12AT7 - swap

[angelodp]

I am looking in my RCA manual and I see that a 6DT8 is listed as identical to 12AT7, and very similar to 6AQ8. I am looking for a tube to use in a Radio project and the 6DT8 are said to be = to 6AQ8 in the FM radio application.

Are they all equivalent and could the 6DT8 ( quite cheap ) be used in an amp circuit in place of the 12AT7.

ange

[Phil_S]

I'm always curious about so-called tube equivalence and the search for cheap holy grail tubes. You got me to look in RC-30 and it appears that you are on the mark. It states clearly that 6DT8 is equivalent to 12AT7, with some differences that are not significant. The 6AQ8/ECC85 looks to me to be similar enough that for our purposes it is functionally equivalent. One advantage of the 6AQ8, if you want to go there, is that it has a higher plate voltage rating.

[David Root]

The 6DT8 does not have a humbucking heater, as pin 9 is used for the internal screen. Not a big negative.

I checked audiotubes.com for pricing, 6DT8 is $3.00, 6AQ8 is $15.00.