How to tell vacuum tube is gone bad??


I recently purchased primaluna prologue 3 and I connect with dynaudio bm6a.

First I saw is lights of three vacuum tubes are dim and

other lights of three vacuum tubes are bright.

Among 6, 1 of vacuum tube has little soot on wall.

When I connect output-2 with bm6a speaker (active speaker), the volume is very low even I tune max volume.

When I connect output-1 with the speaker, the volume is loud enough with 1/3 of preamp volume.

Are these symptom indicated bad vacuum tubes?

Any other way to check vacuum tube??
chunkichunky

Showing 1 response by tls49


The Primaluna Prologue 3 has 2 sets of pre outs labeled 1 and 2. Is the problem actually output 1 and output 2, or is the problem a difference between L and R outputs?