Twin jet help

  • Thread starter Thread starter base341
  • Start date Start date
base341

base341

Active member
I just got a brand new twin jet and have been tweaking and swapping tubes in it to find the combo I like.
I checked the Bias on the power section and it ranged from 16-17ma per tube.
I'm showing about 540v Plate voltage, by my calculation bias should be around 45ma or so right?
Ruby KT88 tubes btw.
Thanks for any help.
 
Using the JJ datasheet and 60 percent of max power I’m getting 51mA as your desired KT88 plate and screen grid combined current.

If you adjust out the screen grid, then the math works out to 46.6mA.

45 would work fine for tube life. I’d stay in the 40mA to 52mA range and wouldn’t go above or below. Above for redplating and tube life due to the very large plate voltage, below for potential crossover distortion. What you have is extremely low for KT88s.
 
One more question.
How are the tubes paired? v7v8, v9v10. Outside pair and inside pair?
I think my XTC is v7v9, v8v10
 
You must log in or register to reply here.
Back
Top