From: crabe@everest.den.mmc.com (Carlyle J. Rabe 7-1697) Subject: Blue tubes? Date: Mon, 3 Aug 1992 20:09:31 GMT The new issue of Glass Audio contains an ad for New Sensor Corp which is selling EL34 Pentodes in Cobalt Glass Envelopes. Is there any advantage to Cobalt (blue) envelopes? Does this have any measurable or subjective advantage? They are imported from eastern Europe, and are priced only 50 cents more than clear tubes. Any insight on this curiousity would be appreciated. Thank you. Carlyle Date: 7 Aug 92 14:16:00 EDT From: "Raymond P. Pichulo" Subject: RE: Blue Tubes Just a guess.. maybe the blue glass is so you won't notice when they get gassy ... 8^) Ray