16-02-2013, 08:48 AM
Hi Rob,
These just have the normal 2 Rs in the cathodes, as the valves age so the Ia's will change for better or worse.
If it rains here next week as predicted I'll knock up a sig gen with an RS chip that I've had for 20yrs and try unbalancing the toroids by varying amounts, just to see what effect it has. I hand wound a 350VA toroid for PP use (2 x 813) and found that if a small compass was placed on the toroid then a 1mA imbalance could be seen.
What effect this has on the sound I really don't know. However the cct that you sent me doesn't seem to worry about this. I had some small toroids cut with a 1mm slot and then wound, I thought about using these for small class A amps but the L is so low that I'm sure that LF would suffer.
My present amp with EL34s runs about 110mA (per bottle) in class A balanced to +/-1mA quiescent after warm-up.
BRs
mike
These just have the normal 2 Rs in the cathodes, as the valves age so the Ia's will change for better or worse.
If it rains here next week as predicted I'll knock up a sig gen with an RS chip that I've had for 20yrs and try unbalancing the toroids by varying amounts, just to see what effect it has. I hand wound a 350VA toroid for PP use (2 x 813) and found that if a small compass was placed on the toroid then a 1mA imbalance could be seen.
What effect this has on the sound I really don't know. However the cct that you sent me doesn't seem to worry about this. I had some small toroids cut with a 1mm slot and then wound, I thought about using these for small class A amps but the L is so low that I'm sure that LF would suffer.
My present amp with EL34s runs about 110mA (per bottle) in class A balanced to +/-1mA quiescent after warm-up.
BRs
mike
