20-07-2015, 07:46 PM
(This post was last modified: 20-07-2015, 07:54 PM by Murphyv310.)
Hi Ref .
Ideally you need separate triodes with each heater fed from an isolated heater winding. Feeding them with a smooth DC supply will help as will letting them float.
I see you still have a problem. As you say it could be smoothing but also check the output stages are properly biased and balanced.
I've built many high power amps and learned lots of tricks to reduce hum. One thing that works well is to feed the heaters on the first preamp from the output valves cathodes, very effective.
Ideally you need separate triodes with each heater fed from an isolated heater winding. Feeding them with a smooth DC supply will help as will letting them float.
I see you still have a problem. As you say it could be smoothing but also check the output stages are properly biased and balanced.
I've built many high power amps and learned lots of tricks to reduce hum. One thing that works well is to feed the heaters on the first preamp from the output valves cathodes, very effective.
