Audio and Video Talk > Valves / Vacuum Tubes

Steinhart Schematic

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Due to an apparent upsurge in popularity of theSteinhart amplifiers, I am attaching the schematic as a "Sticky".

I have a hand-drawn the Steinhart diagram that I scanned some six years ago, from an original sketch done by Gunther. I was after the one with the KT88 valves, the sketch he gave me was for PL519 outputs. He crossed out the PL519 and wrote KT88 in his own handwriting and said "It's the same thing". Filament voltages differ as do the valve base pinouts. He uses a -50V Bias supply here. My amplifier does not have any semiconductors bar the BU208A in the 450V supply. The cathode voltages should be set at 2v for the KT88 valves, this may differ when using PL519 valves.

A word of warning: Gunther did not fit bleeder resistors to discharge the smoothing caps, I fitted some myself. If the caps are not discharged, they store energy, which you will soon discover when the AC power is off and the caps discharge through your fingers.

Pictured below is my TVP800 Amplifier.


Here is a schematic of the TVP77

Bolero Schematics

Hi  I have two Bolero Mono Blocks.  Is there any way to introduce a better / easier bias method?  Also the valves were not mounted in a base - but wires soldered to the valve.  Should we not put bases on?  I thought maybe putting a bit of a silcon sheet between the valve and the PC board as an option?  What could I sell these for?

I do not know the Bolero, but I do frown upon wires soldered directly to the valve base. Cost-cutting! - But to my mind a cheapskate way of doing things. You definitely want to keep the output valves away from the PCB to avoid heat-transfer and subsequent damage to the PCB. Perhaps Mars or Ampdog might be more familiar with this model.

Petty complaints aside, Steinhart amps in general sound very good!



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