2. amps-preamps
  3. 158704-127647

signs that tubes need to be replaced

I have a pair of Cary Audio Six pacs which i bought used about a year ago. They mate well with my tube preamp and i couldn't be more pleased with the setup i have.  I dont know the number of hours on the EL 34s that came with the amps. The previous owner may have replaced them at one time since they look like they were sourced from Tubeco.I have them biased at the recommended 220 ma. and put about 300 hrs/yr on them. Question is, what should I be looking for (sonically) besides obvious tube failure that would signify the tubes are nearing the end of their useful life? Will inability to maintain bias be any indication?

Thanks,
J.Chip
128x128jchiappinelli
rshak
416 posts
 
My PrimaLuna DiaLogue Premium told me when I had a bad KT88 via the "Bad Tube Indicator" feature.  When a power tube goes bad, the amp goes into protection mode, sound cuts off, and a red LED indicates which tube is the culprit .

I knew about this feature when I bought the amp - and wondered if it really worked.  It does and now I'm a believer.  I don't know if this feature is available on other brands, but I'm glad I've got it on my amp.
ebm
9,311 posts
 
No highs no bass and crappy sound this is why i only have tubes(12ax7,6dj8) in my TW phone stage only.Good luck!!
roberjerman
4,319 posts
 
When the silver getter flashes start turning brown at the edges! Eventually all the silver will turn to brown. That is the sign of "old age" - even though the tube will still work!
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decooney
1,896 posts
 

The same exact same Ruby EL34-BSTR (formerly Shuguang Factory made for Ruby batches), same tubes in the Cary SixPacs were also used in my Cary V12R amp.

Don’t underestimate these particular -bstr tubes due to the lower price point. These amps were designed and voiced with them and actually sounded fantastic! Similar reports over the years from friends with same amps. Grab ’em if you can find them, supply was kinda drying up on the BSTR version Ruby’s for a while. Did a search today, fewer carrying them as before. Look for the -bstr version. Snatch up three quads.. good luck.




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