Tubes Asylum Questions about tubes and gear that glows. FAQ

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Tubes Asylum ]

---

[ Alert Moderator ]

---

Test Results...

Posted by Vinyl Valet (A) on February 5, 2015 at 15:50:54

In Reply to: Thank you... posted by Vinyl Valet on February 4, 2015 at 05:45:52:

Phono Stage (no regulators): V1 Vp = 85Vdc (both triodes)
V2 Vp = 80Vdc (both triodes).

Line Stage: Interesting design, can't get schematics. I checked with the designer to make sure my measurements were correct. He confirmed that they are. Vp is reasonable for all twelve measurements, nothing close to excessive. As I point out below, I used new production EH 6922s in this pre previously and after roughly 8000 hours, only one of the six is noisy.

At this point, I believe that I’ve eliminated the possibility that my gear is causing the failures. Please chime in if I’ve missed anything. Here’s a few other interesting points.

I have two new failures in the pre instead of one like I suspected earlier. So the failure rate now is 50%, at or below 400 hours, several at or below 100 hours.

I pulled out an old box of new production EH 6922s that were in this pre for years, I’m guessing maybe 8000 hours. Although other operating parameters indicated near end of life on some of these tubes, all but one were dead quiet. All five worn out EH tubes were quieter (I test by rotating all the tubes through V1 of the phono stage) than my quietest, still functioning Gold Lions. Then I rotated the six remaining good Gold Lions through V1 of the phono stage. Five were okay (still not as quiet as the five old EH) and one sounds like it’s on the way to failure. It’s fine in the final stage of the pre...for now.

Six, possibly seven, bad tubes in less than 400 hours, several gone in less than 100 hours. The Gold Lions were purchased in three groups over the course of a year from an excellent dealer who thoroughly tests after some break-in so it’s unlikely this was one bad production run. Something is seriously wrong. For all the dealers that want to chime in and say that they’ve never seen this, I would reply that the failures are occurring well beyond any reasonable return period and people are just quietly taking the loss. Please post if you are one of them.

I will find out who the US distributor is. I want to send these results to both the distributor and the factory. The response, if any, should be interesting. If I hear anything, I’ll post a follow up.

Thanks again to all (the same cool guys who have helped so many others) for their valuable help in understanding this issue.
Open up your mind, in pours the trash. - Meat Puppets, 1987

This post is made possible by the generous support of people like you and our sponsors:

VH Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---