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Old 20th February 2009, 02:05 PM   #1081
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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
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Old 20th February 2009, 02:45 PM   #1082
Salas is offline Salas  Greece
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Depends on your cartridge. Let us know more about it.
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Old 20th February 2009, 03:38 PM   #1083
vgeorge is offline vgeorge  Greece
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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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Old 20th February 2009, 04:21 PM   #1084
Salas is offline Salas  Greece
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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.

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File Type: gif 56db&buf.gif (6.1 KB, 448 views)
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Old 20th February 2009, 04:24 PM   #1085
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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
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Old 20th February 2009, 04:26 PM   #1086
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Only another question: fets must be selected?
Where can I find how?
Guglielmo
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Old 20th February 2009, 04:39 PM   #1087
vgeorge is offline vgeorge  Greece
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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
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Old 20th February 2009, 04:42 PM   #1088
Salas is offline Salas  Greece
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Quote:
Originally posted by guglielmope
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.

Quote:
Originally posted by guglielmope
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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File Type: gif step-in.gif (6.9 KB, 433 views)
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Old 20th February 2009, 04:49 PM   #1089
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And I can use the shunt of post 961?
Grazie
Guglielmo
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Old 20th February 2009, 04:50 PM   #1090
Salas is offline Salas  Greece
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Quote:
Originally posted by vgeorge
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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