JTM45 KT66 Upgrade

Dax · Post by **Dax** » Sat Jan 22, 2005 3:15 pm

I read somewhere that if you upgrade to KT66's you have to add "Swamp Resistors" Is this just Linking Pins 5 of each tube socket with a 1.5K resistor?

Flames1950 · Post by **Flames1950** » Sat Jan 22, 2005 3:54 pm

When I tried KT66's in my '78 50 watt I didn't add swampers. Just had to use a 100K bias resistor in place of the 47K that was for EL34's.

Billy Batz · Post by **Billy Batz** » Sat Jan 22, 2005 8:44 pm

About what range is the bias with KT66s Flames? I have a 50k pot there and Im wonderin if thats enough even with the 47k with a range of 47k to 97k but I doubt it.

Flames1950 · Post by **Flames1950** » Sun Jan 23, 2005 9:05 am

I doubt you'll make it either. I had the 100K inline with the standard 25K bias pot, and it seemed like they biased almost at the extreme upper end of that range. A 50K proably would have put me in the middle of the bias pot's range.