Bottlehead Forum

Bottlehead Kits => Stereomour II => Topic started by: Samsquatch on May 12, 2020, 10:49:30 AM

Title: Hum issue after DC filament upgrade. [resolved]
Post by: Samsquatch on May 12, 2020, 10:49:30 AM

Hello forum,

So after a number of hours I decided to install the DC filament upgrade only because I had the most minimal (almost non-existent) amount of hum after tweaking with the pots. After I installed the upgrade I have more hum that I can't correct out with the pots BUT if I push down in the right hand 12AT7 or on the chassis plate between the two 12AT7s it goes away to nothing. So I know this thing could be dead quiet but don't want to stand there pushing down on the plate. Could this be a cold solder joint at the tube socket? I've cleaned up the 12AT7 tube pins and installed and removed all the tubes a number of times but no change. I'd like to listen to my Stereomour for many more hours before I get to the shunt regulator but I know how quiet it could be first. Thanks in advance.

Title: Re: Hum issue after DC filament upgrade.
Post by: Doc B. on May 12, 2020, 10:54:13 AM

Sounds like a bad ground connection somewhere. Could indeed be a cold solder joint and it's worth reflowing the tube socket connections. Think about what might have been disturbed when you installed the upgrade and inspect/reflow those connections too if the socket connection reflow does not eliminate the noise.

Title: Re: Hum issue after DC filament upgrade.
Post by: Samsquatch on May 13, 2020, 09:37:40 AM

Thanks Doc,

I'll do that and repost with the results.

Cheers

Title: Re: Hum issue after DC filament upgrade.
Post by: Samsquatch on July 29, 2020, 12:02:04 PM

Hi guys,

Had a hold on progress for a bit.

I reflowed the centre lugs on the 12AT7s and the driver and output stage connections. So very quiet now. Honestly, I've been listening too much with the hum that it is now so quiet I'm going to put off the shunt regulator for a couple more months at least. From my slack comes good things haha.