ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

waddaya think about biasing..........


 
4/18/2000 5:40 PM
dale
email
waddaya think about biasing..........
a marshall with 34's at 5ma under the typical 70% point, and how about 10 ma under? i know the tone will not be as good, but how much difference do you really think it makes in a marshall at stage volumes. [4-5 on the master] i biased mine about 6 ma below and didn't notice any diff, and i assure you i have an ear.how far do you think you can typically go before you hear a obvious drop in tone quality? what are your thoughts?  
 
dale
 
4/18/2000 6:25 PM
A.S
email

I think itīs all a matter of taste.  
I usually stay between 14-17W.  
 
A.S
 
4/18/2000 6:32 PM
Liam
email

At risk of flames, I actually prefer them a little cold. That's how they came out of the factory, as it was safe and the tubes lasted ages. Admittedly they don't sound too good at low volume, but since I don't use a 1/2 stack to practise at home I can live with it.  
 
I run my 2203 (485V B+ I seem to remember?) at around 28-30mA per tube at the moment, and it sounds fine to me. That's less than 60% of maximum dissipation. It's not a clean amp, and I like the tone with just a little crossover in there. It's got the nastiness that a rocking Marshall should have. If I wanted a nice MOR rock tone I'd have bought a Boogie.  
 
Having said that, my 1986 gets quite a bit more bias current, normally 32-34 ma, as it seems to prefer it, and I do a few blues gigs so it doesn't always get driven really hard.  
 
So yes, it IS worth experimenting with low bias currents. Marshall did (especially in the chinese tube era), and I think when they're biased really hot they lose the great Marshall tone.  
 
I know people will disagree, it's a matter of taste after all, but you really ought to try it. BTW, the sound stinks at 24 ma, so there's a limit, but it doesn't wear the tubes out!  
 
Liam
 
4/18/2000 7:16 PM
SpeedRacer
email

I agree Liam.. I set my amps in the 30-35mA range in general (that seems to be where I like the mix of touch vs punch).. I know other techs who prefer the 30mA range.  
AFA cross over dist - this will depend on your OT as much as your idle current. Different amps will respond differently here.
 
4/18/2000 7:13 PM
SpeedRacer
email

FWIW..  
As far as biasing, the 70% rule of thumb is a good "max" point to not exceed in the average amp, but it is not a point which will always automatically sound great, or where you should always set the amp. I think it's a misnomer to consider your amp "10 under" etc.  
For me, the best method is to listen and play the amp, and adjust the bias - being careful not to exceed the max bias current - and wherever it sounds the best is where I leave it.  
It's not a "cut & dry" thing IMO, and since it's the sound you're after, the sound should be your guide (within the confines of the applicable physics that is! :-)
 
4/18/2000 7:23 PM
Trace
email

I agree with Speedracer and Liam. I favor 30-35ma in most Marshalls but as Speed said, it depends on the OT as well as the plate voltage.  
 
Trace
 
4/18/2000 8:42 PM
dale
email

"I agree with Speedracer and Liam. I favor 30-35ma in most Marshalls but as Speed said, it depends on the OT as well as the plate voltage."  
 
ok, then how about the tranny in the silver jubilee 50 watter? do you know if it's similar or the same as a regular 800, and with this tranny and EL34LS at 457 volts, what would you consider a low bias setting that won't compromise the tone while being lower than the max so that the tubes will last a bit better?  
 
dale
 
   Page 1 of 2 Next> Last Page>>