• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

A WE-91B project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
J

jerrylong

Member
Joined 2008
Another OPT is finished
IMG_0760.JPG
IMG_0759.JPG
 
J

jerrylong

Member
Joined 2008
Tonight I finished connecting the circuit and testing. It works, and sounded very good. The voltage of each tube is correct. But massive humming, begin finding the problem. And one more problem, when my hand getting close to the first stage 310A (but not touching it), the humming getting stronger
 
B

Brendanaudio1

Member
Joined 2017
Hi jerry. Very well done so far. I have the very same problem with a valve preamp. I have narrowed it down to a loop, causing the hum. If I run the pre through a isolation transformer, gone. Check your grounding, and try shield the tubes. They are microphonic. This helped me out a lot. Regards
 
J

jerrylong

Member
Joined 2008
Brendanaudio1 said:
Hi jerry. Very well done so far. I have the very same problem with a valve preamp. I have narrowed it down to a loop, causing the hum. If I run the pre through a isolation transformer, gone. Check your grounding, and try shield the tubes. They are microphonic. This helped me out a lot. Regards
Click to expand...

Hi Bren. I will check each stage to find out what causing the hum. I will post the process and help me with that, thanks.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom