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In the Forum: Analog Playback
In the Thread: 7788 tube mic pre design
Post Subject: The 7788 as a driver to drive 2A3?Posted by Romy the Cat on: 11/5/2007
Jim,
It is the super tube – you forgot to mention the amount of noise with its transconductance…. You use the 7788 as a driver to drive 2A3? This is kind of strange: the 7788 has relatively low bias and a typical line voltage should sent 7788 deep into A2 and in clipping. Do you use it with feedback lifting up the bias with signal? You might look for 7721 tube that has the same gain but 1V more on base and generally sound better as a triode-driver, if I am not mistaken I have sent you it the 7721. BTW, in my phonocorrector (Dima’s design) I used 7788 at 150V and input pentode and following tests with voltage variations confirmed that I had better result at 145-160V… Sure, it was the result of my special application and it might not be true in your case.
Rgs, the caT Rerurn to Romy the Cat's Site