles are all the same.  I had never noticed it and I've never seen it advertised.  

Legendary tone in a portable package with classic looks - such a great amp!

  • Case/Cover?: No
  • Dimensions: W24" x H19.5" x D11"
  • Weight: 40 lbs
  • Watts: 35 Watts
  • Date: 1965
  • Where date is noted: Pots, Transformers
  • Speaker 1 Brand/Model: Jensen C15N
  • Speaker 1 Size: 15"
  • Speaker 1 Cone: Original
  • Power Transformer brand and/or codes: E3738A / 5246517
  • Output Transformer brand and/or codes: T3778 / 5246544
  • Extension Speaker Out? NO
  • FX Loop?: No
  • Reverb or other effects?: No
  • Rectifier Tubes: GT5U4
  • Rectifier Tube Brand: GT
  • Power Tubes: 2 x 6L6
  • Power Tube Brand: Svetlana
  • Preamp Tubes: 2 x 12AX7
  • Preamp Tube Brand: ?
  • Filter Caps: Original
  • Pedal: No
  • Pots, Codes: 137 6541
  • Tolex: Original
  • Grille: Original
  • Knobs: Original
  • Handle: Original
  • Power Cord: Updated 3 prong
  • Notes:

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