Simplistic NJFET RIAA

Hello,
I've red all the forum and I'very interested but I've seen too many schematics.
Anybody can help me?
Which is the las tfet riaa and shunt schematic?
May be with buffer stage, I need less then 10k of output impedence to mach with optivol volume control.
Anyone have a pcb available?
Sorry for too many questions but I arrived a bit to late.
Ciao
Guglielmo
 
Hi Salas,

I am collecting parts to built your RIAA, based on your original schematic with 56 db gain. My cartridge is a Shelter 901 with about 0.5 mV output.
You think this is the best choice? It will drive a 10K pot followed by a JC buffer. Also the recomended loading is 100R. I tried different values before but did not like them. Should I try something higher with your RIAA?

Regards
George
 
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Hi George,

You will need a buffered version so to drive the 10k pot successfully. You can try 510R too for loading.

Regards
 

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guglielmope said:
Hello Salas,
I've an old Ortofon OM10 that have 0,1mV output and may be in the future a Denon DL103.
Thanks a lot
Guglilemo

You will need 68dB for the Ortofon or 62dB for the DL103 for proper dynamics. I suggest you to make this I attach, and use a 10X step up transformer. Much preferably without separate box or extra interconnects. Incorporated inside the phono. There are 2 PCBs compatible with it presented here. One by Ikoflexer and one by Kent. Browse back.

guglielmope said:
Only another question: fets must be selected?
Where can I find how?
Guglielmo

It goes without saying, selected and matched. Please read the thread carefully.

Regards
 

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vgeorge said:
Salas thanks!

May I assume that if I use a 50K pot I can use your original schematic or it is still better what you have suggested?
I have a 50k pot I can try with my buffer. Maybe it will work fine. Also thinking to built a B1 to go with it.


Regards
George

The buffer type in the Riaa proved almost transparent. I would use it so to be flexible. If settling over 50k, only then, when really familiar, bypass it and compare. B1 I am the one who presented it capacitor-less in the Pass thread. I am familiar. If you look back in this thread, I have shown how to incorporate one directly on the phono tail, without coupling caps. Don't make another box with another interconnect set and PSU, if it is intended only for the phono. Only losses and much more extra money you will achieve.
 
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vgeorge said:
Thanks once more.
I will stick to your last schematic then. It is better to have a little bit more flexibility to change through differenet preamps.
I have most of the russian capacitors and I missing some resistors and a zener for the shunt. Half of the power supply with a CLC is ready. Will post some pictures when ready.

George

We will be glad to learn about your progress. Good luck.
 
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guglielmope said:
And in your mind which is the best regulator for your design?
Guglielmo

Maybe Ikoflexer's buffered Mosfet driver tweak can be subjectively different, I am not in a position to directly know. The standard 28V LED shunt that Rcruz made, he reported it dead silent. That is all I can personally know.