Tube choice

[Andre]

I'm working on an output stage for a DAC and I have two ways to go, one with 5842 tube , the other with 6688 tube !
Soundwise which should I pick ???
Thanks for answering
Andre

[erichayes]

Hi All,

First off, Andre, is the 6688 triode-wired? If it isn't, I'd go with the 5842, which is a civilian version of the Western Electric 417A that has a cult following.

The problem with both of these tubes is that you are absolutely, totally locked in to that type once you're up and running . . . no tube rolling here. I'd rather see a design using the more common twin triodes with the 9A/9AJ style basing such as 12AX7, 6CG7 or even-ugh--6DJ8 (you can always upgrade to a 6922 or 7308 on the latter). That gives you much greater latitude for experimentation.

[Andre]

Thanks Eric, sorry I forgot: Yes the 6688 will be in triode mode !
So can I conclude that I will get better performance with the 6688 ?
When you say "locked with those tubes" , do you mean I will not be able to try other kind of tube without heavy mods? (English is not my primary language, so sometimes...) correct me if I'm wrong but the 7788 and the E810F are drop-in replacement for 6688 ???

Thanks again for your help !
BTW, I cannot tell you why but the 6922 has a bad reputation
(soundwise) in output-stage DAC !

[erichayes]

Hi Andre,

A triode-wired 6688 probably sounds better than a pentode-wired one, but wouldn't necessarily sound better than the 5842. Having never heard either of these tubes, I wouldn't want to guess which is better; I just wanted to make sure you were comparing apples to apples.

Yes, a 7788 has a basing compatable with the 6688, but that's it. And the 5842 won't cross to anything except a WE 417A which are easier to find than lizard fur, but not much.

I'm not surprised to hear about the 6922. It's a much better version of the 6DJ8, but the only member of that family that's reaaly any good in AF is the 7308.

[Andre]

Thanks Eric for your help, you make me laugh with that lizard !
Andre