Quick Rod bias pot

[ChadVanHalen]

So did my first bias job after some tubes blew and based on plate voltage and seeing Quick Rods should be biased to about 65%, around 32.5 mv (the previous owner had it running around 55, no idea how those tubes lasted 3 years) but I was only able to get it down to something like 36 (I'm at work, can't remember the exact number). I keep turning the pot but it doesn't seem to lower anything... Granted I have it close enough, but is this something anyone else has experienced? Not being able to get their pot to go as far down as they need it?

 

[Chris6870]

I remember Splawns pots have to be turned a lot to get results. Like 10-15 times. I thought mine was broken it reacted so slow.

 

[ChadVanHalen]

I remember Splawns pots have to be turned a lot to get results. Like 10-15 times. I thought mine was broken it reacted so slow.

It was very high/low ratio (whichever means it's super precise and takes a while to move a lot) but there's a point where it just stops lowering the bias. The pot seems like it goes forever but it just stops adjusting on my multimeter

 

[Chris6870]

May just be a hot set of tubes. 36 should be fine unless it sounds bad. I am at 32. Assuming your measuring per tube? 52 would be correct for a pair.

 

[ChadVanHalen]

May just be a hot set of tubes. 36 should be fine unless it sounds bad. I am at 32. Assuming your measuring per tube? 52 would be correct for a pair.

Ya I'm measuring with the Eurotube single tube bias thing... My plate voltage was like 500 or something super hot.

And I figured where it is should be fine, especially coming down from where it was for so long, just thought it was odd

 

[Fragglerick]

I'm having the opposite problem with my QR. The pot will only get up to 30 mv and I like to bias them a little hotter.