6BG6 for KT66

[exurbia]

Is the 6BG6 a direct sub for the KT66 ? My Riders tube sub book doesn't give an answer to this one.
TIA,
Peter.

 

[ErikdeBest]

Hi Peter

As far as my memory goes, the 6BG6 is an octal version of the 6L6 with a different pinout and a topcap. That makes it a sister of the 807, which I know has been succesfully implemented in Quad 2 amplifiers, which originally employed KT66's. So, it should work, but lets wait what others have to say about it!

Erik

 

[Eli Duttman]

It depends on the vintage. In this case, "recent" is better. The last bunch of 6BG6s made have 6L6GC innards. Older samples can't safely dissipate as much power.

If you get newer production 6BG6 stock, they are quite suitable (electrically) as KT66 substitutes.

Look here for more details.

 

[exurbia]

thanks for the help with this one, i have a pair of old williamson amps that run kt66's.
i have quite a stock of "old" 6BG6G's which is why i asked the question.
What if i drop the HT by a couple of volts would that cut the plate dissipation by enough?

 

[Johan Potgieter]

Yea, nothing to really add to what Eli has said, except that 6L6 is a very generic term. It was such a successful design that the structure has not really been changed over decades, except for increasing power handling capacity by larger anode area, layered material and improved electrode mounting. Thus one got a 6L6 and 807 (Pa=19W), 6L6GB and 5881 (23W), 6L6GC (30W) and 7027 (35W)

6L6 characteristics are within tube manufacture spread (10%) of KT66, but heater current 40% less. (I notice Russian KT66s use 6L6 innards anyway.)

Eli has given the full picture. (And for myself, for 6BG6 I rather rewired than use the cumbersome adapter.)