The EL84 and EF86 must be part of the voltage regulator.Maybe somebody that has your unit will have tube rolling ideas for those tubes.It sounds like a nice unit.
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I have a lot of experience rolling tubes in Aesthetix, CAT, Manley and Aria gear with 12ax7, 6922, 12au7, but not the EL84 until I got a Counterpoint SA-2 MC head amp. It had a Sovtek tube in this socket. I tried the Tele EL84 and was vey disappointed. The Mullard too was a disappointment. But when I tried a Valvo, it was magnificent. I was not surprised as Valvo and Amperex have continued to be the winners for me in the 6922 and E182CC tube types.
It's amazing how much a change in a power supply tube can be in terms of dynamics and clarity.
You can easily get one or 2 of these tubes on ebay for $20-30. They might not be new but they could easily last you a couple years and the improvement in performance will truly take you by surprise. It's a killer value.
Thanks for your response. I´m not familiar with DPMC in terms of design/diagram (which I don´t have).
To clarify, power supply (as far as I can see) is a combination of EL84 & EF86 (Svetlana screened for low noise). I also have a volume potentiometer on DPMC for regulating voltage on output.
So yes Hifitime, you seem to know about DPMC or how El84 works.
EL84/EF86 also have to act as a rectifer, cause I only have a bridge diod for rectifying 12 volt DC.
Finally, could sound improve by changing these tubes (or one of them).
Many thanks and have a nice audio weekend!
I have noticed changes in sound when rolling both rectifier and regulator tubes. My Supratek Chenin came with Sovtek 5AR4s, but now I have settled on a Mullard GZ33 as the best for my system. Also I have experimented wth dfferent regulator tubes (Sovtek "5881", NOS Tung-Sol 5881 and Sovtek KT-66) and have settled on the Sovtek KT-66. The combo of the GZ33 and KT-66 is just right for my tastes.