Simplistic NJFET RIAA

Jump to Latest
#3,141
Not that important, but...
Take a DVM, set for max VAC, probes (forget colour) on pin 2 and 3 of the Xfrm: you get something around 225-235 VAC. That is Vin
BE CAREFUL! High Voltage! Don't short anything!

Then set the DVM for 200 VAC, probes on pin 6 and 7 and you get the Vout

Assuming you've wired the Xfrm as per the drawing you attached.

P.S. the Preamp should be on

P.P.S. you have now two shunt regs connected to one Xfrm, right? Thus total I should be around 2 * 200 mA or so....
 
Last edited:
#3,145
Yes, and maybe he wants to know where it goes when the secondaries go series like its needed here. You know Italians, always never worried about top performance in gear and chicks. Ducati, Ferrari, Monica Bellucci etc. :c_flag:🙂 Always about compromising are those guys...😀
 
#3,148
Seems the only way to get the perfection nothing to do with compromising.

I love Ferrari+Alonso, any kind of pasta, pizza, italian coffe (please no other like the expresso), capuccino, Monica Belluci too. I visit Italy several times & I enjoyed other fine things like carpaccio, grana padano, funghi porcini & many other delicatessen, don't forget fashion are the best. The bad thing is traffic when goes more to the south more bad, Milan seems perfect when you drive in Rome, butwhen you drive in Napols or Reggio Calabria you live in other dimension.
 
#3,154
Actually I prefer the two critters as in Merlin's if a cart is 0.4-0.5mV. Because it can go 59dB without Rs bypass capacitor and is more linear without the doubling of Ciss for 4 critters. Now if you think of the gain needed and noise for 0.2mV carts asking for 4, 2 critters are at least the same hiss for 59dB. I believe that the CCT I posted for Guglielmo is very good compromise. Not ultimate. Just adequate compromise of simple, nice, and tweakable. For ultimate I don't know, Italians know.😀
 
#3,157
I was thinking that the 4 critters front end should be good above all for noise, then for gain. Even in the mid gain 36 V version...
Rs bypass: I'd rather avoid it anyway.
Ciss isn't lowered enough by cascoding the 2 or 4 critters? Input capacitance is very important for MM, less for MC AFAIK.

Merlin, moussakà is very good indeed, but is probably not the very best in Greek cusine!
 
#3,158
Ciss is lowering by cascoding but not vanishing. Also 20mA is harder on the BJT than 10mA. 4 are best when the signal level is half normal MC so the THD is still the same. 2 critters is a good midway for better noise on 0.4mV carts and still not overcooking. 4 would unnecessarily push the gain and bring the 3dB noise gain back to equal-, plus a bit more THD. Less is more, don't forget. Merlin skips the Rs noise and goes higher gain. The bypass cap is not compromising as much as you may think by the way. The secret is in fine tuning the Riaa values and components quality there.

P.S. Good report on using 1.2 regs on MC phono. Not for a starter DIYer, and rather complex though. Link.
 
You must log in or register to reply here.
Top Bottom