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Sunday, April 26, 2015

Mercury Vapour Madness

Hi!

I am getting quite a few requests for amps with power supplies using mercury vapour rectifiers lately. Like the recently shown Octal Preamp and 6CB5A power amp.




This time it is a set of power supplies which are meant to be used with SE 300B mono blocks. The amps itself still need to be built as I am waiting for some custom transformers for them. But the PSUs are already finished.




These use a set of 866A mercury vapour tubes.





The 866A is simply stunning with it's large bottle and intense blue glow.






Here is one power supply operating with a previously built 300B amp:




Another view:




The greenish tint in these pictures is due to he light conditions during night. In reality it is blue.

Top view of the PSU:




Front view:




The hybrid arrangement with the two 6AX4 in the rectifier bridge provides a slow warm up which can be nicely seen in this video clip:




The blue glow comes on gradually as the heaters of the 6AX4s warm up and the TV dampers start to conduct. Another video from a different angle:




And a video taken in total darkness:





A photo showing the hybrid bridge:




Close up to the 866A:




Best regards

Thomas



11 comments:

  1. IMHO the electrically equivalent 3B28 xenon rectifiers perform better than these mercury 866 babies. Tried many and frequent comparisons. The 3B28 are more transparent and harmonically rich and display more slam, the bottom end is better defined and firm. But of course this are my impressions only.

    ReplyDelete
    Replies
    1. Hi! The performance of a power supply does not depend on the rectifier type alone. Te entire power supply and also sensitivity of the amp to power supply changes is important. The preference of a certain tube type in one power supply does not necessarily mean it performs as well in another. Just IMHO

      Thomas

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    2. Dear Thomas
      i remember it was blog with schematics for diyers
      could from time to time we see new ones : )
      Thanks for fascinating blog.
      Kind regards
      Chris

      Delete
    3. Hi Chris, there are many schematics on my blog which I share freely. Just end of last year I published schematics for an amp based on the 6GE5. I believe I am sharing more schematics than other people who are commercially into audio. Additional schematics are available if at least a partial kit is purchased from me.

      Best regards

      Thomas

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    4. Hi again Chris, a question comes to my mid: What are you missing? Maybe you don't see so many new stuff since I don't keep changing my design philosophy. I keep using what proved to work well. Many of my amps are still based on the principles as presented here. Also the underlying circuit of the PSU in this post has already been shown.

      thomas

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    5. Dave Slagle : "to me the 3B28 has a solid state sound whereas I find mercury to be very full and musical." (from diyaudio.com).
      And for tonality also don't forget that annex of the PSU, called ... amplifier ;)
      Dan

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  2. Dear Thomas

    You are right :)
    Thanks for your great work and blog.
    Have a nice day
    Chris

    ReplyDelete
  3. How hard is to find those mercury vapour tubes these days?

    ReplyDelete
  4. Hello Thomas,

    Do you use choke input or CLC filtering? If it's CLC, what is the input cap value you're using with the 866A/6AU4 bridge? Thanks.

    ReplyDelete