Why Is The Supro Thunderbolt Considered A Great Amp?

[rp]

If ya build it yourself, its not a relic (unless you 'relic' it these days)

But I'm pretty sure I'm not using any RoHS parts

[Andy Le Blanc]

Its the color that that phase inverter gets you. It can be a real pretty tone.

[LeftyStrat]

I always thought the Supro 1624T sounded closer to the early Zep sound:

https://www.youtube.com/watch?v=wjvKWgRcrhg

[themechanic]

I always thought the Supro 1624T sounded closer to the early Zep sound:

https://www.youtube.com/watch?v=wjvKWgRcrhg

yes, im currently building one mostly like that circuit. honestly, its really hard to explain what these amps have. you just have to play them, and like everything else, its just not for every one. im not really looking to copy anyones sound, these old low power amps just have something special in my heart. i have been lucky enough to play a few vintage supros and a bunch of others, and there is just something special still to be had in a lot of them. some of them are kinda a one trick pony, but they play that trick so well.

[Tobyk]

In the Thunderbolt, the power tubes have different grid leak resistors – 270K and 470K! So the 12K that tries to equalize the signals will never succeed in that. That must be a schematic error, no? But surely adds to the sound of this amp.

[mhuss]

That's my schematic, and that's way the amp was that I had on the bench. I though it weird too, but I just captured what was there.

[statorvane]

That must be a schematic error, no?

The grid leaks in the Thunderbolt power amp schematic appear repeatedly in a lot of other Valco amplifier schematics.

[Tobyk]

I think this imbalansed output stage would make for a lot of harmonic distortion. Yes, it’s seen repeatedly in Supro/Valco schematics. And this in the early 60’s, when distortion was to be avoided..