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About 18 months ago I bought quads of EH, JJ, Svetlana, and Sovtek EL34s, Shuguang and Sovtek GZ34s, Svetlana, Sovtek and later EH 6550s as well as JJ, Svetlana, and Tesla KT88. Also Svetlana 6L6GC and Valve Art KT66 (Shuguang). Preamp tubes evaluated are Ei/Yugo ECC83, ECC 82 and 6CG7, Svetlana 12AX7, Sovtek 12AX7 (3 versions) EH12AX7, JJ 12AX7 and Svetlana EF86. As the JAN Philips 12AX7 is still cheap and available it was included. The EL34s: Svetlana was most neutral, reliable, and tough, with the best bass and power. JJ had the most "vintage" sound but I experienced reliability problems, some of which could have caused catastrophic amp damage. The Sovtek and EH sounded identical-- not great, being thin and "metallic" sounding. Guitar tubes. The 6550s: Svetlana all the way. Sovtek/EH were decent, but I really like the delicate top end and GE 6550A-like bass of the Svet. The Tesla copper base KT88 was the clear KT88 winner; I liked the JJ and Svetlana about equally-- both seemed to be making an attempt at approximating the GEC sound, and achieved instead less detail and punch than the Svetlana 6550, with no added texture. I had 2 Svetlana KT88s fail out of 8. The Svetlana 6L6GC was fantastic! I liked it better than anything except European subs and the WE350B. The VA KT66 was good, too, but would not take more than 400 VDC/20ma w/o hotspotting. As for the GZ34s; the Sovteks were reliable and decent; the Shuguangs were a disaster-- metal on the glasss, arcing etc at 2 weeks for one pair. I hear reliability has improved, but wouldn't use them in MY amp. I bought 6 Sovteks-- I used one pair in my DVD amps and gave the others to friends. We all experienced a predictable tapering of performance in 10-16 months, with no catastrophes. A good tube if NOS isn't your style. As for the preamp tubes-- look no further than Ei/Yugo; they must represent a modern miracle of value. Microphonics is an issue with the 12AX7-- about 5 of the 18 I bought had significant problems. At $6, I had no problem tossing the rejects-- my own selection service. The EH and Sovteks were too bright for my taste. or vintage Mac gear, they might be perfect. The real disappointment was the EF86 from Svetlana. Horrible-- however, with NOS quite cheap, not an issue... for me. The Svet "box plate" 12AX7 was about on par w/ the Phillips (after a break-in period for the Philips) No frills or thrills. The big ?: Where is the good GZ34? Come on, guys! You can make a miniature twin triode that trashes everything but NOS but not a simple diode? Chris


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Topic - current production tubes - Chris Spafford 09:03:07 07/14/02 (25)


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