Simplistic NJFET RIAA

[Salas]

Originally Posted by massimo

I need an help from you, guys.
Before ordering all the parts I need and designing a suitable RIAA pcb, I would like to ask Salas, Ricardo, Disco and others their findings about the right capacitors.

> C out (3.3uF): the suggested type seems to be Obbligato Premium copper or gold. Good sound, nice price I read.
Did anybody try Mundorf Supreme which is more or less in the same price category?

> C 4 (0.1uF): here a huge russian teflon cap (ft-2 or ft-3) seems mandatory. Not expensive and very transparent you reported.
Again, did anybody try an alternative? Obbligato, Mundorf, etc.? What about smaller polypropylene film & foil?
I have some nice old blue Ero KP 1838/63V 2.5% that might fit.

> RIAA Caps (47 & 16 nF) most of you suggest some bulky russian silver mica. Are those really different (read better) from the modern dipped ones? And what about polypropylene film & foil such as the tiny green Wima FKP2 or even Teflon? Not easy to find in the right value, but it's always possible to // them and get the desired values.
I have a lot of FKP2/63V 2.5%, but even some 1% capacitors branded "Madrigal" (most probably teflon) pulled out from and old ML No.25 cannibalized board.
As far as polystyrene, I don't like them too much. They are now cheap and unrealiable. Unfortunately the good silver axial ones manufactured by Philips are no longer available. Not to mention the ps film & copper foil caps manufactured by the Japanese company known for the Noble pots that Hiraga was using many years ago in his Kaneda preamp! Absolutely unobtainable nowadays.

Contibutions highly welcomed!

Teflon is superior in the interstage coupling position. I have tried polypropylene and stacked polysterene there also. PP film & foil I haven't tried.

Those huge micas are better than modern little micas. But if you can find modern pp film & foil its a good alternative. Has to work synergistically with the interstage. You cook. If small and good the layout gets tighter and that is a plus.

Polysterene old is good, modern I am not sure. What about RCL polysterene?

[nicoch58]

for what I read..... modern RT (not rtx)polystirene is the best "cheap" alternative to modern teflon .
silver/mica is more brigth vs poly , but only read......need the Cruz certificate tester

[Salas]

The big Soviet MIL SPEC NOS lacks the brightness. That's good, but its huge for layout. What I do sometimes, is pp//MilSM small value.

[RCruz]

I tryed polystyrenes in 16nF but silver micas are much faster and cleaner there.

[disco]

Guys, before making comparisons on capacitors based on taste and under varying conditions, I'd like to point to this very well written text. It has a scientific nature but it reads easily. Pay attention to the explication of self-resonance on page 6.
Regards, Jaap.

[Salas]

Got a DL 103R. Fortunately says 0.32mV on its individual spec sheet. Not 0.25mV as advertised. Even better. That is for 47k though. Does any body know where the audiophiles tend to usually load it? I would think that 150 Ohm is the minimum since it has 14 Ohm coils.

[nicoch58]

wow good shot salas


I use 180 for my 5ohm , standard is 100 for 5r

[Salas]

So 1:20 minimum you suggest. Then I will have to use min 14:5=2.8*100=280R. Ok will do when ready. 1:36 you use for your 5 Ohm leads me to 504R. A good bracket.

[nicoch58]

some put copper (alu) plate , or copper ring
between arm and cartridge ,and nylon washer

[Tham]

Salas, ready to build my 2nd Simplistic RIAA with recommended parts . Found some Russian silver mica at 15,720pF on eBay. Is that value sufficient or need to // with another 280pF (or about) for exactly 16nF? Will FT-3 be better than FT-2 as inter stage cap?