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Genalex GL GZ-34 Rectifier...Did I just get a bad one? Five months seems

like a terribly short lifespan. I bought it in May and spent the extra money to get a "good" tube. It sounded good while it lived. But it went in a fiery inferno last weekend.  Fortunately it only took out a fuse.

It was running in a Bob Latino VTA ST-70 Dynaco amp. It's a great amp but runs the rectifier a bit hard from my understanding. However the original tube lasted at least 3-4 yrs IIRC. I tried a SS rectifier. YUK!! I put the tube (a spare Sovtek) back in place I've had good luck with the KT-66 Genalex GL's and they have a good reputation (I think). Is this just the luck of the draw. IOW, even a new tube can have a short life span? Or is this odd? Is there any way to avoid it? I'd buy another Gennalex GL if it will last. But I can buy 2 Sovteks for the price of one GL. Sovtek sounds good too.

FWIW, The tube that failed was cryo treated. Could that make a difference in a rectifier tube? As always, Thanks for your help.
128x128artemus_5
artemus_5's avatar
artemus_5 OP
1,992 posts
 
@atmasphere  
 The reason many of the originals worked is that they were Mullards, which were built over-rated in their day.
Does this mean that I need to get a NOS Mullard? If so, which one (if there are differences)?

BTW, I read an article by someone named Campbell who measured the ST-70 for accuracy and concluded that it was among the best measuring amp produced. However, his criticism was the single rectifier tube, noting it should have had 2.
atmasphere's avatar
atmasphere
11,979 posts
 
If you want longer rectifier life, look for a Mullard made in the UK. Beware of fakes on ebay.

I would also look at the cost and compare that to the garden variety. If its more than 4 times the cost, I would just buy the cheaper tubes and get a bunch of them.
artemus_5's avatar
artemus_5 OP
1,992 posts
 
@atmasphere  Can you show me an example of a fake. I'm not sure how one would fake a tube. How is it done? Thanks
swampwalker's avatar
swampwalker
5,138 posts
 
@artemus_5 - Not to step on Ralph/s toes, but fake tubes are re-labelled modern production.  Wipe off the printing on the tube and you can label it anything you want.  Put it in a plain white box and voila...NOS goodness.  Also pulls sold as NOS.  Be VERY careful on eBay.  Most of the "NOS" tubes I bought there turned out to be junk. 
atmasphere's avatar
atmasphere
11,979 posts
 
+1 on that.

New Sensor bought the Mullard trademark so their stuff isn't 'fake' but it does not hold up like the original Mullard rectifier did in the ST-70.
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