The techs at PurePower were awesome, and they're in Canada, so they worked on thanksgiving! We narrowed it down to a safety ground loop. The unit is fine, as is my VAC. Seems this safety ground cannot legally be disabled, so I'm counting on my electrician to at least separate the safety grounds for each circuit so they don't bleed over. What remains a mystery is how this hum got into the signal path... Any ideas?
VAC Preamp: Is my Phono stage failing?
My VAC Standard LE preamp is exhibiting a loud, strange hum, heard in both speakers equally when MC Phono is selected. However, the hum doesn't show up until about 10 minutes of normal sounding LP playback. It gets louder with volume.
I think it may have to do with the unit getting to a certain temperature, since it starts the process over again if I turn everything off for 30 minutes – quiet for 10 minutes or so, then Wham! a loud hum that has me diving for the mute button!
If I switch the selector to any other setting, such as CD... dead silence. Could it be a phono tube going bad, and if so, how is it in both channels?
Any ideas (aside from calling Kevin, which I will do)?
I think it may have to do with the unit getting to a certain temperature, since it starts the process over again if I turn everything off for 30 minutes – quiet for 10 minutes or so, then Wham! a loud hum that has me diving for the mute button!
If I switch the selector to any other setting, such as CD... dead silence. Could it be a phono tube going bad, and if so, how is it in both channels?
Any ideas (aside from calling Kevin, which I will do)?