Simplistic NJFET RIAA

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JimT

Member
Joined 2004
Yes the TP measurements are to ground. Thanks for checking this for me. I was worried that the 20Hz reading was too high.

I have some emergency plumbing to do, but hopefully will be able to get this hooked up to a turntable tomorrow afternoon. My wife seems to think that repairing the kitchen plumbing is more important than this.

Getting it from a loose mess on the bench to a nice arrangement in a chassis will take some time yet.

Jim
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
JimT said:
But you did make me realize that that Salas will need to know that my 2SK369's are IDSS 12.04 ma.

Thanks
Jim
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Just verify that your 1kHz test signal is 5mV exactly. Measure it across the phono input when actually loaded, and the phono is running. You could be losing a fraction of test signal. When the out/in dB is verified to the best of your measurement gear ability, there are easy ways we add or subtract the odd dB. Satisfactory inter-channel gain agreement is the first goal.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
JimT said:
Yes the TP measurements are to ground. Thanks for checking this for me. I was worried that the 20Hz reading was too high.

Jim
Click to expand...

When you got 0.42 at 1kHz and 4.43 at 20Hz that is roughly x10 i.e. 20dB more. That is what RIAA is supposed to do when going that low. To know exact numbers it takes more than casual experimental precision of course but your quick spot checks show that your build behaves at it should vs. frequency.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
Its a matter of system synergy. Get a 0.068uF to be in the middle if 0.047 is tight and 0.1 is loose. Most would like the 0.1 with typically non meaty mid-bass modern MC. Koetsus, DL103s, Shelters, will like the 0.047. Euphonic valve preamps with high Z line inputs or big bit loose reflex speakers in smaller than adequate rooms, or cheaper less controlled TTs may like it too. The MM version should stick to 0.1 for circuitry reasons. The C3 thing is mentioned in the guide notes too.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
Quan for example has two very different TTs, vintage idler and high-end modern, with opposite price spectrum and philosophy carts. He could tell if one value is adequate for both and to what extent. Now I mentioned Quan, its sometime we did not hear from him as to what happened with plans of testing FSP on his higher resolution TT.
 
Turbon

Turbon

Member
Joined 2011
Salas said:
Quan for example has two very different TTs, vintage idler and high-end modern, with opposite price spectrum and philosophy carts. He could tell if one value is adequate for both and to what extent. Now I mentioned Quan, its sometime we did not hear from him as to what happened with plans of testing FSP on his higher resolution TT.
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Yes, quan. I remember now. My TT's are vintage so I would appreciate input on it. On the other hand I don't mind rolling some caps to find which I like most:).

Regards
 
Q

quan

Member
Joined 2007
Salas said:
Quan for example has two very different TTs, vintage idler and high-end modern, with opposite price spectrum and philosophy carts. He could tell if one value is adequate for both and to what extent. Now I mentioned Quan, its sometime we did not hear from him as to what happened with plans of testing FSP on his higher resolution TT.
Click to expand...
Thanks Salas. I did have a quick test with my other rig but too brief to make any comment. I have been playing with my vintage rig and it is very good. There is plenty of bass and top end is silky. I have settled with loading of 220R with my modded denon 103(uwe body/ESC retipped).
Quan
 
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