Aug 272017

I wrote all day yesterday and finished up the review of the Sophia Electric EL34-ST and Aqua 274B vacuum tubes.

The Sophia Electric EL34-ST power tubes (above) and Aqua 274B rectifiers (below) outperformed everything that’s ever graced my Leben CS-600 integrated amplifier, and vintage McIntosh MC30 monaural amplifiers, respectively, and by a large margin.

I don’t know what makes these tubes sound so magnificent musically and sonically. I could be the contribution of the ST bottle shape, or the noise reducing blue glass, the design & materials of their internal structure, or Richard’s prowess in voicing tubes, but the Sophia Electric Aqua 274B rectifiers and the Sophia Electric EL34-ST power tubes are both home runs by Richard, and they are simply superb both musically and sonically.

Your can read the full review here.

 Posted by at 11:00 am

  4 Responses to “The Sophia Electric EL34-ST and Aqua 274B Vacuum Tubes Review is Now Live at Positive Feedback!”

  1. I am looking for 2 quads of el34s. How do these Sophia EL 34ST compare to the NOS Mullard XF2 EL 34s? Do you have an idea?

    • Hi Dan,

      I don’t know how they compare. If you decide to get the Mullard’s let me know how you like them. Brent Jesse has an interesting discussion about the Mullard XF2 EL34’s with both single and dual halo getters here.

      All the best,


  2. Hi Jeff, I read your Sophia Electric Aqua EL34-ST tube review with much interest thank you.
    I’m slightly confused though and am hoping you can help.
    I own a Leben (rs28cx pre and) cs660p power amplifier using 4 Russian NOS 6n3cE tubes and am interested in upgrading the cs660p by changing to the Sophia Elec Aqua EL34-ST tubes.
    My questions are
    1/ how many EL34-ST tubes do I need to buy for my cs660p and
    2/ should I also consider the 274B rectifier tube? (I’m not sure what these do or where they fit) and if so how many do I need?
    3/ now that some more listening time has elapsed, in your opinion is the above worthwhile?
    Kind regards,

    • Hi Stuart,

      The Sophia Electric Aqua EL34-ST tubes should work very well as power tubes in your Leben CS660P, much the same as they did in my CS600. You would need four EL34-ST power tubes for your CS660P.

      You’ll also need to set the switch settings appropriately for the CS660P when using the EL34’s, and using EL34’s will reduce the power output of your CS660P somewhat.

      The SE 274B tubes will not work in your Leben CS660P, as it uses a different method of rectification.

      If you decide to give the Sophia EL34-ST’s a try, be sure to report back and let me know how you like them in your CS660P!

      All the best,


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