01-08-2016, 08:21 PM
(01-08-2016, 06:02 PM)valves4amps Wrote: Hi Trevor, my experience with guitar amps has shown that DC supplies for heaters in output valves serves no purpose. In the preamp yes hum noise contributed in the high gain section can be considerable if not engineered right. Remember the output valves are trying create current gain to derive power in the O/P tx. Noise created from the heaters is so low as to be neglible, more hum in O/P stages occurs when the valves are out of balance.
I would convert the output valve heaters back to AC and save on hassle.
Dave.
Hi Dave.
Yes one of the first things to be done, the stupidity is the outputs are only running on 4.5 volts and the heaters are noticeably dull. It's ridiculous that the customer has actually paid £1500 for this job, it went back twice then the "repairer" disappeared.
The trade was full of cowboys years ago and I actually thought that things had improved but I now wonder.
I'm going to start stripping the rubbish out this week and make a start rebuilding it next week.
