proper heater voltage

[pbman1953]

Sunn 2000s-


I was thinking of installing KT-120's in my amp. I was talking to a tube re-seller I've dealt with and he said to check to see if I have 6.3 v on the heaters. To a quick measurement I pulled one tube to measure pins 2 & 7 which came to 3.2 ac volts each individually. Is that enough for the 6550's I have in there now? Should I think of a getting a filament transformer? Is my power transformer not putting out enough?
Would that effect my pre-amp tubes too?


I have KT-120's in my Traynor Yba3 Custom and have installed a new Hammond filament transformer. Before the Hammond I was at 4.5-5 volts and now a strong 6....


Thanks

[sluckey]

Connect one meter probe to pin 2. Connect the other meter probe to pin 7.

[pbman1953]

6.45 volt


Guess I'm all set.


 

[Raybob]

6.45 volt


Guess I'm all set.


 

Only if your PT puts out enough current @ 6.3v to power all the tubes it needs to.

[HotBluePlates]

Only if your PT puts out enough current @ 6.3v to power all the tubes it needs to.

I have KT-120's in my Traynor Yba3 Custom ...

Then why not just put in one KT120 to replace a 6550, measure heater volts, and if still above 6.3vac, put in the other & repeat.  The heater voltage drop (if any) should make it clear whether the amp can support them.