I thought that this might be of interest as the preamp uses JFETs liberally. This preamp was purchased as new by me. The date stamp on the chassis suggests that it was manufactured in 1984.
The basic circuit block is repeated over and over in every section. A snipet is posted. It looks to me that the basic block is a JFET cascode current mirror followed by a BJT version of a PL B1 buffer.
The basic circuit block is repeated over and over in every section. A snipet is posted. It looks to me that the basic block is a JFET cascode current mirror followed by a BJT version of a PL B1 buffer.
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Interesting! I have an S6020-CP preamp in storage, together with the S6040-CP poweramp.
There is something wrong with the poweramp (1 channel not working) and one day I hope to have time to look at it to see if I can fix it.
I am not sure if I have the full schematic and would appreciate a copy
Cheers,
Albert
There is something wrong with the poweramp (1 channel not working) and one day I hope to have time to look at it to see if I can fix it.
I am not sure if I have the full schematic and would appreciate a copy
Cheers,
Albert
The discrete opamps in the Sherwood preamp look very similar to the old Nikko preamp I have (Beta series). I bought mine used along with a Gamma tuner ~1981 or so. My diy efforts trounce it soundly. I may scoop out its guts and give it a new lease on life if I can clean the volume pot, which is very scratchy these days.
Nice pun. The sliders in the Sherwood are scratchy as well.
My Sherwood pre will serve until I get a proper DIY Pass pre into service.
I never knew that there were JFETs controlling the blocks until I acquired the service manual this week.
Here's one side of the phono preamp from the Nikko Beta II. Unfortunately, the rest of the preamp wasn't treated as meticulously as the phono stage. If that same module had been used throughout, it might have been a real monster. Also, there were lots of electrolytic coupling caps.
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Never mind, I think I found what I was looking for. I stumbled onto an AK thread that made mention of this unit also being sold under the name of Inkel PD2100. A quick search and the schematic is available on the elektrotanya website. It is a good quality scan to boot! Thank you much to 'that person'.
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