School me on EL34/6CA7/KT77

Tom Huff

Tom Huff

New member
I'm looking for an answer to a question but would also like to see some dialog from people about their likes and dislikes and why.
I'm curious, are EL34, 6CA7 and KT77 tubes all interchangeable as long as you bias your amp when replacing?
What are the advantages and disadvantages of each type? Are there pitfalls as far as reliability or stuff like that associated with each?
What brands of each would you use?

Thanks!

-Tom
 
Re: School me on EL34/6CA7/KT77

yes they are all interchangeable because they are basically the same tube. 6ca7 is the american version of the el34. not sure where the kt77 name came from but its basically the same tube. im not sure there is much of a difference currently besides the names and bottle shapes. that doesnt mean that a jj el34 and an eh 6ca7 are going to sound the same though
 
Re: School me on EL34/6CA7/KT77

+1, but the 6CA7 were of two different types. One was a regular European EL34 in the long skinny bottles simply labelled with the American 6CA7 designation. The other is the Big Bottle 6CA7, that has been described as more 6L6 (or some say 6550) guts, but with a EL34 pin out and voltage and bias specs. This tube is associated with early EVH.

The original KT-77 was by GEC as a more heavy duty, beam tretrode, version of the EL34 pentode. The bottle looked about the same and it biased the same, and basically sounded the same. It may have a bit more clean headroom and more bottom. The modern JJ E34L is also a beam tetrode version, as well as their modern KT-77 re-issue.
 
Re: School me on EL34/6CA7/KT77

Trivia: KT stands for Kinkless Tetrode.

edit: deleted that last bit because I'm not sure it was correct.
 
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Re: School me on EL34/6CA7/KT77

The KT77 is almost like an EL34/6L6 hybrid. It has the big lows, chimy highs, and pulled back mids but still has a little bit of the EL34 aggressiveness to it.
 
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