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Bob
Reply with quote  #1 
I know that 300B tube brand comparisons and recommendation were discussed in the forum, but for some strange reason i can''t get back to the articles.  I am estimating for a 300B OTL build and need to get an idea of the estimate.

I'm interested in which ones are most reliable, best quality control, and best SQ.  Not interested in uber expensive brands.

Thanks
Owen Mallia
Reply with quote  #2 
I had the best performance with the Genalex Gold Lion 300B's in my Masterpiece and SE 300B combination. OW
Robbert
Reply with quote  #3 
I have had bad luck with Genalex 300B in my 300B OTL. After 9 months the current through the tube could not be made any more. You can also measure the voltage drop over the current sink.
Then Sophia tubes are the same sound good but after a while distortion kicks in an yes also the current setting through the current sink could not be met.

Then using JJ, sound great and still measure strong after more then a year couple of hours per day use. Current through the current sink is stable. So I would say go for JJ.

Strangely enough I found using a good quality at driver tube is way more audible. I use Genalex here and also RCA clear cap.

I am using now JJ in the masterpiece AND the 300B otl. (never had the masterpiece with any other tube then the JJ. All failures came in the 300B OTL.

By the way, I am using the 300B OTL from the book with the following major mods:

DC voltage to the filllaments by 4 small 5 Volt power supplies.

Use a infividual current sink for each tube with a TL783 with a 10 ohm resistor for current regulation.

use the 12AU7 for diver tube with resistor changes as suggested by bruce in his post.








PetrL
Reply with quote  #4 
I use same Shuguang 300B-98 for 4 years already (near 2000 hrs), first AC, then DC. They are still stable with no apparent sonic degradation.
Capt. Z
Reply with quote  #5 
I don't own any of Bruce's 300B tube amps, but I do recall reading on this forum that Mesh-plate 300B tubes will not hold up in Bruce's amps.
Bob
Reply with quote  #6 
Thanks guys.  Very helpful.  Does anyone remember the discussion on the forum of which brands have recently had problems with quality control and reliability?
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