The Watering Hole

Finally got motivated to open it up and check the bias.  The volume wasn't matched well between the 6V6 and EL84 tubes and it sounded a bit brittle when turned up.

The 6V6's were 8mV under the value stamped on the board and the EL84s were 3.5 under.  I set the EL84s to 47 mV because they sounded great there and the 6V6 to 42.5 to match the volume.  Slightly warmer than spec. by a couple mV and both sets of tubes sound better now.

My advice, always check the bias asap on a new Chinese built amp...

You know, I haven't even tried that yet, or changed a tube to test that.  I really like the amp.  Guess I need to check this!  

I really like the amp too.  I might not have cracked mine open until re-tube time if there wasn't such a marked difference in volume.

My Spider Valve was so far out it ate one of the tubes in two weeks...

It's easy enough to check the bias.  The power tube pins are partially obscured by a board, so I didn't measure plate current, just trusted the spec and my ears to fine tune.