Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
KT88 bias range
Dear Folks,
I built a SE amp, using several ideas from the AX84 forum for the preamp, and a KT88 SE power amp. The amp sounds fantastic, in particular upon driving the input with a Ge booster. I love it. So, the question is, and I would love to learn from other experiences the following:

I am biasing the power section (KT88)  cold (so I believe) at about 25V Anode voltage, and about 50mA current.
I Have a 400ohm anode resistor, in series with a pot and a current meter, so I can monitor the current. I have not yet played min at 10, and it is pretty loud, but if you can enlight me I would appreciate it:

1) can I push the KT88 harder? Why would I do that? Well, in case I need this amp to play  live (when COVID-19 is gone, hopefully)?
2) what are the limits I can have the KT88 running at?
3) are there sonic differences in terms of the harmonic content, or just louder? Of course, I anticipate some distortion happening earlier (in the master volume).
4) How do I measure the power? I read someone saying that the best way is to put a 8 Ohm resistor at the OT secondary and measure the voltage across @400Hz, and calculate the power. From the current could I not have an estimate? Sorry about the noob question.

thanks for reading! If interested, I can post my schematics and sound clips.


Forum Jump:

Users browsing this thread: 1 Guest(s)