November 12, 2012

  • GEC KT88, Part 2

    Today’s installment covers the Genalex KT88 output tube.  The reader is directed to my original posting on these tubes, when used in my Premier 11A, for information regarding their physical construction and initial listening impressions. 

    The Genalex KT88s in this review were used in the Premier 140 power amplifier which passed the 1,000 hour mark, since its upgrade, during their audition.  At this point in time, the CJD capacitors that were installed in the 140 should be fully broken-in.  Other tubes used in conjunction with the review set were Telefunken PCC88s in the Premier 16LS2 preamp and as the input tube for the 140 (I now have a complete set of seven) plus the Sovtek 6H30π-DR phase splitters, also in the Premier 140. 

    The review set were comprised of one quad of Genalex Gold Monarchs and a quad of Genalex KT88s.  The tubes are essentially identical with the only difference being that the Gold Monarchs were intended for sale in the United States while the latter were marketed elsewhere.

    Genalex Gold Monarch KT88                                                                   Review Set

    Genalex KT88                                                                                      Genalex KT88


    The Genalex KT88s replaced the SED 6550C power tubes and my comments below are relative to their differences.


    Listening Impressions

    • The increased power capability (42 watts dissipation for the KT88 versus 35 watts for the 6550C) is immediately apparent with a louder presentation at equal volume settings and a more powerful bass response with greater overall dynamics.  As a result, the music has a more solid foundation.
    • Slapped percussion is more realistic although with less transient snap.  Transients are detailed but not as sharp as with the SED 6550C.
    • Midrange is harmonically richer and voices are more chesty.
    • There is less sparkle in the mid- to upper-treble.  However, chimes, church bells and the like are extremely realistic and reminiscent of the GE 6550A in this regard.
    • The sound stage is populated with denser images that are well-layered.  


    I continue to be very impressed with the Genalex KT88 and these are most definitely a top tier power tube.  Although extremely expensive in today’s market, they reward the listener with a presentation that is natural and always at the service of the music.  The changes in the resolution of the Premier 140, especially with its fully formed caps, highlight this tube’s capabilities.   


Comments (2)

  • Genalex, Gold Lion, Gold Monarch...ah the good old days before free trade and NAFTA. In the 80s, everything from GEC got sold or outsourced to China.

    How long have you had these old stock GEC KT88s? I didn't read about them until the early 90s. By then, they were already unobtainable.

  • @rpghero27 - 

    Most of these (perhaps all) were purchased on Ebay back in 2004. For the older brown base type (such as the ones reviewed in this installment), they cost an average of almost $230 each back then. I also have records for two quads of the later production black base Gold Lion type which may have been the ones you mention that were made in China. I need to dig those out and give them a listen. If I do, I'll report on them and we'll see how they compare and whether or not I was taken. It's quite possible I was.

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