I now see 1V steps look too broad, probably they use an even finer scale, say in 0.5V steps. IF target current is, say, 40 mA, probably tubes needing -48V are rated "1", -49V "2". Say, in a classic Fender amp, nominal -52V bias:
Just *guessing*, there are 2 ways to do it:ġ) measure " bias voltage needed to pass "X" mA". Many will pay a few bucks over average market price in exchange of avoiding the fuzz and expense of biasing, so in fact it´s a useful service they offer. but by keeping it secret they keep you tied up. Obviously those numbers mean something to tube vendor, and you would be able to reproduce them at home if you knew the method/equation they used. Which, by the way, is a "fixed-bias tube amp," as you put it. If you can bias hi-fi amps and Leslies, you can bias a Deluxe Reverb. Maybe the amp is run clean all the time - then you really wouldn't bias it at a spot where you'll be running the volume on 11 all the time.
If you end up biased too cold, you'll know, and for the most part, guitar players don't like that kind of distortion, either. If it's not red-plating and it sounds good, it is good. On another note, there's no reason to just bias a guitar amp as hot as possible just because so-and-so said to. There is no "correct" bias setting - if it SOUNDS good to the musician AND doesn't self-immolate while doing it, then it is correct. That said, I don't trust mew tubes to stay at any rating for long. IOW, one vendor's 38 is not necessarily another vendor's 38. Those numbers don't really mean anything except to the company that did the rating. Shouldn't be any issue replacing with same tube type and "rating" from the same vendor.
0 kommentar(er)
