|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
64.132.61.164
I recently adjusted my bias to just under the recommended max of 49.5 ma, (recommended range 45-50)to my ears it sounds better the closer I am to 50 ma, I can lock all four KT88's in at that level with no problem, however, the next day after significant warm up,( one-two hrs.) I see where the bias has dipped to around 47.5 ma, everything sounds fine but I'm curious, is this typical and the bias will rise with extended play or could it be a sign of ageing Tubes? Thanks
Follow Ups:
It all depends on the time of day. I use to bias some 300B amps early in the evening at 700mv and by midnight when I checked the bias again they would be up to 800mv. On hot summer days when everybody was using their air conditioners,cooking dinner, just using more electricity the voltages in my home would range from 110v then late at night 1-2am I would have 120v. All this made the bias fluctuate.
Just a reommendation for the summer, always bias on the low side early evenings. If biasing when all are asleep go for the high side.
It's likely due to changes in the AC line voltage - as the AC line drifts up and down the bias changes along with it in most amps.
Thanks Jim, also do you have any personal experience with the Chelmer Valve Co. KT 88 GL type, (supposed to be the same tube EAT is selling for much more), and if so, have you also heard Penta Labs solid plate KT 88, how does it compare? Do you prefer one over the other? Thanks
on the penta KT88 below. He seems to like them alot
.
Regards,
"Kico"
nt
This post is made possible by the generous support of people like you and our sponsors: