Apr 222017

It’s been far too long since I’ve done some tube rolling, so I was delighted to hear from Sue & Richard at Sophia Electric that they wanted me to give their new Sophia Electric EL34-ST vacuum tubes a review for Positive Feedback.

The new Sophia Electric EL34-ST vacuum tube.

I’m a real pushover for the ST bottle shape, I just love the way it looks, so the new Sophia Electric EL34-ST vacuum tubes really pushed my visual buttons!

Sophia Electric™ EL34-ST vacuum tube.

I thought it would be fun to try the new Sophia Electric EL34-ST vacuum tubes in my Leben CS-600 integrated amplifier, which has been with me longer than any other amplifier I own.

The Leben CS-600 is just a silly good amplifier, and is definately an old friend at this point!

Vintage McIntosh MC225 stereo amplifier with the A5’s.

I decided I wanted to try my Leben CS-600 with my Altec A5 Voice of the Theatre loudspeakers that I just hot-rodded with Lefson resistors in the crossovers, in my audio-visual system.

I have been using my A5’s with my vintage McIntosh MC225 stereo amplifier and Leben RS100U line stage (above), which is a really nicely matching combination of electronics with the A5’s.

Leben CS-600 with the Altec A5 Voice of the Theatre loudspeakers.

So I got busy and and unhooked the McIntosh MC225 stereo amplifier and Leben RS100U line stage,  set them aside, and then installed the Leben CS-600 integrated amplifier in my vintage Altec A5 Voice of the Theatre based AV system in their place (above).

I set the Leben CS-600 to its 16 Ohms setting for driving my 16 Ohm Altec A5’s.

Back panel of the Leben CS-600.

I’m using the Acoustic Revive Power Reference TripleC NCF AC power cord that’s in for review to provide AC to the Leben CS-600 (far left in the photo above).

The interconnects from my Philips TV to the Leben CS-600 are Belden 8402 microphone cable interconnects with the shield connected at both ends, Yazaki-san style (far right in the photo above).

Speaker cables are Duelund DCA16GA tinned-copper cables with no terminations, and are connected nude to the CS-600.

Oppo UDP-203 Ultra HD Blu-ray Disc Player

For a source I’m using the new Oppo UDP-203 Ultra HD Blu-ray Disc Player that I got a while back.

For interconnects from the Oppo to the Leben CS-600 I’m using Duelund DCA16GA tinned-copper cables terminated with Gold Duelund RCA’s that Chris at Parts ConneXion made for me to try.

By the way, the more I use the Duelund RCA’s the more I’m liking everything about them, they’re very nicely done and still work well with the narrow spacing on vintage gear, which is a requirement with my vintage tastes!

Duelund DCA16GA tinned-copper conductors terminated with Duelund gold RCA’s.

For connecting the Oppo to AC I’m using the superb Sablon Audio Quantum Gran Corona, which really is a sweet match to the Oppo!

Sablon Audio Quantum Gran Corona AC power cord.

Now a little more about the Leben CS-600. I fell in love with the Leben CS-600 integrated amplifier over ten years ago now when I wrote an article about it for 6Moons.

I ended up buying the review unit (the ultimate recommendation) and have been using it nearly every day in my AV system, where it has been reliably been an ongoing delight.

When the Altec A5 Voice of the Theatre loudspeakers displaced my Harbeth Super HL5’s from my AV room, the Leben CS-600 & Harbeth’s became my the system in my master bedroom.

Now the Leben CS-600 is back in my AV room, with the Altec A5’s, so I can try it with the new Sophia Electric EL34-ST vacuum tubes.

You can use a bunch of different tubes in the Leben CS-600 because of its adjustable cathode resistor and plate voltage settings, but primarily it is intended to be used with 6L6GC’s or EL34 tubes.

For those who are into tube rolling, I’ve posted a settings table for the different tubes you can use in the CS-600 here.

The Leben CS-600 integrated amplifier.

In addition to it’s gorgeous exterior, the Leben CS-600 is able to hold its own against pretty much anything out there.

Jonathan Halpern (Tone Imports) has had huge success winning ‘best sound of show’ praise (1, 2) with his Leben CS-600 at a number of hi-fi shows, impressing such hardened audio writers as Stephen Mejias, John Atkinson, Robert Deutsch, John Marks, and Art Dudley, for example, while shaming much larger & more expensive systems with his David versus Goliath system approach.

The CS-600 with the Sophia Electric EL34-ST vacuum tubes patiently awaiting their turn in the CS-600.

What kind of vacuum tubes was Jonathan using in his Leben CS-600 that garnered such impressive praise? If you guessed it was EL34’s you’re exactly right, and that’s what piqued my interest in giving the new Sophia Electric EL34-ST vacuum tubes a go in the CS-600.

A quad of Sophie Electric EL34-ST vacuum tubes for the Leben CS-600 integrated amplifier.

I played the CS-600 with the 5881 tubes I’ve been using in it for a couple of albums, to get a feel for its performance with my Altec A5 Voice of the Theatre loudspeakers, before switching to the Sophia Electric EL34-ST vacuum tubes.

Oh, by the way, the tube complement in my CS-600 is as follows:

  • Four National Electronics 5881 power tubes.
  • A NOS General Electric 6Cj3/6DW4B ‘dumper tube’ (allows for a gradually increasing supply of high voltage (B-Voltage) to the output tubes on turn-on in order to protect them from damage and extend their life).
  • Four NOS Sylvania twin-triode 6CS7’s for the first-stage of amplification (my favorite NOS 6CS7, but getting hard to find).

CS-600 tube complement.

NOS Sylvania twin-triode 6CS7’s.

NOS General Electric 6Cj3/6DW4B.

I should point out that with the 5881 power tubes the CS-600 is good for 32 watts, and with EL34’s 28 watts.

That’s not a lot of power, but the CS-600 is able to effectively drive even less sensitive speakers like my Harbeth’s quite easily, and with the sensitive Altec A5 Voice of the Theatre loudspeakers it’s more than enough!

Sophia Electric EL34-ST vacuum tubes in place in the CS-600.

I powered down the CS-600, removed the 5881 tubes, flipped the cathode resistor & plate voltage switches to their EL34 settings, and installed the Sophia Electric EL34-ST vacuum tubes in the CS-600.

Sophia Electric EL34-ST vacuum tubes in operation.

I powered back up the Leben CS-600 with the new complement of Sophia Electric EL34-ST tubes and let it warm up.

Sophia Electric EL34-ST tubes peeking out over the top of the Leben CS-600.

The Sophia Electric EL34-ST tubes are too tall to be able to put the top back on the CS-600, so it’ll be going topless for a while.

The Sophia Electric EL34-ST vacuum tubes are the very last review in my review queue right now, so it’ll be quite a while before their review for Positive Feedback will be ready, but that’ll give me plenty of time to interview Richard about their construction and his inspiration for their design.

Sophia Electric™ EL34-ST vacuum tube.

As I get some time on them and get a handle on how they’re performing, I’ll check in from time-to-time with an update on their performance in the Leben CS-600.


As always, thanks for stopping by, and may the tone be with you!

 Posted by at 6:32 am

  17 Responses to “The New Sophia Electric EL34-ST Vacuum Tubes in the Leben CS600 Integrated Amplifier!”

  1. Can’t wait to hear what you think of these tubes. The only Sophia Electric tubes I have personally owned were a pair of the mesh plate 2A3, which I used in a Bottlehead Steremour with mixed feelings. With that said, I’ve been REALLY tempted to try some of their other offerings as alot of folks who’s ears I trust have nothing but praise for their tubes.

    Completely off topic here, but is that an old 78 cut for use as a drink coaster? What a cool idea.

    • Hi Anthony,

      I really liked the Sophia Royal Princess 300B’s, and these new Sophia 274B rectifiers sound fantastic in my MC30’s.

      I haven’t listened to the EL34-ST’s long enough yet to have any kind of opinion, but they sure are gorgeous with their ST bottles and blue glass!



  2. Hi Jeff,

    I’ve just installed a quad into my ANK EL34 Mono Blocks. As i’m only half hour in, it’s too early to make a complete judgement, but straight out of the box they sound great.
    Really nice tone.

    I’ll update you after the weekend…..


  3. Hi Jeff,

    I’ve put about 20 hours on them and they’re starting to sound very good. I’d say they do everything the Gold Lion KT77’s do and much more, especially through the midrange. There’s some magic going on there. They’re getting better day by day. I’m loving the sound they produce.

    Can’t wait to see what you think.


  4. Very nice looking tubes, waiting with bated breath for the review 🙂

    Fyi, my cs600 is usually kitted out with either Shuguang treasure KT88’s or nos tungsol 5881’s, both of which sound remarkably similar which is surprising given the difference in plate size! So definitely interested as you have just gone from a set of 5881’s.

    Hopefully this is of interest to the cs600 lovers. I do have a very elegant (read cheap) solution for cs600 owners that want bigger tubes fitted but still like the protection of a top cover. What you need is to purchase/obtain a bunch of hexagonal brass PCB risers, generally found under motherboards, and a set of matching screws. The standard riser have the same thread as the cs600 top plate screws and come in various lengths. Measure the distance required to clear your biggest tube and select the height of the riser based on that measurement.

