Bias pots and selector switch

[Samsquatch]

Hi Bottlehead Forum.

I have just begun my Stereomour II build and am just wondering if there is any benefit from upgrading the 10 Ohm pots and the 4 pole 3 position switch. And if so what would the recommendations be?

Thanks in advance!

 

[Paul Birkeland]

The 10 ohm pot is a hum pot (the Stereomour is an auto biasing amp).  There are very, very few choices available that would work well in that position, so I wouldn't recommend changing out that part. 

Some folks have changed out the 4P3T switch for a Goldpoint. 

 

[Samsquatch]

Thanks Paul.

So would the hum pots become obsolete with the DC filament upgrade?

 

[Paul Birkeland]

The DC filament upgrade does not create, ripple free DC, so the humpot is still quite useful. 

The 2A3 filament itself is a 1 ohm resistance that sits across the hum pot and 22 ohm balancing resistors, so this isn't a mission critical part.  With the DC filament upgrade, there are also some big caps in parallel with the 2A3 filament that are even lower impedance than 1 ohm (at most frequencies).