[santacore]

I just picked up a second hand Lector Zoe tube preamp, and I'm having major noise issues. Immediately upon firing it up I was greeted with a fairly loud of hum/buzz. After checking all connectors and tubes, I decided to try a cheater plug, which instantly killed the noise. This was peculiar since my system is dead quiet and I no issues with any other gear.

So I started playing the unit and enjoying some tunes, when I started hearing random high frequency noise. It's almost like a high pitched(5K+) sweep tone. It seems to come and go a few times a minute. I figured it was a bad set of tubes, so I swapped out a few different sets, none of which solved the problem. Now the Zoe is interesting in that you can use certain 6V and 12V tubes, with the flick of a heater switch. So I tried some 12V varieties and boom, even louder noise.

At this point I'm stumped. I can't tell if it's RF noise or a capacitor of something going bad. The owner mentioned that the HT bypass wasn't working properly, which now makes me wonder if something happened.

Has anyone had similar problems? If so, could you offer any advice as to a potential solution? Thanks!!

[richidoo]

Make sure you have good earth to chassis connection. That could explain why the cheater helped. The tone sound like an oscillation which could be caused by poor grounding of the amp circuit, or unrelated. Maybe there is something simple like a star ground with a loose nut, or a broken solder joint. Just a guess. Good luck.
Rich

[santacore]

Thanks richidoo, I appreciate the input. I'll have to open it up and carefully do a visual check to make things look right.

[tortilladc]

Hi I realize this thread is old but I actually ran into the same problem with my ZOE and was wondering if you solved or were at least able to ID the culprit?