2. amps-preamps
  3. 132951-1089

tube bias question

I have a tubed integrated, Lyric, with biasing performed by turning a screw until a left and right green and red led remain lit.  I have each of the tubes (KT150s) biased so each LED remains lit while music in playing, but when no music is playing only the red LED is lit.  What is the correct way to bias, please???  Or should I adjust so both LEDs on each tube remain lit regardless of signal?
rpeluso
gregf1
19 posts
 
I would give Alfred at Hi End Electronics a call or an email, he sells them. I’m sure he will set you straight. If its anything like a VAC PHI 200 amp then the red light should not be on while music is playing. VAC’s instructions are warm amp for at least 10 minutes, mute the preamp then turn bias adjustment until the red light just goes on then back off the adjustment so the red light just goes off. Hope this helps.
rpeluso OP
1,015 posts
 
Thank you, good advice, I bought the unit from Alfred, I will contact him!
gregf1
19 posts
 
No problem. Correction, the red lights should be off with no music and should beat with music on the VAC. I bet Alfred will answer you tonight. 
nitewulf
419 posts
 
@rpeluso,your manual should have this information, or check with Lyric, they are very communicative.  My personal unit (140 mk2) mentions turning the volume all the way down, and there should not be any incoming signals, switching to the bias mode and turning the screw till both LEDs light up.  So I'm not sure if it's a good idea to pass signal through while biasing.  Unless different models have different biasing procedures...
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