Rebel420
 | Re: waddaya think about biasing..........
quote:
" i run into so many techs who will literally get mad at you if you even suggest that theres are different points at which an amp can be biased depending on the amp" |
Exactly!!! Remembe a while back, I had the marshall that the tubes would runaway, turns out it was an issue with the OT being too close for comfort, and between the hotplate and my speakers having lower imp, the y woul overdissipate, so with that setup, I could bias the amp with the tubes at 20mA to kepe them from running away, and when cranked, it sounded pretty good. with different speakers I could get away with a higher biasing and still sound just as good. Biasing too hot is not recommended by anyone, WITHIN reason... however there is no dispute you will wear out your tubes quicker. AND some tubes can handle running hotter than others.. AN old set of mullards are pretty much bulletproof, whereas some of the chinese el34's have been reported to go within a fewminutes in MusicMans or old plexis (never understood why if you coud afford a plexi, oyu coundt afford good tubes..) Have I ever blown an output tube, even by biasing too hot by mistake no. I've only ever heard 2 output tubes go in my lifetime.. the first was about 10 years ago in a Fender Bassman 10, and last month on a BFSuper Reverb. Did the OT go with them in these cases. No.. could it have.. .yes.. honestly, 20-30 years ago, a lot of people didnt ever bias their amp. Fenders and marshalls were biased slightly cold from the factory, and in most cases people just popped in new tubes and went with it... heck most of the time the tubes werent even matched. And as for tone suffering.... if what they did back then was so 'wrong' why are we today trying to clone the sounds of yesterday! Yea the tone will suffer.... do you like the supposed 'suffering tone'? if yes, then thats what it's all about.... My theory is, the specs are a guideline on where to start, but they cna go either way... remember, we generally try to bias at 70% of the max, so you ahve a bit of play onthe hot side. NOW if the plates start to glow when cranked, or especially when idling, then definitely back things off a bit--here is a case where your tubes are gonna go quick... if the amp will never be cranked, and they are good up to and above where you normally play it, enjoy it! I'm not encouraging anyone to do crazy things, but as long as you know the POSSIBLE outcomes of what you do, remember after all, it is YOUR equipment... you are free to do whatever you like with it...just remember to keep yourself safe.
To summarize, I"m NOT telling you it's OK to grossly bias your tubes too hot, but saying 1 or 2 mA over what is recommended in some cases IS ok, as is way under what is recommended....Maybe i should'nt have posted this...but I AM entitled to my opinion....
P.S. ideas contained in this commentary are not necessarily reflective of the views of this BBS or any of the users on here. Of all things, you are on your own, and do at your own risk. These are strictly the opinion of myself and NOT textbook fact! |
4/19/2000 5:45 PM