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#76 Re: It's time I built a D3a -> 5687 phonostage

Posted: Sun Feb 26, 2023 6:44 pm
by Max N
A bit late now, but I found a circuit in Sound Practices that uses easy to find valves:
https://worldradiohistory.com/Archive-A ... sue-12.pdf
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#77 Re: It's time I built a D3a -> 5687 phonostage

Posted: Sun Feb 26, 2023 7:38 pm
by IslandPink
Hmmm... looks a bit optimistic, i think te 6DJ8 would be squealing trying to drive a 600 EQ.

#78 Re: It's time I built a D3a -> 5687 phonostage

Posted: Sun Feb 26, 2023 10:25 pm
by Max N
Yes, probably about 200 ohm output impedance.
Could dc couple to a cathode follower, but then I guess we are getting close to Nick’s circuit :D

#79 Re: It's time I built a D3a -> 5687 phonostage

Posted: Mon Feb 27, 2023 8:02 am
by Thermionic Idler
Nick wrote: Sun Feb 26, 2023 10:38 am That's rather adventurous. The paradise was a bjt version of the same idea and certainly sounds good. I think PCB layout will be a big part of the work. I do note that the article suggests that the first stage can drive <600 but that's far from saying that it should. They then load it with a 20k network. But I guess that's partly driven by cap size limits they apply.
Interesting, I didn't realise the Paradise was a transimpedance design, I'll have to go back and look at it further.

The Millett stage is sounding pretty darn good after I fixed it yesterday, so this is going to go on the back burner until the Valve DAC is done. Now to see what parts are unobtanium for that little project...