How does an misadjusted biased amp sound?

[CrossHair]

I'm just now dabbling in this area and am wondering if the problem I have with my amps is this. Will an improper adjustment make them noisier such as feedback, buzz n crap?
Thx,
Ken

[Rosewood]

Biased hot will add a little noise but not feedback and buzzing, I think you have another problem. Could be tubes, sockets, solder connections, or all the above.

[Bruce O'D]

If the tubes are biased cold, they are operating in crossover distortion which can result in the amp sounding gritty or harsh at all volume levels. If they are running too hot, you'll eat up the tube life quickly and it can exceed the plate dissipation rating.

Check out the tech info section on Aiken's website:

http:\\www.aikenamps.com\TechInfo_2.htm

[CrossHair]

Thanks Bruce,
You know how they say you ought to first and formost get your basic tone without pedals or coloring it up and work from there? Well I'm trying to achieve that but there's something un-musical about my tone and the little extra noise I get with the amp. I've been trying to handle both with very little success and I'm quickly running out of ideas as to what could be wrong. Yesterday I picked up new 6L6 (7 hardness) power tubes thinking that my "4 rating" was breaking up too quickly. Well being that they are new tubes they helped out somewhat but nothing miraculous. Also got a Monster 2500 pro to remedy the noise situation and volts. It too also helped to some degree but not overwhelming. And lastly got a BDE Sonic Maximizer and it helped somewhat. My tone Does sound a bit harsh, not a smooth distortion at all. Kinda more of a dirty distortion, lifeless. O well that's the latest. Wish I knew how to bias my amps myself... hate the idea of having to drag this heavy sucka across town. I know how to use a multimeter etc... just don't know what components to look for and what to do. Thx pals,
Ken

[Gene]

Which amp are we talking about? Your main issue is not being "smooth distortion"? Is the distortion from the preamp or power amp section? Biasing only goes so far if it is in range.

Gene

[rockon1]

Speakers are the voice of an amp. With the range of speakers I have I can make the same amp sound anything from bright and fizzy distorted to fat and dark with no fizzy. If Im unsure about the tubes I replace them then I work on the amp/speaker combination. When I get it where its close I then tinker with tubes. Of coarse I have different moods and thus a bunch of 1x12 cabs loaded with different speakers too. Bob

[chumbucket]

Hey Crosshair,
The Dual Rectifiers are fixed bias and not adjustable. You would have to get a bias pot installed. They are biased cold from the factory and not known for their smooth distortion. It's gritty,buzzy, and harsh by nature.

[pgissi]

At its worst an improperly adjusted bias sounds like...

a 1979 Silverface Fender Twin with the 135 watts rms output rating (lol) and that terrible Mater Volume Overdrive Pull Pot, simply god awfull. I dont remember the circuit maybe it was the AB763

This amp had one sound very loud and clean to the point of shrill, like an icepick through the cochlea into the brain and there was not a warm distorted or clean tone to be found!

There was no turning this amp up for anything other than pain and turning it up resulted in the most toneless trash you ever heard and you immediatley knew that this was a circuit that was not delivering what the output stage needed let alone any useful tone shaping in the preamp.

This was an amp that even the most courageous dared not to approach but since it was mine, it was my frankenstein and required numerous mods with the most relevant mod to this thread being the factory bias setup which was really just a bias balance setup, was summarily removed and a proper bias circuit was installed which enables me to run it hot or cold. This mod in addition to blackface conversion, independent pre amp and power amp voltage reduction switching, tone and filter cap replacement, speakers, tubes etc., made what was once about 75lbs of waste into something worthy.

PS See the other thread on biasing within this forum