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I see on audiogon an Atma-Sphere M-60 with several upgrades. It has ceramic tube sockets. I have M-60's. Has anyone tried tweaking/upgrading the tube sockets? If it is a worthwile improvement, I am interested.Chris
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I dont own Atma-Sphere,s although they are a hell of an amp.I do remember my acoustat servo tube amps and they were transformerless about 100watts each and they used vertical sweep tubes that failed frequently.It was all because of the sockets arcing so i took out the plastic compactron circuit board mounted ones and put in bakelite sockets on the chasis and hardwired them to the board and i got 3 times the life out of my tubes.Any socket upgrade to an OTL amp os worthwhile for these same reasons.
Ceramic sockets are not particularly helpful in an OTL. The reason is because ceramic is helpful to prevent arc-over damage to the socket that occurs due to high voltages. These voltages do not exist in an OTL.Another reason that ceramic sockets can present issues these days is due to the material used in the contacts. If the contacts are silver or gold, they will fail in fairly short order (perhaps in only 1 or 2 years, depending on how many times tubes are moved in and out of the sockets). This is because such materials are fairly soft and do not survive repeated use very well.
This is why Atma-Sphere amps have had the sockets that they have- tin-plating is much more reliable, plus it has the additional benefit of being corrosion resistant, and is the same material as the tubes in use. So there are less diode elements in the connection.
Ralph,Thank you for the longish answer. You've told me all I need to know.
> Has anyone tried tweaking/upgrading the tube sockets? If it is a worthwile improvement, I am interested.There is nothing inherently wrong with a ceramic tube socket; this said, it is nearly impossible to find a ceramic socket worth owning. Most ceramic sockets sold today are Chinese-cheapos, with gold or silver washed pins. Note I said 'washed' and not 'plated'. Overall quality is pretty shoddy, and the precious metal wash does nothing for the sound of the equipment. What it *does* do, is create a dissimilar metal connection in the tube socket between the tin tube pins and the gold/silver sockets.
To further the problems, the gold/silver wash wears through quickly to expose the base metal. Now we have three (or four, if the pins are base metal -> copper wash -> precious metal) dissimilar metals all at work in a hot location. Not desirable.
All this said, the particular set of amps in question is / was owned by Paul Speltz of ZERO Autoformer fame. I know Paul very well, and I would trust implicitly any piece of gear that has passed through his hands. Also, I have no idea what his source was for the sockets, and Paul tends to be a real stickler for quality.
Tube socket concerns aside, I suspect that this would be a really super set of amps to own. My trust in Paul's workmanship and ethics are unfailing. Also of note, his wife is a great cook ;-)
Thank you Bill.
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