Simplistic NJFET RIAA

[Salas]

IMD is satisfying too.

[Salas]

And the frequency response (RIAA).

[Salas]

Of course the cartridge rules the THD and the disc the noise...
Here is what it does with the Denon DL-160 on a Technics SL1200MK2.

[Salas]

So the above FFT indicates that we may typically expect 1% THD, and 60dB dynamic range for surface noise and rumble, in a logically well sorted out set up. Not necessarily very expensive. That is for a new stylus and good tracking geometry. Also for a silent non worn out disc.

[nicoch58]

Salas

[Thomo]

Hi guys, great thread.

Salas, I am thinking of building the version you posted above for use with a MM cartridge (a Grado Prestige Gold).

Is there a specific reason that C5 & C6 are 330uF?

Could these be safely changed to 220uF? I only ask as I have many 220uF caps I could use. I'm a bit of a noob at phono-stage design, but am willing to learn, but I think I understand the basics.

Thanks in advance,

Lee.

[RCruz]

Hi Lee

Great to have you involved.

[Salas]

Originally posted by Thomo
Hi guys, great thread.

Salas, I am thinking of building the version you posted above for use with a MM cartridge (a Grado Prestige Gold).

Is there a specific reason that C5 & C6 are 330uF?

Could these be safely changed to 220uF? I only ask as I have many 220uF caps I could use. I'm a bit of a noob at phono-stage design, but am willing to learn, but I think I understand the basics.

Thanks in advance,

Lee.

Hi Lee,

As I have practically completed my cascode experiments that I will soon subjectively evaluate more and present, (but for a higher sensitivity), I have modified the 36dB schematic for your requirements, including what I have learned as better in practice. The local bypass cap goes. A local current sourced stabilizer does better job than the divider, using an 8.2V 1W zener and one non matched leftover FET. You can still use the divider instead for simplicity (not the best performance), but without any shunt cap over it's lower resistor, it audibly intrudes.

P.S. The answer to your original question about the bypass cap value, is that the bigger the better. The more the dynamic PSU resistance, the bigger cap decouples lower and better. Best would be a Blackgate non polar 1000uF. But we gracefully avoid such components with the new base bias scheme.

[RCruz]

Originally posted by salas


I have modified the 36dB schematic for your requirements, including what I have learned as better in practice. The local bypass cap goes. A local current sourced stabilizer does better job than the divider, using an 8.2V 1W zener and one non matched leftover FET. You can still use the divider instead for simplicity (not the best performance), but without any shunt cap over it's lower resistor, it audibly intrudes.

Hi Salas

I am now building a PSU for your design on post 166: http://www.diyaudio.com/forums/showt...46#post1628846

After reading your last post, I wonder if these best practices are aplicable in my case and should bring improvements ?

Sorry for the question but I still can not grasp all the concepts with ease.

Ricardo

[Salas]

Hi RCruz,

No, you have a different case. You have a Benz Clear high MC. The MM guys need avoid the input capacitance and need lower sensitivity. The cascode is a necessity for them. It adds more sensitivity to PSU, gets more complex, and yet has to persuade me for any sonic advantages in this kind of phono concept. You need the original circuit you aim at.