    The first bit is a bit fiddly. With the top plate removed, take a riser and one of the purchased screws and screw the riser on the top edge of the cs600 from underneath. Getting the screw to bite is the hard bit and you will drop one or 2 trying, so please make sure the amp is cool and disconnected from power. These do not have to be tight.

    Then progress with enough risers to support the plate, I found 4 was sufficient. Then simply place the top plate on top of the riser and screw in the supplied leben screws to the top of the risers. Tightening this top screw will tighten the whole assembly.

    What you are left with is a floating lid that just covers your tubes giving good protection, and the brass of the risers is close enough to the gold front to look like a bought one!

    If I could post a picture it would have saved about half a page of blabbing 🙂



    p.s great blog Jeff, a constant read and source of great tips.

    • Hi Rob,

      Thanks for the kind words, appreciated!

      I’m intrigued by your solution to raising the top plate of the CS600, it is an approach that makes it much more feasible for running taller than stock tubes.

      If you could email me a photo or two it would be awesome, and I’ll add it to your comment. Also, if you can make a recommendation for where to get the parts, that would be a big help to readers.

      Many thanks for your great comment, I look forward to checking out the raised top plate!

      Kind regards,


  5. Dear Rob,
    Sound slike a great solution – can you email me the pics? pgregoryatgeorgeclinical.com?
    Also interested in the Shuguang treasure as I have some of these and thought about using in the Leben also.
    Happy to hear from you.

    • Hi Philip, I’ll dig out the photos and send them through. Really does work and costs a few dollars.

      The KT88 treasures are my favorites and end up staying in the Leben, and that’s out of a pretty good bunch. The major tubes listed below to give an idea of the competition:

      Tung sol nos 5881 – very very similar to the treasures just a little less power.
      Sylvania nos 6L6GC – very detailed, but a little bit too analytical for me.
      6n3cE – all round good, but not in the same league as the treasures for me
      RCA 6L6GC black plate – just scored 5 of these for about $75 – supreme bargain find! They are used but they still sound damn fine – will be borrowing a friends tester this weekend to see how used. More top end than the treasures, very delicately so, but the treasure are fuller and a tad sharper (in a good way) and after a good stint will go back in.
      Gold Lion Kt77 reissue – one of the best EL34’s, but I always end up going back to either a 6L6 or the treasure in this amp. Still the thought of an ST EL34 by Sophia did pique my interest.
      Tung Sol El34 Re-issue – as above
      Shuguang Treasure KT66 – this is also a superb tube, but on my system was a bit too rich and chocolaty. In a friends system with more detailed speakers and my CS600, the kt66 won over the kt88 – so as all things system dependent. I have a planned speaker upgrade soon to a a DIY all TAD horn 2-way and am thinking the KT66 might go back in for a trial

  6. Hi Jeff,

    I’ve clocked close to 100 hours on the Sophia’s now. I think they surpass the Gold Lion KT77’s in every aspect except bass extension. The KT77’s do bass so well. I’m not saying the Sophia’s are bass light, but i can hear how they gently roll off where the GL’s would just keep going down.
    That aside, the midrange and treble from there Sophia’s are easily the best i’ve heard in my system. There is also much better tone and timbre. The sound stage seems wider and deeper too.
    The sound is very seductive. The Sophia’s will stay in my amps. They are a wonderful tube. I just hope they’re reliable.


  7. Hi Jeff, what’s the verdict?

    • Hi Ridzwan,

      There’s no detailed verdict yet, as I still have a fair number of items ahead of the Sophia tubes in my review queue before I can do a complete analysis of them in order to write them up as a review.

      I can say that I have been getting a lot of time on them with my Altec A5 Voice of the Theatre loudspeakers, they’ve been utterly reliable, and they’re sounding really nice! (not to mention that they’re beautiful looking vacuum tubes!)

      I’m probably still a few months out from writing a full review of them, please wait for it!

      Kind regards,


  8. Yo no necesito tanto calentamiento de cabeza como ustede.mi instalación en el leben es la siguiente,en línea silvania y en salida el34 philips y el leben suena divino.

    • Francisco,

      El Leben es un maravilloso amplificador de sonido. Realmente disfruto de los Sylvania como entradas en combinación con los EL34-ST.
      ¡Gracias por las palabras amables!

      Saludos cordiales,


  9. Amigo, el foro de ustedes me gusta y está muy bien y me gusta.

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