Konrad00711
Member
- Joined
- May 24, 2016
- Messages
- 35
Hi folks!
I think this is a question for more "amp tech" members
I've just got a 2007 BB Ri, the PCB version. It is fully stock and came with 5881 power valves. I decided to go for KT66s (NOS Gold Lions).
The plate voltage (on pin 3, with KT66s mounted) reads 385V. Kinda small?
I set the KTs at 60%, so 25 / 385 x 0.60 = 0.03896, just 0.039. Kinda high?
So, is it correct? I found the plate voltage with KTs kinda low (it was 407V with 5881s), so the bias is higher. I can't go lower than 37mV with onboard bias pot with KTs.
My main concern is both KTs become physically very hot after like 10 min of working - I didn't check the temperature but I can feel they produce more heat than 5881s pair. Additionally, the plate in both KTs become slightly red. Well, it's nothing like typical, glowing "red plate", but if I watch carefully, the plate become a bit orange/red (didn't saw it with 5881s).
Is it like 66s do that or something's wrong? KT66s in Bluesbreaker is rather popular mod but I feel the voltages are not right here.
I think this is a question for more "amp tech" members
I've just got a 2007 BB Ri, the PCB version. It is fully stock and came with 5881 power valves. I decided to go for KT66s (NOS Gold Lions).
The plate voltage (on pin 3, with KT66s mounted) reads 385V. Kinda small?
I set the KTs at 60%, so 25 / 385 x 0.60 = 0.03896, just 0.039. Kinda high?
So, is it correct? I found the plate voltage with KTs kinda low (it was 407V with 5881s), so the bias is higher. I can't go lower than 37mV with onboard bias pot with KTs.
My main concern is both KTs become physically very hot after like 10 min of working - I didn't check the temperature but I can feel they produce more heat than 5881s pair. Additionally, the plate in both KTs become slightly red. Well, it's nothing like typical, glowing "red plate", but if I watch carefully, the plate become a bit orange/red (didn't saw it with 5881s).
Is it like 66s do that or something's wrong? KT66s in Bluesbreaker is rather popular mod but I feel the voltages are not right here.