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Ok, the Headphone “Baby Melquiades” protect is over. Well, kind of over as there are some issues still are hanging in there.

A brief summary. The initial idea was to use the Melquiades’ input stage to drive headphones.  Unfortunately it did not sound as I intended, primary in bass region. The decision to use a tube with lower plate impedance was and I went for 6C19P. After the further experiments the more or less reasonable sounding configuration was found. What I end up is the 6C19P with 125V on plate and minus 33V in grid. The bias is applied in the same way as it is done in Melquiades. I do not think that in the case the 6C19P the “Melquiades-type bias” as effective as it was in case of 6E5P but I desisted to reuse it without experiments with alternative biasing schemas around the 6C19P.

So, as you can see the new Headphone Amplifier has very littlie to do with Melquiades and the heart of the Melq was the 6E5P stage. Therefore I officially remove from this headphone amp the name “Baby Melquiades” and grant to it a new official name: “The Little Amplifier”

The “Little Amplifier” has two transformers: separate filaments and bias and separate plate transformer. All powers supply is identical to the Melq; with exception of bias supply is CRC filter with following gas regulation. The plate supply is LCRC with the last capacitor 6.000uF. The 30mA 6C19P drive in it’s plate the Lundahl’s amorphous core transformer with 50mA core and 60H primary. A positive feedback (a brilliant Dima’s ideas!!!) is taken from the second section of the secondary applied to the cathode of the 6C19P. This gives the necessary “kink” of space that I was so desperately was looking in the headphones...

The  “Little Amplifier” has no gain. It has very good bass, in fact quite phenomenal. I use it with my beloved Audio-Technica ATH-40fs headphones and quite happy with result so far. I know, I know … many people out there would be laughing that I feel that $80 worth ATH-40fs headphones, very much not the “high-end” headphones, are good enough and might be an objective tool for assessment of a headphone amplifier.  I use 40fs for 15 years or even more (had 4-5 pairs of them and when I break one I get other pair) and I prefer them to all other expensive headphones that I owned or heard. As far as I concern all among those to which I was exposed   were too hi-fi and the only the cheap ATH-40fs “sounds right” for me. I was an idiot ounces and read the Six Moon’s “exposing” the Audio-Technica ATH-W1000

http://www.6moons.com/audioreviews/audiotechnica/winning_2.html

I got them and … this peace of crap is still sitting on my self and I’m looking forward to find a fool who would be able to listen this headphone’s torture.

Anyhow…

The idea was to make the “Little Amplifier” very small and I am very pleased how I packed everything inside.  The only problem that I have is that for whatever reasons the positive feedback screws is the ground in the “Little Amplifier”. The amp is build using the properly implemented star groaning, which was followed anal retentively, but the feedback to the cathode screws everything up. No mater how much I tried to shield the run from cathode to the secondary and no mater how I applied the grounds I always picked the 60Hz LF hum. Interesting that with cathodes siting on ground the “Little Amplifier” is dead-quiet with no signs of any noise. Is anything special about the positive feedback grounds that I do not know?

Thanks,
Romy the Cat

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