My 3 years with the BHK preamp specifically; 6v die/change/degrade much faster than 12v tubes.
Sorry to hear about your Tele tube experience…were your Teles
purchased recently…? I wonder if these could have been returns.
Though Teles are not known for early failure…I had been using
Tele 12at7s and 12ax7s pulled from my old 60’s Fisher with
Lord knows how many hours of play or just left on time. My
Fisher was well used. The old bakelite base on the output 7591
tubes were “cooked” though even the old stalwart tubes played
on for many months till I replaced with new ones.
The original Teles from my Fisher still strut their stuff
even after so many countless years of use.
Which leads me to think somehow your Teles were not up
to snuff in the first place.
My Telefunken’s were purchased (June 2014) as a Platinum Grade NOS matched pair from Kevin Deal at Upscale Audio and tested as such on my Hickock 6000A when received. Strangely, they still test good, but their magic is gone!
The symptoms of degradation from tube life are as follows:
- Constant worry
- Posting questions on audio forums
- Persistent consideration of moving to transistors
- Obsessive tube observation, pulling and touching… (fyi, touching your tube can cause blindness)
- Excessive drinking
- Bleeding of cash monies
I have found that swapping out tubes even of the same type/brand can sound different from each other. I recommend keeping a second set and when you get worried, swap them in to test. Beware, just because they may sound “different” does not mean they are degraded.
Bruce in Philly
Ken sorry to hear that…how is the transconductance of each
section measuring ?
Wondering if tube cathode supply, grid bias or plate voltage provided
by your BHK could be an issue.
How your other tubes are performing in your pre?
Best wishes friend
I will get exact T measurments on the tubes tomorrow after checking the calibration on my tester. All other tubes that I have placed in the BHK are functioning and sounding fine.
That’s good to know your other tubes are performing
in your BHK pre