Chinese Rectifiers
On Monday, November 9, 2015 at 1:17:20 PM UTC-5, Big Bad Bob wrote:
On 11/02/15 03:39, Peter Wieck so wittily quipped:
The first one immediately smoked its filament. The second one, after about 20 minutes, melted into a mess - almost cartoon-like. Everything inside the glass is tilted or rippled. The second one tested marginal before the melt, by the way.
Friends don't let friends use Chinese Tubes.
some are good, some are not, apparently. I've heard that Ruby buys
(some of) their tubes from China, then tests them before selling as
'Ruby'. But that might be a rumor.
need reputable sources, for sure.
Bob:
Here is the issue. I remember testing these tubes when they arrived (the amp was well used), and they did rectify. Meaning, any local test will be 'good' until it is not. Of course, this may be written about any tube, irrespective of brand - but Chinese tubes fall into their own category. Most reputable 5AR4 tubes fail fairly gently - not spectacularly.
BUT, over an 8-year period, one apparently got gassy enough to pop the filament, the other slagged. This was 8 years of NO USE.... not 8 years and hundreds of hours - which would be understandable.
The going rate on a functional LK150 is up to/around $1,200 these days. I would not risk such a device to someone else's tests. I am sure that Ruby would replace a slagged tube, but would they replace a slagged power transformer? Somehow, I do not think so. And, yes, I do fuse the primary. I only hope the fuse is fast enough to save things under dire conditions.
And, one of the reasons I am hesitant about re-branded tubes anyway unless I am dead-sure of the provenance.
Peter Wieck
Melrose Park, PA
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