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previous: R.G. Bias/balance is indeed one way to d... -- 8/7/2000 4:08 PM View Thread

Re: Drift in matching and balance fix?

8/8/2000 7:06 PM
dpcoyle
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Re: Drift in matching and balance fix?
R.G.  
" This gets the DC bias right."  
 
So, are you saying that a truly matched pair of tubes will have the same signal strength at a given AC level (as I was dialing up), AND do it while their DC bias point is the same? Their curves are the same, not just that their curves can be made to cross at one point? (I find the tubes don't match at other levels, which is why I set the level to the one I play at.)  
 
"However, if you twiddle the balance of the AC drive coming out of the PI, you can actually match the AC gains of unmatched tubes."  
 
Will different tubes exhibit similar curves, then?  
 
How do you twiddle? Do you have a continously adjustable way?  
 
I take it you're not reffering to DC balance of the output tubes, here, but to manipulating the load resistors in the PI?  
 
Do you mean shunting a pot across a load esistor of one side of the diff pair, as done in Manley and VTL, and if so, doesn't the pot die pretty quickly from the DC?  
 
Or, do you change load resistors till you get them balanced?  
Thanks,  
Dan

 
Replies:
dutch q{I take it you're not reffering to... -- 8/8/2000 9:07 PM
R.G. q{are you saying that a truly match... -- 8/8/2000 10:16 PM