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Re: Help! How do I find the bad output tube(s)?

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Posted by Phil Sieg on October 18, 1999 at 04:52:44

In Reply to: Re: Help! How do I find the bad output tube(s)? posted by DK on October 18, 1999 at 00:20:35:

Hate to be the contrarian here, but an emissions tester is a waste of money. Emissions testers are prone to false positives. Find a good transconductance tester (Hickok or military tester). You won't get it for $20 and, unless eBay has changed, you won't get it for $150 on eBay. But if you are going to test tubes frequently, it's a must.

Second point. I use NOS RCA 6AS7Gs and NOS Sylvania VT-231s as drivers in my Atmas. The NOS RCAs sound way better than the Sovteks and work fine so long as you bias them at 60 mA rather than 75 mA. And the Sovtek and JAN Philips are..well, crappy 6SN7s. VT-231s aren't cheap ($30-$40 each) but the difference is immediately noticeable. Better definition, better depth, deeper bass.

I also find that running only 4 outputs per side is a distinct improvement over the full complement. Greater ease of presentation, more natural. But my speakers have a sensitivity of 97.5 dB. YMMV.

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