|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
24.17.48.137
In Reply to: RE: 6883B plate dissipation IS 35 watts, not 20 posted by Freo-1 on April 10, 2015 at 21:04:44
Yeah, lifetime will be really low. ICAS ratings for tubes are provided for purposes like public address, where there are long resting periods. I don't think I'd run them any harder than 35mA.
Follow Ups:
I've been using this amp for several months now, with the following results:
1) Dropped the bias to 40 ma, and the results have been fine from a reliability standpoint. I had a couple of tubes go early in this project. The failed tubes all had a mid 80's date code from the same time frame. Swapped in tubes with 70's date codes, dropped the bias to 40 ma, and it's been great since.
2) Swapped out the coupling caps to Jupiter Copper foils, and that improved overall performance significantly. The mid range is much more open and life like sounding, and the treble sounds clearer as well.
3) The 6BL7 is a great driver tube. MUCH quieter than the 12SN7. In fact, it is so much better, I'm going to change out the driver tubes in my 1625 DIY amp to run 6BL7's.
All in all, this has been a worth while project. The sound from this amp is outstanding. Very happy with the results.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
I have a bunch of them and have not seen a scheme that I like using them. Specifically, I wanted to try them as a driver for an 813 SE project but don't have the skill to make a design. Maybe your schematic could be adopted to the 813? thank you, Dak
Interesting. I've been running the 1625 amps at 40ma for well over a year now under heavy use, and the tubes still measure very near NOS. I would have thought the 6883B could run at 50ma all day long.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: