Problem with buzzing noise in my THX 789 amp

[Fai9al023]

I'm having the exact same issue with my 789, except the random noise comes from the right channel. To be clear, this issue would only be frustrating to people like me with actual OCD lol

With that being said, I think I found what's causing the problem!
I remembered that I had an issue with a previous amp and it was clear that my phone was causing the interference. I have my phone on a wireless charger pretty close to the 789, so I tried to take it off the charger and placed it a meter away from the amp. I waited for five minutes trying to hear the noise again, and it was gone! I then placed my phone once again on the charger (I don't think the charger has anything to do with it, it's just that the phone is close to the amp), and I heard the noise straight away! I kept the phone there and heard the noise again like two minutes later.

I'm pretty sure this is what's causing the problem, but I'll keep trying the same thing for an extended period this time and I'll report back!

 

[Fai9al023]

I'm having the exact same issue with my 789, except the random noise comes from the right channel. To be clear, this issue would only be frustrating to people like me with actual OCD lol

With that being said, I think I found what's causing the problem!
I remembered that I had an issue with a previous amp and it was clear that my phone was causing the interference. I have my phone on a wireless charger pretty close to the 789, so I tried to take it off the charger and placed it a meter away from the amp. I waited for five minutes trying to hear the noise again, and it was gone! I then placed my phone once again on the charger (I don't think the charger has anything to do with it, it's just that the phone is close to the amp), and I heard the noise straight away! I kept the phone there and heard the noise again like two minutes later.

I'm pretty sure this is what's causing the problem, but I'll keep trying the same thing for an extended period this time and I'll report back!

I just did another test where I kept my phone away from the amp for five minutes, and I heard no noise at all. I then placed the phone exactly where it was near the amp without the wireless charger this time, and a couple of seconds later I heard the noise!

I'm 100% sure that's what's causing the problem so I just moved the my phone and charger to the opposite end of the table. For reference, my setup is the 789 + Modi 3 with only the 789 connected to a power outlet. Also, the noise was heard even without the Modi 3 connected to the 789, and you can hear it on gain 1 with the volume pot at the minimum with nothing playing as Schackmannen said.

I'll post again if the issue somehow arises once again. I hope this helps out anyone with the same issue

 

[KenG]

I just did another test where I kept my phone away from the amp for five minutes, and I heard no noise at all. I then placed the phone exactly where it was near the amp without the wireless charger this time, and a couple of seconds later I heard the noise!

I'm 100% sure that's what's causing the problem so I just moved the my phone and charger to the opposite end of the table. For reference, my setup is the 789 + Modi 3 with only the 789 connected to a power outlet. Also, the noise was heard even without the Modi 3 connected to the 789, and you can hear it on gain 1 with the volume pot at the minimum with nothing playing as Schackmannen said.

I'll post again if the issue somehow arises once again. I hope this helps out anyone with the same issue

This is very helpful. I've had the 789 Amp for about a year and a half and only noticed the slight buzz/interference since the spring. After reading your response, I noticed the wireless phone charger that I use right in front of the amp that I happened to purchase....this past spring. Problem solved!