Gents,
I recently purchased my first hifi project - a Scott 222a. I have done alot of tweaking of pro audio gear for micpres, but am having an issue with this unit - still somewhat of a newbie on a hifi amp- prob just lucky with past mods.
Upon getting this amp, it sounded ok but very dark - severely rolled off up top. Went about replacing electrolytics as well as swapping orange drops for important caps. After doing some replacement, I had a horrible 120hz hum mostly out of one channel but not dependant on volume. When balance was centered it often was a thumping sound that seemed to only be a tube problem. Saw some blue lightning in a tube and it corresponded to sound when pot was centered. Swapped tube and phase splitter tubes and still same issue
After encountering this, I removed all new electrolytics and resoldered to old parts making sure hookups were identical - took multiple pics before touching anything. The problem still remained. I did not swap out the 716p's.
I've checked over and over the wiring for the caps I replaced - don't know - could changing coupling caps etc result in a 2xAC hum throughout?
I'm normally accustomed to a 2 tube micpre and haven't discovered this issue before.
Many thanks, Nathan
I recently purchased my first hifi project - a Scott 222a. I have done alot of tweaking of pro audio gear for micpres, but am having an issue with this unit - still somewhat of a newbie on a hifi amp- prob just lucky with past mods.
Upon getting this amp, it sounded ok but very dark - severely rolled off up top. Went about replacing electrolytics as well as swapping orange drops for important caps. After doing some replacement, I had a horrible 120hz hum mostly out of one channel but not dependant on volume. When balance was centered it often was a thumping sound that seemed to only be a tube problem. Saw some blue lightning in a tube and it corresponded to sound when pot was centered. Swapped tube and phase splitter tubes and still same issue
After encountering this, I removed all new electrolytics and resoldered to old parts making sure hookups were identical - took multiple pics before touching anything. The problem still remained. I did not swap out the 716p's.
I've checked over and over the wiring for the caps I replaced - don't know - could changing coupling caps etc result in a 2xAC hum throughout?
I'm normally accustomed to a 2 tube micpre and haven't discovered this issue before.
Many thanks, Nathan