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Thursday, July 7, 2016

The Ultimate Phono Stage - Part 1

Hi!

In posts about the ultimate line preamplifier I already mentioned a few times that a companion phono stage is planned.




In the meantime the work on this piece has begun.




It is based on the EC8020 differential phono preamplifier which I built earlier this year. It shares the same fully differential circuit topology and of course uses the marvellous Telefunken EC8020 triodes. Like the ultimate line preamp it will get loaded with plenty of silver goodies:




20 silver transformers and chokes!

The chassis layout uses the same arrangement as the copper version:




This time gold anodised plates seemed appropriate. The underside of the top plate:




The tubes plugged in:




Fully differential circuits are a big topic this year. After the differential line stage and phono, I started a scaled down version of the differential phono with D3a tubes and this one will be my ultimate statement in phono preampfification.




It will be just a matter of time until a matching power amp will follow.




Stay tuned for updates.

Best regards

Thomas

6 comments:

  1. Hello Thomas,

    I'm eager to read your impressions of the ultimate differential phono after some listening.. =) I like the gold anodized top plate, understated and not blingy or gaudy at all.. You did build a full DHT phono once IIRC. I'm curious if you will pursue doing DHT phono stages again, and how they will compare to the SE EC8020 LCR versions..

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    1. Hi Rick, I will report when the unit is finished. Yes I built 3 DHT phonos so far. For practicality and lower maintenance I prefer IDHTs like D3a or EC8020 for phono. The DHT phonos I built were very low gain so everything in the system needs to be carefully matched. DHTs in the phono are of course very prone to microphonics and need careful selection and probably exchange after some time. The DHT phonos do have a certain magic which is revealing. But my newest generation phono with IDHTs and especially the differential ones are better to my taste and are more universally usable

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    2. Thanks Thomas, for elucidating the pros and cons and system dependence context.. So next up after this, maybe differential PP 45 or 300B amps.. =)

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  2. Thomas... looks like it will be another show stopper...(and sound like one too.) Can't express how much I enjoy your blog. A guilty pleasure, stereo pornography. Sadly, unless I win the lottery, or fall into a major inheritance, I could never afford such a thing. Perhaps someday one of your more affordable kits.

    However, I'm curious, your first differential phono amp had 28 transformers and chokes and this one only 20? Why the difference? Did you refine the circuit?

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    1. Hi!
      This circuit uses 28 chokes and transformers as well. Only 20 of them are silver. There are 8 more which are not in the signal path, which are copper wound

      Thomas

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    2. Thanks for the clarification Thomas! A large part of what makes your blog so great is your generosity in sharing the details of your work.

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