It's time I built a D3a -> 5687 phonostage

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

Post 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
Page 46
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IslandPink
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#77 Re: It's time I built a D3a -> 5687 phonostage

Post by IslandPink »

Hmmm... looks a bit optimistic, i think te 6DJ8 would be squealing trying to drive a 600 EQ.
"Once you find out ... the Circumstances ; then you can go out"
Max N
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#78 Re: It's time I built a D3a -> 5687 phonostage

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

Post 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...
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
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