[rockadanny]

I used to be askeered of tubes (expense, upkeep, safety) but I loved the sound so I took a minimalist approach - purposely selected gear which had the fewest number of tubes I could get (sound preference, budget) totaling ONLY 12 for my entire system:
CD player: 1
Preamp: 3 (two lines, one rectifier)
Power amps (mono-blocks): 8 (two power, one input, one driver per block)

[mreeter]

Too amany Tubes? Never

20 total in my set-up.

[who?me?]

And really,
we all know that tubes are the best way to heat your home!

[Orientexpedite]

Never too many tubes: 17 tubes to drive a pair of Stax headphones, including 3 rectifiers, 2 regulators, 3 gain stages, 12AU7, 12AX7 (using 5751's), EL34.

The sound of this amp is 90% in the tubes, 5% in Japanese paper-in-oil coupling caps and some custom transformers, 5% in some other bits:)

It's amazing how tubes can transform recordings into a unforgettable performance, even in relatively simple amplification designs!

[FullRangeMan]

Very nice round chassis, congratulations

[sebrof]

Never too many tubes: 17 tubes to drive a pair of Stax headphones, including 3 rectifiers, 2 regulators, 3 gain stages, 12AU7, 12AX7 (using 5751's), EL34.

... even in relatively simple amplification designs!

Beautiful amp. What's the brand?

I'm not sure exactly what you mean by "relatively simple" but I'm pretty sure you don't mean that amp

[FullRangeMan]

It is the Stax Megatron headphone amplifier. I had never see so far a three gain stages tube amp, its not funny repair this amp.
I would like to see a underside photo.

[Orientexpedite]

The coupling caps are accessible for rolling.  This version runs at 500V.  Two pairs of EL34 for OTL output.  Two pairs of EL34 as CCS. One transformer for filaments, one transformer for voltage rails, two transformers as power supply chokes.

No transistors in the signal path.  One transistor step downs the voltage from 500V to 300V for the first two gain stages.  The other transistor helps set operating voltage for the EL34's.

[Orientexpedite]

Thank you for your kind comments.

The amp is actually a very good design for a learner.  The operating voltages are very high, however, so it's best to work with a partner or keep one hand in the pocket:)

[Dieterle Tool]

You guys are just listing the tubes "in" your units... how many sets, pairs sitting on the shelf for rolling. This is where it gets confusing without good records. Dates when used, hours, what unit they were in. Even exact model numbers when they're stored in the white boxes. 

[FullRangeMan]

The coupling caps are accessible for rolling.  This version runs at 500V.  Two pairs of EL34 for OTL output.  Two pairs of EL34 as CCS. One transformer for filaments, one transformer for voltage rails, two transformers as power supply chokes.

No transistors in the signal path.  One transistor step downs the voltage from 500V to 300V for the first two gain stages.  The other transistor helps set operating voltage for the EL34's.

Gracias

[Unison845]

Stax Headphones Amp with different approach: Tube rectifier, 2 triode Stages, 845 DHT transformer coupled, No Signal
Capacitor.



Tested with a battery of Stax Vintage to Recent Headphones