COUNTERPOINT HYBRID PHONO STAGE UPGRADE


This is my first post, but I am well acquainted with this forum. I have recently imported a SA 5000 from a member and I am very impressed with the build quality, and performance of the line stage. It is a vast improvement over my modified SA 3. I have both service and owner's manuals, and the documentation is equally impressive, and worth the asking price.
I intend to do some of the Alta Vista upgrades, and would like to remove the JFET and inductor from the cathode circuit of the phono 1st gain stage as a starting point, and replace with a resistor, using the low gain common-cathode triode option for MM cartridge only.
I have no philosophical objection to hybrid circuitry, and I guess that Mike Elliot would have used the ARC SP11/15 as a reference for his own designs. Tube purists may have scoffed at the hybrid ARC products, but the people who make a living out of reviewing them, raved about it.
However, the Alta Vista upgrades for the SA 5000 and SA 9 involves removing the SS buffers and cathode JFETs, and associated circuitry. Any assistance in providing feedback and guidance on tackling these mods would be greatly appreciated.
Thanks in advance.


ozdiyer

Showing 4 responses by ozdiyer

Thanks nap,
I agree that the phono stage is noisy, that is not the only problem. I need to change the 47K loading for my Garrott Decca cartridge, and whilst I am doing that do some tweaking. I live in Australia in a rural situation, and was hoping that someone would be able to provide instructions or pix, so I can do the mods myself. 

Thanks guys, I have all the Alta Vista upgrades stuff and will try swapping the JFET with a cathode resistor . 

I have 4- NOS Amperex 6922 gold pin 1972 made in Holland. I am going to fit Keystone micro- jacks on the jack board so I can swap resistors to get the right loading for the Decca cartridge. I also have schematic for the SA 5, that could be an option after I remove the JFET and upgrade the coupling caps to Dynamicaps. I don't use the phono all that much since I am getting incredible sound from digital after upgrading the CD player and DAC last year. I had a Koetsu red MC , but I prefer the Garrott- Decca Gold which is in a class of its own, but needs careful set up.